8^ 
 
 attfata, Slew loth 
 
 BOUGHT WITH THE INCOME OF THE 
 
 SAGE ENDOWMENT FUND 
 
 THE GIFT OF 
 
 HENRY W. SAGE 
 
 1891 
 
M' 
 
 V^l 
 
 Cornell University 
 Library 
 
 The original of tiiis book is in 
 the Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924012167734 
 
THE LABYRINTH 
 
THE LABYRINTH 
 
 AN AID TO THE STUDY OF INFLAMMA- 
 TIONS OF THE INTERNAL 
 EAR 
 
 By 
 ALFRED BRAUN, M.D. and ISIDORE FRIESNER, M.D. 
 
 (NEW YORK) (NEW YORK) 
 
 With Fifty Figures in the Text and 
 Thirty-four Half Tones on Twenty-four Plates 
 
 m 
 
 NEW YORK 
 
 REBMAN COMPANY 
 
 Herald Square Building 
 
 141-145 West 36th Street 
 
A.57^SU 
 
 All rights reserved 
 
FOREWORD 
 
 A -work on the labyrinth, at a time when this subject 
 oeoupies the centre of interest in the otological world, 
 requires no apology. 
 
 Although our knowledge of the subject of labyrin- 
 thine inflammations is still in the developmental stage, 
 and opinions which we hold to-day may be contro- 
 verted to-morrow, yet, in order to have a groundwork 
 upon which to base our further study of this fascinat- 
 ing subject, it is necessary for us all to become familiar 
 with those basic truths regarding labyrinthine disease, 
 which have thus far been established beyond doubt. 
 
 These truths we have attempted to present in our 
 book. On those topics, regarding which there is still 
 considerable difference of opinion, we have made no 
 attempt to state all the opinions, since this would only 
 lead to confusion in the readers' minds. We have con- 
 fined ourselves to those hypotheses which seemed most 
 plausible to us. 
 
 In the bibliography, we have made no attempt to 
 mention every work which has been written on this 
 subject, but have referred only to those publications 
 which were used in the preparation of this work. 
 
 The illustrations, made by one of us, are original, 
 with the exception of a few which are modified from 
 other illustrations. 
 
 We wish to thank Dr. Wendell C. Phillips and 
 Dr. T. Passmore Berens for the opportunity they have 
 given us to study cases of labyrinthine disease in their 
 
b THE LABYEINTH 
 
 clinics, and for their helpful suggestions in the prep- 
 aration of the book. Our thanks are due to our col- 
 league, Dr. J. J. Thomson, for his kind criticism and 
 painstaking care in reviewing the manuscript. 
 
 To the Eebman Company our thanks are also due 
 for their liberality and care in producing this book. 
 
 Alfebd Beaun, M.D., Isujoee Fbiesnee, M.D, 
 New Toek Citt. 
 
CONTENTS 
 CHAPTEE I 
 
 ANATOMY 
 
 Bony static labyrinth — ^vestibule and semicircular canals — 
 surgical relations — membranous static labyrinth — saccule, 
 utricle and semicircular canals, canalis reuniens, ductus 
 and saccus endolymphaticus — microscopical anatomy of 
 end-organs, maculae and cristse — ^bony cochlea, modiolus, 
 lamina spiralis ossea, etc. — surgical relations — ^the scales, 
 aqueduetus cochleae, ductus cochlearis — ^microscopical anat- 
 omy of Organ of Corti — ^the eighth nerve and its central 
 connections, vestibular nuclei, etc. — ^pathways through 
 which the movements of nystagmus are intermediated — 
 pathways of the reaction movements 13 
 
 CHAPTEE II 
 
 PHTSIOLOGT 
 
 Static labyrinth an organ for the establishment of body 
 equilibrium — ^manner in which end-organs perform their 
 function — theory of efEect of endolymph movements upon 
 the cristse — ^nystagmus — reaction movements — turning sen- 
 sation — ^nausea and vomiting — ^physiology of cerebellum — 
 physiology of cochlea — ^theories of hearing .... 53 
 
 CHAPTEE III 
 
 METHODS OF EXAMINATION- 
 
 Determination of presence or absence of signs and symptoms 
 indicating change in the normal impulses from static laby- 
 rinth — determination of condition of static labyrinth'by 
 observation of certain reflexes elicited by physiological stim- 
 ulation of end-organs in semicircular canals — ^rotation 
 test — caloric test — fistula test — pointing test, etc. — ^tests 
 for hearing — ^voice, whistle, tuning-forks — noise apparatus. 88 
 
y THE LABYBINTH 
 
 CHAPTBE IV 
 PATHOLOGY 
 
 Description of various patkologieal types of labyrintMne in- 
 flammation — ^pathways of infection — ^metastatic cases — 
 paralabyrinthitis, perilabyrinthitis, endolabyrinthitis, etc. — 
 Final results of labyrinthine inflammation .... 153 
 
 CHAPTEE V 
 
 SYMPTOMS OP LABYKINTHITIS 
 
 Cochlea— subjectiTe noises and deafness — static labyrinths- 
 veri;igo, disturbances in balance, nystagmus, nausea and 
 Tomiting— causes of these phenomena— rdiscussion of vari- 
 ous symptoms— clinical types of labyrinthitis — ^value of 
 functional tests in differentiating these typesr-»^ifferentia- 
 ation betweeji labyrinthitis and other affections -which cause 
 similar symptoms^-hysteria, disease of the eighth nerve, 
 meningitis, and cerebellar abscess and tumor . . . .179 
 
 CHAPTEE VI 
 
 TEEATMENT OF LABYKINTHITIS 
 
 Consideration of the indication^ in the various types of laby- 
 rinthitis — ^non-operative treatment — operative treatment of 
 middle-ear spaces alone — operative treatment of middle- 
 ear spaces combined with, the labyrinth operation — ^types 
 of labyrinth operation, Hinsberg's, Eichard's, Jansen's and 
 Neumann's — technique of operations — after-treatment . 305 
 
LIST OF ILLUSTEATIONS 
 
 FIGUBE PA6B 
 
 4. Planes of the three semicircular canals 16 
 
 5. Planes of the three semicircular canals, with positions of their 
 
 ampuUee 18 
 
 11. Entire bony and membranous labjrrinth from behind. Right 
 
 ear ( schematic) 22 
 
 13. Posterior surface of temporal bone, showing saccus endolym- 
 
 phaticus and aqueductus cochlese 25 
 
 14. Cross-section of crista ampullaris (schematic) 26 
 
 15. Cross-section of ma«ula acustica (schematic) 27 
 
 16. Section across basal whorl of cochlea 30 
 
 17. Section of organ of Corti (schematic) 35 
 
 18. Central connections of cochlear nerve (Modified after Lewan- 
 
 dowsky) 42 
 
 19. Nuclei of eighth nerve (schematic) 44 
 
 20. Tracts involved in nystagmus 47 
 
 21. Tracts connecting cerebellum with spinal cord, mid-brain and 
 
 cerebrum, showing pathways involved in reaction movements. 49 
 
 22. Pathways of nerve impulses to and from cerebellar cortex. ... 51 
 
 23. Diagrams illustrating portions of the cochlea showing degenera- 
 
 tive changes in Siebenmann's experiments with guinea-pigs, 
 exposed to the continuous sound of a tuning fork 86 
 
 24. Rotation of body to left, with head upright 94 
 
 25. After-nystagmus which occurs on stopping, after rotation to the 
 
 left 94 
 
 26. Plane of external semicircular canal, with head vertical, and 
 
 with head tilted 30° forward 97 
 
 27. After-nystagmus to the left, following rotation to the right . . 97 
 
 28. Eight external semicircular canal is non-functionating. Rota- 
 
 tion to left causes short after-nystagmus to right 98 
 
 29. Right external semicircular canal is non-functionating. Rota- 
 
 tion to right causes long after-nystagmus to left 98 
 
 30. 101 
 
 31. Representation of planes of vertical semicircular canals 102 
 
 32. Planes of vertical canals, with head tilted 90° forward 102 
 
 33. Planes of vertical canals with head tilted 90° forward, and 
 
 face turned to right shoulder 103 
 
 34. Right superior and left posterior canals in horizontal plane, 
 
 with head 90° forward, and face turned to right shoulder. 
 After-nystagmus to right, following rotation of body to left. 103 
 
 35. Position of head same as in preceding diagram. Rotatory after- 
 
 nystagmus to left, following rotation of body to right 104 
 
 36. Right superior canal is non-functionating. Long rotatory 
 
 after-nystagmus to left follows rotation of the body to the 
 right 105 
 
10 THE LABYBINTH 
 
 FIGURE PAGE 
 
 37. Eight superior canal is non-functionating. Short rotatory 
 
 after-nystagmus to the right follows rotation of the body to 
 the left 105 
 
 38. Planes of vertical canals with head tilted 90° forward, and face 
 
 turned to left shoulder 106 
 
 39. Right posterior and left superior canals in horizontal canals 
 
 in horizontal plane, with head 90° forward, and face turned 
 to left shoulder. Rotatory after-nystagmus to right, follow- 
 ing rotation of body to left 106 
 
 40. Rotatory after-nystagmus to left, following rotation to right. . 107 
 
 41. Right posterior canal is non-functionating Long after-nystag- 
 
 mus to left, following rotation of body to right 107 
 
 42. Right posterior canal is non-functionating. Short after-nystag- 
 
 mus to right, following rotation of body to left 108 
 
 43. Planes of vertical canals, with head tilted 90° backward 108 
 
 44. Planes of vertical canals with head tilted 90° backward, and 
 
 face turned toward the right shoulder 109 
 
 45. Head bent 90° backward, and face turned toward the right 
 
 shoulder. Rotatory after-nystagmus to the left, following 
 rotation to the left. Nystagmus elicited principally by left 
 posterior canal 109 
 
 46. Rotatory after-nystagmus to right, following rotation to right. 
 
 Nystagmus elicited principally by right superior canal.... 110 
 
 47. Planes of vertical canals with head tilted 90° backward, and 
 
 face turned toward the left shoulder 110 
 
 48. Head bent 90° backward, and face turned toward left shoulder. 
 
 Rotatory after-nystagmus to left, following rotation to left. 
 Nystagmus elicited chiefly by left superior canal Ill 
 
 49. Rotatory after-nystagmus to the right, following rotation to the 
 
 right. Nystagmus elicited chiefly by right posterior canal. . Ill 
 
 50. Relations of semicircular canals to tympanic cavity 116 
 
 51. Right superior canal, showing direction of endolymph flow and 
 
 nystagmus in caloric test 117 
 
 52. Diagram illustrating the influence which endolymph current in 
 
 superior canal exerts on endolymph in posterior canal, as re- 
 sult of common limb 117 
 
 53. Diagram showing direction of endolymph current and nystag- 
 
 mus in caloric test on right external canal 118 
 
 64. Optimum position for caloric test on external semicircular 
 
 canal 119 
 
 55. Briinings' oblique optimum position for the right external 
 
 semicircular Canal 120 
 
 58. Positions of external canal in pessimum position, straight opti- 
 mum position and oblique optimum position for caloric test. 121 
 
 57. Briinings' otocalorimeter 124 
 
 58. BrUnings' otogoniometer 125 
 
 59. Diagram illustrating Ewald's experiment on pigeon with pneu- 
 
 matic hammer 136 
 
LIST OF PLATES 
 
 PLATE MG. PAGE 
 
 I. 1. Coronal Section of Vestibule of Left Ear, Showing 
 
 Openings of Semicircular Canals 14 
 
 I. 2. Outer Wall of Vestibule (Right Ear) 15 
 
 II. 3. Inner Wall of Vestibule of Bight Ear, and Begin- 
 ning of Cochlea 16 
 
 III. 6. Horizontal Section of Left Temporal Bone, Through 
 
 Middle of Vestibule (Lower half) 19 
 
 IV. 7. Horizontal Section of Left Temporal Bone, Through 
 
 Middle of Vestibule (Upper half) 19 
 
 V. 8. Dissection of Left Temporal Bone, From Above.... 19 
 
 VI. 9. Bissection of Semicircular Canals Prom Behind 
 
 (Right Ear) 20 
 
 VII. 10. Radical Mastoid Operation — Cochlea and Semicircu- 
 lar Canals Opened (Right Ear) 21 
 
 VIII. 12. Horizontal Section of Internal Ear 23 
 
 IX. 60. Diffuse Serous Labyrinthitis 153 
 
 X. 61. Diffuse Sero-Fibrinous Labyrinthitis 153 
 
 XI. 62. Chronic Purulent Otitis Media 156 
 
 XII. 63. Fistula in External Semicircular Canal 157 
 
 XIII. 64. Chronic Purulent Labyrinthitis 164 
 
 XIV. 65. Diffuse Purulent Labyrinthitis 165 
 
 XV. 66. Chronic Diffuse Purulent Labyrinthitis 166 
 
 XVI. 67. Complete Atrophy of Corti's Organ and Spiral 
 
 Ganglion 172 
 
 XVII. 68. Diffuse Suppurative Labyrinthitis with Beginning 
 
 Organization 173 
 
 XVIII. 69. Chronic Suppurative Labyrinthitis which has Healed 173 
 XIX. 70. Empyema of Saccus Endolymphaticus Resulting in 
 Interdural Abscess, Sinus Thrombosis and Cerebel- 
 lar Abscess 176 
 
 XX. 71. Hinsberg's Operation on the Labyrinth 217 
 
 XXI. 72. Richards' Operation on the Labyrinth 220 
 
 XXII. 73. Richards' Operation on the Labyrinth 221 
 
 XXIII. 74. Richards' Operation on the Labyrinth 225 
 
 XXIII. 75. Richards' Operation on the Labyrinth 228 
 
 XXIV. 76. Richards' Operation on the Labyrinth 228 
 
 XXV. 77. Richards' Operation on the Labyrinth 229 
 
 XXVI. 78. Richards' Operation on the Labyrinth 229 
 
 XXVII. 79. Jansen-Neumann Operation on the Labyrinth 231 
 
 XXVIII. 80. Jansen-Neumann Operation 232 
 
 XXIX. 81. Jansen-Neumann Operation 232 
 
 XXX. 82. Jansen-Neumann Operation 232 
 
 XXXI. 83. Jansen-Neumann Operation 233 
 
 XXXII. 84. Neumann Operation 233 
 
CHAPTEE I 
 ANATOMY 
 
 The internal ear consists of a membranous labyrinth 
 enclosed in a bony capsule. It comprises the vestibule, 
 the three semicircular canals, and the cochlea. 
 
 THE STATIC LABYRINTH 
 
 The bony static labyrinth consists of a vestibule, 
 and three semicircular canals. The vestibule 
 is situated between the cochlea in front, and the semi- 
 circular canals behind. It lies partly internal to the 
 upper posterior portion of the middle-ear cavity, and 
 partly internal to the aditus. 
 
 It is separated from the middle-ear cavity by the 
 horizontal portion of the facial canal, and by the foot- 
 plate of the stapes, which fills in the oval window. In- 
 ternally, it is separated by a very thin plate of bone 
 from the internal auditory canal. It is separated from 
 ihe cochlea, in front, by a dense plate of bone, which 
 contains the first portion of the facial canal. Thus it is 
 seen that the vestibule is surrounded on two sides by 
 the facial canal, namely, on its anterior and outer sides. 
 This explains the frequent involvement of the facial 
 nei^e in labyrinthine disease. Posteriorly, the vesti- 
 bule is bounded by a thick layer of compact bone. 
 
 The vestibule can be entered, surgically, from two 
 directions, antero-externally, through the oval window, 
 and postero-externally, through the solid-angle between 
 the semicircular canals. 
 
14 THE LABYEINTH 
 
 The roof, floor, anterior and posterior walls of the 
 vestibule, correspond approximately in position to the 
 roof, floor, anterior and posterior walls of the fundus of 
 the internal auditory canal. The roof and the -floor of 
 the vestibule correspond, also, approximately, in posi- 
 tion, to the upper and lower margins of the oval 
 window. 
 
 The vestibule is roughly ovoid in shape, measuring, 
 according to Politzer, 5 to 6 mm. in length, 3 to 4 mm. in 
 width, and 4 to 5 mm. in height. Its capacity is about 
 one minim. 
 
 It is usually described as having six sides, but this is 
 more or less arbitrary, as the sides merge into each 
 other imperceptibly. 
 
 The vestibule has opening into it the five ends of 
 the three semicircular canals, namely, the superior, 
 the posterior, and the external. Each canal has 
 a large or ampuUated extremity and a smaU extremity. 
 Each of the ampullated extremities opens separately 
 into the vestibule. The small ends of the superior and 
 posterior canals join before entering the vestibule, and 
 the small end of the external canal has a separate 
 opening. 
 
 If the vestibule is bisected by a frontal cut, aU of the 
 openings of the semicircular canals can be seen in the 
 posterior half. From above downwards the openings 
 are as follows (Fig. 1, Plate I) : 
 
 1. The ampullated end of the superior canal. 
 
 2. The ampullated end of the external canal. 
 
 3. The common opening of the superior and pos- 
 terior canals. 
 
 4. The small end of the external canal. 
 
PLATE I. 
 
 I AC 
 C 
 
 Fj(i. 1 
 CoROXAL Section of \i:stiijule uf I.kft ]->ai!. Siiowinc Dpemmis of 
 Semioikculai! Cakals 
 (I^ooking at posterior half from in front) 
 311^ — iliddle ear C — Coiiinion (jinl of superior and 
 
 7^-1 C' — Internal ainlitory eannl jiosterinr i-anals 
 
 •S'-i — Ampullaled end of superior /■; — Small end of external eanal 
 
 canal PA — Ampullated enil of i)u^,tei'ior 
 
 EA — Ampullated end of external i-anal 
 
 eanal 
 
 cv 
 
 sv 
 
 LS 
 
 Si 
 AL 
 
 PC 
 
 Fu;. 2 
 
 OfTEK \\'ai.i. of \ESTTiii:LE (Risht Ear) 
 
 Ht — Foot-plate of stapes in oval /S'l' — liesinning of scala \estiljuli 
 
 window //.S' — Beginning' of lamina s])iralis 
 
 AL — Annular ligament I'O — Ampullated eiul of posterior 
 
 C'V — Beginning of crista vestibuli semicircular- canal 
 
ANATOMY 15 
 
 5. The ampuUated end of the posterior canal. 
 
 The opening of the ampuUated end of the superior 
 canal lies at the junction of the roof with the posterior 
 wall of the vestihule. The opening of the ampuUated 
 end of the external or horizontal canal lies just below 
 and to the outer side of the ampuUated end of the su- 
 perior canal. The common opening of the superior and 
 posterior canals lies at about the middle of the junction 
 of the posterior with the internal walls of the vestibule. 
 The opening of the small end of the external canal lies 
 at the lower part of the junction of the posterior and 
 outer walls of the vestibule. The ampuUated end of the 
 posterior canal lies in the floor of the vestibule. 
 
 The inner wall of the vestibule presents two shallow 
 depressions separated by an oblique ridge, called the 
 crista vestibuli. (Fig. 2, Plate I.) This ridge 
 begins on the outer vestibular wall above the oval win- 
 dow, and runs from above and in front, downwards and 
 backwards. The two shallow depressions are the re- 
 cessus sphericus, which is situated in front of and below 
 the ridge, and the recessus ellipticus, which is situated 
 above and behind it. The recessus sphericus lodges 
 the saccule, and the recessus ellipticus, the utricle. 
 
 The inner wall also contains, in the recessus ellipti- 
 cus, just behind the crista vestibuli, a small foramen, 
 the vestibular opening of the aqueductus vestibuli, 
 which lodges the ductus endolymphaticus. It also con- 
 tains a number of minute foramina, the maculae cribro- 
 sae, which transmit the fibres of the vestibular nerve. 
 There are three sets of these foramina, the macula 
 cribrosa superior, for the transmission of the 
 utricular and the superior and external ampuUary 
 
16 
 
 THE LABTBINTH 
 
 nerves; the macula cribrosa media, for the 
 
 transmission of the saccular nerve ; and the macula 
 cribrosa posterior, for the transmi&sion bf the 
 posterior ampiillary nerve. 
 
 The outer wall of the vestibule contains the oval 
 window, which is filled in by the foot-plate of the Stapes, 
 surrounded by its annular ligament. 
 
 At the junction of the floor with the anterior wall of 
 the vestibule is the opening into the cochlea. The ves-- 
 tibule communicates, at this point, with the upper divi- 
 sion of the cochlea, the scala vestibuli. The be- 
 ginning of the bony lamina spiralis of the cochlea is 
 situated on the floor of the vestibule. (Fig. 3, Plate 11.) 
 The bony lamina spiralis, together with the membrana 
 basilaris, shut off the scala tympani from the vestibule. 
 
 The bony semicircular canals are three in number. 
 They are situated in the three planes of space, each at 
 right angles to the other two. (Fig. 4.) There are two 
 
 Fig- 4. 
 ItASTEs OF THE Three Seuicibotilab CAifALS, MoDiixEa> Aiteb Ewalo 
 
 ■vertical canals, the anterior vertical Or superior, 
 and the posterior vertical or posterior. The re- 
 maining canal is horizontal, and ia usually called the 
 
PLATE II. 
 
 HE 
 
 ST 
 
 Fig. 3 
 IxNEK ^^'ALI. OF Vestibule of I'ictit Eai 
 
 RS 
 
 SV 
 LS 
 
 ItE — Kec('ss\is cllipticus 
 
 (V — Cristii vestihuli 
 
 /I'X — Ri.'ii'ssiis sphorirnis 
 
 .sT — Scahi ve.^liliuli of coohk'a 
 
 AXD r)Ei;lNKXING OF COCIII.EA 
 
 LU'yinniiif;' of lamina spiralis, 
 sliowing its origin in iloor 
 of vestibule 
 
 iST — Seala tynipani of cochlea 
 
 A'lr — Round window 
 
ANATOMY 17 
 
 external. It is best to call the canals, superior, 
 posterior and external. The two vertical canals are 
 sometimes called by the Germans, the frontal and 
 sagittal canals. But these are not good terms, for the 
 planes of these canals are not frontal nor sagittal, but 
 form with these planes an angle of about 45°. 
 
 Schoenemann, from a large number of corrosion 
 specimens, has come to the conclusion that the planes of 
 the canals, as well as the angles between them, are very 
 inconstant. The external canal is rarely horizontal. 
 Its plane is tilted downward and backward, and forms 
 with the horizontal plane an angle varying from 0° to 
 30°. This fact is important in interpreting the results 
 of functional examination of the static labyrinth. 
 
 The angle which the plane of the superior canal 
 makes with the medial plane varies between 30° and 
 65°. There may be a difference of 20° between the 
 right and left sides. The angle between the superior 
 and external canals varies between 65° and 90°. The 
 angle between the external and posterior canals is most 
 constant, varying from 90° to 100°, being usually 90°. 
 
 The superior canal of the right side is parallel to the 
 posterior canal of the left, and the superior canal of the 
 left side is parallel to the posterior canal of the right. 
 (Fig. 5.) 
 
 Each semicircular canal comprises about two-thirds 
 of the circumference of a circle, the diameter of which 
 is 7 to 8 mm. They are elliptical on cross-section, and 
 each canal has a slight enlargement at one end, called 
 the ampulla. The canals are a little over 1 mm in di- 
 ameter. The ampullae are about 2% mm in diameter. 
 Both ends of each semicircular canal open into the ves- 
 
18 THE LABYEINTH 
 
 tibule. The narrow ends of tlie superior and posterior 
 canals join before they reach the vestibule, into which 
 they open by means of a common limb. The ampulla of 
 the superior canal lies at its outer end. The ampulla 
 of the external canal lies at its anterior end. The am- 
 pulla of the posterior canal lies at its lower end. The 
 ampuUated ends of all three canals lie nearer to the 
 middle ear than do the small ends. (Fig. 5.) 
 
 Fig. 5 
 
 Planes of the Three Semicirculab Canals, With Positions of 
 Their Ampulla;. 
 Interior of Skull, looking down from above 
 8 — Superior semicircular canal H — External semicircular canal 
 
 P — Posterior semicircular canal T — Tympanic canity 
 
 The middle portion of the external semi- 
 circular canal lies exposed in the attic and aditus. 
 It forms a prominence on the inner wall of the attic and 
 aditus, lying just above and behind the facial nerve, as 
 it curves above and behind the oval window. In this 
 situation, the external semicircular canal is very apt to 
 be eroded by a suppurative process in the middle ear. 
 
PLATE III. 
 
 c 
 
 I AC 
 
 V 
 PA 
 
 AV 
 E 
 
 Fig. 
 
 HciuizoNTAL Section of Left 'J'emporal Bone, Tiirovgh Middle of 
 Vestibule (Lower half) 
 
 CG — Carotid canal 
 
 ET — Bony portion of Eustachian 
 
 tube 
 T — Tympanic cavity 
 i<S' — Beginning of lamina spiralis 
 EAC — External auditory canal 
 FC — Facial canal 
 MA — Mastoid antrum 
 C— Cochlea 
 
 7.-IC — Internal auditory canal 
 
 V — Vestibule 
 
 ]'A — Ampullated end of posterior 
 semicircular canal, in 
 floor of vestibule 
 
 AY — Aqueductus vestibuli 
 
 E — Small end of external semicir- 
 cular canal 
 
 /' — Posterior seniicirculai' canal 
 
PLATE IV. 
 
 cc 
 
 c 
 
 I AC 
 
 V 
 
 SA 
 
 EA 
 C 
 
 ET 
 
 FC 
 EAC 
 
 E 
 
 MA 
 
 Fig. 7 
 
 HoRizoMAL ,Sectio>" OF Left Temporal Boxe, Through Middle of 
 Vestibule (Upper half) 
 
 CC— CarnticI canal 
 
 C — Coflilca 
 
 lAC — liiU'iiial auditory canal 
 
 V — Upper half of vestibule 
 
 /SM — Ampullated end of superior 
 
 canal 
 Eji — Ampullated end of external 
 
 canal 
 C — Conjnion end of superior and 
 
 posterior canals 
 
 P — Small end of posterior canal, 
 befoie it joins superior 
 canal 
 
 ET — ]3ony portion of Eustachian 
 tube 
 
 7' — Tympanic cavity 
 
 FC — Facial canal 
 
 EAC — External auditory canal 
 
 /■; — External semicircular canal 
 
 ilA — Jlastoid antrum 
 
PLATE ^' 
 
 cc 
 
 FC 
 T 
 
 SA 
 E 
 
 r 
 
 I AC 
 
 Fui. 8 
 
 DissECTiuix OF Left Temporal Bone, Fkoh Above 
 
 JJony seiiiieirciilar Ciinals arc dissected out, and cochlea, internal audi- 
 tory canal and bcijinninn; of facial canal uncovered 
 
 CC — Carotid canal 
 
 ]'C — Facial canal 
 
 7' — Tvmyianic cavitv 
 
 ,SM — Solid ansle 
 
 Jj — External scniirireular canal 
 
 C — Portion of cochlea 
 I AC — Internal auditory canal 
 <S' — Superior semicircular canal 
 P — Posterior semicircular canal 
 
ANATOMY 
 
 19 
 
 and, as a matter of fact, this is the most common situa- 
 tion for a labyrinthine fistula. 
 
 The external semicircular canal is a guide in per- 
 forming the simple mastoid operation, the radical mas- 
 toid, and in opening the vestibule. 
 
 In the simple mastoid operation, exposure of the ex- 
 ternal semicircular canal shows that the aditus has 
 been reached. This marks the limit of the operation in 
 that direction. In the radical mastoid operation, the 
 external semicircular canal acts as a guide in deter- 
 mining how far it is safe to take down the posterior 
 wall of the external auditory canal, without endanger- 
 ing the facial nerve, as the external semicircular canal 
 projects outward slightly beyond the level of the facial 
 nerve. 
 
 In opening the vestibule, the external semicircular 
 canal acts as a guide, by marking the anterior limit of 
 the bony excavation. If the chisel-cut passes in front 
 of this canal, the facial nerve will be injured. 
 
 Injury of a normal external semicircular canal dur- 
 ing the performance of a simple mastoid or radical 
 operation is almost impossible, as it is covered by very 
 dense hard bone. Yet occasionally it does occur. 
 
 The superior semicircular canal lies in a 
 plane forming an angle of about 45° to the sagittal 
 plane, passing from behind, outward and forward, the 
 ampullated end being external and in front, and the 
 inner and posterior end joining with the posterior canal 
 to form the common limb. (Fig. 6, Plate III; Fig. 7, 
 Plate IV; Fig. 8, Plate V.) 
 
 The superior canal forms a prominence on the upper 
 surface of the petrous bone, called the emlnentla 
 
20 THE LABYEINTH 
 
 arcuata, beneath which, on the posterior surface of 
 the bone, is a fossa, known as the fossa snbarcuata. 
 This lies a short distance above and to the outer side 
 of the internal auditory meatus. It served, in the fetus, 
 to transmit a large vein from the interior of the 
 petrous bone. The prominence on the upper surface of 
 the bone corresponds in shape to, but does not always 
 actually represent the superior semicircular canal, in- 
 asmuch as the canal is frequently separated from the 
 surface by a layer of cancellous bone, which is some- 
 times as much as a millimeter in thickness. 
 
 The superior canal is the furthest of the three from 
 the mastoid antrum, and is the most difficult to reach 
 in doing the labyrinth operation. The dangers in open- 
 ing the superior canal are the possibility of injuring 
 the dura of the middle fossa, the possibility of injuring 
 the superior petrosal sinus, and the possibility of in- 
 juring the facial nerve, as it winds around the anterior 
 extremity of the canal. 
 
 The posterior semicircular canal lies very 
 close to the inner table of the posterior fossa, its con- 
 vexity corresponding to a point on thei posterior sur- 
 face of the petrous bone, about half way between the 
 inner opening of the aqueductus vestibuli and the inner 
 margin of the groove for the sigmoid sinus. Its plane 
 is parallel to the posterior surface of the petrous bone. 
 It reaches down as low as the level of the round win- 
 dow. Its lower limb lies over the jugular bulb, and just 
 internal to the descending portion of the facial nerve 
 (Fig. 9, Plate VI). Its upper limb joins the superior 
 canal, to form the common limb, and the lower ampul- 
 lated end opens into the floor of the vestibule. 
 
PLATE VI . 
 
 sc 
 
 CL 
 
 lAC 
 
 A 
 
 HA 
 EC 
 
 !'(■ 
 
 FC 
 
 APC 
 
 JF 
 
 Fig. (I 
 
 Dissection of Sejiicircilai! Canals From Beiiixi) (TaoiiT Ear). 
 iS'C — Superior semicircular canal .1 — Aditus 
 
 CL — Coimuon limb of superior and 
 posterior canals 
 
 V — Vestilfule, showing foot plate 
 of stapes and beginning; of 
 scala vestibuli of eoclilea 
 
 lAC — Internal auditoiv canal 
 
 iV.l — Solid angle 
 
 AT' — External semicircular canal 
 
 J'fJ — Posterior semicircular canal 
 
 FC — Facial canal 
 
 AI'C — Ampullated end of post. 
 
 seni. canal 
 •//' — Tugulai' fossa 
 
PLATE VII. 
 
 ss 
 
 ES 
 
 P,s' 
 
 TT 
 
 ET 
 
 FR RW V C 
 
 Fig. 10 
 
 Radical Mastoid Oi'eratiox — Cochlea and Sejiicircular Canals 
 Opened (Right Ear) 
 
 <S'.S' — Su|]orior st'iuicircvilar canal 
 A'*V — External seinioirciilar canal 
 /*iS' — Posterior semicircular canal 
 FR — Ridge containing facial nerve 
 RW — Round window 
 V — Vestibule 
 
 ( 
 
 IJasal wliorl of cochlea. The 
 second and beginning of 
 tlie third whorls are 
 opened, but not marked 
 
 TT — Groove for tensor tympani 
 tendon 
 
 FT — Tympanic orifice of Eustach- 
 ian tube 
 
ANATOMY 21 
 
 The danger in opening the posterior canal consists 
 in the possibility of injuring the cerebellar dura, the 
 facial nerve, and the jugular bulb. 
 
 The angle between the three semicircular canals is 
 composed of cancellous tissue, and is called the solid- 
 an^le. (Fig. 10, Plate VII.) By removing the bone 
 in the solid-angle the vestibule can be entered from its 
 posterior outer side. 
 
 The bony labyrinth consists of a layer of dense ivory- 
 like bone, 2 to 3 mm. in thickness, which in the fetus 
 and the new-born reaches the surface of the petrous 
 bone in many places. In the adult, this capsule is cov- 
 ered over by spongy bone, and shows only at the 
 promontory, the external semicircular canal, and, 
 sometimes, at the superior canal. This dense bony 
 structure is called the labyrinthine capsule. 
 In chronic necrotic processes, the spongy bone about 
 the labyrinthine capsule may be destroyed, and the 
 whole or a large part of the labyrinth may be exfoliated 
 as a single sequestrum. 
 
 The membranous static labyrinth lies within the 
 bony labyrinth, to which it is attached by fibrous bands. 
 It has, roughly, the same shape as the bony labyrinth. 
 
 The membranous labyrinth constitutes a closed 
 fibrous tissue sac, which is not in communication with 
 the endocranial lymph spaces. The fluid within the mem- 
 branous labyrinth passes through the ductus endo- 
 lymphaticus into the saccus endclsmipliati- 
 cus, which is a closed sac, lying between two layers of 
 the dura, on the posterior surface of the petrous bone. 
 
 However, the space outside of the membranous laby- 
 rinth, between the membranous and bony labyrinths. 
 
.J 
 
 22 
 
 THE LABYEINTH 
 
 which contains the perilympli, is in direct commu 
 nication with the subarachnoid space, through the 
 aqueductus cochleae, and the lymph spaces in 
 the internal auditory canal. 
 
 The membranous portion of the static labyrinth con- 
 sists of two sacs, the utricle and the saccule, the canalis 
 utriculo-saccularis, the ductus and saccus endolymph- 
 aticus, the canalis reuniens, and the three membranous 
 semicircular canals and their ampullae. (Fig. 11.) 
 
 Fig. 11 
 
 Entire Bony and Membranous Labyrinth From Behind. Eight Eab 
 
 ( Schematic ) 
 The membranous labyrinth is drawn in solid black 
 
 Sac — Saccule 
 
 MH — Macula sacculi 
 
 lUr — Utricle 
 
 Uu — Macula utriculi lying i 
 
 cessus utriculi 
 07? — Canalis reuniens 
 AG — Aqueductvis cochleae 
 c'isterna perilymphatica ves-J.F — Aqueductus vestibuli 
 tibuli ^S — Ductus endolymphaticus 
 
 HB — Saccus endolymphaticus 
 
 C — Cochlea 
 
 iS — Superior semicircular canal 
 
 P — Posterior semicircular canal 
 
 E — External semicircular canal 
 
 A.M.F — Ampulla of superior canal 
 
 Or — Crista ampullaris 
 
 /S't — Stapes in oval window 
 
 CPY ■ 
 
 The utricle and saccule are two membranous 
 sacs which lie within the bony vestibule. The utricle, 
 the larger of the two, lies above and behind, in the re- 
 
PLATE VIII. 
 
 FSr MC CP St S C 1 
 
 CO 
 
 IISG C'rll 
 
 u 
 
 MS 
 
 T7\" 
 
 CX 
 
 Fig. 12 
 
 Horizontal Section of Inteknal Ear 
 
 CO — Coclilea V — Ut ricle 
 
 T — Tviiipaiiie cavity ilV — Macula utriculi 
 
 L — IJyaiiient of foot-plate of USC — External semicircular 
 
 stapes canal 
 
 8t — Foot-plate of stapes lying in CvH — Crista of external seniicir- 
 
 oval window enlar canal 
 
 CP — Cisterna pcrilynipliatica ves- FN — Facial nerve 
 
 tibnli YN — Vestilnilar nerve lying in in- 
 
 &' — Saccule ternal auditory canal 
 
 M8 — Macula saceuli CS' — Cochlear nerve 
 
ANATOMY 23 
 
 cessus ellipticus, and the saccule, the smaller of the 
 two, lies in front and below, in the recessus sphericus. 
 
 The utricle is an irregularly shaped sac, into which 
 the three membranous semicircular canals open, by 
 five openings. It is attached at its upper and inner 
 surfaces to the bony vestibule. In its upper and an- 
 terior portion there is a pouch, called the recessus 
 utriculi, which contains the nerve end-organ, the 
 macula utriculi. 
 
 The saccule is oval in shape, with its long axis verti- 
 cal. It is attached to the inner wall of the bony vesti- 
 bule. It has two openings, one above and one below, 
 the upper leading to the canalis utriculo-saccularis, and 
 the lower to the canalis reuniens. It contains a macule 
 analogous to that in the utricle. The space between the 
 outer walls of the utricle and saccule, and the outer wall 
 of the bony vestibule, is filled with perilymph, and is 
 called the cisterna periljaupliatica vesti- 
 buli. (Fig. 12, Plate VIII.) 
 
 The two maculae, according to Breuer, lie in planes 
 at right angles to each other. The macule of the utricle 
 lies on the antero-lateral aspect of the recessus utriculi, 
 its base being turned to the cisterna perilymphatica. 
 The macula sacculi lies on the medial wall of the 
 saccule, against the bony inner wall of the vestibule. 
 
 According to Breuer the otoliths of the macula utric- 
 uli glide horizontally, from behind and external, in a 
 direction forward and inward ; while the otoliths of the 
 macula sacculi glide vertically, from above and behind, 
 in a direction downward and forward. 
 
 The saccule is connected to the ductus cochlearis, or 
 membranous cochlea, by means of a short narrow canal, 
 
24 THE LABYBINTH 
 
 the canalis reuniens. The saccule and utricle are joined 
 together by a narrow canal, the canalis utriculo-saccu- 
 laris, consisting of two limbs, which, by their junction, 
 form another canal, the ductus endolymphaticus. The 
 ductus endolymphaticus enters the aqueductus vesti- 
 buli through an opening on the inner vestibular wall, 
 and, passing in a direction backwards and outwards, 
 emerges through an opening on the posterior surface 
 of the petrous bone, midway between the internal audi- 
 tory meatus, and the inner edge of the groove for the 
 sigmoid sinus. Here the ductus endolymphaticus 
 spreads out into a sac-like expansion, the saccus endo- 
 lymphaticus, which lies between two layers of the dura. 
 The tip of the saccus endolymphaticus often reaches to 
 the inner edge of the sigmoid sinus, and sometimes 
 even lies in the medial wall of sinus. (Fig. 13.) 
 
 The membranous semicircular canals have only 
 about one-eighth of the diameter of the bony canals, 
 according to Alexander. The membranous ampullae, 
 however, are almost as large as the bony ampullae. The 
 membranous canals and ampullae are attached to the 
 convex surfaces of the bony canals. 
 
 The space about the membranous canals is called the 
 pe]:*ilyinpliatic space, and is continuous with 
 the cisterna perilymphatica of the vestibule. The peri- 
 lymphatic space is traversed by numerous connective 
 tissue trabeculae, which run from the membranous 
 canals to the bony wall, and which are lined by endo- 
 thelial cells. 
 
 Each of the membranous ampullae contains a nerve 
 end-organ, called the crista-ampuUaris, which is 
 an elevated ridge protruding into the lumen of the 
 
ANATOMY 
 
 25 
 
 ampulla, lying at right angles to the axis of the canal. 
 The crista lies on that side of the ampulla, which is 
 continuous with the convex surface of the bony canal. 
 The crista divides each ampulla into two portions, a 
 longer tubal portion, which is the side in the direction 
 of the canal, and a shorter sinus portion, which is the 
 side directed toward the utricle. 
 
 Fig. 13 
 PosTERioB Surface of Temporal Bone, Showikq Saccus Endoltmph- 
 
 ATICUS AND AQUEDUCTUS COCHLEJS 
 
 SE — Saccus endolymphaticus emerg- SF — Fossa subarcuata 
 
 ing from aqueductus vesti- AG — Aqueductus cochleae 
 bull lAM — Internal auditory meatus 
 
 /SS — Eminence of superior semicircular canal 
 
 The membranous semicircular canals, the utricle and 
 saccule, are all similar in histological structure. They 
 are composed of three layers, an outer fibrous layer, a 
 delicate basal membrane, and a single layer of squa- 
 mous epithelial cells. 
 
26 
 
 THE LABYEINTH 
 
 The fibous layer is similar to the periosteum 
 lining the bony canals and vestibule, with which it is 
 continuous, at the points where the membranous canals 
 are attached to the bone. 
 
 The basal membrane is homogeneous and very 
 
 Fig. 14 
 Cross-Section of Crista Ampullaris (Schematic) 
 S — Submucosa 8us — Nuclei of sustentaeular cells 
 
 BM — Basement membrane N — Nerve fibres breaking up into 
 
 E — Epithelium lining ampulla network to surround bases 
 
 BG — Hair-cells of hair-cells 
 
 C — Cupula 
 
 thin. It, as well as the connective tissue layer, becomes 
 thicker at the maculae and cristae. 
 
 As we approach the maculas and crista the squa- 
 mous epithelium becomes columnar, and in the end- 
 organs changes into neuro-epithelium. 
 
ANATOMY 27 
 
 The histological structure of the maculjE and cristse 
 is very similar. (Fig 14.) The cristae are raised above 
 the inner surface of the ampullae, whereas the macute 
 are flush with the inner surfaces of the utricle and sac- 
 cule. The gelatinous membrane overlying the maculae 
 contains otoliths, while the membrane overlying the 
 cristfe contains none. The end-organs consist of an 
 outer fibrous layer, a basal membrane, and neuro- 
 epithelium. The neuro-epithelium consists of 
 two kinds of cells. The so-called fibre cells, which are 
 supporting cells, are elongated and slightly expanded at 
 
 Fig. 15 
 Cross-Section of Macula Aooustica (Schematic) 
 8 — Submucosa HC — Hair-cells 
 
 BlI — Basement membrane N — Nerve fibres breaking vip into 
 
 E — Epithelium lining saccule and network to surround bases 
 
 utricle of hair-cells 
 
 Stis — Nuclei of sustentacular cells Oil — Membrane containing otoliths 
 
 the lower and upper ends, and traverse the entire thick- 
 ness of the epithelium. They have an oval nucleus, 
 situated below the level of the second type of cells, the 
 hair-cells. The bair-cells are the real nerve end- 
 organs. They occupy only the upper half of the 
 epithelium. They are flask-shaped, with a lower 
 rounded end, which contains a large spherical nucleus. 
 (Fig. 15.) 
 
 From the surface of the haii'-cells are given off long 
 delicate hairs, 20 to 25 microns in length. These hairs 
 enter the gelatinous membrane, which overlies the end- 
 
28 THE LABYRINTH 
 
 organ. The membrane which overlies the crista is 
 called the cupula. It is a clear, gelatinous mem- 
 brane, which coagulates after death. It overrides the 
 crista like a saddle. The hairs of the hair-cells pene- 
 trate this structure, and when the motion of the endo- 
 lymph is imparted to it, all of the hairs move with it. 
 
 The membrane over the maculse, which is called the 
 otolith-membrane, is similar to the cupula, with 
 the exception that it contains otoliths, which are small 
 stones, 2 to 25 microns in diameter, composed of cal- 
 cium carbonate and calcium phosphate. 
 
 The end-organs are supplied by the terminal fila- 
 ments of the vestibular nerve. The nerve fibres, when 
 they reach the basilar membrane under the neuro- 
 epithelium, lose their medullary sheaths, and break up 
 into terminal filaments, which ascend between the sup- 
 porting cells to the bases of the hair cells, which they 
 surround by means of a basket-like network. 
 
 Cajal claims that the nerves are not equally dis- 
 tributed to the hair-cells in the cristas, the cells at the 
 top of the crests being much more richly supplied by 
 nerve fibres than those on the declivities. 
 
 Kolmer, Bruehl and Bielschowsky think that they 
 have proven that the nerve fibrils terminate in the hair- 
 cells themselves, whereas Cajal claims that they merely 
 surround the cells. There are anastomoses between 
 the nerve fibrils, and each nerve fibril supplies a large 
 number of hair-cells. 
 
 THE COCHLEA 
 
 The cochlea is embedded in the petrous portion of the 
 temporal bone, between the internal auditory canal and 
 
ANATOMY 29 
 
 the cavity of the tympanum. It is snail-like in shape, 
 and consists of a canal 28 to 30 mm. long, which, start- 
 ing from the vestibule, winds a little more than two and 
 a half times around its axis. The turns, in their begin- 
 ning, are directed from the vestibule behind and above, 
 toward the carotid canal below and in front. The diam- 
 eter of the canal, at the beginning, is about 2 mm., and 
 gradually grows smaller as the canal approaches its 
 superior extremity. 
 
 The cochlea is in close relation to two large blood- 
 vessels. The basal whorl lies directly above the dome 
 of the jugular bulb, while the internal carotid artery is 
 in front of and external to the cochlea, and its canal is 
 separated from the latter by only a thin layer of spongy 
 bone. 
 
 The central structure of the cochlea, about which the 
 canal winds, is known as the modiolus. This is con- 
 ical, and begins with a broad base at the external end of 
 the internal auditory canal, then taking a general direc- 
 tion outward, forward and upward, extends almost to 
 the apex or cupola of the cochlea. The base of the modi- 
 olus is considerably thinner at its edges than it is at its 
 centre. In the direction of the axis of the modiolus, from 
 its base to its apex, there are numerous canals contain- 
 ing nerves and blood-vessels. In the centre of the modi- 
 olus the canalis centralis modioli runs from the base to 
 the apex. In the lower part of the modiolus the axial 
 canals, including the canalis centralis, are not com- 
 pletely filled by their contents, but as the canals ap- 
 proach the apex their walls lie closer to the contained 
 vessels and nerves. Richards has shown that in un- 
 capping the cochlea, the modiolus may be removed from 
 
30 
 
 THE LABYEINTH 
 
 its apex toward its base, to a point corresponding to 
 the termination of the first cochleal whorl, without caus- 
 ing the loss of cerebro-spinal fluid, i. e., without placing 
 the operative field and intracranial contents into gross 
 communication. 
 
 S*. v 
 
 Fig. 16 
 
 Section Ackoss Basal Whorl of Cochlea 
 
 ST — Scala tympani Sp.L. — Bony lamina spiralis 
 
 SV — Scala vestibuli N — Nerve fibres passing to Corti'a 
 DC — Ductus eochlearis organ 
 
 jB — Membrane of Eeissner CO — Organ of Corti 
 
 BM — Basilar membrane MT — Membrana tectoria 
 
 LS — Ligamentum spirals L — Limbus 
 
 COM — Canalis centralis modioli, Sulc. SP — Sulcus spiralis 
 
 containing cochlear nerve Str. V — Stria vascularis 
 
 and vessels VP — Vas prominens 
 G8 — Ganglion spirale 
 
 Winding about the modiolus, on the outer surface, at 
 its point of junction with the osseous lamina, is the 
 canali:?; spiralis of Rosenthal, which contains the 
 spiral ganglion. (Fig. 16.) Beginning at the lower 
 limit of the oval window, and apparently continuous 
 
ANATOMY 31 
 
 with the floor of the vestibule, a thin plate of hone, the 
 lamina spiralis ossea, winds about the modiolus, 
 at right angles to it, partially dividing the canal of the 
 cochlea. The outer edge of this bony plate gives attach- 
 ment to the membranous spiral lamina, which, grad- 
 ually becoming broader as it ascends, completes the 
 division of the cochlear canal into a lower and an upper 
 scala. The lower scala is called the scala tym- 
 pani, and ends at the fenestra rotunda, where 
 the memhrana tympani secundaria separates it from 
 the tympanic cavity. The upper is called the scala 
 vestibuli, and communicates with the vestibule. 
 The scalse communicate with each other at the 
 apex of the cochlea through the helicotrema Bersch- 
 etti. 
 
 Two portions of the cochlea present in the inner tym- 
 panic wall. They are the promontory and the round 
 window. The cochlea, however, runs considerably far- 
 ther forward than the anterior boundary of the tym- 
 panum, and lies partly internal to the Eustachian tube, 
 and partly internal to the carotid artery. The promon- 
 tory represents the outer wall of the first cochleal 
 whorl. This wall is usually thick and dense, but occa- 
 sionally it is so thin that it is penetrated by the knife- 
 blade in performing a paracentesis, thus establishing a 
 communication between the infected middle ear and the 
 labyrinth. The basal whorl may be indicated on the 
 inner tympanic wall by a line drawn from a point on 
 the posterior tympanic wall, midway between the oval 
 and the round windows, downward and forward, to the 
 junction of the anterior tympanic wall with the floor. 
 This line forms an angle of about 45° with the hori- 
 
32 THE LABYBINTH 
 
 zontal plane. The round -window li«s at tlie bottom 
 of a recess situated at the middle of the posterior part 
 of the inner tympanic wall. In looking at the latter 
 through the external canal, one can see only the recess 
 and not the round window itself, as the plane of the 
 window is at right angles to the plane of the inner tym- 
 panic wall. The secondary tympanic membrane lies in 
 the coronal plane. It is therefore impossible to injure it 
 in doing a paracentesis. Infections from the cochlea 
 may reach the intracranial contents by two routes ; one 
 through the internal auditory canal, along the sheaths 
 of the nerves and vessels, and the other through the 
 aqueductus cochleae. 
 
 The internal auditory canal begins in a 
 large orifice, the meatus auditorius internus, about the 
 centre of the posterior surface of the pyramid. From 
 the internal auditory meatus it runs obliquely outward 
 and backward. It is in direct line with the external 
 auditory canal, the two being separated from each 
 other by the labyrinth and middle ear. In regard to its 
 length and width, the canal varies considerably in dif- 
 ferent individuals. Its outer end is divided by a trans- 
 verse shelf of bone into an upper and a lower fossa. In 
 the anterior part of the upper fossa is an opening which 
 marks the beginning of the facial canal, and transmits 
 the facial nerve. In the posterior part of the upper 
 fossa there are openings for the passage of some of the 
 branches of the vestibular nerve. At the bottom of the 
 lower fossa are the spirally arranged openings at the 
 base of the modiolus, for the transmission of the divi- 
 sions of the cochlear nerve. There are, besides, a few 
 small openings on the posterior wall of the internal au- 
 
ANATOMY 33 
 
 ditory canal, througli which some branches of the ves- 
 tibular nerve pass. 
 
 As has been described, the canal of the cochlea is di- 
 vided into two scalae by the lamina spiralis ossea and 
 the lamina spiralis membranacea, or membrana basi- 
 laris. The latter arises from the edge of the bony 
 lamina, and extends to the outer wall of the cochlea, 
 where it is attached to the ligamentum spirale, a vascu- 
 lar fibrous thickening of the endosteum. Extending 
 from the upper surface of the osseous lamina, near its 
 outer edge, to the ligamentum spirale, above the inser- 
 tion of the membrana basilaris, is the membrane 
 of Reissner. 
 
 This is a thin, homogeneous, radially striated mem- 
 brane, containing occasional spindle-cells. By means 
 of the membrane of Reissner, the scala vestibuli is di- 
 vided into a large upper part and a smaller lower one. 
 The lower section, called the ductus eochlearis, is the 
 endolymph space of the cochlea, and contains the ter- 
 minal filaments of the cochlear nerve. The ductus 
 eochlearis is triangular on cross section, bounded 
 above by the membrane of Reissner, externally, by the 
 ligamentum spirale, and below, by the mem- 
 brana basilaris. It is lined by a layer of flat- 
 tened epithelium, and terminates near the cupola, 
 above, and at the round window, below, in rounded 
 blind extremities. Its only communication is with 
 the saccule, by means of the delicate canalis 
 reuniens. 
 
 The scala tympani, and the large upper division of 
 the scala vestibuli, are the perilymph spaces of the 
 cochlea. They communicate with each other at the 
 
34 THE LABYEINTH 
 
 apex of the cochlea by means of the helicotrema. The 
 scala vestibuli is continuous behind with the vesti- 
 bule. Just beyond the fenestra rotunda, in the floor of 
 the scala tympani, an opening leads to a fine canal, 
 which extends to the inferior surface of the petrous 
 bone near its posterior border, where it communicates 
 with the subarachnoid space. The canal is called the 
 aqueductus coclilese, and affords an avenue of 
 communication between the perilymph sac and the sub- 
 arachnoid space. 
 
 On the upper surface of the bony spiral lamina, 
 between its free edge and the point of origin of 
 Eeissner's membrane, there is a thickening of the 
 periosteum, that has a toothed ridge. From this 
 ridge there projects outward a gelatinous structure 
 of relatively considerable thickness. This is the 
 tectorial membrane, and it runs outward al- 
 most to the outermost point of the organ of Corti, 
 and lies on the upper surface of the latter like a thick 
 cushion, the hairs of the hair-cells projecting into or 
 against it {A. A. Gray). (Fig. 17.) The membrana 
 tectoria is analogous to the gelatinous cupula of the 
 crista ampuUaris, and the otolith membrane of the ma- 
 cula. Beneath it, is the organ of Corti, which may be 
 considered as composed of five parts, viz. : 
 
 1. Sense epithelial cells, or hair-cells. 
 
 2. Sustentacular cells (rods of Corti, and the cells of 
 Deiters). 
 
 3. The membrana tectoria, already described. 
 
 4. A reticular membrane which overlies the hair- 
 cells, and is connected with the sustentacular cells. 
 
 5. The endings of the auditory nerve fibres. 
 
ANATOMY 
 
 35 
 
 The hair-cells are columnar in shape, with rounded 
 bases. The lower part of the cell contains the nucleus, 
 and is in contact with the terminal nerve-filaments. 
 The hair-cells form four or five rows. These are ar- 
 ranged in two series, an inner and an outer, and are 
 separated from each other by the rods of Corti. The 
 inner series consists of a single row, and is next to the 
 spiral lamina. The outer series consists of three or 
 four rows. The hair-cells of Corti 's organ differ from 
 
 Section of Organ of Cobti (Schematic) 
 
 .]V — Nerve-flbres 
 V8 — Vas spirale 
 IHO — Inner hair-cell 
 OffO— Outer hair-cells 
 DC — Deiters' cells 
 Ben. G — Hensen's cells 
 CI. C— Claudius' cells 
 
 IR — Inner rod 
 OB — Outer rod 
 CT — Tunnel of Corti, with nerve- 
 
 flbres passing across 
 IBC — Inner basilar cell 
 OBO — Outer basilar cell 
 MB — ^Membrana basilaris 
 TM — Tectorial membrane 
 
 those of the maculae in that the cilia of the former are 
 comparatively short and are arranged in the form of 
 a crescent on the free surface of the cell. According to 
 Scott, the cilia are gathered together in bundles like 
 sheaves of corn, and pass down into the substance of 
 the cells. 
 
 Separating the inner and outer rows of hair-cells are 
 
36 THE LABYBINTH 
 
 the rods of Corti. These form a double row of pe- 
 culiarly shaped cells, which, starting far apart, in broad 
 bases, on the membrana basilaris, incline toward each 
 other as they rise, and finally meet at their apices. They 
 enclose a triangular passage, the tunnel of Corti. They 
 rise stiffly from the membrana basilaris, and from their 
 arrangement, are evidently supporting cells. To their 
 upper free ends the reticular membrane is attached. 
 Lying between the outer hair-cells are the cells of 
 Deiters. These also rise stiffly from the membrana 
 basilaris to the reticular membrane, and with the latter 
 and the rods of Corti form a protecting framework for 
 the hair-cells. The rods of Corti and the cells of Deiters 
 are analogous to the supporting cells of the crista am- 
 puUaris. Beyond the outer hair-cells the epithelium 
 (cells of Hensen) gradually changes in form, becoming 
 cylindrical (cells of Claudius), and finally cuboidal. 
 The latter type is continued along the membrana basi- 
 laris to the ligamentum spirale. Internal to the inner 
 row of hair-cells, the epithelial cells gradually become 
 shorter, until they merge imperceptibly into the flat- 
 tened epithelium lining the ductus cochlearis. 
 
 The reticular membrane is a net-like structure, con- 
 nected with the free ends of the rods of Corti and the 
 cells of Deiters. Through its apertures project the 
 hairs of the hair-cells. These extend to or into the soft 
 gelatinous membrana tectoria. 
 
 The nerve fibres of the cochlea are derived from 
 bipolar cells which form a spiral ganglion at the 
 outer surface of the modiolus, at its junction with the 
 spiral bony lamina. The fibres then pass through radi- 
 ally arranged channels in the latter, and enter the 
 
ANATOMY 37 
 
 organ of Corti, near the bases of the hair-cells. As the 
 nerve leaves its bony channel it loses its sheath; only 
 the axis-cylinder enters ' the organ of Corti, Some 
 fibres end at the inner row of hair-cells, others, piercing 
 the tunnel enclosed by the rods of Corti, pass to the 
 outer hair-cells. Kishi believes that the nerve fibres 
 which pass to the outer hair-cells lie on the floor 
 (membrana basilaris), and not above it, as 
 they pierce the tunnel of Corti. The central axons of 
 the bipolar cells, in the spiral ganglion, pass through 
 the channels which have been described in the modio- 
 lus, and are then collected to form the cochlear division 
 of the auditory nerve. 
 
 The cochlea receives its blood-supply through the 
 internal auditory artery, a branch of the ba- 
 silar. According to Siebenmann, this artery sends but 
 a single twig into the labyrinth itself. The remaining 
 branches supply the bony capsule, the roots of some of 
 the cranial nerves, and part of the under surface of the 
 cerebellum. This single labyrinth artery divides into 
 three main branches. 
 
 1. Tlie vestibular artery, which accompanies 
 the vestibular nerve, sends branches to the upper part 
 of the saccule and utricle, and to the ampullae of the 
 superior and external semicircular canals. Small ves- 
 sels follow the canals along their concave surfaces. 
 
 2. Tbe cocblear artery, which winds in the 
 canalis spiralis, and here, according to Bottcher, sends 
 capillary branches into the ductus cochlearis. 
 
 3. The vestibulo-cochlear artery, which 
 supplies part of the cochlea, the lower part of the ves- 
 tibular structures, and the ampulla of the posterior 
 
38 THE LABYBINTH 
 
 canal. PoUtser has shown that an anastomosis of the 
 labyrinthine with the tympanic vessels occurs through 
 the medium of vessels traversing the outer bony laby- 
 rinthine wall. 
 
 The veins of the labyrinth are collected into three 
 trunks. One forms a rich plexus in the internal audi- 
 tory canal, a second follows the aqueductus vestibuli, 
 while the third accompanies the aqueductus cochleae. 
 All three empty into the inferior petrosal sinus. 
 
 THE EIGHTH NERVE AND ITS 
 CENTRAL CONNECTIONS 
 
 The auditory, or better the eighth nerve, arises 
 from the medulla by two large roots, a mesial, or 
 radix vestibularis, and a lateral or radix 
 cocblearis. The nerve thus formed lies external 
 to the facial, and passes forward, in company with 
 the latter, to the internal canal. From the com- 
 mon trunk of the eighth nerve, a filament is given 
 off, which supplies the ampulla of the posterior semi- 
 circular canal. The remainder of the nerve bundle is 
 divided into two principal branches, a lower, which 
 enters the cochlea, and an upper, which is further sub- 
 divided. The upper division, the utriculo-ampuUaric, 
 runs, at first, in common with the facial, then separate 
 ing from it, passes through the inner wall of the vesti- 
 bule, to its anterior surface, where its deep fibres sup- 
 ply the utricle, and are distributed ultimately to the 
 macula utriculi; its superficial fibres supply the am- 
 pulla of the superior semicircular canal, and a lateral 
 
ANATOMY 39 
 
 bundle passes to the ampulla of the external canal. 
 Between the two principal branches of the eighth nerve 
 the filament which supplies the saccule is given off. The 
 vestibular ganglion is common to both the saccular and 
 the utriculo-ampuUaric nerves, at their point of en- 
 trance into the bone, and it follows the utriculo-ampul- 
 laric branch a short stretch into the bone. Winkler 
 showed that ganglion cells are scattered along the 
 course of the vestibular nerve, and that the vestibular 
 ganglion in the guinea-pig is in close contact with the 
 medulla. 
 
 Wittmaack, Marx and others proved, by section of 
 the eighth nerve in the internal auditory canal, that 
 despite complete loss of function of the static labyrinth, 
 the vestibular nerve showed no decided degenerative 
 changes, while the cochlear nerve showed a distinct de- 
 scending degeneration throughout its entire extent, 
 even to the neuro-epithelium. 
 
 As has already been described, the cochlear nerve has 
 its large bipolar ganglion cells in the canalis spiralis. 
 From this point the nerve fibres arise out of the gan- 
 glion cells and pass through the radiating canals of 
 the lamina spiralis, where they anastomose freely. 
 Only the axis-cylinders pass out of the canals, and are 
 distributed to the hair-cells of the organ of Corti. 
 Whether the filaments enter the cells, or merely sur- 
 round them, is still a mooted question. 
 
 The maculae of the vestibular structures, and the 
 cristse of the canals, are supplied by the filaments of 
 the vestibular branches. The nerve-fibres, when they 
 reach the basement membrane under the neuro-epi- 
 thelium, lose their sheaths, and break up into terminal 
 
40 THE LABYEINTH 
 
 filaments, which, after a free anastomosis, are dis- 
 tributed to the hair-cells. Here also, the question as to 
 whether they enter the cells, or are distributed in a 
 basket-like formation about their bases, is still un- 
 settled. 
 
 With regard to the important role which the eighth 
 nerve plays in the extension of labyriathine suppura- 
 tion to the intra-crauial contents, Lange states: "The 
 eighth nerve, at its entrance into the internal auditory 
 meatus, is surrounded by a more or less loosely adher- 
 ent process of the arachnoid. This process runs free in 
 the canal, unattached to the dural lining of the latter, 
 until it reaches the fundus, at which point it becomes 
 adherent to the wall. To the facial, this arachnoid cov- 
 ering is attached chiefly in front and above, and it fol- 
 lows the nerve for a short distance into its canal, where 
 it merges with the lining of the latter. The sheath 
 leaves the vestibular and cochlear nerves, however, 
 sooner than it does the facial, and so attaches itself to 
 the dura, as to enclose the entire areae cribrosaB. With 
 individual differences, there exists, in the depths of the 
 internal auditory canal, a larger or smaller cavity, al- 
 most exactly funnel-shaped — an extension of the sub- 
 arachnoid space — in which the nerve breaks up into its 
 branches. Between the nerve fibres in the cochlea there 
 are large lymph spaces, which also play an important 
 part in the extension of inflammatory processes from 
 within this organ. The subdural space has no commu- 
 nication with this extension of the subarachnoid space 
 in the internal auditory canal." 
 
 Just as the peripheral fibres arise in the ganglia 
 along the course of the eighth nerve, so, too, do the cen- 
 
ANATOMY 41 
 
 tral fibres, and while the former are distributed to the 
 end-organs, the latter are gathered into bundles, which 
 finally merge to form the two roots in which the eighth 
 nerve arises. Of these two roots the radix cochlearis 
 (lateral root) passes to the outer side of the restiform 
 body, where it is enlarged by numerous nerve cells, and 
 terminates about the cells of the ventral and dorsal 
 nuclei of the eighth nerve, some of the fibres being ap- 
 parently continuous with the auditory striae on the 
 floor of the fourth ventricle. 
 
 The central connections of the cochlear division of 
 the eighth nerve, according to Lewandowski, are as 
 follows (Fig. 18) : 
 
 From the ganglion of the lateral root GL, and the 
 ventral accessory nucleus Vn of the cochlear nerve, the 
 fibres pass across the medulla and pons, to the opposite 
 side, principally, through the trapezium Tr to the nu- 
 cleus of the trapezium TrN, through E eld's acoustic 
 fibres H to the upper olive UO, and through the acoustic 
 striae St, to the upper olive. Some of the fibres pass di- 
 rectly to the nucleus of the lateral fillet NLF. A few 
 fibres do not cross over, but pass up through the lateral 
 fillet of the same side. 
 
 From the upper olive, and the nucleus of the trape- 
 zium, fibres pass through the lateral fillet LF and its 
 nucleus NLF, to the posterior corpus quadrigeminum, 
 PCQ. 
 
 Through the brachium of the posterior corpus quad- 
 rigeminum BCQ, fibres pass to the internal geniculate 
 body ICB, and from here they pass to the cortex of the 
 temporo-sphenoidal lobe C. 
 
 There is a commissure P, described by Probst, be- 
 
42 
 
 THE LABYRINTH 
 
 m^ 
 
 LF 
 
 N t p 
 
 Fig. 18 
 
 Central Connections of Cochlear Nerve. (Modified after 
 Le wandowaky ) 
 
 (The uncrossed fibres are not indicated, for the sake of clearness) 
 
 MdP — Junction of medulla and 
 
 MB — Mid-brain 
 
 Co — Spiral ganglion of cochlea 
 
 CON — Cochlear nerve 
 
 VN — Ventral accessory nucleus 
 
 eighth nerve 
 GL — Ganglion of lateral root 
 Tr — Trapezium 
 TrN — Nucleus of trapezium 
 H — Held's acoustic fibres 
 8t — Striae acousticse 
 UO — Upper olive 
 
 ponsLF — Lateral fillet 
 
 A'LF— Nucleus of lateral fillet 
 P — Probst's commissure 
 PCQ — Posterior corpus quadrigemi- 
 of num 
 
 COM — Commissure between poster 
 
 rior corpora quadrigemina 
 BCQ — Brachium of posterior corpus 
 
 quadrigeminum 
 IGB — Internal geniculate body 
 C — Cortex of temporo-sphenoidal 
 
 lobe 
 
ANATOMY 43 
 
 tween the two nuclei of the lateral fillet, and a commis- 
 sure COM between the two corpora quadrigemina. 
 Through the commissures, as well as through the few 
 fibres of the secondary auditory tracts which do not 
 cross to the opposite side, each cerebral cortex is 
 brought into communication with both ears. 
 
 The radix vestibularis (mesial root) passes obliquely 
 backwards on the inner side of the restiform body to its 
 central nuclei in the floor of the fourth ventricle. It 
 has not, as yet, been possible to isolate and follow sepa- 
 rately the sacculo-utricular and ampuUaric elements of 
 the vestibular root. Kolliker and Cajal have shown 
 that the fibres, in their course to the central nuclei be- 
 hind the descending root of the trigeminus, divide into 
 ascending and descending limbs, forming with the trunk 
 a letter Y. 
 
 According to Kohnstamm, the following are the cen- 
 tral nuclei of the vestibular root (Fig. 19) : 
 
 1. Large-celled nucleus of Deiters. 
 
 2. Small-celled or ventro-caudal nucleus of Deiters. 
 
 3. Nucleus triangularis. 
 
 4. Nucleus angularis, or Bechterew's nucleus. 
 
 5. Nucleus embolo-globosus. 
 
 From the other so-called vestibular nuclei the large- 
 celled Deiters' is distinguished by the fact that by the 
 Marchi method no vestibular fibres can be proven to 
 enter it. These fibres, however, probably do act upon 
 it through the intervention of the nucleus triangularis. 
 Into the ventro-caudal or small-celled Deiters' nucleus 
 vestibular fibres can be traced. This nucleus, gradually 
 growing smaller as it descends, passes downward in the 
 
44 
 
 THE LABYEINTH 
 
 medulla, along with the fibres of the descending root 
 of the vestibular nerve, for a short distance. 
 
 The nucleus triangularis is in the floor of the fourth 
 ventricle, and bears such a close relation to the nuclei 
 of the vagus, that it is possible for an impulse to one 
 
 Fig. 19 
 
 Nuclei op Eighth 
 
 8p0 — Spiral ganglion of cochlear 
 nerve 
 
 OG — Geniculate ganglion of vestib- 
 ular nerve 
 
 CN — Cochlear nerve 
 
 yy— Vestibular nerve 
 
 VG — Ventral accessory ganglion 
 of cochlear nerve 
 
 GLR — Ganglion cells in lateral 
 root 
 
 NT — Nucleus triangularis ( Dor- 
 sal nucleus) 
 
 Neeve (Schematic) 
 DN — Deiters' nucleus 
 yCjD2Vr— Ventro-caudal Deiters' 
 
 nucleus 
 DR — Descending root of vestibular 
 
 nerve 
 BN — Becheterew's nucleus ( nucl. 
 
 Angularis) 
 NEG — Nucleus embolo-globosus 
 NTA — Nucleus trigemino-angularig 
 DNV — Nucleus of the descending 
 
 root of the fifth nerve 
 CR — Corpus restiforme 
 
ANATOMY 45 
 
 centre to be radiated to the other. This explains the 
 nausea and vomiting which occur with vestibular 
 vertigo. 
 
 Before the work of Kohnstamm and Quensel noth- 
 ing was known regarding the function of the nucleus 
 angularis {Bechterew). This nucleus extends dorsally, 
 without any demonstrable dividing line, into the nu- 
 cleus embolo-globosus of the cerebellum. Ventrally it 
 extends into the nucleus of the descending spinal root 
 of the fifth nerve, through the interposed bridge of the 
 nucleus trigemino-angularis. (Fig. 19.) The nucleus 
 angularis, the nucleus embolo-globosus and the nucleus 
 trigemino-angularis are identical as regards the form 
 of their cells, and in preparations, cannot be differen- 
 tiated. They may really be regarded as parts of a sin- 
 gle nucleus. In its degenerative changes, the nucleus 
 trigemino-angularis resembles the sensory trigeminal 
 nucleus more than it does the nucleus angularis (Bech- 
 terew). Kohnstamm states that for a long time he had 
 observed what was published by May and Horsley, 
 viz., that many fibres from the degenerated root of the 
 fifth nerve can be followed into Bechterew 's nucleus. 
 
 The nucleus embolo-globosus, which is intermediary 
 between Bechterew 's nucleus and the central nuclei of 
 the cerebellum must also be considered among the ves- 
 tibular nuclei. For degenerated fibres of the vestibular 
 nerve can be followed to a point that is beyond Bech- 
 terew 's nucleus, and within the nucleus embolo-globo- 
 sus. Moreover, in injuries to the mid-brain, which are 
 followed by widespread degenerative changes of Bech- 
 terew 's nucleus, the nucleus embolo-globosus also shows 
 tigrolysis. 
 
46 THE LABYRINTH 
 
 By the Marchi method it is impossible to demonstrate 
 completely the physiologic-anatomical relations of the 
 vestibular nuclei. For in their positions these bear 
 such complicated relationships to one another, that they 
 cannot be affected singly through lesions artificially 
 produced, and so the dependence of degenerated fibres 
 upon one or another of the nuclei cannot be determined 
 with absolute precision. However, in the, vestibular 
 nuclei the central tracts of the vestibular nerve begin. 
 These have been demonstrated successfully by the 
 Nissl method. 
 
 According to Cajal, the fibres of the ascending limb 
 of the root of the vestibular nerve terminate in the 
 cells of Deiters' nucleus and Bechterew's nucleus. The 
 fibres of the descending limb terminate in the nucleus 
 triangularis, Deiters' nucleus, and the ventro-caudal or 
 accessory Deiters' nucleus, in the last of which the 
 fibres exhaust themselves. 
 
 According to Kohnstamm, however, Deiters ' nucleus 
 does not receive any vestibular fibres directly, the im- 
 pulses reaching Deiters' nucleus through the triangular 
 nucleus. 
 
 From the vestibular nuclei secondary tracts pass 
 down through the spinal cord and up through the pons 
 and mid-brain. Kohnstamm was able to identify the 
 following connections by the Nissl method in guinea- 
 pigs (Fig. 20) : 
 
 From Deiters' nucleus fibres pass down through the 
 Deiterso-spinal tract of the same side. This tract 
 passes through the antero-lateral tract of the spinal 
 cord Deit Sp, sending collaterals to the anterior horn 
 cells of the cord. 
 
ANATOMY 
 
 47 
 
 From the nucleus angularis (Becliterew's nucleus) 
 fibres pass upward through the posterior longitudinal 
 fasciculus PLF, in the posterior part of the reticular 
 formation of the pons, and the tegmentum of the mid- 
 brain, on both sides, the fibres being more numerous 
 on the same side. In the mid-brain the fibres terminate 
 about the cells of the nuclei of the nerves supplying the 
 ocular muscles. 
 
 Fig. 20 
 Tracts Involved in Nystagmus 
 MB — Mid-brain VM — Ventro-caudal Deiters' nu- 
 
 M d P — Junction of medulla and cleus 
 
 pons PLF — Posterior longitudinal fas- 
 
 V — Vestibule ciculus 
 
 Nucl. V — Vestibular nucleus N3d6 — Nuclei of third and sixth 
 
 Vest 7f — Vestibular nerve nerves 
 
 BN — Bechterew's nucleus EM — Ocular muscles 
 
48 THE LABYEINTH 
 
 From the ventro-caudal or accessory Deiters' nu- 
 cleus, a few fibres pass down through the dorsal longi- 
 tudinal bundle of the cord, to the anterior horn cells on 
 both sides ; and a few fibres pass upwards, through the 
 posterior longitudinal bundle of the pons and mid-brain 
 PLF, on both sides, to the nuclei of the nerves supply- 
 ing the ocular muscles. 
 
 Consequently the reflex paths, through which the 
 movements of nystagmus are intermediated, are as fol- 
 lows : From the vestibule, through the vestibular nerve, 
 to the vestibular nuclei. From Bechterew's nucleus 
 and the ventral accessory Deiters ' nucleus to the pos- 
 terior longitudinal fasciculus on both sides, to the 
 nuclei of the nerves of the ocular muscles, and through 
 the third, fourth and sixth nerves, to the ocular 
 muscles. 
 
 The following are the pathways of reaction move- 
 ments, according to Bar any: The pathways for 
 reaction movements of the extremities are differ- 
 ent, in a portion of their course, from those of the 
 body. 
 
 The impulses for reaction movements of the extrem- 
 ities pass from the vestibule through the vestibular 
 nerve to Deiters' nucleus (Fig. 21, Deit), and the 
 ventro-caudal nucleus VD. From here, through the 
 corpus dentatum of the cerebellum DN, to the cortex of 
 the cerebellar hemisphere. From the cerebellar cortex, 
 fibres pass through the brachium conjunctivum to the 
 red nucleus of the tegmentum of the opposite side RN. 
 From here they pass down through Monakow's bundle 
 Mon across to the lateral tract of the spinal cord, to the 
 anterior horn cells of the opposite side. Thus the 
 
ANATOMY 
 
 49 
 
 Fig. 21 
 
 Teacts Connecting Cebebeixum With Spinal Cord, Mid-Beain and 
 Ceeebrum, Showing Pathways Involved in Reaction Movements 
 
 MC — Motor cortex of cerebrum 
 
 MB — Mid-brain 
 
 CP — Cerebellum and pons 
 
 BC — Spinal cord 
 
 F— Vestibule 
 
 Vest.'N — Vestibular nerve 
 
 KN — Red nucleus 
 
 Din — ^Dentate nucleus of cerebel- 
 lum 
 
 Deit.N — Deiters' nucleus 
 
 VD — Ventro-caudal accessory 
 Deiters' nucleus 
 
 NTect — Nucleus tecti 
 
 PN — Pontine nuclei 
 
50 THE LABYKINTH 
 
 OC — Clarke's column of cells in DW — Tract from Deiters' nucleus 
 posterior horn of spinal to cerebellar worm 
 
 cord Braoh.O. — Braehium conjunctivum 
 
 A.SC — Anterior horn cell MT — ^Motor tract 
 
 TM — Trunk muscles and muscles Mon — Monakow's tract 
 
 of extremities TU — ^Tractus uncinatus 
 
 MN — ^Motor nerves of muscles of PC — Tract from pontine nuclei to 
 trunk and extremities cerebellar cortex 
 
 PL — Flechsig's tract CPT — Crossed pyramidal tract. 
 
 Oow — Gowers' tract (Direct pyramidal tract 
 
 DC — Tract from Deiters' nucleus is not indicated, for sake 
 
 to cortex of cerebellar of clearness) 
 
 hemisphere Deit.Sp. — ^Deiterso-spinal tract 
 
 cortex of each cerebellar hemisphere is connected with 
 the anterior horn cells of the same side of the cord. 
 
 The following is the pathway for reaction movements 
 of the body ; from the vestibule through the vestibular 
 nerve to Deiters' and the ventro-caudal nucleus. From 
 here to the cerebellar worm DW. Then to the nucleus 
 tecti N Tect. From here they pass through the tractus 
 uncinatus TV, back to Deiters' nucleus, from which 
 they pass through the Deiterso-spinal tract Deit 8p, to 
 the anterior horn cells of the cord. 
 
 In addition to the centripetal impulses from the ves- 
 tibule, sensory impulses reach the cerebellum through 
 two tracts, Fleclisig''s tract or the direct cerebel- 
 lar tract Fl, and Go-wers' tract or the antero- 
 lateral ascending cerebellar tract Gow. These tracts 
 arise from the cells of Clarke's and Stilling-'s 
 columns, at the base of the posterior horn of the 
 spinal cord, around which the posterior nerve root 
 fibres terminate. The fibres of these two tracts pass up 
 through the lateral columns of the cord, and reach the 
 cerebellum through its inferior peduncle. They pass 
 through the central nuclei of the cerebellum to the 
 cerebellar cortex. 
 
 The fibres of the motor tract, in passing down 
 
ANATOMY 
 
 51 
 
 througli the pons, give off collaterals to the pontine 
 nuclei. From here, fibres cross through the middle 
 cerebellar peduncle to the cerebellar cortex of the 
 opposite side. 
 
 In the cerebellar cortex motor impulses from the 
 cerebrum meet impulses from the vestibule, and sensory- 
 impulses from the muscles, joints, etc., which pass up 
 through Flechsig's and Gowers' tracts. 
 
 Following up the pathways of the impulses in the 
 cerebellar cortex somewhat more in detail, we learn the 
 following facts: Impulses pass from the vestibule toi 
 the dentate nucleus of the cerebellum. From here cells 
 reach the dendritic processes of the cells in the granular 
 layer of the cerebellar cortex (Fig. 22). The cells of 
 the granular layer send axis-cylinder processes into the 
 molecular layer, where they divide into two branches, 
 
 riG. 22 
 
 Pathways of Neevb Impulses to and Feom Cebebeixae Cortex 
 mij — Molecular layer of cerebellar FGfr— "Fibre grimpante," passing 
 -—'- — from motor cortex of 
 
 cortex 
 PJ — Purkinje's cells 
 Or.L. — Granular layer 
 DN — Dentate nucleus 
 Bask.O — ^Basket cell 
 QrO — Cell in granular layer 
 
 cerebrum to Purkinje 
 
 cell 
 
 A — ^Axons of Purkinje cells 
 Sp — Tract to spinal cord 
 V — Tract from vestibular nuclei 
 
52 THE LABTEINTH 
 
 running at right angles to the dendritic processes of 
 the Purkinje cells, to which they transmit the impulses. 
 In the molecular layer there are so-called basket cells, 
 which terminate about the bodies of the Purkinje cells, 
 in basket-like ramifications. The cells in the granular 
 layer connect the rows of the Purkinje cells in the 
 frontal plane, while the basket cells connect them in 
 the sagittal plane. In this way each impulse from the 
 vestibule is spread to the Purkinje cells over the entire 
 cerebellar cortex. The impulses from the cerebral cor- 
 tex, on the other hand, are individualized, each fibre 
 surrounding one Purkinje cell, by means of the so- 
 called "fibres grimpantes." 
 
 From the Purkinje cells the axis-cylinder processes 
 pass down to the dentate nucleus. From here cells send 
 axis-cylinder processes down to the spinal cord, in the 
 tracts already mentioned {Bar any). 
 
CHAPTEE II 
 
 PHYSIOLOGY 
 
 In the physiology of the vestibular structures and the 
 semicircular canals, particularly of the latter, we have 
 advanced much further than we have in the physiology 
 of the cochlea, for the reason that animal experiments 
 by a host of independent observers have led to many 
 well-established conclusions. The function of the ves- 
 tibular structures and the semicircular canals is sepa- 
 rate and distinct from that of the cochlea. Although 
 there is some ground for the belief that in the dog 
 destruction of the cochlea is not followed by absolute 
 deafness, yet in man there have been many instances 
 where complete deafness was associated with a nor- 
 mally excitable static labyrinth. The cochlea is con- 
 cerned only with hearing, while the utricle, saccule and 
 canals (considered as a siagle organ) help to establish 
 our body balance. These are therefore called collect- 
 ively the static labyrinth, differentiating them thus 
 from the auditory labyrinth (the cochlea). Accord- 
 ing to Ewald, the static labyrinth exercises a tonic in- 
 fluence over all the striated muscles of the body. It 
 has been found in animals that an abnormal atony of 
 the limbs develops after removal of the labyrinth, and 
 that a general atrophy of the muscles ensues after 
 plugging the semicircular canals. This theory has been 
 supported by the later examinations of Asch, Drey fuss, 
 Willgerodt, Bethe and Frolich, who observed in lower 
 animals a falling off of the motor force, with a simul- 
 
54 
 
 THE LABYRINTH 
 
 taneous increase of the reflexes (Politzer). The view 
 that any part of the so-called static labyrinth con- 
 tributes to our perception or orientation of sounds has 
 been abandoned. 
 
 The static labyrinth, however, is not the only source 
 of impulses which help to maintain our equilibrium. 
 Flourens, Goltz, Breuer, Ewald and many others have 
 shown that, while the destruction of the static laby- 
 rinths is followed by marked loss of balance, this loss is 
 only temporary. 
 
 The other sources of impulses for the preservation of 
 our equilibrium perform the function of the static laby- 
 rinths vicariously, or, what is far more probable, the 
 centres in which all these impulses are gathered accom- 
 modate themselves to the loss of the normal influence 
 of the static labyrinths, and a compensation results. 
 Ewald demonstrated that pigeons, both of whose laby- 
 rinths were destroyed several months before, behaved 
 in a perfectly normal manner as regards their equilib- 
 rium, when subjected to certain tests, and he concluded 
 that the destruction of both labyrinths entailed ulti- 
 mately a complete loss of vertigo ; i. e., animals with de- 
 stroyed labyrinths could no longer become dizzy. More- 
 over, deaf-mutes whose labyrinths were destroyed by 
 disease in early childhood, are able to maintain their 
 equilibrium almost as readily as normal individuals. 
 
 Some believe that the static labyrinth in man is a 
 rudimentary organ, but studies in comparative anatomy 
 give no ground for such a conclusion. Moreover, if it 
 were true, as some suppose, that this organ is normally 
 quiescent and rarely gives rise to impulses, its sudden 
 destruction would not cause the marked disturbances 
 
PHYSIOLOGY 55 
 
 to be observed in animals, nor would its destruction by 
 disease in man be followed by the severe symptoms to 
 be observed clinically. And if we do not see these se- 
 vere symptoms frequently, it must be remembered that 
 the destruction of the labyrinth by disease is, as a rule, 
 a slow process, so that the centres gradually accom- 
 modate themselves to the loss of the normal impulses. 
 It is true, however, that the more rapid the spread of 
 a pathological process through the labyrinth the more 
 severe are the symptoms. 
 
 Just how the impulses from the static labyrinths 
 share with those from other sources in maintaining our 
 equilibrium is a difficult matter to determine. Without 
 doubt, however, all of these centripetal impulses com- 
 bine harmoniously and, partly reflexly, at all events 
 automatically, establish our balance without our real- 
 ization of the processes involved. Every "dishar- 
 mony" in these impulses which serve to maintain our 
 equilibrium causes, if sufficiently pronounced, a marked 
 disturbance in balance. If the discordant factor be but 
 temporary, this disturbance will last until the normal 
 state is re-established. If, however, the disturbing ele- 
 ment be due to a permanent condition, such as the de- 
 struction of one or both static labyrinths, then the loss 
 of body balance will continue until such time as the 
 function of the destroyed organ or organs is performed 
 vicariously, or the centres accommodate themselves to 
 the absence of the normal impulses. The static laby- 
 rinth is probably always active, in the sense that it con- 
 stantly sends to the centres impulses acquainting us 
 with our position in space, and also with the changes in 
 our position, i. e., motion in a straight line and rotation. 
 
56 THE IjABYEINTH 
 
 With regard to the physiology of the component 
 parts of the static labyrinth, Breuer and Mach are of 
 the opinion that the function of the maculsB (the end- 
 organs of the saccule and utricle) is solely to enable us 
 to orient the body in space and to perceive motion in a 
 straight line. Wittmaack believes that the most im- 
 portant, if not the exclusive function of the vestibular 
 apparatus is the development of impulses which ac- 
 quaint us with the position of our bodies in space, and 
 so help, with other impulses from the eyes, muscles, 
 joints, etc., to establish our equilibrium. There is stUl, 
 however, considerable uncertainty as to the manner in 
 which the maculas are stimulated. Breuer states that 
 in mammals the macule of the utricle lies at right angles 
 to that of the saccule, and he believes that the otolith 
 membrane of the macula utriculi glides in a horizontal 
 direction from without and behind, inwards and for- 
 wards, while that of the macula saeculi glides more or 
 less vertically, from above and behind downwards and 
 forwards. 
 
 Each macule contains a groove, and these grooves 
 are at right angles to each other. In this way he 
 assumes that, in accordance with the position of the 
 head, the otolith membranes are acted upon by grav- 
 ity and glide in their respective grooves. He was led 
 to this gliding hypothesis by the peculiar anatomical 
 construction of the maculae in fishes. Here the nerve 
 endings are distributed in a long groove in which the 
 otolith membrane lies. In Breuer's opinion the otolith 
 membrane can move only in the long axis of the groove 
 and not at right angles to it. It has been shown, how- 
 ever, that these grooves frequently present irregulari- 
 
PHYSIOLOGY 57 
 
 ties which would make gliding of the otolith membrane, 
 such as Breuer assumes, impossible. According to 
 Barany, the question as to whether the otolith mem- 
 brane does or does not glide is still unsettled. More- 
 over, he believes it imnecessary to assume such gliding, 
 since all that he considers essential to stimulate the 
 end-organ is that the otolith membranes because of 
 their weight should be acted upon by gravity, in accord- 
 ance with the position of the head, and so cause tension 
 on or relaxation of the hairs of the hair-cells. 
 
 It has not been possible, up to the present, to stimu- 
 late the maculae alone experimentally. It is evident that 
 rotating the body must have some effect upon the macu- 
 las as well as upon the cristas, although the semicircular 
 canals are, from their construction, better adapted to 
 be aroused by turning than are the vestibular struc- 
 tures. If the axis of rotation passes through the oto- 
 lith membrane itself, a torsion of the latter must result, 
 with tension of the hairs on one side of the macula and 
 relaxation of the hairs on the other side. Whether 
 under these circumstances the tension and relaxation 
 neutralize each other completely, so that no impulse 
 results cannot be stated positively. Such a condition, 
 however, is not probable. Moreover, this form of rota- 
 tion must be very rare. The usual rotation occurs 
 about an axis which does not pass through the otolith 
 membrane, and here there is combined with the rotation 
 a degree of forward motion which in all probability 
 stimulates the maculae. Then, too, the experiments of 
 Wittmaack, who found the otolith membranes torn 
 from the hair-cells after rapid rotation (2000 times 
 per minute), show that centrifugal force probably 
 
58 
 
 THE LABYEINTH 
 
 plays an important role in stimulating these end- 
 organs. 
 
 In animals Breuer, Lee, Kuho and others have shown 
 that certain reflex movements of the eyes, caused by 
 movements of the head in space, are dependent upon 
 the otolith organs. These movements of the eyes 
 change with the various positions of the head. Barany 
 states that these reflexes do not occur in normal man. 
 In the blind, however, Breuer found eye movements 
 analogous to the reflexes which occur in animals. 
 
 Barany ascribes sea-sickness, particularly that due 
 to the pitching of a vessel, to stimulation of the otolith 
 organs. The peculiar discomfort caused by rapid 
 ascent or descent in elevators, "roller coasters" or 
 gravitation roads he also believes to be due to the influ- 
 ence of the same end-organs. For he proved upon him- 
 self, while sea-sick, that by changing the position of his 
 head forward or backward through an arc of 90°, so 
 that he lay prone upon his face or upon his back, he felt 
 no ill effects from the pitching of the boat, but as soon 
 as he raised his head up from the horizontal position, 
 even while lying on his back, he at once experienced 
 nausea and was compelled to vomit. The same for- 
 ward or backward movement of the head abolished the 
 discomfort due to rapid ascent or descent in elevators, 
 "roller coasters" or gravitation roads. He reasons 
 that these phenomena can be caused only by an organ 
 contained within the head, and he concludes that only 
 the otolith organs come into consideration. 
 
 The foundation upon which the physiology of the 
 semicircular canals is built we owe to Flourens. This 
 observer noted that in pigeons a lateral movement of 
 
PHYSIOLOGY 59 
 
 the head with rotation of the body around its vertical 
 axis occurred when the horizontal semicircular canal 
 was cut through, that a movement of the head back- 
 wards and forwards, with a tendency of the body to fall 
 backwards, occurred when the posterior canal was de- 
 stroyed, and that destruction of the superior canal 
 caused the animal to fall forwards. Despite the fact 
 that Flour ens observed these phenomena, he did not 
 realize that he was dealing with an organ whose func- 
 tion it was to help maintain our equilibrium, but con- 
 sidered the semicircular canals a special apparatus to 
 regulate the direction of our movements. His observa- 
 tions were confirmed by Brown-Sequard, Vulpian, 
 Golts, Loewenberg, Cyon and many other investigators. 
 There was, however, no unanimity of opinion regarding 
 the cause of the phenomena. Some experimenters 
 failed to see in the severing of the semicircular canal 
 an adequate cause for the reactions, and ascribed them 
 to a variety of other causes, such as loss of blood, 
 injury to the cerebellum, etc. Through the work 
 of other investigators, however, and particularly 
 through that of Breuer, the relation between the 
 phenomena observed and the severed canal was finally 
 established. 
 
 Golts was the first investigator to grasp the true sig- 
 nificance of the function of the semicircular canals. 
 According to his view the semicircular canals are a 
 special peripheral sense organ through which we be- 
 come aware of the position of the head. The canals 
 are, he continues, a sense organ for the establishment 
 of the balance of the head and, through this, of the 
 entire body. He believed that a stimulus was aroused 
 
60 
 
 THE LABTEINTH 
 
 by the pressure of a column of endolympli upon the 
 walls of the ampulla, and that this stimulus varied 
 with the height of the column of endolymph which 
 changed in different positions of the head. 
 
 In the vestibular structures, the otolith membranes, 
 because of their weight, cause a degree of pressure on 
 the hairs of the hair cells which develops a contiuuous 
 impulse, a rest-tone (Euhetonus) as it were, "Whether 
 such an impulse exists in the semicircular canals has 
 not yet been determined. While the difference ia 
 specific gravity between the cupula and the surrounding 
 endolymph is not sufficient to warrant such a conclu- 
 sion, yet it is probable that a rest-tone does exist in the 
 cristse, even though it may be secondary in physiologi- 
 cal importance to that of the maculae. Besides, it may 
 be aroused in some way not dependent upon the weight 
 of the cupula, but through some influence upon this 
 structure which causes it to undergo a constant move- 
 ment either molecular or en masse. 
 
 The chief function of the semicircular canals is un- 
 questionably to respond to rotation of the body and 
 acquaint us with the changes in the speed and direction 
 of such rotation, so as to help maintain our equi- 
 librium. 
 
 It is the generally accepted opinion that the end- 
 organ in each semicircular canal is its crista, and that 
 the process which stimulates this is a movement of 
 the endolymph, which, when it reaches the cupula, dis- 
 places the latter from the position it occupies when the 
 body is at rest. This movement of the cupula must be 
 exceedingly small, according to Barany .01 mm. or less, 
 for any considerable movement, such as that caused by 
 
PHYSIOLOGY 61 
 
 cutting through the canal, would tear the cupula from 
 the hair cells. 
 
 As to the manner in which rotation of the head 
 arouses a stimulus in the canals, let us consider for a 
 moment the left horizontal semicircular canal during 
 rotation of the body (head) to the left. At the begin- 
 ning of rotation the endolymph, because of its inertia, 
 remains stationary while the canal moves. This is 
 equivalent to a movement of the endolymph in a direc- 
 tion opposite to that of the rotation of the body, and 
 causes a displacement of the cupula toward the utricle, 
 with the corresponding reaction. If the rotation is con- 
 tinued at a uniform speed, the endolymph gradually 
 acquires a rate of speed equal to that of the canal, and 
 the cupula, partly for this reason and partly through 
 the elasticity of the hairs which project iato it, is re- 
 turned to its usual position. If the rotation cease sud- 
 denly, then the endolymph, because of its momentum, 
 continues to move in the direction of the turning (left) 
 while the canal is still, and the cupula is displaced away 
 from the utricle. Here again, because of the elasticity 
 of the hairs and the cessation of movement in the endo- 
 lymph, the cupula regains its usual position. The 
 cupula itself shares with the endolymph the inertia at 
 the beginning of the rotation, and the momentum when 
 the rotation ceases. 
 
 These phenomena occur irrespective of the speed or 
 duration of the turning, but their intensity varies with 
 these, and the central reactions to impulses of varying 
 degrees of strength, differ decidedly. If the rotation is 
 slow or if it comprise but a small arc of a circle, the 
 apparent reaction when rotation has ceased is nil. On 
 
62 THE LABYEINTH 
 
 the otlier hand, if the rotation is rapid and through a 
 number of turns, there is a manifest reaction when it 
 has ceased. In our opinion, however, there is no 
 ground for the belief that there exists an essential dif- 
 ference between the impulse aroused by the former and 
 that aroused by the latter. How, then, can we explain 
 the fact that rotation which is slow or lasts but a short 
 time calls forth no apparent reaction? We believe that 
 the static labyrinth is always active and responds to the 
 slightest rotation, for it is apparent that in reacting to 
 these slight turns this organ performs its usual func- 
 tion. The centres of the vestibular nerves, however, 
 have a degree of tolerance, which varies not only in dif- 
 ferent individuals, but at different times in the same 
 individual. It is established by a series of checks and 
 balances brought about by the influence of aU the cen- 
 tripetal impulses whose fimction it is to preserve our 
 equilibrium. So long then as the strength of an im- 
 pulse aroused in the labyrinth does not exceed this tol- 
 erance limit, the centres are able to accommodate them- 
 selves to it, and no apparent reaction occurs. As soon, 
 however, as such an impulse exceeds this tolerance limit 
 the checks and balances are no longer able to control, 
 and a manifest reaction supervenes. 
 
 Breuer, who in his experiments took no account of 
 nystagmus, believed that the sensation of turning when 
 rotation had ceased was dependent upon and synchro- 
 nous with the displacement of the cupula. Although 
 we accept the former hypothesis, the latter does not 
 agree with the facts. According to Barany, if we rotate 
 a number of individuals, the sensation of turning after 
 rotation has ceased varies in duration in different in- 
 
PHYSIOLOGY 63 
 
 stances despite the fact that the manner of rotating is 
 the same in each. If we carefully observe the nystag- 
 mus after rotation, we will frequently find that of two 
 individuals who have nystagmus lasting equally long, 
 one will have the sensation of turning synchronous with 
 his nystagmus, while the other feels little or no sensa- 
 tion of turning at all. Nystagmus is a far better indi- 
 cation of the stimulation of the cristse than is the turn- 
 ing sensation, for the former can be observed object- 
 ively. Thus the fact that in two cases the nystagmus 
 lasts equally long, while the duration of the turning 
 sensation is unequal, controverts Breuer's hypothesis. 
 Although we accept as a fact that so long as the cupula 
 is displaced there is a change in the normal centripetal 
 impulse, we cannot believe that the condition of the end- 
 organ is alone responsible for the duration of the reac- 
 tion. This is true as well for nystagmus as for the turn- 
 ing sensation. If we rotate an individual he will have a 
 far stronger reaction if we cease after ten turns, than 
 if we cease after thirty turns. This fact alone demon- 
 strates that the centres play an important part in con- 
 trolling the reactions to these peripheral stimuli. 
 
 In an exceedingly interesting recent communication 
 on this subject Shamhaugh takes the position that the 
 duration of nystagmus is coextensive with the periph- 
 eral stimulation, and that the latter lasts as long as 
 there is an endolymph current. 
 
 Before entering into a discussion of the effect of 
 endolymph movements upon the crista, it is necessary 
 to call attention to some anatomical peculiarities of 
 the latter, which have a bearing upon the physiology 
 of this organ. The crista is a comb-like hill of cells 
 
64 THE LABYEINTH 
 
 placed at right angles to the course of the canal. It is 
 composed of hair-cells held in place by supporting cells. 
 "While in many animals the hair-cells are absent in a 
 zone surrounding the apex of the crista, in man they 
 cover the latter from its base to its apex. Each hair- 
 cell has a number of cilia, which run free a short dis- 
 tance out of the cell, and then pass into canals in the 
 overlying gelatinous cupula. These canals are longer 
 than the contained hairs. Breuer and Kolmer state 
 that the cupula is apparently secreted by the support- 
 ing cells of the crista and is constantly wearing off at 
 its upper part. For this reason the canals are longer 
 than the hairs. 
 
 According to Cajal the nerves of the crista are not 
 uniformly distributed. The cells of the upper part are 
 far more richly supplied with nerve filaments than are 
 the cells of the remaining portions. This probably indi- 
 cates a greater functional activity of the upper cells. 
 Whether the nerves actually reach into the cells or 
 merely surround them is irrelevant, so far as the physi- 
 ology of the organ is concerned. For it is of no import 
 whether the stimulus reaches the nerve endings di- 
 rectly or is translated to them from the cells. 
 
 "With regard to the process through which stimula- 
 tion of the crista by endolymph movements is trans- 
 formed into nerve impulses, Breuer has developed an 
 interesting theory, which, while it does not satisfy all 
 objections to it, yet offers a working hypothesis and 
 goes far toward clarifying our views concerning the 
 physiology of this organ. Breuer assumes that a 
 movement of the endolymph which displaces the cupula 
 toward the utricle causes tension on the hairs of the 
 
PHYSIOLOGY 65 
 
 canal side of the crista and relaxes those of the utricu- 
 lar side. He assumes further that only tension on the 
 hairs develops a stimulus. If a rest tone, such as has 
 been described above, exists in the crista, then it fol- 
 lows that relaxation of the hairs, by disturbing this rest 
 tone, would also produce a stimulus. In man, the hair- 
 cells cover the entire crista, and the hairs of the cells 
 situated at the apex would be made tense whether the 
 cupula were moved toward or away from the utricle. 
 
 It is necessary, therefore, to assume that the hairs of 
 the apical cells react in such a way that, irrespective 
 of whether the cupula is moved toward the utricle or 
 away from it, tension arouses the central equivalent 
 of a movement in only one of these directions. Only 
 the corresponding central relations are necessary to 
 bring about such a state of affairs. In other words, 
 just as any stimulus to the retina arouses an impulse 
 which is always translated centrally into the sensation 
 of light, so tension on these hairs at the apex of the 
 crista, no matter how such tension is caused, arouses 
 the central equivalent of a movement of the endolymph 
 in only one direction. With this hypothesis it is easy 
 to explain the results of the classical experiments of 
 Ewald. The latter proved that while the mechanical 
 irritation remained the same, the intensity of the reac- 
 tion varied, depending upon the direction of the move- 
 ment of the endolymph, and therefore of the cupula. 
 Thus he showed that in the horizontal canal a movement 
 of the endolymph toward the ampuUa causes a reaction 
 about twice as strong as a movement toward the small 
 end. In the vertical canals (the superior and pos- 
 terior) the reverse of this is true, i. e., the movement of 
 
66 THE LABYEINTH 
 
 the endolymph toward the ampulla causes the weaker 
 reaction. 
 
 Let us examine these processes of stimulation for a 
 moment in the light of the foregoing hypothesis. Given 
 a movement of the endolymph in the horizontal semi- 
 circular canal toward the ampulla, there would follow 
 a displacement of the cupula toward the utricle. Here- 
 upon the hairs of the apex and of the canal side would 
 be made tense, while those of the utricular side would 
 be relaxed. Let us now assume that in the horizontal 
 semicircular canal, tension on the apical hairs of the 
 crista arouses the central equivalent of a movement of 
 the cupula only to'ward tbe utricle. Then the 
 central reaction to a movement of the cupula toward the 
 utricle would be the resultant of a stimulus from the 
 apex cells, plus that from the canal-side cells, minus 
 that from the utricular-side cells, provided, of course, 
 that relaxation of the hairs is capable of producing a 
 negative reaction. If we suppose the displacement of 
 the cupula to be away from the utricle, then the central 
 reaction would be the resultant of the stimulus from 
 the utricular-side cells, minus that from the apex cells 
 as well as that from the canal-side cells. If the peculiar 
 distribution of the nerves in the crista, as shown by 
 Cajal, has any physiological significance, i. e., if the 
 apex cells exercise proportionately a greater functional 
 activity than the cells of the rest of the crista, then we 
 have in this an additional cause for the fact that in the 
 horizontal semicircular canal a movement of the cupula 
 toward the utricle is followed by a far stronger reac- 
 tion than a movement in the opposite direction. It must 
 be apparent that in any group of hairs the impulse 
 
PHYSIOLOGY 67 
 
 aroused by tension (plus impulse) exceeds in strength, 
 that aroused by relaxation (minus impulse). 
 
 For the apex cells of the cristas in the vertical canals, 
 we must assume such central relations, that the impulse 
 aroused by tension on their cilia is translated centrally 
 into a movement of the cupula only away from the 
 utricle. 
 
 As has been stated above, every "disharmony" in 
 the impulses which serve to maintain our equilibrium 
 causes, if sufficiently pronounced, a marked disturbance 
 in balance. The character of this disturbance varies 
 with the physiological peculiarities of the end-organ in 
 which the ' ' disharmonic ' ' impulse arises. The function 
 of the static labyrinth is to acquaint us with our posi- 
 tion in space and with the changes in that position, i. e., 
 acceleration or retardation of motion in a straight line 
 and rotation. Under ordinary circumstances there are 
 constantly aroused with these perceptions of our posi- 
 tion and its changes, reflex stimuli, whose purpose it is 
 to cause the eye muscles and the body muscles to ac- 
 commodate themselves to the conditions that call forth 
 these perceptions. If, however, an impulse is aroused 
 in the labyrinth so strong that the central checks and 
 balances can no longer control, then there ensues a dis- 
 turbance of the equilibrium whose characteristics de- 
 pend upon the functional activities of this organ. Thus 
 there occur disturbances in our perception of position, 
 sensation of turning, along with disturbances of the eye 
 muscles (nystagmus), and disturbances in the body 
 muscles (reaction movements). Finally, if the impulse 
 is very strong, radiation from the central vestibular nu- 
 clei, in the floor of the fourth ventricle, to the vagus 
 
68 THE LABYBINTH 
 
 nuclei occurs and nausea and vomiting supervene. Such 
 a powerful impulse may be aroused in the semicircular 
 canals in various ways ; mechanically by rotation or by 
 air pressure if there be a fistula ; calorically by hot or 
 cold water or other fluids ; chemically by the application 
 of substances directly to the exposed membranous 
 canal; and electrically by the application of the gal- 
 vanic current. 
 
 Of the reactions which follow a strong impulse 
 aroused in the semicircular canals, the most important 
 by far, from a clinical standpoint, is nystagmus. 
 This may be defined as a rhythmic to-and-f ro motion of 
 the eyes, consisting of two components, a slow move- 
 ment in one direction, which is followed at once by a 
 rapid movement in the opposite direction. Although it 
 has been proven {Etvald, Bar any and others) that the 
 slow component is the vestibular reflex, the reaction has 
 been named according to the direction of the rapid 
 component. Thus we speak of nystagmus to the right 
 when the rapid component is directed to the right. 
 
 Ewald has shown that nystagmus always occurs in 
 the plane of that semicircular canal in which the im- 
 pulse calling forth the nystagmus arises. He proved 
 further that the slow component always takes the same 
 direction as the endolymph movement, or that the rapid 
 component takes a direction opposite to that of the 
 endolymph movement. 
 
 If a stimulus is aroused in the labyrinth during a 
 state of unconsciousness, only the vestibular reflex 
 (slow component) appears, while the voluntary reaction 
 (rapid component) is abolished. If we perform a ca- 
 loric test of a labyrinth upon a patient during narcosis 
 
PHYSIOLOGY 69 
 
 the eyes will deviate to the side, toward which the slow 
 component would be directed if there were a nystag- 
 mus. From the fact that the slow component is the ves- 
 tibular reflex, while the rapid component is influenced 
 by the will, it is easy to understand why the rapidity 
 of nystagmus is influenced by the direction in which the 
 eyes are fixed. The greater the effort to fix the eyes 
 in the direction of the rapid component, the more rap- 
 idly the eyes are drawn back after the conclusion of the 
 slow component. Barany observed that, when the eyes 
 were directed toward the side of the rapid component, 
 the slow movements were smaller but more frequent. 
 
 The rapidity of the nystagmus, however, depends 
 primarily upon the rapidity of the rapid component, 
 and not, as some hold, upon the resistance to the slow 
 component. If the resistance to the slow component 
 increased as the eyes were turned toward the side of 
 the rapid component, it would be impossible to explain 
 (1) that an artificially aroused nystagmus becomes ap- 
 parent first when the eyes are turned to the side of the 
 rapid component; (2) that after such a nystagmus is 
 aroused it may frequently be abolished by fixing the 
 eyes in the direction of the slow component; (3) that 
 spontaneous nystagmus may be abolished by directing 
 the eyes toward the side of the slow component. These 
 facts seem to us to prove that the resistance to the ves- 
 tibular reflex (slow component) increases as the eyes 
 are turned away from the side of the rapid component, 
 and that this resistance is greatest when the eyes are 
 directed to the side of the slow component. 
 
 In a way, this resistance gives us a gauge of the in- 
 tensity of the nystagmus. If the latter becomes appar- 
 
70 THE LABYRINTH 
 
 ent only when the eyes are turned to the side toward 
 which the rapid conaponent is directed, we speak of a 
 nystagmus of the first degree. If the nystagmus is 
 evident when the eyes are directed forward as well, 
 we speak of a nystagmus of the second degree, and if 
 the nystagmus is apparent even when the eyes are di- 
 rected toward the side of the slow component, we speak 
 of a nystagmus of the third degree. When nystagmus 
 is aroused artificially it becomes apparent first, as has 
 been mentioned, when the eyes are turned to the side 
 toward which the rapid component is directed. In the 
 extreme lateral positions of the eyes there are fre- 
 quently to be observed nystagmic movements which are 
 physiological. These are directed to the side toward 
 which the eyes are turned, are usually horizontal, but 
 sometimes rotatory, and are as a rule of short duration. 
 Since the rhythmic movements of the eyes in vestibu- 
 lar nystagmus result exclusively from the reflex stim- 
 uli aroused by vestibular irritation, they are most clear 
 when least influenced by voluntary, restraining move- 
 ments of the eyes. Thus they are most marked when 
 the eyes are closed or in individuals who are blind. 
 Fixing the vision may influence vestibular nystagmus 
 not only by causing accommodation but also by arous- 
 ing optical nystagmus. The former by the associated 
 convergence of the eyes causes one of them to turn 
 toward the side of the rapid component, while the other 
 takes the opposite direction. The latter (optical nys- 
 tagmus) is usually caused by an attempt to fix the 
 vision upon constantly changing objects, which have 
 the same relative position to the body and actually or 
 apparently move by. 
 
PHYSIOLOGY 71 
 
 The best example of this form of nystagmus is seen 
 in the eyes of an individual who looks out of the win- 
 dow of a rapidly moving car. In the presence of a ves- 
 tibular nystagmus, an optical nystagmus is aroused by 
 attempting to fix the vision upon an object situated to 
 one side or the other, which apparently moves by. This 
 results in a to-and-fro motion of the eyes which par- 
 allels the vestibular nystagmus. It must be apparent, 
 then, that if this optical nystagmus is directed to the 
 same side as the vestibular nystagmus, they accentuate 
 each other, while if the optical nystagmus is directed 
 opposite to the vestibular nystagmus they oppose each 
 other. 
 
 A vestibular nystagmus to the right begins with a 
 slow movement toward the left, which is followed at 
 once by a rapid movement to the right. The observa- 
 tions of Edgyes, which were substantiated by Bartels, 
 show that if all the ocular muscles, with the exception 
 of either the rectus internus or externus, be dissected 
 free from the bulb, the remaining muscle alone is ca- 
 pable of executing nystagmic movements in both direc- 
 tions. Bartels separated the muscles from the eye ball 
 and arranged an apparatus in such a way that each 
 muscle wrote for itself its contractions and relaxations. 
 Thus he showed that the rectus internus or externus of 
 either eye is capable of executing nystagmic movements 
 both to the right and to the left. 
 
 If we consider alone the activity of the rectus ex- 
 ternus of the right eye during a nystagmus to the right, 
 we find that the slow component to the left can occur 
 only through a slow relaxation of this muscle, while 
 the rapid component must result from a rapid contrac- 
 
72 THE LABTBINTH 
 
 tion. For the rectus internus, the reverse of this is 
 true, i. e., the slow component to the left results from 
 a slow contraction of this muscle, while the rapid com- 
 ponent to the right is due to a rapid relaxation. 
 Bartels has proven that these muscular phenomena 
 actually occur. The muscular activities of the left eye, 
 during a nystagmus, are the reverse of those that occur 
 in the right. Thus while during the slow movement to 
 the left, the right rectus externus slowly relaxes, the left 
 rectus externus slowly contracts. The eye ball in de- 
 scribing the slow component, starts from its position of 
 rest, so that if this movement to the left is executed in 
 the right eye by the rectus externus alone, there must 
 be an abolition of the normal rest-tone of this muscle 
 which results in an "active relaxation." 
 
 An endolymph movement in the right horizontal 
 semicircular canal which displaces the cupula toward 
 the utricle has, as a result, a nystagmus directed toward 
 the right. In order to produce the slow component of 
 this nystagmus the following muscular phenomena 
 must occur : 
 
 1. Slow relaxation of the rectus externus. 
 
 2. Slow contraction of the rectus internus. 
 
 Eight Eye 
 Left Eye 
 
 1. Slow contraction of the rectus externus. 
 
 2, Slow relaxation of the rectus internus. 
 
 According to Barcmy, the simultaneous contraction 
 of one set of muscles with the relaxation of the other 
 set can be considered of peripheral origin, provided we 
 accept the presence of a rest-tone in the cristae of the 
 canals. He believes, further, that from these muscular 
 phenomena he can deduce relations between definite 
 
PHYSIOLOGY 73 
 
 groups of hair cells and the central nuclei of individual 
 eye muscles. Whether this be true or not, and whether 
 the muscular mechanism of nystagmus is controlled en- 
 tirely by conditions in the peripheral organ (tension or 
 relaxation of the hairs) or is solely under the dominion 
 of the centres, one fact stands out clearly, viz., either 
 labyrinth is in relation with the central nuclei of the 
 muscles of both eyes, and a powerful impulse aroused 
 in one labyrinth, even after the complete destruction 
 of the opposite labyrinth, is capable of causing both 
 eyes to execute nystagmic movements in all planes, 
 and directed either to the sound side or to the other. 
 
 In addition to nystagmus, there are other phenomena 
 which result from powerful impulses aroused in the 
 semicircular canals. These reactions are partly sub- 
 jective and partly objective. The objective phenomena 
 (reaction movements) are so closely allied to 
 the cerebellar tests of Barany, that their further de- 
 scription wUl be deferred until the discussion of that 
 subject. The subjective phenomena consist of sensa- 
 tions, on the part of the individual in whom the semi- 
 circular canals are stimulated, of being turned himself 
 and of an apparent turning of the objects in his envi- 
 ronment. 
 
 These sensations bear a striking analogy to the nys- 
 tagmus, but are less uniform in their behavior than the 
 latter, and are therefore far less valuable as tests of 
 labyrinthine function. The sensation of turning varies 
 considerably in different individuals who have been 
 subjected to the same tests. In some it is quite marked, 
 while in others it is almost totally absent. It is felt 
 most clearly when the eyes are closed. As a rule the 
 
74 THE LABYEINTH 
 
 apparent turning of the body is in the direction of the 
 rapid component, and like the nystagmus is influenced 
 by the direction in which the eyes are fixed. If the 
 eyes are fixed in the direction of the rapid component 
 the turning sensation is increased. Fixing the eyes in 
 the opposite direction has, of course, the opposite ef- 
 fect. The apparent turning or passing by of objects in 
 the environment of an individual who has a vestibular 
 nystagmus also varies. As a rule the objects seem to 
 pass in the direction of the rapid component. Some- 
 times, however, they seem to oscillate, tip over or even 
 move in the direction of the slow component. The 
 manner in which objects seem to move is evidently the 
 result of the retinal impression, as a rule during the 
 progress of the slow component. 
 
 Van Rossem has carefully worked out the relation 
 between the sensation of being turned, the reaction 
 time, etc., and the speed of rotation, but as yet these 
 facts have not attained any clinical significance. 
 
 The disturbances in our sensation of position are 
 doubtless due to some extent, at least, to impulses from 
 the otolith organs as well as from the cristaB, particu- 
 larly if the labyrinth is stimulated by rotation. Here, 
 of course, the otolith membranes must be affected by 
 centrifugal force. 
 
 During a horizontal nystagmus, nausea, vomiting, dis- 
 turbances in the heart's action and in respiration rarely 
 occur, but they are not at all uncommon in the presence 
 of either a vertical or a rotatory nystagmus. Barany 
 has shown that sea-sickness, with its attendant symp- 
 toms, is largely due to the influence of the otolith 
 organs. Moreover neither Neumann nor Ruttin ob- 
 
PHYSIOLOGY 75 
 
 served nystagmus during sea-sickness, so that the semi- 
 circular canals probably play little or no part in this. 
 These facts seem to indicate a closer central relation- 
 ship between the vertical canals and the otolith organs, 
 than between the latter and the horizontal canals. 
 
 All the centripetal impulses, whose purpose it is to 
 maintain our equilibrium, are gathered together in the 
 cerebellum, so that the latter may be considered, in a 
 sense, the centre for the static labyrinth. There prob- 
 ably is no single, definite (static sense) centre upon 
 which all of the centripetal impulses exert their influ- 
 ences. The cerebrum must play a very subordinate 
 role in this static sense, however, for it has been en- 
 tirely removed in dogs without causing any loss of 
 equilibrium. On the other hand, removal of even half 
 the cerebellum results in very decided loss of balance. 
 
 The cerebellum may be considered as a sensory-motor 
 subcortical central organ. It receives centripetal im- 
 pulses from the static labyrinth, sensory impulses from 
 the muscles and joints and visual impulses from the 
 eyes, and it sends out motor impulses to the muscles of 
 the head, trunk and extremities, the purpose of which 
 is to maintain the equilibrium of the body. 
 
 All of the motor impulses, however, which have for 
 their purpose the maintenance of the body equilibrium, 
 do not originate in the cerebellar cortex. Some of the 
 movements are more or less under the dominion of 
 the will, and these originate in the motor area of the 
 cerebral cortex. The impulses which arouse these move- 
 ments, however, pass through the cerebellar cortex on 
 their way down to the spinal cord. In the cerebellar cor- 
 tex they meet the centripetal impulses from the static 
 
76 THE LABYBINTH 
 
 labyrintlas, the muscles, the joints and the eyes, and are 
 there acted upon in such a way as to become effective in 
 maintaining the equilibrium of the body. According to 
 LewandowsJty , the function of keeping the body in a 
 condition of equilibrium may be described as that com- 
 bined action of the muscles of the extremities, trunk, 
 head and eyes which results in the holding of the body 
 in an upright symmetrical position, in the possibility 
 of moving about in certain planes and directions, and 
 in the compensation for passive rotation of the head 
 and body. 
 
 The connections between the static labyrinth and the 
 cerebellum, between the joints and muscles and the 
 cerebellum, and between the cerebral cortex and the 
 cerebellum have been carefully worked out. 
 
 Impulses from the vestibule and semicircular canals 
 pass through the vestibular nerve to Deiters' nucleus. 
 From Deiters' nucleus a pathway leads to the corpus 
 dentatum of the cerebellum, and from here to the cor- 
 tex of the worm and cerebellar hemispheres of both 
 sides. 
 
 Sensory impulses from the muscles and joints pass 
 into the spinal cord through the posterior nerve roots, 
 where the fibres terminate about the cells in Clarke's 
 and Stilling 's columns at the base of the posterior 
 horns. From these cells fibres pass up through the 
 lateral tracts of the cord in Flechsig's and Gower's 
 columns. These fibres reach the central nuclei of the 
 cerebellum through the inferior cerebellar peduncles. 
 From the central nuclei fibres reach the cerebellar 
 cortex. 
 
 From the motor cortex of the cerebrum impulses 
 
PHYSIOLOGY 77 
 
 pass down through the internal capsule and the crura 
 cerebri to the pons. Here collaterals are given off, 
 which terminate in the pontine gray matter. From the 
 latter, fibres pass across through the middle cerebellar 
 peduncle to the cerebellar cortex of the opposite side. 
 From the cerebellar cortex, according to Lewandowsky, 
 motor impulses pass down in two ways : 1. From the 
 cortex of the cerebellar hemispheres to the dentate nu- 
 cleus. From here through the brachium conjunctivum 
 to the red nucleus of the tegmentum of the opposite 
 side. From here fibres pass down through Monakow's 
 bundle, across to the opposite lateral tract of the spinal 
 cord, where they terminate about the anterior horn 
 cells. 2. From the cortex of the cerebellar worm to the 
 nucleus tecti. From here through the tractus uncinatus 
 to Deiters' nucleus and the ventro-caudal Deiters' of 
 the opposite side. From here, impulses pass down 
 through the Deiterso-spinal tract and the posterior 
 longitudinal bundle of the cord to the anterior horn 
 cells. 
 
 Thus it is seen that the cerebellar hemispheres are 
 connected with the anterior horn cells of the same side 
 of the spinal cord. 
 
 Impulses reach Purkinje's cells in the cerebellar cor- 
 tex, from the vestibular apparatus, muscles and joints, 
 through the intermediation of the cells of the granular 
 layer. The axis-cylinder processes of the granule cells 
 are distributed to a large number of Purkinje cells. 
 The Purkinje cells are further joined together by means 
 of the basket cells. In this way each impulse from the 
 static labyrinth is transmitted to a large number, or 
 possibly even all of the Purkinje cells. On the other 
 
78 THE LABYKINTH 
 
 hand, the impulses from the cerebrum reach Purkinje's 
 cells through the so-called "fibres grimpantes," one of 
 which goes to only one Purkinje cell. This connection 
 is therefore strictly individualized. From Purkinje's 
 cells the impulses pass down through the motor tracts 
 to the anterior horn cells of the spinal cord. 
 
 The pathways concerned in the nystagmus reflex are 
 as follows: from the static labyrinth impulses pass 
 through the vestibular nerve to Bechterew's and the 
 ventro-caudal Deiters' nucleus. From here impulses 
 pass to the posterior longitudinal fasciculus of both 
 sides, the fibres of which pass up through the pons and 
 mid-brain, where they terminate about the nuclei of the 
 third, fourth and sixth cranial nerves. Through these 
 nerves impulses pass to the ocular muscles. 
 
 The pathways through which reaction movements of 
 the body and the extremities are intermediated, are not 
 so direct, since the cerebellar cortex is involved in this 
 circuit. The pathways for the reaction movements of 
 the extremities differ in part of their course from those 
 for the reaction movements of the body. Impulses for 
 the reaction movements of the extremities pass from 
 the static labyrinth through the vestibular nerve, to 
 Deiters' nucleus and the ventro-caudal accessory nu- 
 cleus. From here they pass through the dentate 
 nucleus to the cortex of the cerebellar hemispheres. 
 From here they pass through the brachium conjuncti- 
 vum to the red nucleus of the tegmentum of the oppo- 
 site side. From here they pass through Monakow's 
 tract to the lateral colurons of the cord on the opposite 
 side, where they terminate about the anterior horn 
 cells. 
 
PHYSIOLOGY 79 
 
 Impulses for reaction movements of tlie body pass 
 from the static labyrinth, through the vestibular nerve, 
 to Deiters' nucleus. From here they pass to the cortex 
 of the cerebellar worm. They then pass down to the 
 nucleus tecti, from which fibres pass through the 
 tractus uncinatus, to Deiters' nucleus and the ventro- 
 caudal nucleus of the opposite side. From here they 
 pass through the Deiterso-spinal tract to the anterior 
 horn cells, which send the impulses to the muscles of 
 the body. 
 
 The voluntary element of the reaction movements 
 reaches the cerebellar cortex by way of collaterals 
 which are given off from the motor tract as it passes 
 through the pons. These collaterals terminate about 
 cells in the pontine gray matter. These cells send 
 neurons through the middle cerebellar peduncles to the 
 cerebellar cortex. 
 
 PKYSIOIiOGY OF THE COCHLEA 
 
 The cochlea is the end-organ which is concerned in 
 the sensation of hearing. Just how the cochlea utilizes 
 the sound waves, and transforms them into impulses 
 which are perceived as sound is not definitely known. 
 Our knowledge in this field is based entirely upon 
 theoretical considerations. 
 
 All are agreed that the sound waves are taken up in 
 some way by the hair cells of the organ of Corti, and 
 transformed by them into nerve impulses, which pass 
 through the fibres of the cochlear nerve to the cortex 
 of the temporo-sphenoidal lobe of the brain, where they 
 are recorded as sensations of sound; but here the 
 
80 
 
 THE LABYBINTH 
 
 unanimity of opinion ends. There are innumerable 
 theories as to how the sound waves are imparted to the 
 hair-cells, and as to whether the analysis of sound 
 occurs in the cochlea, or in the cortex of the brain. 
 
 The majority of physiologists and otologists seem to 
 be of the opinion that the sound analysis occurs in the 
 cochlea. In support of this theory are the following 
 facts : the extreme complexity of the cochlea, with the 
 many thousands of hair cells and nerve fibres ; the oc- 
 currence of tone islands, i. e., the absence of hearing 
 for certain notes when portions of the cochlea are dis- 
 eased; the occurrence of diplacusis, i. e., the double 
 hearing of a single tone analogous to double vision; 
 and the experiments of Wittmaack, Siehenmann and 
 YosMi, who showed that certain definite portions of the 
 cochlea degenerated in animals, as the result of ex- 
 posing them for a long time to a continuous sound of a 
 certain pitch. 
 
 One of the oldestj and perhaps the most widely ac- 
 cepted of the theories which postulate peripheral sound 
 analysis, is the resonator theory of Eelmholtz. Helm- 
 holts' s theory of hearing is as follows: The molecular 
 air vibrations of sound, on reaching the membrana tym- 
 pani, are transformed into molar or mass vibrations. 
 The membrana tympani is so constructed that it vi- 
 brates equally well for all tones. That is, it is not 
 attuned to any special tone which it will pick out and 
 magnify. From the membrana tympani the vibrations 
 are carried through the three ossicles to the foot-plate 
 of the stapes, by which the impulse is imparted to the 
 perilymph in the vestibule. Since the perilymph fluid 
 is much more dense than air, it is necessary for the 
 
PHYSIOLOGY 81 
 
 sound vibrations to be increased in intensity, in order 
 to produce adequate stimulation of the hair cells. In 
 increasing the intensity the extent of the oscillations is 
 diminished. 
 
 It is the function of the membrana tympani and the 
 ossicular chaia to transform oscillations of slight iaten- 
 sity and large range into oscillations of greater inten- 
 sity and lesser range. This is brought about in three 
 ways : first by the difference in size between the mem- 
 brana tympani and the foot-plate of the stapes, the 
 former being many times larger than the latter. The 
 impulse which is imparted to the large surface of the 
 membrana tympani is concentrated onto the smallei? 
 surface of the foot-plate of the stapes, and is conse- 
 quently increased in intensity. Second, the handle of 
 the hammer is half again as long as the vertical process 
 of the incus. The shortening of this lever again in- 
 creases the intensity of the force. Finally, the shape 
 of the membrana tympani has a similar effect. The 
 drum membrane is shaped like a funnel, at the apex of 
 which is the end of the hammer handle. The sides of 
 the funnel are curved, the convexity being directed out- 
 ward. When an impulse is imparted to the convex 
 membrane the latter has a tendency to flatten. The 
 impulse is transmitted to the apex of the funnel, where 
 the movement is diminished in extent and increased in 
 force. 
 
 The foot-plate of the stapes transmits the impulse to 
 the perilymph fluid in the vestibule. The impulse 
 passes through the perilymph in the scala vestibuli to 
 the apex of the cochlea, where it passes through the 
 helicotrema to the scala tympani. It then passes down 
 
82 
 
 THE LABYBINTH 
 
 through the scala tympani to the round window, where 
 it sets into vibration the secondary tympanic mem- 
 brane. 
 
 From the perilymph in the scala vestibuli and tym- 
 pani the impulse is transmitted to the endolymph in 
 the ductus cochlearis through Eeissner's membrane 
 and the basilar membrane. 
 
 If a note is struck on a piano, and there is in the 
 vicinity another string of the same length as the piano 
 string which was struck, this second string will vibrate 
 in harmony with the first. Each tone has a string of a 
 certain length which can be made to vibrate in harmony 
 with it. The higher the pitch of the tone, the shorter is 
 the string which is made to vibrate in harmony with it. 
 Columns of air can be made to vibrate in harmony with 
 a tone in the same way as strings. Cylinders, which 
 contain such columns of air, are called resonators, and 
 are used to intensify the volume of tones. 
 
 The membrana basilaris, although a membrane, can 
 be considered a series of strings, as it consists of radi- 
 ating fibres bound together by a soft, interfibrillary 
 substance. The fibres pass from the bony spiral lamina 
 to the ligamentum spirale. It is estimated by Basse 
 and Retsius that there are from 15,000 to 25,000 fibres 
 in the basilar membrane. They are shortest at the 
 beginning of the basal whorl and gradually become 
 longer toward the apex of the cochlea. According to 
 Hensen they are 0.041 mm. long at the base and 0.495 
 mm. long at the apex of the cochlea. In other words, 
 they are twelve times as long atlhe apex as at the base. 
 HelmhoUs considered that each one of the fibres can 
 vibrate independently of all the rest. Each fibre vi- 
 brates in harmony with a certain tone. When the vibra- 
 
PHYSIOLOGY 83 
 
 tions causing a certain tone are carried to the peri- 
 lymph, the fibre which is in harmony with that tone is 
 set into vibration. The vibration is transmitted to the 
 hair-cells overlying this fibre, and converted by the 
 hair-cells into nerve impulses, which are carried by the 
 fibres of the cochlear nerve to the brain. There are as 
 many nerve fibres as there are hair-cells. Thus each 
 nerve fibre always transmits the impulse aroused by 
 the same tone. 
 
 In reality Helmholtz did not consider that one fibre 
 vibrated with each tone, but that a group of fibres was 
 set into vibration, the central fibre vibrating strongest, 
 and the vibration gradually diminishing in the fibres on 
 either side. The vibration of the central fibre is so 
 much stronger than the others that the tone to which 
 it corresponds predominates. 
 
 The fibres at the base of the cochlea, being the short- 
 est, intermediate the highest tones, and those at the 
 apex, being the longest, intermediate the lowest tones. 
 The normal range of hearing is from 16 double vibra- 
 tions to 40,000 double vibrations per second. 
 
 Ewald believed that the fibres of the membrana basi- 
 laris do not vibrate individually, but that the entire 
 membrane vibrates as a whole. He stretched a rubber 
 membrane, shaped about like the basilar membrane, on 
 a wooden frame, and imparted the vibrations of tuning 
 forks to it. By coating the rubber with oil, he was 
 enabled to see the waves of vibration on the membrane. 
 Each tone gave rise to standing waves of certain shape, 
 which were constant. The higher tones gave rise to 
 narrow waves, which were close together, and the lower 
 tones to broader waves, which were further apart. 
 
84 THE LABYRINTH 
 
 There is a certain "vibration picture" for each tone. 
 Ewald believed that such vibration pictures occur on 
 the basilar membrane, and that all the hair cells at the 
 apices of the waves being stimulated, gave rise to the 
 sensation of hearing for that tone. 
 
 Barth believes that sound waves are transmitted to 
 the perilymph fluid, not as mass movements but as 
 molecular movements. Whether the oscillations which 
 are transmitted through the membrana tympani and 
 ossicles are molecular or molar is doubtful, but sound 
 waves are unquestionably transmitted to the perilymph 
 directly through the bones of the skull in the form of 
 molecular motion, although part of this motion is im- 
 parted to the membrana tympani and reaches the peri- 
 lymph through the ossicular chain. 
 
 Barth believes that the acoustic nerve impulses are 
 not produced by a movement of the hairs of the hair 
 cells with the movement of the endolymph, but by the 
 resistance offered by the hairs to the movement of the 
 endolymph. 
 
 It is not probable that the vibration is transmitted 
 directly to the hair-cells from the. endolymph without 
 intermediation, for there is no apparent difference be- 
 tween the individual hair-cells such as would make it 
 probable that each cell would respond to a different 
 tone. 
 
 Basse, Siebenmann, Von Stein, Kishi, Hardesty and 
 Shambaugh believe that it is not the basilar membrane 
 but the membrana tectoria whose vibrations stimulate 
 the hair-cells. Shambaugh found that in parts, the basi^ 
 lar membrane was so thick and rigid that it could not 
 possibly vibrate. 
 
PHy BIOLOGY 85 
 
 At the beginning of the basal whorl he found it ab- 
 sent, although there was a perfectly formed Corti's 
 organ present here. The vas spirale is attached to the 
 lower surface of the basilar membrane. As this vessel 
 is sometimes dilated and at other times contracted, it 
 must change the resonating quality of the radiating 
 fibres of the basilar membrane, from time to time, so 
 that the same fibre is not always attuned to a tone of 
 the same pitch. 
 
 In order to overcome these objections, Shambaugh 
 has assumed the tectorial membrane to be the vibrating 
 organ. The impulse is transmitted directly from the 
 scala vestibuli through Eeissner's membrane to the tec- 
 torial membrane. The tectorial membrane lies directly 
 over the hair cells, the hairs being imbedded in the sub- 
 stance of the membrane. In this way movement of the 
 tectorial membrane is imparted directly to the hairs of 
 the hair cells. This theory brings the action of the 
 end-organ in the cochlea into harmony with the action 
 of the end-organs in the vestibule and semicircular 
 canals. The otolith-membrane in the vestibule, the 
 cupula in the ampullae of the semicircular canals, and 
 the tectorial membrane in the organ of Corti all overlie 
 the hair-cells. 
 
 The hairs are embedded in these membranes, and 
 movement in the membranes is imparted directly to the 
 hairs. The tectorial membrane varies in size at differ- 
 ent parts of the cochlea, being smallest at the begin- 
 ning of the basal whorl and largest at the apex of the 
 cochlea. 
 
 Rutherford considered that the entire basilar mem- 
 brane vibrated with every tone, very much as the disc 
 
86 THE LABYRINTH 
 
 of a telephone receiver vibrates. Each tone is carried 
 to the brain by all of the nerve fibres of the cochlear 
 nerve, and the sound analysis takes place in the brain. 
 This is known as the telephone theory. 
 
 W. S. Bryant supports this theory of central analysis 
 by a report of twenty-six ears collected from the litera- 
 ture in which functional tests were made, and, after 
 death, complete histological examinations. In these 
 cases there was no uniformity in the relationship be- 
 tween the tones that were not heard and the portions 
 of the cochlea which were diseased. 
 
 In contradiction to these findings, however, are the 
 results of experiments made on animals by Wittmaack, 
 Siehenmann and Yoshii. They subjected guinea-pigs 
 to the hearing of the same tone repeated over and over 
 again, through a long period of time. The animal was 
 then killed and the cochlea examined histologically. In 
 these animals, where a tone of high pitch was employed, 
 there were regularly found degenerative changes in 
 
 ^ 
 
 Diagrams Iixustrating Poetions of Cochlea Showing Degenerative 
 Changes in Sibbenmann's Experiments With Guiotia-pigs, 
 Exposed to the Continuous Sound of a Tuning Fork 
 C— Shaded portion indicates re- tive changes when f fork 
 
 eion showing degenera- la used 
 
 tive changes when C fork ^—Shaded portion indicates re- 
 is used 5}°^ showing degenera- 
 f— Shaded portion indicates re- tive changes when g fork 
 gion showing degenera- is used 
 
PHYSIOLOGY 87 
 
 Corti's organ in the basal whorl of the cochlea. Where 
 a low-pitched tone was used, the degenerative changes 
 appeared in the upper whorls. 
 
 Siebenmann exposed a guinea-pig to the sound of a 
 C° whistle for several hours each day during several 
 months. On examining the cochlea he found degenera- 
 tive changes in the organ of Corti in the basal whorl 
 (Fig. 23). In a guinea-pig which was subjected to the 
 tone of the F^ whistle, degeneration was found in the 
 middle whorl. In a guinea-pig subjected to the tone of 
 a Gt pipe the changes were found in the upper whorl. 
 That these degenerative changes were not accidental 
 nor due to post-mortem changes was proven by the 
 fact that the same changes were found repeatedly, in 
 different guinea-pigs, when exposed to sound of the 
 same pitch. 
 
CHAPTEE III 
 
 METHODS OF EXAMINATION 
 
 The fxmctional examination of tlie static labyrinth 
 may be divided into two parts : 
 
 1. The determination of the presence or absence of 
 signs and symptoms which indicate a loss, a diminution 
 or an increase in the normal impulses from the static 
 labyrinth (decompensation symptoms). 
 
 2. The determination of the condition of the static 
 labyrinth by observation of certain reflexes, which are 
 elicited by physiological stimulation of the end-organs 
 in the semicircular canals. 
 
 The first portion of the examination consists in the 
 recognition of symptoms which are already present. 
 In the second portion of the examination we produce 
 reactions to stimuli, by which we determine the effi- 
 ciency of the static labyrinth. 
 
 Disturbance in the function of the static labyrinth 
 manifests itself by certain objective signs and subjec- 
 tive symptoms. The objective signs are a spontaneous 
 nystagmus and reaction movements. The subjective 
 symptoms are a sensation of rotation of surrounding 
 objects, and of the body itself, and sometimes nausea 
 and vomiting. 
 
 The normal physiological stimuli which are aroused 
 in the static labyrinth during ordinary movements 
 of the body do not elicit any visible reflexes, as far 
 as we can determine by examination. But if these 
 physiological stimuli are increased in intensity there 
 
METHODS OP EXAMINATION 89 
 
 result reflex movements in the eye muscles, and in tlie 
 muscles of the body and extremities. The reflexes of 
 the eye muscles are called nystagmus, and those of the 
 muscles of the body and extremities are called reaction 
 movements. Failure to elicit these reflex movements 
 by means of adequate stimuli, means that the end- 
 organs in the semicircular canals have been impaired 
 or destroyed. An increase or a diminution in the ease 
 with which these reflexes can be aroused, as compared 
 with a normal individual, indicates a condition of in- 
 creased or diminished irritability, respectively, of the 
 end-organs in the semicircular canals. An increase or 
 diminution in the intensity or duration of the reflex 
 aroused may be interpreted in the same way. 
 
 "We wiU first consider the second method of examina- 
 tion of the static labyrinth, namely, by arousing reflex 
 movements in the muscles of the eyes (nystagmus), and 
 of the body and extremities (reaction-movements). 
 
 A study of the nystagmus reflex is of more value than 
 that of the reaction-movements. When properly elic- 
 ited, nystagmus is a pure reflex, uninfluenced by the 
 will, whereas in the reaction movements there is usually 
 a considerable voluntary element. Besides, nystagmus 
 can be elicited by a much weaker stimulus than is re- 
 quired to arouse reaction-movements, and therefore 
 entails less discomfort to the patient. 
 
 These reflexes for the purpose of testing the function 
 of the semicircular canals may be elicited by four dif- 
 ferent methods : 
 
 1. By rotation (rotation- test). 
 
 2. By irrigation of the ear with cold or hot water 
 (caloric test). 
 
90 THE LABYRINTH 
 
 3. By means of the galvanic current (galvanic test). 
 
 4. By compression or aspiration of the air in the ex- 
 ternal auditory canal (fistula test). 
 
 The actual manner of stimulation of the end-organs 
 in the semicircular canals is probably the same in all 
 four methods. It consists in the production of a move- 
 ment in the endolymph in the semicircular canals, which 
 causes a displacement of the cupula. The latter drags 
 on the hair-cells. The endolymph movements caused 
 by these tests are much more violent than those which 
 take place in ordinary movements of the body. 
 
 In the rotation test, the endolymph movement is 
 caused by the inertia of the endolymph at the beginning 
 of rotation of the body, and the momentum which the 
 fluid possesses, when the rotation of the body ceases. 
 In the caloric test, the endolymph movement is caused 
 by differences in the specific gravity of cold and warm 
 portions of the endolymph. In the galvanic test, the 
 endolymph movement is supposed to be the result of 
 kataphoresis. In the fistula test, the endolymph move- 
 ment is the result of displacement by direct air- 
 pressure and suction. 
 
 Our tests are applied to the semicircular canals only, 
 since we assume that when they are diseased, the ves- 
 tibule is diseased also. We have no means of experi- 
 mentally exciting the vestibular end-organs. 
 
 The four tests above mentioned can be performed so 
 as to give us either qualitative or quantitative knowl- 
 edge. Thus we are enabled to determine, first, the pres- 
 ence or absence of any function, and second, if function 
 be present, its degree. The information given by the 
 qualitative tests is very definite. Quantitative tests tell 
 
METHODS OF EXAMINATION 91 
 
 US whether the labyrinth is in a condition of irritation 
 or of depression, and give us a measure of this impair- 
 ment of function. Unfortunately, these data are not 
 very reliable, because there are so many inconstant 
 factors which enter into the production of these re- 
 flexes. Some of these factors we will mention in the 
 description of the various tests. Many of the factors 
 we are completely ignorant of. However, as our knowl- 
 edge of the functions of the labyrinth increases, we will 
 learn to control these factors in such a way that our 
 quantitative tests will be, in reality, quantitative. 
 
 The value of quantitative tests lies in the fact that 
 they enable us to make an early diagnosis of intra- and 
 para-labyrinthine lesions; to determine the improve- 
 ment or aggravation of the disease; and finally, for 
 comparison, in scientific publication. 
 
 Quantitative determination of the irritability of the 
 static labyrinth is made in one of three ways : 
 
 1. By determining the strength of irritation which is 
 necessary to arouse nystagmus. This is called by the 
 Germans the determination of the "Reizschwelle." In 
 the rotation test, the strength of irritation is measured 
 by the number of rotations of the body necessary to 
 arouse an after-nystagmus. In the caloric test, it is 
 measured by the time from the beginning of irrigation 
 to the onset of the nystagmus, or by the amount of 
 water, at a constant temperature, used to bring on nys- 
 tagmus. In the galvanic test, it is measured by the 
 strength of current necessary to produce nystagmus. 
 
 2. By determining the duration of nystagmus, with a 
 constant strength and duration of the irritation. It is 
 questionable whether the duration of the nystagmus is 
 
92 THE LABYEINTH 
 
 proportional to the intensity of the irritation. Baranif 
 thinks that the duration of the nystagmus depends upon 
 the amount of energy which is stored up in the central 
 nuclei of the vestibular nerve. He thinks the stimulus 
 aroused by the irritation causes the centre to unload 
 its store of energy, and that the nystagmus continues 
 until the centre is emptied of its energy. 
 
 3. By determining the intensity of the nystagmus, 
 with a constant strength and duration of the irritation. 
 The intensity of the nystagmus aroused by one laby- 
 rinth is measured by attempting to neutralize it by 
 means of a nystagmus in the opposite direction, which 
 is elicited from the opposite labyrinth. If one laby- 
 rinth is less irritable than the other, there wiU be a 
 nystagmus toward one or the other side (depending 
 upon the form of stimulation), when the same stimulus 
 is applied simultaneously to both sides. This compara- 
 tive test can be performed only by the caloric and gal- 
 vanic methods of irritation, for in the rotation test the 
 irritation of one labyrinth does not oppose, but re- 
 enforces that of the opposite labyrinth. 
 
 The comparative tests are made either between the 
 two ears of the same person, simultaneously or succes- 
 sively, or between the suspected ear and the ear of a 
 normal individual. 
 
 THE ROTATION- TEST 
 
 If a person is rotated about a vertical axis which 
 passes through his own body there will be elicited cer- 
 tain reflex movements of the eyes and body. These 
 reflexes are the result of endolymph movements in the 
 semicircular canals. The character of the reflexes de- 
 
METHODS OP EXAMINATION" 93 
 
 pends upon the direction of rotafion, and the position 
 of the head. The strongest endolymph movement is 
 set up in those semicircular canals which lie in the hori- 
 zontal plane. The greater the angle which the canals 
 form with the horizontal plane the less will their endo- 
 lymph contents be acted upon by rotation about a ver- 
 tical axis. When a canal lies in the vertical plane its 
 contents are not affected at all. 
 
 The various canals are tested by placing the head in 
 such a position that the canals to be examined lie in 
 the horizontal plane. 
 
 At the beginning of rotation there is an endolymph 
 movement in a direction opposite to the rotation, as a 
 result of the inertia of the fluid. This causes a nystag- 
 mus, the slow component of which is in the direction 
 opposite to the rotation of the body. After a few ro- 
 tations at uniform speed, the endolymph moves at the 
 same rate of speed as the body. It is then at rest in 
 relation to the body, and the nystagmus ceases. When 
 the rotation is stopped, the endolymph, having acquired 
 a certain momentum, keeps on moving for a short time, 
 in the direction in which the body was rotated. This 
 causes an after-nystagmus, the slow component of 
 which is in the direction of rotation ; in other words, an 
 after-nystagmus opposite to the direction of the rota- 
 tion. 
 
 To take a concrete example, we will place the head in 
 an upright position. This places the external semicir- 
 cular canals approximately in the horizontal plane. If 
 the body is rotated to the left there will result, at first, 
 an endolymph movement to the right in both external 
 semicircular canals (Fig. 24). This will cause a hori- 
 
94 
 
 THE LABYEINTH 
 
 ^1/V'X/**'^ 
 
 Fio. 24 
 Rotation op Body to Left, With Head Upright 
 iJfl — ^Right external semicircular TJ — ^Utricle 
 
 canal A — Ampulla 
 
 LH — ^Left external semicircular 
 canal 
 The arrow within the canal shows the direction of the endolymph 
 current 
 
 The straight arrow, outside of the diagram, indicates the direction 
 of rotation of the body 
 
 The wavy arrow indicates the direction of the nystagmus 
 
 zontal nystagmus to the left. When the rotation is 
 stopped the endolymph keeps on moving to the left for 
 a short time (Fig. 25). This will give rise to a hori- 
 zontal after-nystagmus to the right. 
 
 /vwvw>^ 
 
 Fio. 25 
 
 Aftee-Ntstagmus, Which OccxrBS on Stopping, Aftee Rotation 
 
 to the Lett 
 
 The nystagmus during rotation is in the direction of 
 
METHODS OP EXAMINATION 95 
 
 the rotation ; the after-nystagmus is in a direction oppo- 
 site to that of the rotation. 
 
 In performing the rotation test at least two canals 
 are always acted upon at the same time. As the direc- 
 tion of the endolymph current in the two external semi- 
 circular canals is the same, during the rotation of the 
 body, the nystagmus produced by one horizontal canal 
 re-enforces that produced by the other. 
 
 In performing the rotation test observation of the 
 nystagmus during turning is attended with such diffi- 
 culty that we discard it, and rely entirely upon observ- 
 ing the after-nystagmus. 
 
 In the succeeding descriptions, therefore, we will dis- 
 regard the nystagmus during rotation, and consider 
 only the after-nystagmus. 
 
 The external semicircular canal does not lie exactly 
 in the horizontal plane, but is tilted about 30° down- 
 ward and backward, when the head is in the upright 
 position. In order to bring the canal into the horizon- 
 tal plane for the rotation test, the head should be tilted 
 about 30° forward (Fig. 26). This brings the superior 
 and posterior canals into the vertical plane. The endo- 
 lymph in these two canals is therefore not influenced 
 by the rotation. As the nystagmus is parallel to the 
 plane of the semicircular canal which causes it, we will 
 have a purely horizontal nystagmus, when the head is 
 tilted 30° forward. 
 
 The rotation test can be performed in one of two 
 ways: 
 
 1. The person is rotated a certain number of times 
 at a constant rate of speed, and the duration of the 
 after-nystagmus is noted. 
 
96 THE LABYBINTH 
 
 2. The mimber of rotations whicli is required to cause 
 the onset of an after-nystagmus is noted. In this 
 method the patient is rotated once, and after-nystag- 
 mus is watched for. If it does not appear he is rotated 
 twice, and again observed. In this way the number 
 of rotations is increased until an after-nystagmus 
 appears. 
 
 In the first method the person is rotated ten times. 
 Barany found that ten rotations give the maximum 
 amount of after-nystagmus. If the rotations are in- 
 creased beyond this number the after-nystagmus dimin- 
 ishes in duration. He also found that in a normal indi- 
 vidual ten rotations, at the rate of about 2" for each ro- 
 tation, give rise to an after-nystagmus which lasts from 
 20" to 40". There are considerable variations between 
 different individuals, between the two sides of the same 
 individual, and in the same individual on different 
 days. 
 
 The rotation test is used in order to compare the two 
 labyrinths. We are enabled to do this because of the 
 fact that in the external canals, stimulation caused by 
 displacement of the cupula toward the utricle is greater 
 than that caused by displacement of the cupula away 
 from the utricle, and in the vertical canals, stimulation 
 caused by displacement of the cupula toward the utricle 
 is less than that caused by displacement of the cupula 
 away from the utricle. 
 
 These facts are made use of in the following way : 
 
 With the head vertical, or tilted 30° forward, the pa- 
 tient is rotated 10 times to the left, at a constant rate 
 of speed. When the rotation is stopped the endolymph 
 keeps moving to the left for a short while. This causes 
 
METHODS OP BXAMINATIOM- 
 
 97 
 
 an after-nystagrmis to the right, lasting 20" to 40", if 
 the right labyrinth is normal (Fig. 25). He is then 
 rotated 10 times to the right. On stopping, the endo- 
 
 TSta. 26 (A) 
 
 Fio. 26 
 
 Fio. 26 (b) 
 
 Plane op Extebnal SEMicmcuLAB Caitai., With Head Yebtical, and 
 
 With Head Tilted 30° Foewaed 
 
 E — ^External semicircular canal 
 
 lymph continues to move to the right for a short time. 
 This gives rise to an after-nystagmus to the left, last- 
 ing 20" to 40", if the left labyrinth is normal (Fig. 27). 
 
 Fig. 27. 
 Afteb-Ntstagmbs to the Left, Following Botation to the Right 
 
 Let US now assume that the right labyrinth is not 
 functionating. The results will then be as follows : 
 
 After rotating the patient 10 times to the left, the 
 endolymph continues to move to the left for a short 
 
98 
 
 THE LABTBINTH 
 
 time. This will cause an after-nystagmus to the right. 
 The duration of this after-nystagmus is short, because 
 the displacement of the cupula in the left external canal 
 is away from the utricle (Fig. 28). Occasionally there 
 is no after-nystagmus whatever. 
 
 yxA> 
 
 Pig. 28 
 
 Right External Semicibculab Canal is Non-Punctionatesto. Eota- 
 TioN TO Left Causes Short After-Nystagmus to Eight 
 
 After rotating 10 times to the right the endolymph 
 continues to move to the right for a time. This causes 
 an after-nystagmus to the left, which lasts a compara- 
 tively long time, because the cupula in the left semi- 
 circular canal has been displaced toward the utricle 
 (Fig. 29). 
 
 .^IA/VV(W\. 
 
 Pig. 29 
 
 Eight External Semicibculab Canal is Non-Punctionating. Eota- 
 TioN TO Eight Causes Long After-Nystagmus to Left 
 
METHODS OF EXAMINATION 99 
 
 The labyrinth on the side opposite to the direction of 
 rotation is stimulated strongest when the rotation is 
 stopped. 
 
 The labyrinth on the side toward which the nystag- 
 mus is directed is stimulated strongest. 
 
 A marked difference in the duration of the after- 
 nystagmus following rotation to the right and to the 
 left indicates that the canal of one side is not func- 
 tionating. The difference must be more than double 
 in order to be of diagnostic value. Often the difference 
 is even greater than this. The after-nystagmus in one 
 direction may be only 4" or 5", while that in the oppo- 
 site direction is 20" or 25". 
 
 After-nystagmus in the direction of the functionating 
 canal lasts longer than that in the direction of the non- 
 functionating canal. Eotation toward the destroyed 
 labyrinth causes a longer after-nystagmus than rota- 
 tion toward the healthy labyrinth. In the above exam- 
 ple, with the right labyrinth destroyed, rotation to the 
 right caused a longer after-nystagmus (after-nystag- 
 mus to the left) than rotation to the left (after-nys- 
 tagmus to the right). 
 
 The rotation test is performed as follows : 
 
 The patient is seated in a revolving chair, with a 
 back and foot-rest. It is advisable to strap him in the 
 chair, as he may fall out during the rotation. In most 
 cases we test only the external semicircular canals by 
 rotation. The head is consequently tilted 30° forward. 
 It is advisable to place ground-glass spectacles before 
 the patient's eyes, according to Bar any, in order to 
 eliminate fixation, and accommodation with conver- 
 gence, as these influence the nystagmus. Fixation of 
 
100 THE LABYBINTH 
 
 objects in the room has the effect of shortening the du- 
 ration of the nystagmus. "With the eyes in the lateral 
 position, convergence affects the nystagmus in the two 
 eyes in different ways. It increases the nystagmus in 
 one eye and decreases it in the other. In order to elim- 
 inate this disturbing influence Barany uses ground- 
 glass spectacles. Bartels achieves the same result by 
 using strong convex lenses, through which the patient 
 cannot see clearly. They have the added advantage 
 that the observer can see the patient's eyes magnified, 
 through the glasses, and so can better observe the 
 nystagmus. 
 
 The patient is rotated 10 times to the right, at a con- 
 stant rate of speed, the 10 rotations taking about 20". 
 On stopping, the patient is told to look to the left, and 
 the duration of the after-nystagmus, which m this case 
 is a horizontal nystagmus to the left, is noted by means 
 of a stop-watch. The reason for directing the patient 
 to look to the left is in order to elicit the maximum 
 amount of nystagmus. The nystagmus is always great- 
 est when the eye looks in the direction of the rapid 
 component. 
 
 After several minutes of rest the patient is rotated 
 to the left 10 times, at the same rate of speed. On stop- 
 ping he is directed to look to the right, and the dura- 
 tion of the after-nystagmus, which in this case is a hori- 
 zontal nystagmus to the right, is noted with the stop- 
 watch. 
 
 If the duration of the after-nystagmus is normal in 
 time, and approximately the same in both directions, it 
 is probable that both labyrinths are normal. If the 
 duration of the after-nystagmus in one direction is less 
 
METHODS OF EXAMINATION 
 
 101 
 
 than one-half that of the after-nystagmus in the oppo- 
 site direction, it is probable that the end-organ in the 
 external semicircular canal of one side is not function- 
 ating. The non-functionating labyrinth is on the side 
 of the lesser after-nystagmus, as in rotation, each laby- 
 rinth arouses the greater after-nystagmus in its own 
 direction. 
 
 In order to test the vertical semicircular canals by 
 means of rotation, they must be brought into the hori- 
 zontal plane. The superior canal of one side being 
 parallel to the posterior canal of the opposite side, it is 
 possible to bring these two canals into the horizontal 
 
 Fig. 30. 
 
 plane together. The two superior canals, or the two 
 posterior canals cannot be brought into the horizontal 
 plane together. 
 
 The changes in the position of the head, which must 
 be made in order to make the vertical canals horizon- 
 tal, can be understood very readily by manipulating 
 two oblong pieces of cardboard, cut half way down the 
 middle, and joined together at right angles to each 
 other, as in Figs. 30 and 31. 
 
 Place the cards in the vertical plane, so that each 
 one is at 45° to the sagittal and transverse planes of the 
 head. The anterior halves of the two cards lie in the 
 planes of the two superior semicircular canals, and the 
 
102 
 
 THE LABYEINTH 
 
 posterior halves in the planes of the two posterior semi- 
 circular canals. By rotating these cards in various di- 
 rections, it can readily be determined how it will be 
 necessary to rotate the head in order to bring the indi- 
 vidual vertical canals into the horizontal plane. 
 
 If the head is bent 90° forward all four vertical semi- 
 circular canals lie in planes 45° to the horizontal (Fig. 
 32). If the head is now rotated so that the face looks 
 
 Fig. 31 
 Representation of Planes of 
 
 VeBMOAL SeMICIECUXAB CANAIiS 
 
 RP — ^Eight posterior semicircular 
 
 canal 
 BS — ^Right superior semicircular 
 
 canal 
 LP — ^Left posterior semicircular 
 
 canal 
 LS — ^Left superior semicircular 
 
 canal 
 
 Fig. 32 
 
 Planes of Vebtical Canals, 
 With Head Tilted 90° Fobwabd 
 RP — Eight posterior semicircular 
 
 canal 
 RS — ^Right superior semicircular 
 
 canal 
 LP — Left posterior semicircular 
 
 canal 
 LS — ^Left superior semicircular 
 
 canal 
 
 toward the right shoulder, the right superior and 
 the left posterior canals lie in the horizontal plane 
 (Fig. 33). 
 
 If, with the head in this position, the patient is ro- 
 tated to the left 10 times, the endolymph, on account 
 of its momentum, will continue to move to the left, in 
 the right superior and the left posterior canals, after 
 
METHODS OF EXAMINATION" 
 
 103 
 
 Fig. 33 
 
 Planes of Vebucal Canals With Head Tilted 90° Forward and Face 
 Turned to Eight Shoulder 
 
 the rotation is stopped. This will give rise to a rota- 
 tory after-nystagmus to the right (Fig. 34). A rota- 
 tory nystagmus to the right means a nystagmus in 
 ■which the upper end of the vertical meridian of the 
 iris moves downward and to the right during the rapid 
 phase. 
 
 ^JV/VU,^ 
 
 Fig. 34 
 Bight Supbbiob and Left Postemob Canals in Horizontal Plane, 
 With Head 90° Forward, and Face Turned to Right Shoul- 
 der. KOTATOBT AfTER-NTSTAGMUS TO RiGHT, FOLLOWING 
 
 Rotation of Body to Left 
 
104 THE LABYBINTH 
 
 In the right superior canal the cupula is displaced 
 away from the utricle, and in the left posterior canal it 
 is displaced toward the utricle. Since, in the vertical 
 canals, the crista is stimulated more powerfully when 
 the cupula is displaced away from the utricle than when 
 it is displaced toward the utricle, the rotatory after- 
 nystagmus to the right is elicited principally by the 
 right superior canal. In this regard, therefore, the 
 conditions in the vertical canals are similar to those 
 in the horizontal canals. 
 
 x--^ 
 
 Fig. 35 
 
 Position of Head Same as in Preceding Biagbam. Kotatoby Apteb- 
 Nystagmus to Left, Following Potation of Body to Right 
 
 If, with the head in the above-described position, the 
 patient is rotated to the right 10 times, there will result 
 a rotatory after-nystagmus to the left (Fig. 35). This 
 nystagmus is elicited priacipally by the left posterior 
 canal, as in this canal the cupula is displaced away 
 from the utricle, while in the right superior canal the 
 cupula is displaced toward the utricle. 
 
 If the right superior canal has a non-functionating 
 end-organ, rotation to the right will cause a longer rota- 
 
METHODS OF EXAMINATION 
 
 105 
 
 tory after-nystagmus (to the left) than rotation to the 
 left (after-nystagmus to the right) (Figs. 36 and 37). 
 
 r% 
 
 Fig. 36 
 
 KioHT Stjperioe Canal is Not Functionating. Long Eotatobt Afteb- 
 
 Nystagmus to the Left Follows Rotation of the Body 
 
 TO THE Right 
 
 <r 
 
 S^ 
 
 Fig. 37 
 
 Right Supeeioe Canal is Not Functionating. Short Eotatoby Afteb- 
 
 Nystagmus to the Eight Follows Rotation of the 
 
 Body to the Left 
 
 In this regard the vertical canals react like the hori- 
 zontal canals. 
 
 If, with the head bent 90° forward, the face is turned 
 to the left shoulder, the left superior and the right pos- 
 terior canals are brought into the horizontal plane 
 
106 
 
 THE LABYBINTH 
 
 Fig. 38 
 
 FiiAiois OF Veehcal Canai-s With Head Tilted 90° Foewaed, and 
 Face Tuened to Left Shouideb 
 
 .s^"^ 
 
 Fig. 39 
 
 Right Posteeiob and Left Sujpeeioe Canals in Hoeizontal Plane 
 
 With Head 90° Fobwaed, and Face Tuened to Left Shoul- 
 
 DEB. RotatoeyAftee-Ntstagmus to Right, Following 
 
 Rotation of Body to Left 
 
 (Fig. 38). If, with the head in this position, the pa- 
 tient is rotated 10 times to the left, the endolymph in 
 the left superior and right posterior canals will con- 
 tinue to flow for a short time to the left, after the rota- 
 tion has stopped. This will give rise to a rotatory af- 
 
METHODS OF EXAMINATION" 
 
 107 
 
 ter-nystagmus to the right, the nystagmus being elicited 
 principally by the right posterior canal, since the 
 cupula in this canal is displaced away from the utricle 
 (Fig. 39). 
 
 If the patient is rotated to the right, there will be a 
 rotatory after-nystagmus to the left. The nystagmus 
 is elicited chiefly by the left superior canal (Fig. 40). 
 
 If the right posterior canal has a non-functionating 
 end-organ, rotation to the right will cause an after- 
 nystagmus (to the left) of longer duration than rota- 
 
 ,ir^ 
 
 Fig. 40 
 
 KOTATOBT AFTEE-NYSTAGMTJS TO LeFT, FOLLOWING ROTATION TO RlQHT 
 
 -> 
 
 r^ 
 
 Fig. 41 
 
 Eight Postebioe Canal is not Functionating. Long Eotatoht Afteb- 
 Ntstaomus to Lett, Following Rotation of Body to Right 
 
108 
 
 THE LABYRINTH 
 
 tion to the left (rotatory after-nystagmus to the right) 
 (Figs. 41 and 42). AH three semicircular canals, 
 therefore, arouse a stronger after-nystagmus toward 
 their own side, than toward the opposite side. 
 
 < 
 
 Fio. 42 
 Eight Posteeioe Canai is not Functionating. Shobt Eotatoet Afteb- 
 
 NTSTAGMtrS TO ElGHT, FOIXOWINQ KoTATION OF BODT TO IiEFT 
 
 Tho rotatory after-nystagmus produced by rotation 
 does not last as long as the horizontal after-nystagmus 
 produced in this way. 
 
 If, instead of bending the head forward, it is bent 
 backward 90°, and the face turned to the right, the right 
 superior and left posterior canals come to lie in the 
 horizontal plane (Figs. 43 and 44). 
 
 Fig. 43 
 Planes op Vertical Canals, With Head Tilted 90° Baokwabd 
 
METHODS OF EXAMINATION 
 
 109 
 
 Fio. 44 
 
 Planes op Vertical Canals, With Head Tilted 90° Backwabd, and 
 Face Tukned Towaed the Right Shoxtldeb 
 
 After rotation to the left, the endolymph in the right 
 superior and left posterior canals continues to flow to 
 the left for a short time. But the rotatory after-nysr 
 tagmus is to the left, because the vertical canals are 
 pliaced in a position opposite to that in which they lay 
 when the head was bent forward (Fig. 45). This nys- 
 
 ^r^ 
 
 Fig. 45 
 
 Head Bent 90° Backwabd, and Face Tubned Towaed the Right 
 Shoulder. Eotatoby Ajtee-Nystagmus to Left, Following 
 Rotation to the LiEft. Nystagmus Elicited Prin- 
 cipally BY Left Posterior Canal 
 
110 
 
 THE liABYEINTH 
 
 tagmus is elicited principally by the left posterior canal. 
 Here, again, the after-nystagmus is aroused mainly by 
 the canal on its own side. If the bead is rotated to the 
 right, there will follow a rotatory after-nystagmus to 
 the right, aroused mainly by the right superior canal 
 (Fig. 46). 
 
 /^ 
 
 Fig. 46 
 
 KOTATOKT AfTEB-NtSTAGMUS TO RlGHT, FOIXOWING ROTATION TO KiGHT. 
 
 Nystagmus Euoited Pbincipaixt by Eight Supeeiob Caital 
 
 If, with the head turned 90° backward, the face is 
 turned to the left, the left superior and right posterior 
 
 Fig. 47 
 
 Planbs op Vertioal Canals, With Head TIlted 90° Bacewabd, and 
 
 Face Tdkned Towaed the Left Shoulder 
 
METHODS OP EXAMINATION 
 
 111 
 
 canals come to lie in the horizontal plane (Fig. 47). If 
 the patient is now rotated to the left there follows a 
 rotatory after-nystagmus to the left, elicited mainly by 
 the left superior canal (Fig. 48) . 
 
 /-X 
 
 Fig. 48 
 Head Bent 90° Backwabd, and Face Tubned Toward Left Shoulder. 
 
 EOTATOBY AFTER-NTSTAGMUS TO LEFT, FOLLOWING ROTATION TO LEFT. 
 
 Nystagmus Elicited Chieflt by Left Supeeiob Canal 
 
 If the patient is rotated to the right there results a 
 rotatory after-nystagmus to the right, which is aroused 
 principally by the right posterior canal (Fig. 49). 
 
 -^ 
 
 /^^^ 
 
 Fig. 49 
 
 KOTATOEY AFTEB-NYSTAGMUS TO THE ElGHT, FOLLOWING EOTATION TO THE 
 
 Right. Nystagmus Elicited Chiefly by Right Posteeior Canal 
 
112 THE LABYBINTH 
 
 When the head is bent forward 90° all four vertical 
 canals lie at 45° to the horizontal plane. If the patient 
 is now rotated all four vertical canals are acted upon 
 to the same degree, and there results a rotatory nys- 
 tagmus, which is due to the combined effects of aU four 
 vertical canals. After rotation to the right, there is a 
 rotatory after-nystagmus to the left, and after rotation 
 to the left, a rotatory after-nystagmus to the right. 
 When the head is bent backward 90°, the same results 
 are obtained, except that the nystagmus is in the oppo- 
 site direction; i. e., after rotation to the right, there 
 follows a rotatory after-nystagmus to the right, and 
 after rotation to the left, there follows a rotatory after- 
 nystagmus to the left. 
 
 If the head is tilted 90° to one shoulder, and the pa- 
 tient rotated, there results a vertical nystagmus. In 
 this position all four vertical canals are also 45° to the 
 horizontal plane. The reason we get a vertical nystag- 
 mus in this position instead of a rotatory nystagmus, 
 is probably because the relative positions of the indi- 
 vidual canals to the horizontal and vertical planes, 
 when the head is tilted toward the shoulder, is not the 
 same as when the head is tilted forward. 
 
 When the head is bent 90° to the right shoulder, and 
 the patient is rotated to the right, there follows a ver- 
 tical after-nystagmus downward. If he is turned to the 
 left, there follows a vertical after-nystagmus, upward. 
 
 With the head bent 90° to the left shoulder, and the 
 patient rotated to the right, there follows a vertical 
 after-nystagmus, upward. When the patient is rotated 
 to the left, there is a vertical after-nystagmus, down- 
 ward. 
 
METHODS OF EXAMINATION 113 
 
 If the head is held between the vertical position and 
 90° forward, all six semicircular canals are affected by 
 rotation, and there results a combination of rotatory 
 with horizontal nystagmus. The more nearly vertical 
 the head is held the more will the horizontal nystagmus 
 predominate over the rotatory, and the more the head 
 is bent forward, the more will the rotatory nystagmus 
 predominate over the horizontal. 
 
 If the head is held between the vertical and 90° back- 
 ward, there will be a combined rotatory and horizontal 
 nystagmus, but the rotatory component will be in a di- 
 rection opposite to that of the horizontal component. 
 For instance, after rotation to the right, there will fol- 
 low a horizontal after-nystagmus to the left, combined 
 with a rotatory after-nystagmus to the right. If the 
 patient looks toward the left the rotatory element will 
 disappear, and there will be a pure horizontal nystag- 
 mus to the left. If he looks toward the right the hori- 
 zontal element will disappear, and there will be a pure 
 rotatory nystagmus to the right. 
 
 From the above facts the following general law was 
 deduced by Barony: 
 
 "In rotating a person about a vertical axis, the char- 
 acter of the nystagmus is indicated by the line in which 
 the horizontal plane cuts the cornea." 
 
 When spontaneous nystagmus is present the inter- 
 pretation of the results of the rotation test is much 
 more difficult. If the spontaneous nystagmus is present 
 only when the patient looks in one direction, we can use 
 Barany's "blickfixator," or Briinings' modification of 
 this instrument, which he calls the "otogoniometer." 
 The "blickfixator" consists of a head-band, to the front 
 
114 THE LABYBINXH 
 
 of wMcli is attached a projecting horizontal rod, abont 
 15 cm. in length, which can be moved from side to side. 
 At the end of the horizontal rod is a short vertical rod, 
 to the lower end of which is attached a small knob. The 
 patient is told to fix his eyes upon' the knob, and the 
 horizontal rod is turned until it is in such a position, 
 that when the patient fixes the knob the spontaneous 
 nystagmus disappears. 
 
 After the patient is rotated he is told to look at the 
 knob again. In this way the spontaneous nystagmus 
 does not obscure the nystagmus which is elicited by 
 the rotation test. 
 
 When the spontaneous nystagmus is present in every 
 position of the eyes, we must try to estimate the effect 
 upon the spontaneous nystagmus by the nystagmus 
 produced by rotation. If, for instance, there is a spon- 
 taneous nystagmus to the right, and we rotate the pa- 
 tient to the left, there will result, upon cessation of the 
 rotation, an after-nystagmus to the right. For a time 
 the spontaneous nystagmus will be intensified. When 
 the after-nystagmus has ceased the spontaneous nys- 
 tagmus will resume its normal intensity. We measure 
 the length of time during which the nystagmus was in- 
 tensified. On rotating the patient to the right there 
 will follow an after-nystagmus to the left. This will 
 diminish the intensity of the spontaneous nystagmus 
 for a time. We now compare the length of time during 
 which the spontaneous nystagmus was intensified, with 
 the length of time during which it was weakened, and 
 draw our conclusions in regard to the functional activ- 
 ity of the two labyrinths therefrom. 
 
METHODS OF EXAMINATION 115 
 
 THE CALORIC TEST 
 
 Schmiedekam and Eensen discovered, in 1868, that 
 cold water poured into the ear caused vertigo and vom- 
 iting. Cohn and Urbantschitsch discovered that cold 
 and hot water, poured into the ear, caused nystagmus. 
 But Barany made a systematic study of the principles 
 of the caloric reaction, and made of it a valuable means 
 for the estimation of the functional activity of the 
 semicircular canals. 
 
 He found that if the head is held in an upright posi- 
 tion, and cold water is poured into one ear, there will 
 result a combined rotatory and horizontal nystagmus 
 toward the opposite ear. If water which is warmer 
 than the temperature of the body is poured into the ear 
 there will result a combined rotatory and horizontal 
 nystagmus toward the irrigated ear. If water of body- 
 temperature is used no nystagmus results. If the head 
 is rotated forward 180°, so that the vertex points down- 
 ward, the conditions are reversed. Cold water now 
 causes nystagmus toward the irrigated ear, and warm 
 water, away from the irrigated ear. Thus it is seen 
 that the direction and character of the caloric nystag- 
 mus depend on the temperature of the water and the 
 position of the head. If cold or hot water elicit no nys- 
 tagmus the labyrinth on that side is non-functionating, 
 or has impairment of its function. 
 
 Earlier observers thought that the nystagmus elicited 
 by cold and hot water was due to the pressure of the 
 water. But Barany proved that this could not be the 
 case, for the following reasons : 
 
 1. The reaction can be elicited in favorable cases (for 
 instance, in an epidermatized radical cavity), by means 
 
116 THE LABYBINTH 
 
 of water dropped from a medicine dropper. In such a 
 case there is practically no pressure whatever. 
 
 2. "When the water is of body temperature there is no 
 reaction. 
 
 3. The nystagmus is in one direction when cold water 
 is used, and in the opposite direction when warm water 
 is used. 
 
 4. Changing the position of the head changes the 
 direction of the nystagmus. 
 
 Barany ascribes the reaction to an endolymph move- 
 ment produced by the difference in specific gravity of 
 cold and warm portions of the endolymph. When cold 
 water is poured into the ear the cold penetrates through 
 the inner tympanic wall to the labyrinth. The anterior 
 portion of the external semicircular canal, and the am- 
 puUated end of the superior canal, lie nearest to the 
 middle-ear cavity, and consequently the endolymph in 
 these portions of the semicircular canals is chilled first 
 (Fig. 50). 
 
 Pig. 50 
 Relations of Semicibctjlae Canals to Tympanic Cavitt 
 TO — Tympanie cavity E — ^Ampulla of external canal 
 
 S — ^Ampulla of superior canal P — Ampulla of posterior canal 
 
 The arrow indicates the direction of the current of cold or hot water 
 
 If cold water is poured into the right ear the endo- 
 lymph in the ampulla of the right superior semicircular 
 
METHODS OF EXAMINATION 
 
 117 
 
 canal becomes chilled. As the diminution in tempera- 
 ture makes it heavier it drops toward the utricle (Fig. 
 51). The endolymph in the outer limb of the supe- 
 
 /^-^ 
 
 Fig. 51 
 
 Bight Sufebiob Cawal. Straight Abrow on Outside Indicates Point 
 
 OF Apfucation of Cold Water. Abbows Within the Canal 
 
 AND Utbicij! Indicate Dieection of Endolymph Cubbent. 
 
 Wavy Abbow Indicates Dibection of Nystagmus 
 
 rior canal follows the chilled endolymph, which has 
 dropped, and it, in turn, becomes chilled by the cold 
 water in the middle ear. In this way an endolymph 
 current is set up in the superior canal, toward the utri- 
 
 FlG. 52 
 
 Diagram Iixustbating the Influence Which Endolymph Current 
 
 IN SuPEEioR Canal Exerts on Endolymph in Posterior 
 
 Canal, as Kesult op Common Limb 
 
 S — Superior canal P — Posterior canal 
 
 t7— Utricle 
 
118 THE LABYBINTH 
 
 ele. The current continues until all of the fluid is of 
 tlie same temperature. 
 
 The endolymph movement in the superior canal sets 
 into motion the fluid in the posterior canal, because 
 both canals have a common limb (Fig, 52). The endo- 
 lymph movement in both the vertical canals is toward 
 the utricle. This gives rise to a rotatory nystagmus 
 toward the opposite side, i. e., toward the left. 
 
 The horizontal canal is tilted backward about 30°. 
 The endolymph in its anterior portion becomes chilled, 
 and flows downward and backward. This gives rise to 
 an endolymph movement away from the utricle (Fig. 
 53), which results in a horizontal nystagmus, also to the 
 
 Fig. 53 
 
 Right External Canai,. Straight Abbow on Outside Indicates 
 Point op Application of Cold Water 
 
 opposite side, i. e., to the left. As the horizontal canal 
 is tilted only 30° from the horizontal plane, and the 
 vertical canals are almost vertical, when the head is in 
 the upright position, the horizontal element of the nys- 
 tagmus is much less conspicuous than the rotatory 
 element. 
 When hot water is used the warmed endolymph is 
 
METHODS OF EXAMINATION 119 
 
 pushed up by the cooler fluid, and the current is in the 
 opposite direction. This gives rise to a rotatory and 
 horizontal nystagmus toward the same side. 
 
 A portion of the external semicircular canal lies ex- 
 posed in the aditus. Here the endolymph is most acces- 
 sible to the cold water which is poured into the ear. 
 If it were possible to bring the external semicircular 
 canal to lie in the vertical plane, an endolymph move- 
 ment could be set up in this canal long before it would 
 be aroused in the other two canals. This can easily be 
 done as follows ; the external semicircular canal makes 
 an angle of 30° with the horizontal plane, when the head 
 is upright. If the head is tilted backward 60° the 
 external canal lies in the vertical plane (Fig. 54). 
 
 Fig. 54 
 "Optimum Position" fob Caloric Test on Exteenal Semicircular 
 
 Canal 
 E — ^External semicircular canal 
 
 Brunings found that with the head in this position the 
 external canal responds very quickly to the caloric test. 
 The position may be rendered still more favorable by 
 the following manoeuvre; after tilting the head back- 
 
12Q 
 
 THE LABYRINTH 
 
 ward 60°, rotate it 45° about its antero-posterior axis, 
 so that the ear to be irrigated is depressed toward the 
 shoulder of that side. If the right ear is being exam- 
 ined, that ear should be depressed toward the right 
 shoulder (Fig. 55). The result of this manoeuvre is to 
 
 Fig. 55 
 
 Bbunings' "Oblique Optimum Position" foe the Eight ExteenaIi 
 Semicibcuiae Canai^ Head Tuted 60° Backward 
 
 AND 45° TOWAED BlGHT ShOULDEE 
 
 rotate the external canal about an axis at right angles 
 to its plane, so that the point of application of the cold 
 water is at a greater distance above the bottom of the 
 column of endolymph; in other words, the fall of the 
 endolymph is greater (Fig. 56). 
 
 This position of the head Brunings calls the "oblique 
 optimum position" for the external semicircular canal. 
 
 With the head in this position, an almost pure hori- 
 zontal nystagmus to the opposite side is obtained with 
 cold water, and to the same side with hot water. 
 
 With the head bent 30° forward, or 120° backward, 
 the external semicircular canal is brought into the hori- 
 zontal plane. In either of these positions the caloric 
 reaction gives an almost pure rotatory nystagmus. 
 
METHODS OF EXAMINATION 121 
 
 The advantages in using the optimum position of the 
 external semicircular canal, in performing the caloric 
 test, are the following : 
 
 1. The reaction is rapidly obtained with water which 
 is not very cold, so that the amount of discomfort to 
 the patient is reduced to a minimum. 
 
 Fig 
 
 1 — Position of Bxteenai Canai, in "Pessimum Position" fob 
 
 Caloric Test 
 2 — Position of Exteenai Canal in "Straight Optimiim: 
 
 Position" foe Caloric Test 
 
 3 — Position of External Canal in "Oblique Optimum 
 
 Position" for Caloric Test 
 
 Arrow indicates point of application of cold water 
 
 2. As soon as the nystagmus is aroused it can be 
 checked by throwing the head forward 90°, i. e., 30° 
 forward from the vertical position of the head (the so- 
 called pessimum position of the external canal), thus 
 cutting short the vertigo. 
 
 3. It helps in an accurate quantitative estimation of 
 the caloric irritability. 
 
 4. It allows a separate examination of the external 
 and the vertical canals. This is done as follows : 
 
 The head is placed in the oblique optimum position, 
 i. e., 60° backward and 45° toward the shoulder of the 
 side to be examined. Cold water is allowed to flow into 
 
122 THE LABYRINTH 
 
 the ear. If no nystagmus results the external canal is 
 non-functionating. The head is now thrown forward 
 into the pessimum position, i. e., 30° forward from the 
 upright position. If there results a rotatory nystagmus 
 in this position the vertical canals are intact. In this 
 way a circumscribed labyrinthitis confined to the ex- 
 ternal semicircular canal, resulting in the loss of its 
 function, can be determined. Brunings was able to 
 make this diagnosis in several cases. 
 
 If there is a positive reaction with the head in the 
 optimum position, there is no need to test for the reac- 
 tion in the vertical canals ; for an isolated labyrinthitis 
 in the vertical canals is practically unknown. 
 
 With failure to obtain a reaction in the optimum po- 
 sition, after a reasonable time, it is usually unnecessary 
 to continue the irrigation, in order to obtain the rota- 
 tory nystagmus in the pessimum position, the endo- 
 lymph being already suflSciently cooled to give the reac- 
 tion. After discontinuing the irrigation, a horizontal 
 nystagmus, with the head in the optimum position, is 
 immediately checked, and a rotatory nystagmus sub- 
 stituted, when the head is thrown into the pessimum 
 position. 
 
 The caloric test has the advantage over the rotation 
 test, in that by it each labyrinth can be tested sep- 
 arately. 
 
 Ordinarily the caloric test is performed with cold 
 water. The use of hot water is much more disagree- 
 able to the patient, as it is necessary to use water of at 
 least 110° F. in order to elicit a "hot water nystag- 
 mus." Hot water is of use chiefly in those cases where 
 a spontaneous nystagmus is present. If there is spon- 
 
METHODS OF EXAMINATIOUT 123 
 
 taneous nystagmus to the left, and we suspect disease 
 in the right labyrinth, the right ear is irrigated with 
 hot water. If the right labyrinth is still functionating, 
 the caloric nystagmus, which is aroused by the hot 
 water, and which is directed toward the right, will neu- 
 tralize or overcome the spontaneous nystagmus toward 
 the left. If the spontaneous nystagmus is unaffected 
 the labyrinth is non-functionating. 
 
 If the spontaneous nystagmus is not present in every 
 position of the eyes, Barany's "blickfixator" or Briin- 
 ings' "otogoniometer" may be used. By means of 
 either of these instruments the eyes are held in a posi- 
 tion in which there is no spontaneous nystagmus. Cold 
 water is then used to elicit a caloric nystagmus. 
 
 Brunings has attempted to estimate the caloric irri- 
 tability of the labyrinth, quantitatively. In this he was 
 more or less successful only in normal cases. In order 
 to make a quantitative caloric test the following factors 
 must be made constant : 
 
 1. The temperature of the water. 
 
 2. The rate of speed of the flow of the water. 
 
 3. The direction of the current of water in the ex- 
 ternal auditory canal. 
 
 4. The positions of the semicircular canals, i. e., the 
 position of the head. 
 
 5. The position of the eyes. 
 
 Brunings was enabled to make these factors fairly 
 constant by means of his "otocalorimeter" and "oto- 
 goniometer." The otocalorimeter (Fig. 57) consists of 
 two glass vessels attached to an upright board, one 
 above the other. They are connected by means of rub- 
 ber tubing, in the course of which is interpolated a 
 
124 THE LABYRINTH 
 
 double-current ear-tip. In the upper vessel are placed 
 a, thermometer and a funnel, both of which are inserted 
 into air-tight plugs. Through the funnel water is 
 poured into the vessel, and kept at a constant tempera- 
 ture. The double current tip is inserted into the ear to 
 
 Fig. 57 
 
 BBtJNINGS' OtOCALORIMETEE 
 
 a certain depth, beyond which it cannot penetrate. The 
 return flow passes into the lower vessel, which is also 
 air-tight, and graduated. From these graduations the 
 amount of water used is read off. The rate of speed of 
 the flow and the pressure are constant in this instru- 
 ment. 
 
METHODS OP EXAMINATION 125 
 
 The positions of the semicircular canals and the posi- 
 tions of the eyes are fixed by means of the otogoni- 
 ometer (Fig. 58). This instrument consists of a head- 
 
 FiG. 58 
 Bbuninqs' Otogoniometeb 
 
 band, to the front of which are attached, by movable 
 joints, two rods. The upper rod moves in a vertical 
 plane, and the lower in a horizontal plane. The upper 
 rod has a graduated arc attached to it, near its junction 
 with the head-band. The horizontal rod has a small 
 mirror attached to its distal end. This rod moves 
 across the upper surface of a graduated arc, which is 
 attached to the front of the head-band. The upper rod 
 is used to determine the position of the external semi- 
 circular canal. With the head upright, this rod is raised 
 through an arc of 30°. The rod now corresponds to 
 the plane of the external semicircular canal. The head 
 is then bent backward until the rod is exactly vertical. 
 In this position of the head the external semicircular 
 canal is vertical. 
 
 The lower rod, with the mirror at the end, is used to 
 fix the position of the eyes. The rod is rotated 50° to 
 one or the other side of the median line, according to 
 which ear is being tested. The patient is then directed 
 
126 THE LABYRINTH 
 
 to look into the small mirror, which is rotated from side 
 to side, until the patient can see some object in the 
 room reflected in the mirror. In this way the accom- 
 modation and convergence which occur in the use of 
 Barany's "blickfixator" are avoided. If the patient 
 looks more than 50° to the side there often occurs a 
 spontaneous physiological nystagmus, which is very 
 disturbing during the examination. 
 
 The quantitative caloric test is performed as follows : 
 the head is placed in the optimum oblique position for 
 the external semicircular canal. The eyes are directed 
 by means of the otogoniometer 50° toward the opposite 
 side. Water of a temperature of 27° C. or 80° F. is 
 allowed to flow into the ear from the otocalorimeter. 
 As soon as nystagmus sets in the flow of water is 
 stopped, and the amount used is read off from the lower 
 receptacle. The rate of flow is such that 300 cc of water 
 are used up in 3 minutes. 
 
 Brunings found that in normal ears the average 
 amount of water at 27° C. used to arouse nystagmus 
 was 70 cc. The time required was between % and 1 
 minute. In cases where water of 27° C. does not elicit 
 nystagmus in 3 or 4 minutes, colder water is used. In 
 pathological cases the quantitative caloric test does not 
 give very reliable data, because, in addition to changes 
 in the internal ear, and the retrolabyrinthine paths, the 
 time of onset of the nystagmus is influenced by changes 
 in the temperature-conductivity to the internal ear. 
 These disturbances of temperature-conductivity may be 
 due to : 
 
 1. Defects in the drum-membrane. A small perfora- 
 tion does not influence the temperature-conductivity 
 
METHODS OF EXAMINATION 127 
 
 mucli. But where most of the drum-membrane is gone, 
 or in an epidermatized radical cavity, nystagmus can be 
 aroused in half or even quarter of the usual time. 
 
 2. Stenosis of the external auditory canal. 
 
 3. Granulations in the middle ear or canal. 
 
 4. Cholesteatoma. 
 
 Any of these three conditions, or all three together, 
 may delay the onset of the nystagmus considerably. 
 
 5. Inflammatory hyperaemia of the middle-ear. In 
 acute inflammation of the middle-ear, the large quan- 
 tity of blood which passes through the mucous mem- 
 brane of the middle-ear delays the chilling of the endo- 
 lymph by the cold water considerably. 
 
 Kiproff and Bech, as a result of a series of tests, 
 came to the conclusion that the time required to bring 
 on caloric nystagmus depends upon extra-labyrinthine 
 conditions, whereas the duration of the nystagmus de- 
 pends upon labyrinthine or central conditions. 
 
 Kiproff examined a large number of normal and dis- 
 eased ears by the caloric method, and found that where 
 the labyrinth was not involved the duration of the nys- 
 tagmus was the same in all cases (with an equal inten- 
 sity of stimulus), but the time of onset varied consider- 
 ably in the different pathological conditions. 
 
 His tests were made as follows: water of 30° C. or 
 86° F. was allowed to run into the ear, with the eyes 
 directed toward the opposite side. At the moment of 
 onset of the nystagmus the eyes were directed straight 
 ahead, and the irrigation continued until nystagmus 
 began in this position of the eyes. Then the irrigation 
 was stopped, and the eyes turned back to the first posi- 
 tion. The time from the onset of the nystagmus in the 
 
128 THE LABYBINTH 
 
 oblique position to the cessation of the nystagmus was 
 noted. 
 
 He found that the onset of the nystagmus was most 
 rapid in the cases of chronic suppuration with total de- 
 struction of the membrana tympani, and in healed radi- 
 cals. The next most rapid were the normal ears. Less 
 rapid was the onset of the nystagmus in the chronic 
 suppurative ears with granulations, cholesteatoma, etc. 
 It was slowest in acute middle ear suppurations. How- 
 ever, the duration of the nystagmus was about 2 
 minutes in aU of the cases. 
 
 Bech examined a number of acute suppurative ears 
 by means of the caloric test, each day, from the onset of 
 the disease until they healed. He found that as the in- 
 flammation subsided the time of onset of the nystagmus 
 diminished, but the duration iof 'the nystagmus re- 
 mained the same at all times. By the use of adrenalin 
 in the ear, in these cases, he was also able to diminish 
 the time of onset of the nystagmus. 
 
 Ruttin makes a quantitative caloric test by compar- 
 ing the diseased with the sound ear of the same person. 
 He has constructed an apparatus whereby both ears 
 are irrigated simultaneously, with water of the same 
 temperature, at the same rate of flow. If both laby- 
 rinths are normal there will be no nystagmus^ for the 
 nystagmus from the right labyrinth neutralizes that 
 from the left. If the right labyrinth is less irritable 
 than the left there wiU result a nystagmus to the ri^t 
 (with cold water). 
 
 In some cases, as, for instance, where there is a dry 
 perforation in the drum-membrane, or in a recently 
 operated radical mastoid, it is inadvisable to use cold 
 
METHODS OF EXAMINATION 129 
 
 water. In such a ease cold air can be substituted for 
 the water. Aspissoff, Block and Ruttin have devised 
 apparatuses for this purpose. 
 
 THE GALVANIC TEST 
 
 Up to the present the galvanic test has not proven to 
 be of very much value for the diagnosis of labyrinthine 
 disease. The reason for this is that even after the de- 
 struction of the labyrinth the galvanic current still 
 elicits nystagmus, by direct stimulation of the vestibu- 
 lar nerve. 
 
 In performing the galvanic test both labyrinths may 
 be stimulated together, the anode or positive pole being 
 placed over one ear and the kathode or negative pole 
 being placed over the other; or one labyrinth may be 
 stimulated alone, one pole being placed over one ear, 
 and the other pole over some indifferent part of the 
 body, such as the sternum, arm, hand, etc. 
 
 When both ears are stimulated together a very weak 
 current is sufficient to elicit nystagmus, as the stimula- 
 tion from one labyrinth re-enforces that of the other. 
 But for clinical purposes this method is useless, for it 
 does not differentiate between the functional conditions 
 of the two labyrinths. When one pole is placed over 
 one ear and the other pole over the sternum or some 
 other part of the body, a stronger current is necessary 
 in order to elicit nystagmus. 
 
 The galvanic test is performed as follows: Two 
 moistened sponge electrodes are used, one being placed 
 over the sternum or in the hand, and the other directly 
 in front of or behind the ear to be examined. The gal- 
 
130 THE LABYEINTH 
 
 vanic current is then turned on, the current being grad- 
 ually increased in strength until a nystagmus is elicited. 
 The strength of current is read from the milliampere- 
 meter, which is attached to the instrument. The 
 strength of current necessary to arouse nystagmus is 
 a measure of the irritability of the labyrinth. In turn- 
 ing off the current it should be gradually weakened, and 
 not turned off suddenly, in order not to shock the pa- 
 tient unnecessarily. 
 
 The character of the nystagmus is a combination of 
 rotatory and horizontal elements, indicating that all 
 three semicircular canals are stimulated together. It 
 has thus far been found impossible to stimulate one 
 semicircular canal alone by the galvanic current, even 
 when the canals have been dissected out and both elec- 
 trodes placed over one canal. 
 
 The direction of the nystagmus depends upon which 
 pole is placed over the ear. When the kathode or nega- 
 tive pole is placed over the ear, the nystagmus is toward 
 that side. When the anode or positive pole is placed 
 over the ear, the nystagmus is toward the opposite side. 
 The nystagmus is in the direction of the flow of the gal- 
 vanic current. The current flows from the positive to 
 the negative pole. When the kathode is placed over the 
 ear the current leaves the body at that point. The 
 direction of the current corresponds with the direction 
 of the nystagmus, which is toward the examined ear. 
 When the anode is placed over the ear the current 
 enters the body at that point. The direction of the cur- 
 rent corresponds with the direction of the nystagmus, 
 which is away from the examined ear. 
 
 When the anode is placed over one ear and the 
 
METHODS OF EXAMINATION 131 
 
 kathode over the other there is nystagmus toward the 
 kathode. 
 
 When one pole is placed over each ear a current of 
 2 to 5 ma is sufficient to arouse nystagmus. When only 
 one labyrinth is examined at a time a current of 5 to 10 
 ma is necessary. 
 
 The position of the head has no influence on the char- 
 acter or direction of the nystagmus in this test. 
 
 When the labyrinth, as well as the vestibular nerve 
 are destroyed, the galvanic current does not cause any 
 nystagmus. However, if the vestibular nerve is not 
 yet degenerated, it will respond to the stimulation. 
 
 If the anode is placed over the sternum, and two 
 sponges are attached to the kathode, one of which is 
 placed before each ear, there will be no nystagmus, if 
 both labyrinths are normal. If one labyrinth is de- 
 stroyed, or if its excitability is diminished, there will 
 result a nystagmus toward the sound ear. If a double 
 anode be placed before the ears the nystagmus will be 
 toward the diseased ear. However, in order to elicit a 
 nystagmus with a double electrode, a very strong cur- 
 rent is necessary. In fact, the required current may be 
 so strong as to cause unendurable pain to the patient. 
 
 The actual method of stimulation of the end-organs 
 in the labyrinth by means of the galvanic current is not 
 yet positively known. The most plausible hypothesis is 
 that laid down by Brunings, which is as follows; the 
 galvanic current sets up a kataphoretic current in the 
 endolymph, or the cupula is set into motion directly by 
 the kataphoresis. As a result of this movement of the 
 endolymph or cupula, the hair-cells are stimulated. 
 
 Kataphoresis is an electro-endosmosis. It is a mo- 
 
132 THE LABYBINTH 
 
 tion which is produced in liquids by the galvanic cur- 
 rent, the fluid moving from one pole to the other. Solid 
 particles which are present in the fluid are also set into 
 motion. On the basis of this theory it would seem that 
 the kataphoretic movement in the endolymph is away 
 from the kathode and toward the anode. 
 
 This theory brings galvanic stimulation into harmony 
 with the mechanical methods of stimulating the semi- 
 circular canals, namely rotation, cold and heat, and 
 compression and aspiration. 
 
 All of the phenomena of galvanic irritation can be 
 explained by this theory ; but it is still a theory. It has 
 not been proven. 
 
 Many observers claim that there is a direct stimula- 
 tion of the vestibular nerve by the galvanic current, as 
 the reaction can be obtained after complete destruction 
 of the semicircular canals. But although the nerve can 
 be directly stimulated by the galvanic current, yet this 
 apparently does not occur when the semicircular canals 
 are intact. The results of galvanic stimulation of the 
 labyrinth do not agree with our experience in electrical 
 stimulation of nerves in other parts of the body. The 
 differences are the following : 
 
 The labyrinth can be stimulated by the galvanic cur- 
 rent only, whereas a nerve can be stimulated by both 
 galvanic and faradic currents. The stimulation of the 
 labyrinth occurs during the flow of the current, whereas 
 a nerve can only be stimulated during the make or 
 break of the current. A change in the direction of the 
 current causes a change in the direction of the nystag- 
 mus. This cannot be explained by assuming the nys- 
 tagmus to be due to direct stimulation of the nerve. 
 
METHODS OF EXAMINATION 133 
 
 The nystagmus lasts after the current has stopped, 
 whereas the effect of electrical stimulation of a nerve 
 does not continue after the current has stopped. The 
 vestibular nerve is deeply situated in the skull, in close 
 relationship with the cochlear and facial nerves. If the 
 vestibular nerve were directly stimulated by the cur- 
 rent, how can we explain the fact that neither the coch- 
 lear nor the facial nerve are stimulated at the same time 
 as the vestibular nerve ? 
 
 Breuer noticed that a much stronger current was 
 needed to arouse nystagmus after the labyrinth was 
 destroyed than before ; and that when the labyrinth was 
 destroyed both the anode and kathode caused movement 
 of the head away from the stimulated side. This corre- 
 sponds to nystagmus toward the stimulated side, 
 
 Barany explains the galvanic reaction in the follow- 
 ing way : 
 
 There is a constant flow of impulses from both laby- 
 rinths to the eye-muscles. The impulses from the right 
 labyrinth tend to cause nystagmus to the right, and 
 those from the left labyrinth, nystagmus to the left. 
 These impulses counterbalance each other, normally. 
 When the kathode is applied to the ear the vestibular 
 nerve is placed in a condition of kathelectrotonus, dur- 
 ing which its conductivity is increased. As a result of 
 this increase in conductivity, the impulses from the 
 labyrinth of that side overbalance those from the oppo- 
 site side, and the result is a nystagmus toward the side 
 of the kathode. When the anode is applied to the ear 
 the nerve is placed in a condition of anelectrotonus, 
 during which its conductivity is diminished. This in- 
 terferes with the transmission of the normal impulses 
 
134 THE LABYEINTH- 
 
 from the labyrinth of that side, so that they are over- 
 balanced by the impulses from the opposite labyrinth. 
 This results in a nystagmus away from the anode. This 
 theory is controverted by the following fact; if cold 
 water is poured into the right ear, there results a com- 
 bined rotatory and horizontal nystagmus to the left. If 
 the kathode is placed over the right ear at the same 
 time, the kathelectrotonus of the right vestibular nerve 
 ought to increase its conductivity for the caloric irrita- 
 tion, in which case the nystagmus toward the left should 
 be increased. But, as a matter of fact, the galvanic nys- 
 tagmus to the right neutralizes the caloric nystagmus 
 to the left, so that the nystagmus ceases altogether. 
 
 Brunings believes he is able to diagnose a fistula in 
 the external semicircular canal by means of the gal- 
 vanic test. If, with the head in the optimum position 
 for the external semicircular canal, the caloric reaction 
 is diminished or absent, and there is a normal or in- 
 creased galvanic excitability, he concludes that there is 
 a fistula or a localized perilabyrinthitis in the external 
 canal. He calls this the galvanic fistula test, and ex- 
 plains it as follows ; the caloric reaction depends upon 
 a free movement of the endolymph in the semicircular 
 canals. However, the kataphoretic movement caused 
 by the galvanic current is not interfered with by a ste- 
 nosis of the semicircular canal, such as occurs with a 
 circumscribed perilabyrinthitis. In fact, it may even 
 be increased, on account of the improved conductivity 
 for the current. Hence a diminished caloric reaction 
 with a normal or increased galvanic excitability, means 
 a mechanical interference with the flow of the endo- 
 lymph current, and a normal nervous ampuUary organ, 
 
METHODS OF EXAMINATION 135 
 
 which is the condition in a fistula of the external semi- 
 circular canal. 
 
 THE FISTULA TEST 
 
 The fistula test can be elicited, as a rule, only in 
 pathological conditions. The two factors which are 
 necessary for its production are a fistulous opening in 
 the bony labyrinthine wall, and functionating end- 
 organs within the labyrinth. It cannot be elicited in 
 the presence of a fistula, with a destroyed labyrinth. 
 
 The test consists in causing an endolymph-movement 
 in the semicircular canals by means of compression and 
 aspiration of the air in the external auditory canal and 
 middle ear. This test is identical with E wold's classi- 
 cal experiment on pigeons, with the pneumatic hammer. 
 In Ewald's experiment, however, he was able to control 
 accurately the direction of the endolymph current, 
 whereas, in the fistula test, the factors which determine 
 the direction of the endolymph current are not under 
 our control. 
 
 Ewald exposed the semicircular canals of a pigeon, 
 and made two small openings in the bony wall of the 
 external canal, without injuring the membranous canal. 
 Into the opening furthest from the ampulla he drove a 
 metal plug, which completely obliterated the lumen of 
 the canal at that point. Into the second opening, which 
 lay between the plugged opening and the ampulla, he 
 fitted a small pneumatic hammer, which he attached by 
 means of plaster-of -Paris to the vertex of the pigeon's 
 skull. The end of the hammer touched the membranous 
 canal lightly. This hammer could be driven forward 
 
136 THE LABYRINTH 
 
 and backward by compressing and relaxing a rubber 
 bulb, which was attached to the hammer by means of a 
 long rubber tube. As the canal was plugged at one 
 point, the direction of the endolymph flow, upon com- 
 pression and relaxation of the bulb, could be readily 
 determined. On compressing the bulb the endolymph 
 flow was toward the utricle, and on relaxation of the 
 bulb it was away from the utricle (Fig. 59). 
 
 Pig. 59 
 
 BiAGRAM Illustrating Ewald's Experiment on Pigeon With 
 
 Pneumatic Hammer 
 
 Ewald observed that there was always a movement 
 of the eyes and of the head in the direction of the endo- 
 lymph flow, and in the plane of the canal which was 
 stimulated. In the right external semicircular canal, 
 on compressing the bulb, there was a rotation of the 
 head and eyes to the left, in the horizontal plane, and 
 on relaxation of the bulb the movement was to the right. 
 With the left external canal the movements were re- 
 versed. Movements of the endolymph in the vertical 
 
METHODS OF EXAMINATION 137 
 
 canals, he f ouiid, cause movements of the head and eyes 
 in their planes also. In the external canals he found 
 that the reaction resulting from an endolymph flow 
 toward the utricle was greater than that resulting from 
 an endolymph flow away from the utricle. In the ver- 
 tical canals the opposite was the case ; namely, the endo- 
 lymph flow away from the utricle aroused a greater 
 movement of the eyes and head than a flow toward the 
 utricle. The movement of the eyes corresponds to the 
 slow movement of the nystagmus, and the movement 
 of the head corresponds to the reaction movement. 
 
 In the fistula test the direction of the endolymph 
 movement depends on the location of the fistula, and 
 the location of stenoses in the canals. 
 
 The fistula test is performed as follows: the olive 
 tip of a Politzer bag is fitted air-tight into the canal of 
 the ear. In cases where there is a mastoid wound, a 
 Bier's cup is attached to the Politzer bag, and placed 
 so as to cover the entire ear and wound. Slow steady 
 pressure is made upon the bag. If a fistula is present, 
 and the labyrinth is functionating, one of several things 
 will happen. The most common result is a rotatory or 
 horizontal or combined rotatory and horizontal nys- 
 tagmus toward the examined ear. There may be a slow 
 movement of the eyes away from the examined ear. 
 Sometimes there is a nystagmus away from the exam- 
 ined ear, or a slow movement of the eyes toward the 
 examined ear. Occasionally, accompanying the nystag- 
 mus, there is a movement of the head in the direction 
 of the slow component of the nystagmus. 
 
 On releasing the bulb, and producing suction, there 
 results a nystagmus or a slow movement of the eyes, in 
 
138 THE LABYRINTH 
 
 a direction opposite to that produced by compression 
 of the bulb. This nystagmus is usually weaker than 
 that produced by compression, and it is often wanting 
 altogether. Aspiration seems to produce a weaker 
 stimulation than compression. 
 
 The commonest form of reaction to the fistula test, 
 namely, nystagmus toward the examined ear, would 
 seem to indicate that compression of the air in the ex- 
 ternal auditory canal and middle ear caused an endo- 
 lymph flow in the external semicircular canal, toward 
 the utricle, and aspiration, away from the utricle. 
 
 In performing the fistula test one must not use very 
 much force, nor repeat the test too often, as it may 
 cause a rupture of the membranous canal at the site of 
 the fistula, with a spread of the infection from the mid- 
 dle ear into the labyrinth. 
 
 REACTION MOVEMENTS 
 
 Thus far we have concerned ourselves with only one 
 of the reactions aroused by stimulation of the labyrinth, 
 namely, nystagmus. There is a second reaction which 
 can be aroused by stimulation of the labyrinth, that is, 
 reaction movements of the extremities and trunk. Al- 
 though these are not as important as nystagmus, for 
 the purpose of diagnosis, yet a careful study of these 
 movements will give us considerable additional infor- 
 mation in regard to the condition of the labyrinth. 
 Since the recent investigations by Barany, of the rela- 
 tionship between these movements and the cerebellar 
 functions, they have proven of considerable importance 
 in the diagnosis of cerebellar lesions. 
 
METHODS OF EXAMINATION 139 
 
 The reaction movements are not a simple reflex like 
 the nystagmic movements. They consist, according to 
 Barany, of voluntary movements, which are modified in 
 the cerebellar cortex by abnormal centripetal impulses 
 from the semicircular canals. In the cerebellar cortex, 
 motor impulses from the cerebrum are met by centrip- 
 etal impulses from the semicircular canals. If these 
 centripetal impulses are rendered abnormal, through 
 disease or abnormal stimulation of the semicircular 
 canals, the normal voluntary movements are changed 
 in such a way as to result in reaction movements. 
 
 The reaction movements can be influenced to a cer- 
 tain extent by the will, and consequently they are most 
 marked in individuals who have not a highly devel- 
 oped muscular and kinaesthetic sense, to warn them of 
 the occurrence of the reaction movements. For this 
 reason they are much more marked in children than in 
 adults. 
 
 A reaction movement is a movement of the extrem- 
 ities or body, elicited by stimulation of the labyrinth, 
 in the plane of the stimulated semicircular canal, and 
 in the direction of the endolymph current, i. e., in a 
 direction opposite to the nystagmus. 
 
 Barany was the first to notice the influence of the 
 position of the head upon the reaction movements. The 
 nystagmus remaining unchanged, a change in the posi- 
 tion of the head will cause a change in the direction of 
 the reaction movements. 
 
 We will first consider reaction movements of the ex- 
 tremities. If a patient is rotated to the left, a number 
 of times, and then the rotation is stopped, there follows 
 a horizontal after-nystagmus to the right. If, during 
 
140 THE LABYBINTH 
 
 this nystagmus, the patient be told to extend his right 
 arm straight in front of him, it will be seen that the arm 
 slowly deviates to the left, i. e., in a direction opposite 
 to the nystagmus. If the patient notices this deviation 
 he will correct it by a rapid movement of the arm in 
 the direction of the nystagmus. 
 
 If, with the horizontal nystagmus to the right, the head 
 is tilted 90° to the left shoulder, the arm moves down- 
 ward as the nystagmus is directed upward in space. If 
 the head is tilted 90° to the right shoulder, the arm 
 moves upward. If cold water is allowed to flow into the 
 right ear, we have a rotatory nystagmus to the left. If 
 the right arm is extended horizontally in the frontal 
 plane it will deviate downward. The left arm will devi- 
 ate upward. If the head is now tilted forward 90°, both 
 arms will deviate to the right. If the head is tilted 90° 
 backward, the arms will deviate to the left. If the head 
 is turned 90° to the left, both arms held in front of the 
 body will deviate downward. If the head is turned 90° 
 to the right, both arms held in front of the body, will 
 deviate upward. Provided the nystagmus and the po- 
 sition of the head remain unchanged, a change in the 
 position of the arm will make no difference in the reac- 
 tion movement. It makes no difference whether the 
 arm is pronated or supinated, the movement will be to 
 the left, provided the nystagmus is a horizontal nystag- 
 mus to the right, and the head is in the upright 
 position. 
 
 The same reaction movements can be obtained with 
 the legs, but these are not as constant as those in the 
 arms. 
 
 In order to arouse reaction movements, much 
 
METHODS OF EXAMINATION 141 
 
 stronger stimulation is necessary than to arouse nys- 
 tagmus. 
 
 Barany has devised a method for testing reaction 
 movements in the extremities, which he calls the point- 
 ing test. It can be applied to each joint separately, the 
 shoulder, elbow or wrist, or the hip, knee or ankle. 
 
 The test (for the wrist-joint, for iastance) is per- 
 formed as follows: If spontaneous nystagmus is not 
 present, nystagmus is aroused by rotation or cold 
 water. With the eyes closed, the patient's forearm is 
 allowed to rest on the back of a chair, and held in place 
 with one of the examiner's hands. 
 
 The patient is told to perform dorsal flexion at the 
 wrist, his index-finger being extended. The back of his 
 index-finger is allowed to touch the palmar surface of 
 the index-finger of the examiner's hand, which is held 
 above that of the patient. The patient is now told to 
 flex his hand as far as possible, and then to again touch 
 the examiner 's finger, which has not moved in the inter- 
 val. If the patient has a horizontal nystagmus to the 
 right, he will point past the examiner's finger to the 
 left. It is advisable that the patient should not be 
 warned of the fact that he has pointed past, as this will 
 influence the succeeding tests. For this reason the ex- 
 aminer should touch the patient's finger, so as to make 
 him believe that he has not pointed past. 
 
 As before mentioned, this reaction movement is 
 aroused in the cerebellar cortex, as a result of impulses 
 reaching the cerebellum from the semicircular canals 
 and motor cortex. From the cerebellar cortex, prob- 
 ably from Purkinje's cells, the impulses reach the 
 muscles of the extremities, through the brachium con- 
 
142 THE LABYBINTH 
 
 junctivum, red nucleus and Monakow's tract. If a por- 
 tion of the cerebellar cortex is destroyed, as the result 
 of abscess, tumor, etc., irritation of the semicircular 
 canals will fail to arouse a reaction-movement. 
 
 Barany was able to prove experimentally that there 
 are certain areas in the cerebellar cortex which govern 
 movements in certain joints, and in certain directions. 
 In a case of cerebellar abscess of the right hemisphere, 
 which had healed, and in which the cerebellum was cov- 
 ered only by cicatricial tissue, he froze portions of the 
 cerebellar cortex by means of an ethyl-chloride spray, 
 applied for about 3 minutes. 
 
 Before the freezing the patient pointed correctly 
 with both arms and legs. On freezing the right cere- 
 bellar hemisphere, the patient pointed past to the right, 
 with the right arm and leg. The left extremities were 
 unaffected. On rotating him to the left, and producing 
 a horizontal after-nystagmus to the right, the right 
 arm and leg did not point past to the left. That is to 
 say, there was no reaction movement. After two or 
 three minutes the conditions again returned to the nor- 
 mal, i. e., there was no spontaneous pointing past, and 
 on arousing nystagmus, there was a normal reaction 
 movement. 
 
 On repeated examinations, by freezing small areas 
 of the right cerebellar cortex, he came to the following 
 conclusions : 
 
 1. During the freezing there is no nystagmus. 
 
 2. The left arm and leg are not influenced in their 
 reaction movements. 
 
 3. Immediately behind the ear is the centre for move- 
 ment to the left, of the right arm. When this spot is 
 
METHODS OF EXAMINATION 143 
 
 frozen there occurs spontaneous pointing-past of the 
 right arm to the right ; and with horizontal nystagmus 
 to the right, there is no reaction movement to the left. 
 
 4. Immediately behind the arm centre is the centre 
 for movement to the left, of the right foot. 
 
 As the result of pathological findings, Barany be- 
 lieves that the centres for movement to the left, of the 
 right elbow and wrist joints lie in front of the arm 
 centre. 
 
 With a lesion in the fibre-tract between the cerebellar 
 cortex and the anterior horn cells in the spinal cord, we 
 also get a loss of the reaction movements of the extrem- 
 ities. But as the fibres are collected into a small bun- 
 dle, a lesion here will cause a loss of reaction move- 
 ments in numerous joints, in all directions, whereas a 
 lesion in the cerebellar cortex will affect only one joint 
 in one direction, unless the lesion is very extensive. 
 
 The reaction movements of the body are tested by 
 having the patient stand up, with his feet together and 
 his eyes closed. A reaction movement of the body is 
 not noticeable if it occurs in the horizontal plane. If 
 it occur in any other plane than the horizontal, however, 
 it will cause the patient to fall. Just like the reaction 
 movements of the extremities, so reaction movements 
 of the body depend upon the canal which is stimulated, 
 and the position of the head. In this way it is differ- 
 entiated from the loss of equilibrium which is due to 
 other causes, such as cerebellar disease or hysteria. 
 
 In the presence of a spontaneous nystagmus, the pa- 
 tient is told to stand up, with his feet together, and his 
 eyes closed. If he has a rotatory nystagmus to the left, 
 he will fall toward the right. If the head is now ro- 
 
144 THE LABYEINTH 
 
 tated 90° to the left he will fall forward. If the head 
 is turned 90° to the right he will fall backward. 
 
 If there is no spontaneous nystagmus present, the re- 
 action movements of the body are best examined by 
 means of the caloric test. (Eotation test with the head 
 upright is of no use here, because it causes a reaction 
 movement in the horizontal plane, which cannot be ob- 
 served, as it does not cause the patient to fall.) 
 
 After eliciting a caloric nystagmus, the test is per- 
 formed just as with spontaneous nystagmus, 
 
 A loss of reaction movements of the body in the pres- 
 ence of a powerful rotatory nystagmus means disease 
 of the cerebellar worm, or of the tract which leads from 
 the worm to the anterior horn cells of the cord, namely, 
 through the nucleus tecti, tractus uncinatus and Dei- 
 terso-spinal tract. 
 
 The various methods of stimulating the labyrinth 
 which we have described vary in their intensity. The 
 caloric stimulation is the weakest of all. The stimula- 
 tion by rotation is stronger, and stimulation by com- 
 pression is the strongest; for there are many cases 
 which do not respond to the caloric or rotation tests, 
 and respond very readily to the fistula test. 
 
 Coming now to the second portion of our examina- 
 tion, namely, an examination of the spontaneous symp- 
 toms caused by disease of the labyrinth, we must dis- 
 tinguish between the manifest and the latent stages of 
 the disease. 
 
 During the early or manifest stage of the disease the 
 symptoms are usually very violent and easy to recog- 
 nize. We examine for spontaneous nystagmus. In 
 labyrinthine disease this is usually a combination of the 
 
METHODS OP EXAMINATION" 145 
 
 rotatory and horizontal form, and in a direction away 
 from the diseased ear. We look to see whether it 
 is present in every position of the eyes, or only in cer- 
 tain positions. 
 
 We notice the impairment of equilibrium. In severe 
 cases the patient is unable to stand, always falling 
 toward the diseased side. The direction of the fall is 
 influenced by the position of the head, as described in 
 the discussion of reaction movements. 
 
 The patient prefers to lie on the side of his sound 
 ear. This is because of the fact that in lying down the 
 tendency is to look away from the pillow. When the 
 patient lies on the sound ear, on looking away from the 
 pillow, the nystagmus, and consequently the subjective 
 symptoms also, are diminished, for, as we have already 
 mentioned, looking in the direction of the slow compo- 
 nent diminishes the intensity of the nystagmus. 
 
 When questioned most patients complain of an ap- 
 parent rotation of objects in the room. The direction 
 of the apparent rotation is usually in that of the rapid 
 component of the nystagmus, i. e., toward the sound ear. 
 Sometimes objects appear to move in both directions, 
 and rarely in the direction of the slow component of 
 the nystagmus. 
 
 When the eyes are closed there is a sensation of ro- 
 tation of the body in the direction of the rapid com- 
 ponent of the nystagmus. 
 
 In many cases there is a history of nausea and 
 vomiting. 
 
 In the late or latent stage of the disease we must 
 look carefully for the spontaneous symptoms of the dis- 
 ease. These symptoms consist in impairment of equi- 
 
146 THE LABYKINTH 
 
 librium. In this stage of the disease the impairment 
 of equilibrium is so slight that special tests are required 
 to bring them to light. Such a series of tests was elabo- 
 rated by von Stein. 
 
 He divided his tests into two sets, the first set to 
 determine the static muscular efficiency, and the second, 
 the dynamic muscular efficiency. 
 
 The determination of the static muscular efficiency 
 deals principally with the functions of the utricle and 
 saccule. The tests are all performed with the eyes 
 closed. They are as follows : 
 
 1. Standing still, with feet together. 
 
 2. Standing still, on toes, with feet together. 
 
 3. Standing on one foot. 
 
 4. Standing on an inclined plane. 
 
 In this fourth test a quantitative estimation is at- 
 tempted. The plane on which the patient stands is 
 gradually made more oblique until the patient falls. 
 The instrument used is the goniometer. In a normal 
 person, the anterior inclination which can be held 
 without falling is 36° to 40°, the posterior inclination, 
 26° to 30°, and the lateral inclination, 37° to 38°. In 
 disease of the labyrinth the angles are much smaller 
 than these. 
 
 The determination of the dynamic muscular efficiency 
 deals principally with the functions of the semicircular 
 canals. These tests are also performed with the eyes 
 closed. They are as follows : 
 
 1. Walking straight forward and backward on level 
 floor. 
 
 2. Hopping on toes forward and backward, with feet 
 together. 
 
METHODS OF EXAMINATION 147 
 
 3. Hopping on one foot, forward and backward. 
 
 4. Kotation about vertical axis of body, with feet to- 
 gether, to right and left. 
 
 5. Eotation on one foot. 
 
 By means of these various tests small degrees of loss 
 of equilibrium can be determined. However, the results 
 of these tests are not absolutely to be relied upon, be- 
 cause other factors, besides the labyrinths, must be 
 taken into account, namely, the muscular and joint 
 senses. Impairment of these senses would cause the 
 same loss of equilibrium as disease of the labyrinth. 
 Besides, normal individuals show marked differences 
 in regard to the ease with which they execute compli- 
 cated manceuvres. Physical training during childhood 
 has a good deal to do with this. However, as a supple- 
 ment to our other methods of testing the functions of 
 the labyrinth, these methods have their place. 
 
 Since the internal ear is composed of two parts, each 
 of which has a separate and distinct function, it is nec- 
 essary to extend our examination to the cochlea as well 
 as to the vestibular apparatus. 
 
 In testing the hearing by the various means in vogue 
 we wish to emphasize the fact that, particularly in the 
 presence of unilateral labyrinthine disease, many of 
 these tests are almost without value, unless the ear not 
 to be tested is absolutely excluded from the possibility 
 of hearing. In order to accomplish this, the closure of 
 the external meatus with the moistened finger is not 
 sufficient, and recourse must be had to more eflficient 
 means. Among the instruments designed for this pur- 
 pose the noise apparatus of Barany and that of White 
 are the best. 
 
148 THE LABYBINTH 
 
 The usual means of testing the hearing in a suspected 
 ear are the following,: 
 
 1. Voice. 
 
 2. Whisper. 
 
 3. Acoumeter or watch. 
 
 4. Tuning forks. 
 
 a. Weber. 
 
 b. Einne. 
 
 c. Schwabach. 
 
 The Wetaer test is based upon the fact that any 
 interference with the sound-conducting mechanism 
 causes the tone of a vibrating tuning fork, placed upon 
 the vertex, to be referred to the ear in which the inter- 
 ference exists. In the presence of unilateral disease of 
 the sound perceiving apparatus, however, the tone is 
 referred to the unaffected ear. 
 
 The Rinne test is a comparison between aerial 
 conduction and bone conduction in the same ear. Nor- 
 mally, if a vibrating tuning fork is placed on the mas- 
 toid, and the perception of the tone has ceased, the 
 fork should be heard again, if it be removed from the 
 mastoid and held near the auricle, in front. This is 
 called a positive Einne. The time of perception of the 
 tone by aerial conduction would be approximately twice 
 that by bone conduction, provided the ear were normal. 
 In this connection it must be remembered, that in the 
 presence of unilateral labyrinthine disease, with the 
 loss of cochlear function, the tone of a fork placed upon 
 the mastoid of the diseased ear would be perceived 
 through bone conduction in the sound ear. Under 
 these circumstances the Einne would be negative oo. 
 In other words, there would be no perception by aerial 
 
METHODS OF EXAMINATION 149 
 
 conduction if the vibrating fork were held close to the 
 diseased ear. 
 
 The SchTrabach test consists of a comparison 
 between the perception time, by bone conduction, of the 
 suspected ear and that of an ear known to be normal. 
 Thus the vibrating tuning fork is first placed upon the 
 mastoid of the examiner. In this way the normal per- 
 ception time is determined. 
 
 In examining an ear in which labyrinthine disease is 
 suspected, the conclusions to be drawn from testing the 
 hearing by means of the voice are decidedly uncertain, 
 unless the unsuspected ear is absolutely excluded by 
 the noise apparatus. If, after the application of such 
 an instrument to the opposite ear, the individual who is 
 examined fails to hear speech, no matter how loud, 
 when emitted even close to the tested ear, we may safely 
 conclude that the latter is deaf to the voice. In addition 
 to testing with the voice, it has been our custom to test 
 the suspected ear by whistling through the lips, the pitch 
 of the note thus made approximating g^. Here the blast 
 of air must be directed in such a way that the patient is 
 unable to feel it. So many individuals confuse the 
 feeling of the blast of air in the whistling test and of the 
 vibration of the forks in the tuning fork tests, with the 
 hearing of the sounds, that the greatest care must be 
 exercised lest this confusion lead to error. Needless 
 to state that during the tests with the voice and by 
 whistling, the patient must not observe the ex- 
 aminer. 
 
 Deafness to the voice, however, is not alone sufficent 
 to enable us to conclude that all the cochlear function 
 has been destroyed. To further substantiate this we 
 
150 THE LABYBINTH 
 
 use the tuning fork tests. These alone may give us the 
 data for a fairly certain diagnosis of total unilateral 
 deafness. Thus, if the "Weber is lateralized to the sound 
 ear, while the Einne is negative co, i. e., if the tuning 
 fork is heard only by bone conduction, and if, in addi- 
 tion to this, the Schwabach shows a shortening of bone 
 conduction for the high pitched forks while the low 
 forks are not heard at all, then we have sufficient data 
 to establish a highly probable diagnosis of unilateral 
 deafness. It seems to us, however, that in the noise 
 apparatus we have so sure a means of establishing a 
 diagnosis of deafness positively and beyond a doubt, 
 that we have come to rely upon this adjunct to our 
 examinations. 
 
 The Weber test as usually made is notoriously uncer- 
 tain. In combination with the noise apparatus, how- 
 ever, it gives us accurate and valuable information. 
 This modified Weber test is carried out as follows ; both 
 ear pieces of the White apparatus are snugly fitted into 
 the ears. The air stream is then turned on either from 
 the balloon of the White instrument or from a com- 
 pressed air apparatus. We now determine positively 
 through voice, whistling and fork tests, that both ears 
 are thus excluded from hearing. Then, after the air 
 current is shut off, the ear piece in the suspected ear 
 is removed, while that in the ear not to be tested is care- 
 fully held in place. The rubber tube connected to the 
 ear piece which has been removed is clamped or knot- 
 ted. After the air is again turned on the vibrating fork 
 is placed upon the vertex, glabella, chin, teeth, or mas- 
 toid. If the patient hears the fork he can do so only 
 with the tested ear. It is customary, in these tests, to 
 
METHODS OF EXAMINATION 151 
 
 use a fork of medium pitcli, c^ 512 V., but the method 
 is applicable to the high and low forks as well. It is in 
 the tests with the low pitched forks, however, that the 
 greatest confusion between the feeling of the vibration 
 and the perception of the sound is encountered. 
 
CHAPTEE IV 
 PATHOLOGY 
 
 Labyrinthitis, or inflammatioii of the internal ear, 
 may be classified in many different ways. 
 
 The most important method of classification, for 
 practical purposes, is upon a clinical basis, into 
 
 1. Circumscribed labyrinthitis, and 
 
 2. Diffuse labyrinthitis. 
 
 The circumscribed form may be further subdivided 
 into paralabyrinthitis, perilabyrinthitis, and a form in 
 which there is a combined para- and perilabyrinthitis. 
 Endolabyrinthitis alone has never been observed. 
 
 The diffuse form may be divided into a combined 
 peri- and endolabyrinthitis, which is known as empy- 
 ema of the labyrinth, and panlabyrinthitis, which is a 
 combination of para-, peri- and endolabyrinthitis. 
 
 Paralabyrinthitis is an inflammation of the bony cap- 
 sule of the labyrinth. Perilabyrinthitis is an inflam- 
 mation of the perilymph spaces, and endolabyrinthitis 
 is an inflammation of the endolymph spaces. 
 
 Both the circumscribed and the diffuse forms of 
 labyrinthitis may be acute, subacute or chronic. 
 
 The above outlined clinical basis of classification is 
 important, because upon it are based, to a large extent, 
 our indications for treatment. 
 
 A second method of classification is based upon the 
 pathologic changes in the labyrinth. According to this 
 classification, we divide labyrinthitis into the exudative, 
 plastic and necrosing forms. 
 
PLATE IX. 
 
 Vn CPV St Sa 
 
 DC 
 
 Fig. 60 
 
 Diffuse Serous Ladyrixtiiitis 
 
 I AC 
 
 DC — Dilated ductus cochlearis 
 
 ['' — Dilated utricle 
 
 8a — Saccule 
 
 St — Foot-plate of stapes 
 
 CFV — Compressed cisterna peri- 
 
 Ij'mphatica vestibuli 
 YIl — Facial nerve 
 lAC — Internal auditory canal 
 
PLATE X. 
 
 Fig. 01 
 
 Diffuse SEEO-Finnixous LAByitiKTiiiTis 
 Deposits of fibrin in the peri- and endolymphatic spaces of the cochlea 
 
PATHOLOGY 153 
 
 The exudative may be subdivided into the serous 
 (Fig. 60, Plate IX) and purulent types; the plastic 
 may be subdivided into the sero-fibrinous (Fig. 61, 
 Plate X) and fibrino-purulent forms; and the ne- 
 crosing may be divided into those in which the necrosis 
 is limited to the soft tissues, and those in which the 
 bony capsule is invaded also. 
 
 Etiology forms the basis for a third method of clas- 
 sification. Here we have the scarlatinal, cholesteato- 
 matous, tuberculous, traumatic forms, etc. 
 
 Finally, we may classify labyrinthritis upon an anat- 
 omo-topographic basis, i. e., according to the location 
 of the portal of infection. According to this method we 
 may divide the cases into primary and secondary. No 
 undoubted case of primary labyrinthitis has ever been 
 reported. The secondary cases may be divided into 
 meningeal, tympanic and metastatic types. 
 
 In the meningeal cases the infection reaches the laby- 
 rinth in one or more of the following ways : 
 
 1. Through the internal auditory canal. 
 
 2. Through the aqueductus cochleae. 
 
 3. Through the aqueductus vestibuli. 
 
 4. By necrosis of the inner labyrinthine wall. 
 
 5. Through the hiatus subarcuatus. 
 
 In the tympanic cases, the infection reaches the laby- 
 rinth through one or several of the following path- 
 ways: 
 
 1. Oval window. 
 
 2. Eound window. 
 
 3. Fistula in one of the semicircular canals. 
 
 4. Fistula in the promontory. 
 
 The metastatic cases are those in which the infection 
 
154 THE LABTBINTH 
 
 reaches the labyrinth through the circulation, as in 
 mumps. These cases are very rare. 
 
 The most common location for circumscribed labyrin- 
 thitis is in one of the semicircular canals. Here the 
 conditions are most favorable for circumscription of 
 an inflammatory process. The gradual onset of the in- 
 fective process, the small calibre of the bony canals, and 
 the large number of connective tissue septa in the peri- 
 lymph spaces, favor a walling off of the inflammatory 
 focus from the rest of the labyrinth. However, a cir- 
 cumscribed labyrinthitis may occur in almost any por- 
 tion of the labyrinth. A low-grade infection through 
 the oval window may give rise to a localized inflamma- 
 tory focus in the cisterna perilymphatica of the vesti- 
 bule. Alexander states that the thick fibrous septimi 
 which separates the cisterna perilymphatica from the 
 utricle is firm enough to resist the spread of infection 
 for a considerable length of time. This septum divides 
 the labyrinth into two portions. On one side lie the 
 utricle and semicircular canals, and on the other the 
 cisterna perilymphatica, the saccule and the cochlea 
 (Fig. 12, Plate VIH). An inflammatory focus can re- 
 main localized to one or the other side of this septum 
 for some time. 
 
 The perilymph spaces of the ampullae are almost com- 
 pletely shut off from the vestibule by connective tissue 
 septa. These serve to limit an inflammatory process 
 within the perilymph spaces of the semicircular canals, 
 or in the cisterna perilymphatica of the vestibule. With 
 inflammatory thickening of the cristse, these septa may 
 form an effective barrier across the entire lumen of 
 the bony canals. 
 
PATHOLOGY 155 
 
 The inflammatory process may involve the entire 
 perilymph space, leaving the endolymph spaces free. 
 
 In inflammation of the cochlea it is possible for the 
 disease to be limited to the first half of the basal whorl. 
 In fact, this is the most common location for a circum- 
 scribed inflammatory focus in the cochlea. Even in 
 the cases of diffuse labyrinthitis the inflammatory 
 changes are more advanced in the first half of the basal 
 whorl than in the rest of the cochlea. The inflammation 
 seems to start in the beginning of the basal whorl. 
 
 Ruttin explains these facts upon a purely mechanical 
 basis. In cases where the middle ear infection is not 
 very virulent, a perforation through the annular liga- 
 ment of the stapes, which develops gradually, results 
 first in a deposit of pus on the vestibular surface of 
 the foot-plate. After a sufficient quantity has accumu- 
 lated a portion of the pus falls down into the beginning 
 of the scala vestibuli of the basal whorl of the cochlea, 
 and rests on Eeissner's membrane. The lower half of 
 the basal whorl forms the lowermost portion of the 
 cochleal cavity in every position of the head. Ruttin 
 found that by placing a triton-shell, with its axis in a 
 position corresponding to the human modiolus, and re- 
 moving a portion of the outer wall of the upper half of 
 the basal turn, a globule of mercury dropped through 
 this opening into the lower half of the basal turn could 
 not be made to leave this portion of the canal, when the 
 position of the horn was changed to correspond to vari- 
 ous positions of the human head. From this experi- 
 ment he draws the conclusion that the reason for the 
 frequent circumscription of an inflammatory process in 
 
156 THE LABYBINTH 
 
 the lower half of the basal whorl of the cochlea is a 
 mechanical one. 
 
 When a perforation occurs through the secondary 
 tympanic membrane the infective process reaches the 
 beginning of the scala tympani first (Fig. 62, Plate 
 XI). If the infection is mild the inflammatory process 
 is very likely to be limited to the scala tympani of the 
 lower half of the basal whorl of the cochlea. 
 
 Consequently, with the same intensity of infection^ 
 the prognosis with regard to function is worse in per- 
 forations through the oval window than in those 
 through the round window. For ia the former both the 
 vestibule and the cochlea are invaded, while in the latter 
 only the cochlea is involved. 
 
 Ruttin states that where a purulent involvement of 
 the cisterna perilymphatica results in a rupture into 
 the endolymph spaces, the location of the rupture is 
 always in a deeply situated portion of the membranous 
 labyrinth, i. e., in the saccule, canalis reuniens, coecum 
 vestibulare, or the vestibular portion of the ductus 
 coehlearis. 
 
 The most common situation for a circumscribed laby- 
 rinthitis is in the external semicircular canal. The 
 most common cause is cholesteatoma. A portion of the 
 bony capsule of the external semicircular canal lies ex- 
 posed in the aditus. In this situation it is subjected to 
 the eroding action of the cholesteatoma. As the bony 
 capsule is eroded it is replaced by granulation tissue. 
 When the destructive process has gone through the 
 entire thickness of the bony capsule, the endosteum, 
 covered on its outer surface by granulations, is exposed 
 at the bottom of the fistulous opening. Up to this stage 
 
PLATE XI. 
 
 VAN 
 
 FN 
 
 V 
 
 AV 
 
 s 
 
 IAN 
 
 
 Chronic Plkilent Otitis Media, With Pekforation Through the 
 
 Upper Part of ANisaiLAR Ligament of Stape.s, and Through 
 
 Secondary Tympanic Memkhane 
 
 AL — Peifoi'ation through upper 
 part of annular ligament 
 
 STil — Peifoi-ation through sec- 
 rindaiv tympanic mem- 
 brane 
 
 CPV — Purulent exudate in cis- 
 terna perilymjjhatica ves- 
 tihuli 
 
 (ST — Purulent exudate in scala 
 tympani of beginning of 
 cochlea 
 
 TC — Tympanic cavity filled with 
 
 ])us and granulations 
 /' — Promontory 
 
 A'h'W — Recess of round window 
 I — Utricle (not involved) 
 <S' — Saccule (not involved) 
 .IT — Beginning of aqueductus 
 
 vestibuli 
 iSta — Stapes 
 FN — Facial nerve 
 VAIV — Utriculo-ampullaric nerve 
 /.liV — Inferior ampullaric nerve 
 
PLATE XII. 
 
 s 
 
 Fig. 63 
 
 Fistula in External Semicircular Canal 
 
 Paralabyrinthitis. Suppurative perilabyrinthitis. Membranous canal 
 
 is normal 
 
 F — Fistula in bony capsule filled 
 with granulation tissue. 
 Endosteum is destroyed 
 in this location 
 
 M — Normal membranous canal 
 
 P — Granulation tissue and pus in 
 
 perilymph space 
 E — Endosteum 
 /S' — Connective tissue septum in 
 
 perilymph space 
 
PATHOLOGY 157 
 
 the process is known as a paralabyrinthitis. It may 
 remain in tMs stage for a considerable length of time. 
 Sooner or later, however, the granulations erode 
 through the endosteum and enter the perilymph spaces. 
 In response to the irritation of the infective process 
 there results an inflammatory thickening of the endos- 
 teum and of the connective tissue septa, which bridge 
 across the spaces between the endosteum and the mem- 
 branous semicircular canal. This thickening shuts in 
 the inflammatory focus and prevents the infection from 
 becoming general. The condition is now called a peri- 
 labyrinthitis (Fig. 63, Plate XII). The wall of the mem- 
 branous canal and its contents are normal. 
 
 After a time the wall of the membranous labyrinth 
 becomes hyperaemic and thickened, and there occurs a 
 fibrinous deposit upon its inner surface. The crista 
 becomes infiltrated with round cells. Its epithelial ele- 
 ments become swollen and necrotic. Small abscesses 
 may form in the wall of the membranous labyrinth. 
 This wall finally perforates and the endolymph space 
 becomes filled with pus. The infection in the endo- 
 lymph space may remain limited to the one semicircu- 
 lar canal or it may spread through the entire labyrinth. 
 While fistulae are most common in the external semi- 
 circular canal, they may occur in any of the canals, or, 
 in fact, in any portion of the labyrinthine capsule. 
 When they occur in the superior or posterior canal they 
 are much more apt to escape observation at the time 
 of operation, on account of the spongy character of 
 the bone which surrounds these canals. 
 
 The fistula which is commonly seen in the wall of the 
 external semicircular canal is usually trough-shaped. 
 
158 THE LABYEINTH 
 
 It is about Imm wide. It averages 3 to 4 mm in length. 
 Sometimes granulations are seen in the canal. It is 
 extremely rare for pus to be seen exuding from the 
 fistula. In some cases the entire eminence of the canal 
 is destroyed, and there are seen two holes, each corre- 
 sponding to one limb of the canal. 
 
 When the bony wall has been partially eroded, either 
 from within or from without, the contents of the semi- 
 circular canal can sometimes be seen, as a dark brown 
 streak, through the very thia layer of bone that re- 
 mains. This is sometimes mistaken for a fistula, but 
 such a case would naturally give a negative fistula test. 
 
 A diffuse labyrinthitis may be diffuse from the be- 
 ginning, or it may start as a circumscribed labyrinthitis 
 and become diffuse by breaking down its barriers. 
 
 Cases of diffuse labyrinthitis may change to the cir- 
 cumscribed form after a time. On microscopic exami- 
 nation these cases show a circumscribed labyrinthitis, 
 with degenerative changes in the nerve end-organs of 
 the remaining portions of the labyrinth. 
 
 The cases of diffuse labyrinthitis may be divided 
 into serous, sero-fibrinous, and purulent types. The 
 serous and sero-fibrinous types may be classed together, 
 as there is no way of differentiating them clinically, 
 and their course and outcome is the same. The puru- 
 lent cases may be divided into those with and those 
 without bone involvement. The cases of purulent laby- 
 rinthitis without bone involvement are known as em- 
 pyema of the labyrinth. When the bony capsule is in- 
 volved the condition is known as a panlabyrinthitis. 
 
 Diffuse serous labyrinthitis may be either secondary 
 to a circumscribed purulent labyrinthitis, with a fistula. 
 
PATHOLOGY 159 
 
 or it may spread through an intact labyrinthine wall. 
 The latter form is called induced serous labyrinthitis. 
 
 Induced serous labyrinthitis may occur during the 
 course of an acute or chronic purulent otitis media. It 
 may come on after a radical mastoid operation, either 
 within 24 to 48 hours after the operation, or at any 
 later time, until the cavity has healed. 
 
 It was at one time thought that induced labyrinthitis 
 was due to a transmission of the infection from the 
 middle ear to the labyrinth through the minute vascular 
 anastomosis which exists in the outer labyrinthine 
 wall, between the tympanic and the labyrinthine circu- 
 lations. But this is probably not true ; for if it were so, 
 induced labyrinthitis would be a much more common 
 condition than it is. Voss considers it to be a collateral 
 inflammatory oedema of the labyrinth, resulting from 
 the middle ear inflammation. 
 
 0. Mayer, Lange and Nager examined cases histo- 
 logically, which have demonstrated the true pathogene- 
 sis of this condition. In Mayer's case there was an 
 acute purulent inflammation of the middle ear. The 
 recesses of the oval and round windows contained large 
 numbers of bacteria. The annular ligament of the 
 stapes and the secondary tympanic membrane showed 
 an oedema, with a beginning necrosis of the cellular ele- 
 ments of these membranes. On the vestibular surfaces 
 of the foot-plate of the stapes and the secondary tym- 
 panic membrane, as well as in the various other por- 
 tions of the labyrinth, there were fibrinous deposits. 
 There were a few round cells in the fibrinous deposits, 
 which had apparently migrated from the dilated ves- 
 sels in the ligamentum spirale. There were no bacteria 
 
160 THE LABYRINTH 
 
 to be found either in th.e peri- or tlie endolymphatic 
 spaces of the labyrinth, nor in the annular ligament or 
 secondary tympanic membrane. 
 
 The sequence of events was probably as follows : the 
 bacteria in the middle ear, which had accumulated in 
 the recesses of the oval and round windows, on account 
 of the favorable conditions for their development in 
 these locations, elaborated toxines, which passed into 
 the annular ligament and secondary tympanic mem- 
 brane, and then through these structures, into the peri- 
 lymph and endolymph spaces of the labyrinth. Here 
 the irritation of these substances produced a dilatation 
 of the labyrinthine blood-vessels, with an exudation of 
 serum, fibrin, and a few round cells. Mayer believes 
 that labyrinthitis toxica would be a better name for the 
 condition than induced labyrinthitis. 
 
 If the necrotic changes in the annular ligament and 
 secondary tympanic membrane are sufficiently intense, 
 perforation takes place, with the occurrence of a puru- 
 lent labyrinthitis. 
 
 Just as a purulent inflammation of the middle ear 
 may cause an induced serous labyrinthitis, so a puru- 
 lent peri labyrinthitis may give rise to a serous inflam- 
 mation in the endolymph spaces. "We sometimes see in 
 histological examinations purulent inflammation in one 
 portion of the labyrinth and serous inflammation in 
 another portion. 
 
 The pathological changes which occur in a diffuse 
 serous or sero-fibrinous labyrinthitis consist of a dila- 
 tation of the labyrinthine blood-vessels, an increase in 
 the peri- and endolymphatic fluids, deposits of fibrin in 
 various portions of the labyrinth, migration of a few 
 
PATHOLOGY 161 
 
 round cells into the peri- and endolymphatic spaces^ 
 swelling and some necrosis of the epithelial elements 
 in the nerve end-organs, and desquamation of endo- 
 thelial cells. 
 
 Increase in the perilymph is shown by dilatation of 
 the cisterna perilymphatica vestibuli, with compression 
 of the utricle and saccule, and compression of the duc- 
 tus cochlearis. Increase in the endolymph is shown by 
 dilatation of the utricle and saccule, and especially by 
 ectasia of the ductus cochlearis (Fig. 60, Plate IX). 
 The ductus cochlearis may be three or four times its 
 natural size. Eeissner's membrane is bowed out with 
 its convexity toward the scala vestibuli, and its point 
 of attachment to the outer cochleal wall is displaced 
 upward. 
 
 Ruttin explains the occurrence of ectasia of the duc- 
 tus cochlearis in several ways. 
 
 He noticed that in many cases the ectasia was limited 
 to the basal whorl of the cochlea, while the ductus 
 cochlearis was collapsed in the upper whorls. He be- 
 lieves that in some of the cases the increase of the peri- 
 lymph in the upper whorls causes a collapse in the 
 ductus cochlearis. The fluid which is forced out of this 
 portion of the endolymph tube causes a dilatation of the 
 ductus cochlearis in the basal whorl. 
 
 In other eases an increase of the endolymph causes a 
 dilatation of the ductus cochlearis directly. 
 
 Ruttin noticed that as far as the ectasia extended, 
 Eeissner's membrane was covered by a layer of fibri- 
 nous exudate on the side toward the scala vestibuli. 
 He believes that this fibrinous exudate falls by reason 
 of its weight from the cisterna perilymphatica vestibuli 
 
162 
 
 THE LABYBINTH 
 
 into the scala vestibuli of the lower half of the basal 
 whorl of the cochlea. The thickening which is thus pro- 
 duced, suffices to hold Eeissner's membrane in the ab- 
 normal position, into which it has been pushed by the 
 increase of endolymph in the ductus cochlearis. 
 
 He believes that in some cases the fibrinous deposit, 
 in the process of organization, causes traction on 
 Eeissner's membrane, producing in this way an ectasia 
 of the ductus cochlearis. 
 
 Diffuse serous or sero-fibrinous labyrinthitis is al- 
 ways acute. It never lasts more than a week or two, 
 and results in complete restitutio ad integrum, or in 
 permanent destruction of portions of the labyrinth with 
 secondary atrophic changes. 
 
 A purulent infection which reaches the labyrinth 
 from the middle ear almost always makes its entrance 
 through a rupture in the labyrinthine wall. But it can 
 occur as the result of emigration of bacteria through 
 an unruptured annular ligament, as in a case ob- 
 served by Grunherg, or through an unruptured sec- 
 ondary tympanic membrane, as in a case observed by 
 0. Mayer. 
 
 Diffuse purulent labyrinthitis may be acute or 
 chronic. In the acute cases bone destruction is uncom- 
 mon, except in scarlatinal infections. In the chronic 
 cases bone destruction is very frequent. 
 
 The pathological changes which occur in diffuse pur- 
 ulent labyrinthitis are divided by Alexander into me- 
 chanical lesions and inflammatory changes. The me- 
 chanical lesions are due to the breaking through of the 
 pus, and consist of the tearing of Eeissner's membrane 
 and of other portions of the membranous labyrinthine 
 
PATHOLOGY 163 
 
 wall, mechanical destruction of the neuro-epithelial 
 cells, and displacement of the membrana tectoria. 
 
 The inflammatory changes consist of dilatation of the 
 blood vessels, infiltration of the soft tissues with serum 
 and round cells, exudation of pus into the perilymph 
 and endolymph spaces, and swelling and necrosis of the 
 epithelial cells. The hairs are more resistant than the 
 bodies of the hair-cells. The hairs of the cristas and 
 maculae are more resistant than those of Corti's organ. 
 
 The neuro-epithelium and nerve-fibres may remain 
 intact for some time after the endolymph spaces are 
 filled with pus. A case examined by Alexander, in 
 which the labyrinthine functions could not be aroused 
 before death, showed, on post-mortem examination, the 
 labyrinth filled with purulent exudate, but the nerve 
 end-organs intact. From this he draws the conclusion 
 that a normally constituted endolymph fluid is neces- 
 sary to enable the end-organs to functionate properly. 
 
 After a time the end-organs are completely de- 
 stroyed. Suppuration may extend into the aqueductus 
 cochleae and aqueductus vestibuli. But the entrances to 
 these passageways are often occluded by a swelling of 
 their fibrous or epithelial lining or by desquamated 
 epithelial cells. In this way a spread of the infection 
 through these canals is prevented. 
 
 The spiral ganglion is usually infiltrated with round 
 ceUs. The nerve-fibres in the modiolus and in the in- 
 ternal auditory canal, as well as the lymph spaces about 
 the nerve-fibres, are infiltrated with round cells. The 
 nerve-fibres may be degenerated. 
 
 Politser and Lange found in many cases an abscess 
 
164 
 
 THE LABYEINTH 
 
 at the fundus of the internal auditory canal, over the 
 areae cribrosae, which was sharply differentiated by a 
 well-marked line of circumscription from the remainder 
 of the nerve-bundle. This abscess lies in the subarach- 
 noid space, and is walled off by the attachment of the 
 arachnoid sheath of the nerves to the dural lining of 
 the internal auditory canal, which occurs near the 
 fundus of the canal, and which separates the subarach- 
 noid from the subdural space in this situation. 
 
 An abscess located at the fundus of the internal audi- 
 tory canal destroys not only the nerve fibres, but also 
 the blood vessels which supply the soft tissues and por- 
 tions of the bony capsule of the labyrinth, namely, the 
 internal auditory artery. The interruption of their 
 blood-supply results in necrosis of these tissues. Ne- 
 crosis may also be caused by the inflammatory process 
 within the labyrinth causing embolism or thrombosis of 
 the branches of the internal auditory artery. 
 
 The endosteum is the most resistant of all the soft 
 structures within the labyrinth, and reacts to the in- 
 flammatory irritation by becoming thickened, and by 
 the formation of granulations upon its free surface. 
 These granulations may partly or completely fill the 
 labyrinthine spaces, and may cause destruction of their 
 bony walls (Fig. 64, Plate XIII). 
 
 The destructive bone changes which occur in diffuse 
 purulent labyrinthitis are of two kinds, caries and ne- 
 crosis. Usually both forms are present together. 
 
 In caries of the labyrinthine capsule the inflamma- 
 tion usually starts in the membranous labyrinth. When 
 the inflammatory process in the membranous labyrinth 
 is very intense there occurs necrosis of the soft tissues. 
 
PLATE XIII. 
 
 MC 
 
 Chronic Purulent Labyrinthitis, With Caries of Bony Wall of 
 Semictrculak Canal From Within 
 
 8C — Perilymph space of semicir- 
 cular canal, full of gran- 
 ulation tissue and con- 
 nective tissue 
 
 MC — Remnant of membranous 
 canal full of pus 
 
 C — Inner portion of bony wall of 
 canal destroyed by cari- 
 ous process 
 
OH" ,S7 
 
 PLATE XIV. 
 
 TC P C 
 
 I AC A 
 
 Fig. 65 
 
 Diffuse Pckulext Labyrinthitis Foli^owino Laege Perforation in 
 Region of Oval Window 
 
 Oir — Large perforation in region 
 
 of oval window 
 >S7 — Remains of stapes 
 TC — Tj'nipanic cavity filled with 
 
 pus and granulations 
 V — Vestibule, with membranous 
 
 portion destroyed 
 P — Proniontorv 
 
 C — Cochlea, filled with purulent 
 exudate 
 
 A — Sharply circumscribed abscess 
 in fundus of internal au- 
 ditory canal 
 
 I A C — ^Internal auditory canal, 
 containing cochlea and 
 vestibular nerves infil- 
 trated with pus cells 
 
PATHOLOGY 165 
 
 This arouses a reactive inflammation in the surround- 
 ing bony capsule with its periosteal covering. Granu- 
 lations invade the bone canals, and cause a resorption 
 of the bone tissue, the destroyed bone being replaced 
 by granulation tissue. Caries is an interstitial granu- 
 lation involvement of bone. The Haversian canals be- 
 come wider and wider. The dense bone becomes porous 
 and the cavities are filled with round cells, a gelatinous 
 intercellular substance and numerous blood-vessels. 
 Osteoclasts lie in Howship's lacuna. The bone cor- 
 puscles lie in partly opened bone canals. 
 
 This inflamed bone has a strong affinity for eosin 
 stain. At a later stage the bone takes very little stain 
 or none at all. 
 
 The picture is one of bone resorption. There is a 
 softening, perhaps through pathological decalcification, 
 during which the cells, which before lay in bone-canals, 
 become free, swell up, and change their shape. 
 
 Necrosis of the labyrinthine capsule consists of death 
 of the bone, due to a cutting off of its blood-supply. A 
 large portion of the labyrinthine capsule receives its 
 blood-supply through the internal auditory artery. 
 This vessel is practically an end-artery, as the anasto- 
 mosis between it and the middle-ear vessels, through 
 the promontory, is so minute as to be negligible. An 
 abscess in the internal auditory canal (Fig. 65, Plate 
 XIV), by destroying the internal auditory artery, will 
 cause necrosis of a large portion of the labyrinthine 
 capsule. In acute scarlatinal middle-ear disease the in- 
 fective process is so intense that it causes necrosis of 
 the soft tissues within the labyrinth. This results in 
 destruction of the branches of the internal auditory 
 
166 THE LABYRINTH 
 
 artery in the labyrinth, and thus portions of the bony 
 capsule are rendered necrotic. 
 
 As a result of necrosis of a portion or all of the bony 
 capsule there is set up a reactive inflammation in the 
 surrounding bone in the form of caries. The surround- 
 ing bone is gradually eroded until eventually the ne- 
 crotic bone lies free, as a sequestrum, in a bed of granu- 
 lation-tissue. As the necrotic bone contains no blood- 
 vessels it cannot be absorbed. If a portion of the inner 
 tympanic wall is included in the necrosis the seques- 
 trum may be extruded through the middle ear. If no 
 portion of the tympanic wall is included in the necrosis 
 the sequestrum lies enclosed in a bony shell, and cannot 
 be extruded until the overlying bone is destroyed by 
 carious inflammation. 
 
 The cochlea is the portion of the labyrinth which is 
 most frequently extruded as a sequestrum (Fig. 66, 
 Plate XV). Necrosis of the semicircular canals or ves- 
 tibule is far less common. Exfoliation of only a portion 
 of the labyrinth does not mean that the disease is lim- 
 ited to that portion. Usually the entire labyrinth is 
 diseased. 
 
 No case of undoubted primary labyrinthitis has yet 
 been observed. Labyrinthitis may be secondary to in- 
 tracranial disease, to disease in the middle ear, or it 
 may be metastatic. Of intracranial diseases, by far the 
 most common cause of labyrinthitis is epidemic cere- 
 bro-spinal meningitis. According to various statistics 
 from 15 to 50% of the cases of cerebro-spinal menin- 
 gitis are followed by deafness. In 19 temporal bones 
 taken from 10 patients who died of epidemic cerebro- 
 spinal meningitis, Goerke found inflammatory changes 
 
PLATE XV. 
 
 .1/ 
 
 I AM 
 
 Fig. or; 
 
 Chronic Difftse Pukulext Labykixtiiitis, With Caries of Laby- 
 KiNTiiiXE Capsule axd Necrosis and Sequestration of Modiolus 
 
 il/ — Keerotie modiolus 
 
 lAM — Abscess at bottom of in- 
 ternal auditory canal 
 
 B — Cochleal canal full of granu- 
 lations 
 
 -Carious labyrinthine capsule 
 replaced by granulation 
 tissue 
 
 -Tympanic cavity full of gran- 
 ulation tissue 
 
PATHOLOGY 167 
 
 in the internal ear 17 times. In most of the cases there 
 was a circumscribed labyrinthitis present. 
 
 According to Friedrich and Einsberg, there is 1 case 
 of labyrinthitis in every 100 cases of middle-ear suppu- 
 ration. At first glance these figures would seem to indi- 
 cate that intracranial disease was a much more prolific 
 cause of labyrinthitis than is disease of the middle ear. 
 But middle ear disease is so much more common than 
 cerebro-spinal meningitis that the number of cases of 
 labyrinthitis actually caused by the former is much 
 greater than that caused by the latter. 
 
 In addition to cerebro-spinal meningitis, labyrinthitis 
 can be caused by purulent leptomeningitis, or by epi- 
 dural abscess in the posterior or middle fossa. A laby- 
 rinthitis which is caused by a middle ear infection may 
 spread to the meninges. The meningitis may reinfect 
 the labyrinth or infect the labyrinth of the opposite ear 
 through the internal auditory canal or aqueductus 
 cochleae. 
 
 The most frequent pathways of infection from the 
 intracranial cavity to the labyrinth are through the 
 internal auditory canal and through the aqueductus 
 cochleae. Infection through the aqueductus vestibuli 
 is rare, but it does occur. A subdural abscess may 
 erode the bony capsule of the posterior or superior 
 semicircular canal, and thus infect the labyrinthine 
 cavity. 
 
 Einsberg observed a case in which an extradural ab- 
 scess, caused by infection through the vessels which 
 pass through the fossa subarcuata, eroded the wall of 
 the superior semicircular canal, and thus infected the 
 labyrinth. 
 
168 THE LABYEINTH 
 
 The cases of labyrintMtis which are secondary to 
 middle ear conditions, we may divide into those due to 
 inflammatory disease of the middle ear, and those due 
 to injuries. 
 
 The middle ear inflammations which cause labyrin- 
 thitis may be acute or chronic. Chronic middle eaf 
 disease is responsible for the vast majority of the cases. 
 Out of 137 cases of labyrinthitis observed by Jansen 
 only three occurred with acute otitis media. But in 
 the chronic middle ear conditions an acute exacerba- 
 tion of the inflammation is usually responsible for the 
 extension into the labyrinth. 
 
 The most common of the acute middle ear diseases 
 which cause labyrinthitis is that due to scarlatina. 
 Scarlatinal otitis is especially apt to cause bony de- 
 structive changes in the labyrinth. 
 
 Of the chronic middle ear conditions cholesteatoma 
 is responsible for most of the labyrinthine infections. 
 Next in frequency is tuberculosis of the middle ear. 
 Of 121 cases of fistulse of the semicircular canals ob- 
 served by Jansen, 71 occurred with cholesteatoma and 
 16 with tuberculosis. 
 
 Cholesteatoma causes labyrinthine disease by pro- 
 ducing a gradual erosion of the bony labyrinthine cap- 
 sule, to which is added an infective process from the 
 middle ear cavity. The cholesteatoma sometimes ex- 
 tends into the labyrinth. 
 
 Middle ear suppuration may extend to the labyrinth 
 through a fistulous opening in one of the semicircular 
 canals, through the oval window, the round window, 
 or through a fistulous opening in the promontory. 
 Goerke reported a case where extension to the cupola 
 
PATHOLOGY 169 
 
 of the cochlea occurred through a fistulous opening at 
 the tympanic orifice of the Eustachian tube. Grunert 
 reported a case where the infection took place through 
 a fistulous opening in the facial canal. 
 
 In regard to the relative frequency of the point of 
 entry of the infection there is still some dispute. It is 
 probable that the most frequent point is through a 
 fistula in the external semicircular canal. The statis- 
 tics which are compiled from clinical observations in- 
 dicate an overwhelming predominance of fistulas in the 
 semicircular canals, whereas histological examinations 
 show a predominance of fistulas in the oval window. 
 The reason for this is that infections which take place 
 through the oval window are much more apt to produce 
 fatal complications than those occurring through a fis- 
 tula in the semicircular canal. 
 
 The oval and round windows are favorable sites for 
 the transmission of disease to the labyrinth, on account 
 of the fact that the recesses of these windows fill with 
 granulations and connective tissue, causing a stagna- 
 tion of pus in these regions. The annular ligament and 
 the secondary tympanic membrane, being membranous, 
 offer less resistance than the bony capsule, to the de- 
 structive process. The various changes which may bQ 
 seen in the oval window are : 
 
 1. Destruction of part or the whole of the annular 
 ligament. 
 
 2. Destruction of part or the whole of the foot-plate 
 of the stapes. 
 
 3. Displacement of the foot-plate of the stapes. 
 
 4. Destruction of the cartilaginous and bony margin 
 of the oval window. 
 
170 THE LABYEINTH 
 
 5. Pus may be seen exuding from tlie oval window, 
 or it may be filled with granulations. 
 
 Defects in tbe secondary tympanic membrane can- 
 not be observed clinically, on account of the position of 
 this membrane in the wall of the recess of the round 
 window. 
 
 There may be one or several fistulge leading from the 
 middle ear into the labyrinth. When two or more fis- 
 tulse are present they may all be primary; i. e., they 
 may all arise from the disease-process in the middle 
 ear, and act as portals of entry for the infection into 
 the labyrinth; or one fistula may be primary and the 
 remaining fistulse secondary to the disease within the 
 labyrinth. Out of 14 cases of labyrinthitis examined 
 microscopically by Lange, he found a single primary 
 fistula in 3 cases, multiple primary fistulsB in 6 cases, 
 and primary and secondary fistulse in 5 cases. The 
 primary fistulse were located in one of the semicircular 
 canals 9 times, in one of the windows 4 times, and in 
 the windows and semicircular canals once. 
 
 Lange explains the occurrence of secondary fistulse 
 as follows; he found that secondary fistulse occurred 
 only where there was necrosis of the soft tissues within 
 the labyrinth. The labyrinthine contents become in- 
 fected, for example, through a fistula in the external 
 semicircular canal. If a necrosis of the soft tissues in 
 the labyrinth occurs, there is set up a reactive inflamma- 
 tion in the surrounding tissues. As the oval and round 
 windows lie at the border line between the necrotic and 
 reactive tissues, the annular ligament and the second- 
 ary tympanic membrane are among the first tissues to 
 be destroyed in the demarcation zone. In this way sec- 
 
PATHOLOGY 171 
 
 ondary fistulse occur. The secondary fistula can occur 
 in any portion of the labyrinthine wall. 
 
 Lange does not believe the term fistula should be ap- 
 plied to the primary cases, but only to the secondary 
 cases, as, strictly speaking, a fistula means an opening 
 through which an abscess cavity has established com- 
 munication with the surface, and indicates that the dis- 
 ease has progressed from within outward. 
 
 The traumatic cases of labyrinthitis may be divided 
 into those due to fracture at the base of the skull, those 
 due to hemorrhage, those due to a projectile or foreign 
 body, and those caused by operation. 
 
 In fracture through the base of the skull the line of 
 fracture often passes through the internal ear. The 
 eighth nerve may be torn through in the internal audi- 
 tory canal. Even if the line of fracture does not pass 
 through the internal ear the functions of the laby- 
 rinth may be destroyed as the result of a hemor- 
 rhage into its cavity. Bullets or foreign bodies, such 
 as hatpins, or a paracentesis knife may enter the laby- 
 rinth through the external auditory canal and middle 
 ear. 
 
 Operation, especially a radical mastoid operation, 
 may be a causative factor in producing a labyrinthitis, 
 in several ways : 
 
 1. By causing dislocation of the stapes. 
 
 2. By^ opening the external semicircular canal or 
 promontory. 
 
 3. The traumatism of the operation may result in the 
 breaking down of adhesions about a circumscribed laby- 
 rinthitis, making it diffuse. This has been determined 
 histologically in several cases. There was found an old 
 
172 THE LABYRINTH 
 
 fistula, with evidences of recent inflammation in the 
 remainder of the labyrinth. 
 
 4. The trauma may increase the virulence of in- 
 offensive bacteria which are present in the middle 
 ear. 
 
 The infection is occasionally carried to the labyrinth 
 through the circulation, as in mumps. But this means 
 of transmission is comparatively rare. 
 
 A labyrinthitis may end in one of three ways : 
 
 1. Eestitutio ad integrum. 
 
 2. Healing with permanent changes. 
 
 3. Extension to the intracranial cavity. 
 Complete return to the normal is possible only in the 
 
 serous and sero-fibrinous forms. But every case of 
 serous and sero-fibrinous labyrinthitis does not return 
 to the normal. In a certain number, as well as in a 
 large number of the purulent cases, atrophic changes 
 occur. These atrophic changes are seen in the maculae, 
 cristas, and organ of Corti, in the ganglion spirale, and 
 in the nerve-filaments leading to the end-organs (Fig. 
 67, Plate XVI). 
 
 Wittmaack describes three grades of degenerative 
 changes in the organ of Corti. 
 
 1. Mild degree. — Degeneration of a few sensory epi- 
 thelial cells, with normal supporting cells. 
 
 2. Moderate degree. — Degeneration of many sensory 
 epithelial cells, with moderate flattening of the support- 
 ing structures, especially of Deiters' cells. The rods 
 are somewhat depressed. There is adhesion of the tec- 
 torial membrane to the organ of Corti. 
 
 3. Marked degree. — The organ of Corti consists of a 
 flat epithelial hillock, without recognizable sensory or 
 
PLATE XVI. 
 
 CO 
 
 so 
 
 KiG. 07 
 
 Complete Athophv of Corti's Organ and Spirai, Ganglion 
 CO — Atrophic organ of Corti )S'6r — Atrophic spiral ganglion 
 
PLATE XVH. 
 
 SV MR DC 
 
 SG 
 
 M 
 
 LS 
 
 AC ST 
 Fig. 08 
 
 Diffuse Suppukative Labyrinthitis With Beginning Organization 
 
 8T — Scala tympani filled with 
 
 connective tissne 
 AC — Coclileal opening of aque- 
 
 diictus eoehleise 
 L8 — Liganientum spirale i n f i 1 - 
 
 trated Avith round cells 
 .ST/ — Spiral gan;>lion infiltrated 
 
 with round cells 
 ,1/ — Modinlns 
 
 &T' — Seala vestibiili of cochlea, 
 full of pus. Beginning 
 organization at medial 
 and lateral margins 
 ilR — Eeissner's membrane 
 DC — Ductus cochlearis, full of 
 pus. Organ of Corti and 
 niemlirana tectoria are 
 paitly destroyed 
 
\ 
 
 PLATE XVIII. 
 
 Frd. 09 
 
 Chroxic SupptUATtvE Labyuixtiiitis, Which Has Healed, the Puru- 
 lent Exudate J'ecomino Okgaxized; the Cochleal Cavity is En- 
 tirely Filled With New-Eoumed Bone, and Connective Tissue 
 
PATHOLOGY 173 
 
 supporting cells, to the surface of which the membrana 
 tectoria may be adherent. 
 
 In the ganglion spirale there is shrinking of the pro- 
 toplasm of the ganglion nerve cells. Vacuoles appear. 
 There is disappearance of the Nissl granules, and 
 finally complete destruction of the cells. The canal of 
 Eosenthal is then occupied by an empty network of 
 connective tissue. 
 
 In a large proportion of the cases of purulent laby- 
 rinthitis, organization of the exudate takes place. 
 The round cells are replaced by connective tissue 
 cells, which are gradually transformed into connect- 
 ive tissue fibres (Fig. 68, Plate XVII). Thus the 
 entire labyrinthine cavity may be filled with connective 
 tissue. 
 
 The irritation of the endosteum gives rise to the pro- 
 duction of a hyperplastic or ossifying periostitis, which 
 results in a bony transformation of the connective tis- 
 sue, which fills the labyrinthine cavity (Fig. 69, Plate 
 XVIII). The new-formed bone is distinguished from 
 the older bone by 
 
 1. Its greater affinity for eosin. 
 
 2. The lack of a regular lamellar structure. 
 
 3. The presence of irregular large bone corpuscles. 
 
 4. The simultaneous occurrence of all stages, from 
 osteoid tissue to finished bone. 
 
 The infection may spread from the labyrinth to the 
 intracranial cavity. It may result in meningitis, cere- 
 bellar abscess, epidural abscess, interdural abscess, or 
 sinus thrombosis. The most frequent of these compli- 
 cations is diffuse purulent leptomeningitis. Circum- 
 scribed purulent leptomeningitis and the serous form 
 
174 THE LABYEINTH 
 
 also occur. Alexander states that more tlian 80% of 
 the cases of otitic cerebellar abscess are due to laby- 
 rinthitis. 
 
 The pathways of infection from the labyrinth to the 
 intracranial cavity are : 
 
 1. The internal auditory canal. 
 
 2. The aqueductus cochleae. 
 
 3. The aqueductus vestibuli. 
 
 4. Along the vessels which pass through the fossa 
 subarcuata. 
 
 5. Through necrosis of the posterior or superior sur- 
 faces of the petrous pyramid. 
 
 6. By metastasis. 
 
 The most frequent pathways are the internal audi- 
 tory canal and the aqueductus cochleae. Extension 
 through these channels usually results in a diffuse 
 purulent leptomeningitis. Extension through the othei* 
 pathways is more apt to result in the production of a 
 localized intracranial lesion. 
 
 Fortunately in many cases the lining membrane of 
 the aqueductus cochleae reacts to the irritation of the 
 inflammatory process within the labyrinth in such a 
 way that the lumen of the canal is closed by swelling 
 of the soft tissues. Otherwise every case of diffuse 
 purulent labyrinthitis must of necessity spread to the 
 meninges, as this passageway ends in the subarachnoid 
 space by means of a wide open mouth. Furthermore, 
 its inner opening is situated in the floor of the begin- 
 ning of the scala tympani of the basal whorl of the 
 cochlea, where the cochlear inflammation is most often 
 localized. 
 
 In the internal auditory canal the infection travels 
 
PATHOLOGY 175 
 
 through the foramina in the areas cribrosae, and along 
 the sheaths of the nerve-fibres. 
 
 Politser found the following changes in the internal 
 auditory canal in cases in which this canal served as the 
 avenue of infection to the intracranial contents. 
 
 1. Pus along the nerve-fibres. 
 
 2. Pus in the empty nerve-canals in the arese cri- 
 brosae. 
 
 3. Pus between the nerves and the inner walls of the 
 meatus. 
 
 4. The walls of the meatus partly destroyed by 
 caries. 
 
 5. An abscess in the fundus of the canal. 
 
 6. The modiolus partly or wholly destroyed. 
 
 7. Nerve fibres infiltrated with pus cells, or with 
 hemorrhagic extravasations. 
 
 8. Nerve fibres replaced by connective tissue. The 
 connective tissue enters the meatus from the interior 
 of the labyrinth. 
 
 9. In several cases there was a sharp line of demarca- 
 tion between the peripheral infiltrated portion of the 
 nerve and the central portion, which was more or less 
 normal. 
 
 In most cases, with purulent infiltration in the in- 
 ternal auditory canal, the facial nerve was intact. This 
 is explained by Lange by the fact that the facial nerve 
 has greater resisting power than the eighth nerve ; by 
 the fact of its arachnoidal sheath being more closely ad^ 
 herent to it; and by the fact that it is supplied by a 
 separate vessel, which accompanies it from the middle 
 ear (a branch of the stylo-mastoid artery). 
 
 Steinbriigge, Hahermann, Hersog and Alexander de- 
 
176 
 
 THE LABYEINTH 
 
 scribed cases in which there was inflammatory infil- 
 tration of, and hemorrhage into the facial nerve, with- 
 out any impairment of its function. 
 
 Infection sometimes reaches the intracranial cavity 
 through the aqueductus vestibuli. This is not a very 
 com m on pathway, for the reason that the lining-mem- 
 brane of the passageway often becomes so swollen as 
 to occlude its lumen. Where the infection does travel 
 along this route it results in an empyema of the saccus 
 endolymphaticus. This is a small sac lying between 
 two layers of the dura on the posterior surface of the 
 petrous bone, about half way between the internal 
 auditory meatus and the inner margin of the lateral 
 sinus. 
 
 An empyema of the saccus endolymphaticus is very 
 apt to spread beyond the limits of the sac, between the 
 two layers of the dura which enclose it, especially in an 
 outward and downward direction, where the meshes 
 of the fibrous tissue are very loose. Here the abscess 
 is apt to lie in the posterior wall of the lateral sinus, 
 the lateral sinus lying to its outer side, and the cere- 
 bellum to its inner side (Fig. 70, Plate XIX). Kramm 
 reported a case in which such an interdural abscesS 
 ruptured in both directions, resulting in an infective 
 sinus thrombosis and cerebellar abscess. 
 
 However, every collection of pus in the location of 
 the saccus endolymphaticus is not necessarily a saccus- 
 empyema. A histological examination is necessary to 
 determine this point. It is necessary to demonstrate 
 the fact that the walls of the abscess cavity are lined 
 by a layer of epithelial cells, in order to be certain that 
 we are dealing with a case of saccus-empyema. 
 
PLATE XIX. 
 
 LS IDA P 
 
 AV 
 
 D 
 P 
 
 CA OD ID 
 
 FiCi. 70 
 
 surface of petrous 
 
 SaCCUS ExdOLYMPIIATICUS EeSILTING IX IXTERDUKAI, 
 , SiXUS TlIRUlir.OSIS AND C'EIiELELLAK AlSCESS 
 
 D — Dura mater 
 
 (_)l) and //' — Outer and inner lay- 
 ers of dura enclosing sac- 
 <-us and interdural ab- 
 scess 
 
 ]' — I'ia mater 
 
 (' — ( ercliellum 
 
 CA — t'creliellar abscess 
 
 Empyema of 
 Aesces, 
 
 F — Posterior 
 Ijone 
 
 AT' — Outer ajierture of ac^ueduc 
 tus vestibuli 
 
 IDA — Interdural abscess result- 
 ing from empyema of sac 
 eus endolyniphaticus 
 
 LS — Latei'al sin\is 
 
PATHOLOGY 177 
 
 The following conditions may exist in the saccus re- 
 gion, according to Lange: 
 
 1. Interdural abscess without involvement of the sac- 
 ens. Such a case was described by Wagener. 
 
 2. Lange saw a case of interdural abscess below the 
 apertura externa of the aqueductus vestibuli, resulting 
 from destruction of the bony labyrinthine capsule at 
 this point. 
 
 3. Empyema of the saccus, extending through the 
 ductus endolymphaticus from a labyrinthine suppura- 
 tion. Such cases were described by Goerke and 
 Kramm. 
 
 4. Infection of the saccus endolymphaticus from an 
 epidural abscess was observed by Lange. 
 
 5. Infection of the saccus from a thrombosed lateral 
 sinus was observed by Lange. 
 
 6. Empyema of the saccus endolymphaticus may per- 
 forate through its outer wall into the epidural space, 
 giving rise to an epidural abscess. 
 
 In cases of necrosis of the soft tissues within the laby- 
 rinth, there is always necrosis of the ductus endolymph- 
 aticus up to the apertura externa of the aqueductus 
 vestibuli, where the ductus joins the saccus endo- 
 lymphaticus. The saccus is never involved, because it 
 has a separate blood-supply. It is supplied by the 
 dural vessels. 
 
 The vessels which pass through the fossa subarcuata 
 run from the spongiosa in the medial antral wall, under 
 the arch of the superior semicircular canal, to the dura 
 of the posterior fossa. They are surrounded by a proc- 
 ess of the dura. With disease of the bone about the 
 superior semicircular canal the infection may spread to 
 
178 THE LABTBINTH 
 
 these vessels, and result in thrombosis of the inferior 
 petrosal sinus, or epidural abscess. 
 
 Suppuration in the middle ear or mastoid cells may 
 give rise to an epidural abscess on the superior or pos- 
 terior surfaces of the petrous bone. Pus in these loca- 
 tions can erode the bony capsule of the superior or pos- 
 terior semicircular canal, and invade their contents. 
 
 Suppuration in the labyrinth may give rise to infec- 
 tive thrombi in the labyrinthine vessels. In this way 
 the intracranial contents may be infected by metastasis. 
 
CHAPTEE V 
 SYMPTOMS OF LABYRINTHITIS 
 
 The inner ear combines two organs whose functions 
 are absolutely distinct from each other. The cochlea is 
 concerned only with hearing, while the static labyrinth 
 (vestibule and semicircular canals) is one of the 
 peripheral sources of those impulses whose function 
 it is to establish our equilibrium. As in every other 
 end-organ, so in the internal ear as well, there are 
 definite functional disturbances if the nerves which 
 supply the end-organs are either irritated or de- 
 stroyed. 
 
 In the cochlea nerve irritation makes itself known 
 through subjective noises, while nerve destruction re- 
 sults in deafness. Here the differentiation is clear and 
 well defined. In the static labyrinth, on the other hand, 
 the signs of nerve irritation are so similar to those of 
 nerve destruction, that no positive differentiation can 
 be made and no hard and fast line can be drawn be- 
 tween them. 
 
 If a static labyrinth is abnormally stimulated, so that 
 its impulses prevail over the other impulses for the 
 preservation of body balance, there follow functional 
 disturbances with a nystagmus directed to the side of 
 the stimulated labyrinth. These phenomena we have 
 called sig'ns of stimulation disharmony. If 
 a static labyrinth is destroyed, then there ensue func- 
 tional disturbances, essentially the same as those which 
 follow abnormal stimulation, but the nystagmus is di- 
 
180 THE LABYEINTH 
 
 rected to the sound side. To these disturbances we 
 have applied the term sig-ns of destruction 
 disharmony. 
 
 As the functions of the two organs in the inner ear 
 differ, so too do the symptoms that result from their 
 irritation and destruction by disease. If the cochlea is 
 affected there arise subjective noises and loss of hear- 
 ing, while disease of the static labyrinth causes vertigo, 
 disturbances in equilibrium, nausea, vomiting and 
 nystagmus. 
 
 Subjective noises are very inconstant. While they 
 may occur at any stage of the labyrinthitis, they are 
 but rarely sufficiently annoying to arouse complaint. 
 Undoubtedly the reason for this lies chiefly in the fact 
 that the other disturbances are vastly more important 
 to the patient, so that the subjective noises are crowded 
 out of his consciousness. Occasionally, too, subjective 
 noises have existed for some time, and the patient does 
 not differentiate between those which were caused by 
 the chronic purulent otitis media and those due to the 
 labyrinth infection. Subjective noises may occur in 
 the presence of a diffuse labyrinthine suppuration, 
 when hearing has been totally destroyed. It has been 
 shown that, in cases of diffuse suppurative labyrin- 
 thitis, cells in localized areas of Corti's organ may re- 
 main unaffected by the pathological changes. If one 
 may judge from the histological appearance of these 
 cells, it is probable that they are still susceptible to irri- 
 tation. The subjective noises, therefore, may be due to 
 stimulation of these intact cells by the inflammatory 
 products in the cochlea. The noises may persist, or 
 even begin only after the operative destruction of the 
 
SYMPTOMS OF LABYBINTHITIS 181 
 
 labyrinth. Neumann believes this to be due to degen- 
 erative changes in the ganglion cells. 
 
 So long as a labyrinthitis is localized the hearing, as 
 a rule, is not completely lost. In some cases, indeed, it 
 is surprisingly good. As soon, however, as the patho- 
 logical process becomes diffuse, either spontaneously or 
 as the result of a radical mastoid operation, hearing is 
 abolished. There are, of course, exceptions to this rule. 
 In the beginning of even a diffuse purulent labyrin- 
 thitis there may be some hearing, but it is retained for 
 only a very short time. 
 
 In acute diffuse labyrinthine suppuration the hear- 
 ing is usually lost before the functions of the static 
 labyrinth are destroyed. This is probably due to the 
 fact that the hair-cells of the organ of Corti are less 
 resistant than those of the maculae and eristse. In cases 
 of diffuse serous labyrinthitis the hearing is frequently 
 completely lost, and may remain so even after the laby- 
 rinthine inflammation has subsided. 
 
 Vertigo and disturbances of equilibrium show the 
 widest variations in their intensity. While in some 
 cases there may be only a slight sense of unsteadiness, 
 in others the disturbances may be so severe that the 
 patient is unable to walk unsupported. The more rapid 
 the destruction of the end-organs within the labyrinth, 
 the more violent are the disturbances in balance. 
 
 Nausea and vomiting commonly accompany the other 
 disturbances that result from labyrinthine disease. 
 Vomiting usually follows active movements, but it is 
 sometimes aroused by passive movements as well. 
 Lifting a patient in or out of bed may bring on an 
 attack. The vomiting due to a labyrinthitis differs 
 
182 THE LABYRINTH 
 
 from that caused by intra-cranial complications in that 
 the former is always accompanied by nausea and is 
 never of the projectile type. Food, per se, does not 
 arouse the vomiting in labyrinthitis so much as the 
 movements of the head incident to taking nourishment. 
 
 In addition to the symptoms described and the nys- 
 tagmus, which we have reserved for separate consider- 
 ation, there are two of considerable importance, viz., 
 fever and facial paralysis. 
 
 From many observations it has been established that 
 an uncomplicated labyrinthitis, no matter of what type, 
 causes little or no elevation of temperature. This is 
 not surprising when we consider that from this minute 
 closed bony cavity little or no absorption can take place. 
 Therefore any considerable rise of temperature asso- 
 ciated with a labyriuthitis must be regarded as an indi- 
 cation that the disease is probably extending beyond 
 the confines of the labyrinth. If such a rise of tempera- 
 ture cannot be ascribed to other causes, and if the func- 
 tional tests of the labyrinth indicate destruction of 
 the end-organs, radical interference is the only means 
 at our command of averting a meningeal infection. 
 
 The inclusion of a portion of the facial nerve in the 
 labyrinthine capsule, renders it extremely liable to be 
 involved when the labyrinth is attacked by disease and 
 its walls are destroyed. Neumann states that 80% of 
 cases of labyrinthine necrosis are accompanied by 
 facial paralysis. From the rapidity with which, in some 
 instances, these paralyses clear up after the radical 
 mastoid operation has been performed, we must con- 
 clude that they are often due not to a neuritis, but to 
 the pressure of sequestra or of granulations. 
 
SYMPTOMS OF LABYRINTHITIS 183 
 
 Just as in the phenomena which result from arti- 
 ficial stimulation of the normal end-organ, so too in the 
 spontaneous disturbances that are caused by labyrinth- 
 ine disease, nystagmus is in the foreground of clinical 
 interest. The spontaneous nystagmus shows the same 
 components (i. e., slow and rapid) as that which is 
 aroused artificially. With regard to its plane, it re- 
 sembles closest the nystagmus which is aroused through 
 the action of the galvanic current. As a rule a nystag- 
 mus caused by disease within the labyrinth, is of a com- 
 bined rotatory and horizontal type. As an explanation 
 for this, the theory has been offered that in disease 
 processes in the labyrinth the three cristse are irritated 
 equally. While this might hold good so long as there 
 were signs of stimulation disharmony, i. e., so long as 
 the impulse aroused by irritation was transmitted to 
 the centres, it certainly fails to explain why the nys- 
 tagmus of destruction disharmony also has a combined 
 rotatory and horizontal character. 
 
 With regard to the direction of the nystagmus, a 
 majority of cases of labyrinthitis follow the rule that 
 the nystagmus is directed to the sound side. 
 
 Like the artificial, the spontaneous nystagmus is in- 
 fluenced by the direction in which the eyes are turned. 
 Frequently a spontaneous nystagmus becomes evident 
 only when the eyes are turned to the side toward which 
 the rapid component is directed. Increasing the resist- 
 ance to the nystagmic movements by turning the eyes 
 toward the side of the slow component, retards and 
 may even completely abolish the nystagmus. It has 
 been shown above how this fact is made use of in esti- 
 mating the intensity of the nystagmus, as well as in 
 
184 THE LABYEINTH 
 
 making tlie functional tests when a spontaneous nys- 
 tagmus is present. 
 
 Just as in the artificially aroused phenomena, so in 
 the spontaneous disturbances resulting from labyrin- 
 thine disease, the nystagmus is accompanied by sub- 
 jective and objective symptoms. "We find here the fa- 
 miliar sensation of turning of the body, and the appar- 
 ent turning or passing by of objects in the environ- 
 ment. These follow the same laws which govern the 
 analogous reactions to artificial stimuli. Thus they are 
 directed similarly with regard to the direction of the 
 nystagmus (rapid component), and are intensified or 
 retarded by corresponding fixation of the eyes. 
 
 With the spontaneous nystagmus, too, there are 
 linked the reaction movements. From a diagnostic 
 point of view these are of greatest importance. In the 
 presence of a vestibular nystagmus, the reaction move- 
 ments of the body are so constituted that they cause a 
 tendency to fall in the direction of the slow component 
 of the nystagmus. Thus if a nystagmus to the left 
 exists, the body will have a tendency to fall to the right. 
 If the face be turned toward the left shoulder, the body 
 will fall forwards, and if the face be turned to the right 
 shoulder the body will fall backwards. We have, there- 
 fore, in this test a means of determining whether the 
 disturbances of equilibrium are of vestibular origin or 
 not. If the tendency to fall is not in the direction of 
 the slow component, whatever the position of the head, 
 we must believe that the disturbances are not of ves- 
 tibular origin. 
 
 The severity of the symptoms of labyrinthitis is pro- 
 portional to the intensity of the disease process, and 
 
SYMPTOMS OF LABYEINTHITIS 185 
 
 particularly to the rapidity with which the latter 
 spreads over the nerve endings. The remarkable varia- 
 tions which are observed in the symptoms resulting 
 from labyrinthine disease, can be explained by differ- 
 ences in the pathological processes. The more rapidly 
 the function of the organ is destroyed, the more apo- 
 plectiform and severe are the resulting symptoms. On 
 the other hand, in the insidiously destructive processes, 
 the symptoms may be so slight that they give rise to 
 no disturbances of which the individual is conscious. 
 
 In the earlier descriptions of this affection, the symp- 
 toms which accompanied a labyrinthitis were consid- 
 ered to be the result of irritation in the diseased organ. 
 But as our knowledge of labyrinthine functions wid- 
 ened, and particularly through the medium of the 
 modern functional tests of the static labyrinth, this 
 opinion became untenable, and has now been almost 
 universally abandoned. 
 
 The symptoms of labyrinthine disease are identical 
 with the phenomena which occur after the application 
 of cocaine to the membranous labyrinth, or after the 
 destruction of this organ or the eighth nerve. This fact 
 leaves no doubt that they are due, in most instances, to 
 the abolition of the normal function of the organ. 
 
 The fact that the symptoms of labyrinthine disease 
 so closely resemble the phenomena following artificial 
 stimulation of the end-organs of the static labyrinth, is 
 not so remarkable when we consider that both are due 
 to disturbances in the normal harmony of all the cen- 
 tripetal impulses, which have for their purpose the 
 preservation of our body balance. 
 
 A disturbance of equilibrium which has its origin in 
 
186 THE LABYBINTH 
 
 the labyrinth., can arise in but one of the following two 
 ways. First, it can be due to an overbalancing by the 
 impulses from an abnormally aroused labyrinth over 
 the normal static influences from the other peripheral 
 sources (stimulation disharmony), or, secondly, it may 
 be due to a loss of the normal influences of the static 
 labyrinth. This would cause an overbalancing by the 
 remaining normal centripetal impulses (destruction 
 disharmony). In the first instance (stimulation dishar- 
 mony), the resulting reaction would be influenced di- 
 rectly by the over-stimulated end-organ. In the second 
 instance (destruction disharmony), the reaction would 
 be influenced only indirectly by the end-organ whose 
 function was abolished, and would be influenced directly 
 by the impulses from the remaining centripetal balance 
 sources. Herein, according to Wittmaach, lies the ex- 
 planation of the fact that the nystagmus resulting from 
 stimulation disharmony changes its plane, according to 
 the canal in which the impulse arises, while, on the 
 other hand, the nystagmus due to destruction dishar- 
 mony always has a uniform combined rotatory and 
 horizontal character. 
 
 It was formerly believed that the phenomena, which 
 resulted from the destruction of a labyrinth, were due 
 to an overbalancing by the impulses from the remaining 
 sound side. This view, however, does not agree with 
 the observations after experimentally destroying first 
 one and then the second labyrinth in the same animal. 
 
 If we destroy one labyrinth completely, or cut through 
 one eighth nerve, there follow typical signs of destruc- 
 tion disharmony, i. e., disturbances of equilibrium with 
 nystagmus directed to the sound side. So long as the 
 
SYMPTOMS OF LABYRINTHITIS 187 
 
 animal caniiot orient itself without the help of impulses 
 from the destroyed labyrinth, the disturbances of bal- 
 ance will continue. If, when they have disappeared, 
 and the animal is again apparently normal, we destroy 
 the second labyrinth or cut through the remaining 
 eighth nerve, there will ensue disturbances of equilib- 
 rium quite as severe as those which followed the first 
 operation. Now, however, the nystagmus is directed 
 to the side of the first-destroyed labyrinth, despite the 
 fact that this has remained totally without function. 
 
 Thus it is apparent that these disturbances depend 
 neither exclusively nor even chiefly upon the impulses 
 from the labyrinth itself. There can be no doubt that 
 the manifestations, after the destruction of a laby- 
 rinth, result from an exceedingly complicated process, 
 in which all the remaining centripetal balance impulses 
 play a part. How the latter share in this activity can- 
 not be determined, but it is clear that the result is 
 largely influenced by vestibular function, even though 
 the vestibular end-organs are, in this regard, secondary 
 in importance to the vestibular centres. 
 
 The fact that no nystagmus occurs when both laby- 
 rinths are destroyed simultaneously indicates that the 
 disharmonic impulses, aroused through the simulta- 
 neous destruction of both end-organs, oppose each other 
 completely, in the same way that the impulses from 
 both labyrinths aroused by simultaneously applied ca- 
 loric or galvanic irritation neutralize each other. If, 
 however, even in the presence of totally destroyed end- 
 organs, a pathological process (meningitis, abscess, tu- 
 mor, etc.) should attack the retrovestibular paths, typi^ 
 cal symptoms of balance disturbance may develop. 
 
188 THE LABYRINTH 
 
 Barany believes that the disturbances in equilibrium, 
 which, together with deafness, follow the labyrinthitis 
 that complicates cerebro- spinal meningitis, are due to 
 the involvement of the cerebellar cortex, and not to the 
 destruction of the labyrinths. With this view Voss 
 also agrees. 
 
 Early in a pathological process in the labyrinth the 
 nerve endings are irritated and signs of irritation or 
 stimiilation disharmony occur. Later, when the nerves 
 are destroyed by the disease and the organ has lost its 
 power to functionate, signs of destruction disharmony 
 supervene. It must not be supposed, however, that at 
 any stage of its development a pathological process in 
 the labyrinth can arouse impulses through physiologi- 
 cal means, i. e., through endolymph movements. 
 
 Pathological processes in the labyrinth destroy the 
 normal function of this organ in several ways. The 
 normal activity of the end-organs may be disturbed by 
 changes in the endolabyrinthine pressure or by changes 
 in the physical properties of the endolabyrinthine 
 fluids. Again, inflammatory changes may attack the 
 end-organ itself and destroy its power to functionate, 
 and, lastly, changes in the nerve fibres and ganglia may 
 prevent the transmission of impulses to the centres. 
 
 As we have stated above, it is but reasonable to sup- 
 pose that, during the inception of a disease process 
 within the labyrinth, the end-organ is irritated, and, 
 therefore, there should occur signs of stimulation dis- 
 harmony. It seems that these actually occur, even 
 though in man it is rare to observe them. There have 
 been observed, in early labyrinthine inflammations, 
 evidences of stimulation disharmony with a nystag- 
 
SYMPTOMS OF LABYRINTHITIS 189 
 
 mus directed to the diseased side. On the other hand, 
 cases have been recorded in which, despite the fact that 
 tie diseased labyrinth was still irritable, there was a 
 pronounced nystagmus to the sound side. Here is an 
 apparent contradiction which, up to the present, has 
 not been satisfactorily explained. Sometimes signs of 
 stimulation disharmony (nystagmus to the diseased 
 side) coexist with those of destruction disharmony 
 (nystagmus to the sound side). 
 
 An attempt to explain this contradiction has been 
 made by assuming that, coincident with the disease in 
 the end-organ, there occur changes in the nerve which 
 reduce the conductivity of the latter. Just as in disease 
 of the cochlear nerve, subjective noises and loss of hear- 
 ing occur simultaneously. 
 
 Against this assumption, however, must be urged the 
 fact that the nerve is apparently very resistant, and 
 even after complete destruction of the labyrinth retains 
 its irritability for a long time. For several months 
 after a labyrinth is destroyed in an animal, nystagmus 
 may be aroused by the application of the galvanic cur- 
 rent. It must not be forgotten, however, that there is 
 a vast difference between the effect that aseptic de- 
 struction of the labyrinth has upon the nerve and that 
 caused by destruction of this organ by disease. More- 
 over, it has been shown that even in early serous laby- 
 rinthitis advanced changes in the nerve endings, fibres 
 and even ganglia of both the cochlear and vestibular 
 nerves can occur. On the other hand, Ruttin found a 
 positive reaction to the galvanic test in cases in which 
 the labyrinth operation had been performed two or 
 three years previous. 
 
190 THE LABYEINTH 
 
 It is remarkable, nevertheless, that in observing 
 cases of labyrinthitis, even in their earliest stages, we 
 so rarely see signs of irritation, i. e., stimulation dis- 
 harmony. Wittmaack states that the impulses aroused 
 by stimulation disharmony oppose those aroused by 
 destruction disharmony, and it is not remarkable if the 
 latter, because of their greater strength, completely 
 overshadow the former. According to this idea there 
 would be a constant struggle for supremacy, between 
 the impulses of stimulation disharmony and those of 
 destruction disharmony, and since, in the development 
 of the disease, the factors that augment the impulses 
 of destruction disharmony at the same time weaken 
 those of stimulation disharmony the former soon pre- 
 vail. Thus in labyrinthine disease a nystagmus di- 
 rected solely to the diseased side is rarely observed. 
 
 If the impulses of stimulation and destruction dis- 
 harmony are about equally strong, there is no nystag- 
 mus so long as the eyes are directed forward. 
 
 But if, under these conditions, the eyes be turned to 
 one side or the other, a nystagmus directed to the side 
 toward which the eyes are turned will develop. By 
 turning the eyes to one side, we increase the resistance 
 to that nystagmus which is directed opposite to the 
 side to which the eyes are turned, and at the same time 
 diminish the resistance to the nystagmus which is di- 
 rected to the side toward which the eyes are turned. 
 
 A nystagmus directed to both sides, if it be of ves- 
 tibular origin, occurs as a rule only when the function 
 of the diseased labyrinth has not been totally destroyed, 
 i. e., the labyrinth is still irritable. We find it, there- 
 fore, as we should expect, in eases of circumscribed 
 
SYMPTOMS OF LABYBINTHITIS 191 
 
 labyrintliitis. In these cases the diseased labyrinth re- 
 sponds to the functional tests. As soon as the end- 
 organ is destroyed, or its function is interfered with 
 beyond a point where it is capable of being irritated or 
 of transmitting irritation, signs of destruction dishar- 
 mony, with nystagmus directed to the sound side, 
 supervene. 
 
 A vestibular nystagmus, therefore, which is directed 
 to both sides must be regarded as evidence of incom- 
 plete destruction of function in the diseased labyrinth. 
 Alexander strongly supports this view by the state- 
 ment that this combination of nystagmus, both to the 
 sound and to the diseased sides, occurs at the begin- 
 ning of labyrinthitis, and when, after having been 
 abolished, the functions return as the inflammation 
 subsides. 
 
 A consideration of the symptoms of labyrinthitis is 
 incomplete without a word regarding the functional 
 tests of the static labyrinth. Unfortunately these tests 
 create powerful impulses, out of all proportion to those 
 wliich are aroused through the normal activity of this 
 organ. The tests themselves differ in the strength of 
 the impulses which they arouse. Thus the weakest 
 among them is the caloric test. The response to this 
 may be lost and the labyrinth still be susceptible to rota- 
 tion and to the fistula test. Again, the response to the 
 fistula test may be retained alone, while neither the 
 caloric test nor rotation is capable of stimulating the 
 diseased labyrinth. 
 
 The simultaneous application of galvanic or caloric 
 stimulation to both sides gives us a means of comparing 
 the susceptibility of the nerves and the end-organs of 
 
192 THE LABYBINTH 
 
 the two sides. However, the ratio between the loss of 
 irritability and the loss of function has not yet been 
 determined. We have seen an instance of labyrinthine 
 fistula in which there was a marked response to all the 
 functional tests. At the time of the radical mastoid 
 operation, the labyrinth was destroyed mechanically 
 and thereafter remained totally without function. If 
 this labyrinth had been functionating normally, as the 
 responses to the tests led us to suppose, its sudden de- 
 struction should have entailed severe symptoms of de- 
 struction disharmony. On the contrary, those that 
 ensued were exceedingly mild. We must conclude, 
 then, that here was an instance in which, despite the 
 fact that the labyrinth responded readily to all the func- 
 tional tests, its functional activity had decreased and 
 the centres had already accommodated themselves to 
 the partial loss of the normal impulses. 
 
 All cases of chronic purulent otitis media, and in par- 
 ticular those cases in which the radical mastoid opera- 
 tion is contemplated, should be thoroughly examined as 
 to function. It is true that the functional tests of the 
 static labyrinth offer little in the way of accurate 
 knowledge regarding the quantity of function retained, 
 but the condition of the labyrinth, determined by its 
 susceptibility to the functional tests, reveals accurately, 
 as a rule, the pathological changes that have taken 
 place within this organ. The estimation of these 
 changes is of greatest importance, for upon it rests, iii 
 large measure, our determination of the surgical indi- 
 cations. 
 
 From a clinical standpoint labyrinthitis may be di- 
 vided into serous and suppurative, circumscribed and 
 
SYMPTOMS OP LABYEINTHITIS 193 
 
 diffuse, latent and manifest. These divisions are but 
 stages of the same pathological process. In reality the 
 clinical picture of serous (and sero-fibrinous) laby- 
 rinthitis is neither a clear nor a sharply defined one. 
 It is probable that a serous labyrinthitis, like a serous 
 pleuritis, is in many instances but a forerunner of a 
 purulent process. Whether and when the serous exu- 
 date becomes purulent depends upon the intensity and 
 duration of the inflammatory process. In fact, both 
 serous and suppurative forms may co-exist in the same 
 labyrinth. 
 
 Although these categories are more or less artificial, 
 they are, nevertheless, of great value; first, because 
 they furnish us with definite clinical groups, and, sec- 
 ondly, because the surgical indications are determined, 
 for the most part, strictly in accordance with the clin- 
 ical data that form the basis for these groups. 
 
 A circumscribed labyrinthitis, as a rule, 
 gives rise to attacks of vertigo, disturbances of equilib- 
 rium, nausea and vomiting; in short, to those phe- 
 nomena which we call labyrinthine symptoms. Their 
 onset is sudden and, after the first attack, there are fre- 
 quent recurrences which sooner or later lead these pa- 
 tients to seek relief. In many instances, where the 
 attacks are of short duration, they are undoubtedly due 
 more to circulatory disturbances and changes in the 
 intralabyrinthine pressure brought about by defects in 
 the bony walls, than to pathological changes within the 
 labyrinth itself. In these cases the vertiginous attacks 
 are frequently brought on by stooping, straining or 
 moving the head rapidly backwards and forwards or 
 from side to side. 
 
194 THE LABYEINTH 
 
 There is more or less loss of hearing, yet the hearing, 
 in many of these cases of circumscribed labyrinthitis, 
 is remarkably good, and it must be borne in mind that 
 good hearing does not preclude the existence of a cir- 
 cumscribed labyrinthitis. Subjective noises are infre- 
 quent. In 50 cases reported by Ruttin they were pres- 
 ent in only 17, severe in but 2. As a rule there is a 
 history of only occasional tinnitus. 
 
 At the time of the examination the vertiginous attack 
 may or may not be present, i. e., the labyrinthitis may 
 be manifest or latent. If these symptoms are not pres- 
 ent they may frequently be aroused by the rapid move- 
 ments of the head described above. 
 
 There may be no spontaneous nystagmus, or there 
 may be a rotatory nystagmus directed either to the dis- 
 eased side or to the sound side, or to both sides, accord- 
 ing to the direction in which the eyes are turned. 
 
 Eotation shows both labyrinths to be functionating 
 normally, the caloric reaction and the fistula test are 
 positive. 
 
 Diffuse serous labyrintliitis may follow a 
 circumscribed labyrinthitis spontaneously or after a 
 radical mastoid operation. It may occur, too, where 
 there has been no circumscribed labyrinthitis and where 
 the labyrinthine capsule is intact. This induced laby- 
 rinthitis probably results from the absorption, by the 
 labyrinth, of the toxic products of bacterial activity in 
 the cavities adjacent to the inner ear. If a diffuse 
 serous labyrinthitis follows the radical mastoid opera- 
 tion, it manifests itself from the first to the third day, 
 i. e., from 12 to 72 hours after the operation. In contra- 
 distinction to this, the signs of destruction disharmony, 
 
SYMPTOMS OF LABYRINTHITIS 195 
 
 "which ensue after the labyrinth is injured mechanically 
 during a radical mastoid operation, appear at once. 
 
 When a diffuse serous labyrinthitis has run its 
 course, and either restitutio ad integrum or destruction 
 of function has occurred, the disease cannot be consid- 
 ered latent, so that only the manifest form comes into 
 consideration. 
 
 In a diffuse serous labyrinthitis there is a rapid 
 diminution in hearing associated with labyrinthine 
 symptoms, i. e., nystagmus directed to the sound side, 
 nausea and vomiting, vertigo and disturbances in bal- 
 ance, which, if the patient be in bed, manifest them- 
 selves in a disposition to lie on the sound side, so that 
 the eyes may be readily directed to the side of the slow 
 component of the nystagmus. 
 
 The severity and duration of the symptoms vary in 
 different instances. Ruttin states that, on an average, 
 they last from 3 to 5 days. There are cases of circum- 
 scribed labyrinthitis in which, on the day following the 
 radical mastoid operation, there ensue labyrinthine 
 symptoms (i. e., loss of hearing, vertigo, nausea and 
 vomiting and nystagmus) of such short duration that 
 they must be ascribed to circulatory disturbances, or 
 probably to pressure from retained secretions or pack- 
 ing rather than to inflammatory changes in the laby- 
 rinth. In these instances, when the fleeting symptoms 
 have passed, there is little or no loss of hearing or of 
 irritability of the static labyrinth. On the other hand, 
 when the disturbances last, as they usually do, from 
 several days to two weeks, there is frequently some loss 
 of function when they have disappeared. 
 
 While the labyrinthine symptoms are at their height 
 
196 THE LABYEINTH 
 
 there is never a total loss of function, i. e., there is 
 either some hearing or the static labyrinth responds to 
 at least one of the functional tests. If the caloric reac- 
 tion is negative the hearing is, as a rule, destroyed. If 
 there is no response to the caloric test, rotation may 
 still arouse the diseased labyrinth, and when this too 
 fails the fistula test is positive if a fistula is present. 
 
 By the fact that some function is retained, a diffuse 
 serous labyrinthitis differentiates itself clearly from 
 the suppurative stage. This differentiation, of course, 
 is artificial, but clinical experience has shown that so 
 long as a labyrinthitis is serous, i. e., so long as some 
 function remains, extension of the infection to the in- 
 tracranial contents, while it may occur, is exceedingly 
 rare. Moreover, even after the inception of the puru- 
 lent stage, i. e., when all function has been destroyed, 
 there is a short time, varying between several hours 
 and several days, before the labyrinthine infection ex- 
 tends to the meninges. In this interval, since the laby- 
 rinthine functions are destroyed, we are unable to esti- 
 mate the progress of the disease. 
 
 When we consider that at present, the only means at 
 our command to differentiate between the comparative 
 safety of a serous labyrinthitis and the imminent dan- 
 ger of the suppurative stage are the functional tests, we 
 readily appreciate the importance of carefully making 
 these tests in every instance where the radical mastoid 
 operation is contemplated or where, after the opera- 
 tion has been performed, labyrinthine symptoms super- 
 vene. A case illustrating the value of the functional 
 tests is reported by Neumann. A radical mastoid oper- 
 ation was performed for the relief of a chronic suppu- 
 
SYMPTOMS OF LABYBINTHITIS 197 
 
 rative otitis media of many years' standing. The func- 
 tional tests before the operation showed that consider- 
 able hearing remained and that the static labyrinth was 
 normally irritable. Two days after the operation there 
 occurred, with a slight rise of temperature, vertigo, 
 vomiting and nystagmus directed to the sound side. 
 Functional examination now showed deafness, with 
 complete loss of irritability of the static labyrinth of the 
 operated side. Upon these data the labyrinth operation 
 was undertaken. The promontory was found necrosed, 
 and was removed by pressure with the chisel alone, 
 without resorting to the use of the mallet. Undoubt- 
 edly there had existed here a necrosis of the labyrinth 
 wall, while the labyrinth itself remained intact until the 
 trauma incident to the operation, caused a rapid exten- 
 sion of the middle ear suppuration. The comparison of 
 the tests before operation with those made at the time 
 of the labyrinthine symptoms proved this beyond a 
 doubt, and served, moreover, as a basis for the surgical 
 procedures. 
 
 In contradistinction to diffuse serous labyrinthitis, 
 the suppurative variety may be either manifest or 
 latent. The two forms are vastly different. 
 
 In the manifest form the symptoms are most violent. 
 There is sudden deafness, associated with severe dis- 
 turbances in equilibrium, persistent vomiting and a ro- 
 tatory nystagmus directed to the sound side. The pa-- 
 tient is unable to walk unassisted and lies in bed on the 
 side of his sound ear. The functional tests show total 
 loss of hearing and of irritability of the static laby- 
 rinth. 
 
 In the latent variety of diffuse suppurative 
 
198 THE LABYEINTH 
 
 labyrinthitis there are frequently no symptoms at 
 all. Not only are there no symptoms at the time of the 
 examination, but there is often absolutely no history of 
 vertiginous attacks. In these latent diffuse suppurative 
 eases we may occasionally elicit some history of slight 
 disturbances if we question the patients very carefully. 
 It must be remembered, too, that patients do not grasp 
 the relationship between the attacks of nausea, vomit- 
 ing and vertigo, and the diseased ear. Such symp- 
 toms, if they have occurred, have been ascribed to dis- 
 turbances in other (particularly the digestive) organs, 
 and are therefore not associated, in the patient's mind, 
 with the ear trouble. 
 
 The functional tests show a complete loss of hearing. 
 The caloric and fistula tests are negative. If the dis- 
 ease has existed a long time, and if the labyrinthitis 
 has been followed by the formation of new bone filling 
 the intralabyrinthine spaces, the rotation test, accord- 
 ing to Buttin, behaves peculiarly. The duration of the 
 after-nystagmus to the sound side equals the duration 
 of that to the diseased side, but both are shorter than 
 normal. Ruttin ascribes this to the fact that the sound 
 labyrinth compensates for the complete loss of function 
 in the diseased labyrinth. 
 
 The diffuse latent suppurative form of labyrinthitis 
 is frequently as dangerous as it is insidious. Here, 
 again, the functional tests are of inestimable value, for 
 Hinsberg ascribes more than half the meningitides 
 which follow either polyp extraction or the radical mas- 
 toid operation, to intracranial extension of latent sup- 
 purative labyrinthitis. If the functional tests indicate 
 a diffuse latent suppurative labyrinthitis, polyp ex- 
 
SYMPTOMS OP LABYRINTHITIS 199 
 
 traction, or even the radical mastoid operation, must be 
 looked upon as incomplete operative interference. As 
 such they are exceedingly dangerous. 
 
 Necrosis and sequestration of the labyrinthine wall, 
 as a rule, give us the clinical picture of a latent diffuse 
 suppurative labyrinthitis. This is, of course, not inva- 
 riably true as the case of Neumann (cited above) and 
 the cases reported by Buttin show. However, if a 
 chronic suppurative otitis media has led to necrosis and 
 sequestration of the labyrinthine capsule, there is often 
 associated with the deafness and loss of irritability of 
 the static labyrinth, a facial paralysis. The determina- 
 tion of the presence or absence of sequestration can 
 sometimes be based upon the presence or absence of 
 facial paralysis. This determination is of great impor- 
 tance, for the surgical indications may rest upon it. 
 
 Thus if latent suppurative labyrinthitis has existed a 
 long time and compensation — as shown by the rotation 
 test — ^has taken place, we may expect one of two condi- 
 tions in the labyrinth. Either necrosis and sequestra- 
 tion or a new bone formation which has filled out the 
 intralabyrinthine spaces. If the latter has occurred the 
 labyrinth operation would, of course, be contraindi- 
 cated. If, on the other hand, sequestration of the laby- 
 rinth wall has occurred, the labyrinth operation is indi- 
 cated, at least the removal of the necrosed bone and the 
 establishment of efficient drainage is necessary. Here 
 a facial paralysis, which was not of too long duration, 
 would act as a guide, since such a paralysis would exist 
 only with necrosis and sequestration. 
 
 Even though the occurrence of disturbances of bal- 
 ance, loss of hearing, vomiting and nystagmus are 
 
200 THE LABYRINTH 
 
 strongly suggestive of the most commoii cause of such, 
 symptoms, viz., labyrinthitis, it must not be forgotten 
 that other conditions too may arouse almost identical 
 phenomena. 
 
 It is possible for retained secretions in the middle ear 
 to cause labyrinthine symptoms by increasing the intra^ 
 labyrinthine pressure. If this occurs during an acute 
 otitis media, while the membrana tympani is still intact 
 or before efficient drainage has been established, a free 
 paracentesis will bring speedy relief. The passing 
 labyrinthine disturbances, which occasionally ensue 
 after a radical mastoid, have also been ascribed to an 
 increase in the intralabyrinthine pressure due to re- 
 tained secrefions or to gauze too firmly packed into the 
 middle ear. 
 
 Labyrinthine inflammation must be differentiated 
 from hysteria, affections of the eighth nerve, menin- 
 gitis and abscess or tumor of the cerebellum. 
 
 From hysteria, a labyrinthitis may sometimes be dif- 
 ferentiated by the condition of the middle ear, which in 
 the former affection may show no pathological changes. 
 If nystagmus is present in hysteria, it is not of the ves- 
 tibular type, nor are the disturbances in equilibrium 
 such as are caused by labyrinthine disease. In hysteria 
 the body may have a tendency to fall backwards or for- 
 wards, or to either side, i. e., it follows no definite rule, 
 while in labyrinthitis the tendency to fall is always in- 
 the direction of the slow component of the nystagmus, 
 whatever the position of the head. In hysteria deafness 
 may be simulated, but the static labyrinth will react to 
 the functional tests. 
 
 The symptoms that occur in affections of the eighth 
 
SYMPTOMS OP LABYKIKTHITIS 201 
 
 nerve simulate those of labyrinthine inflammations. 
 Sometimes disease of the nerve develops in the pres- 
 ence of an apparently normal middle ear. 
 
 Under such circumstances, of course, an infective 
 labyrinthitis, unless it be metastatic, can be excluded. 
 Eapidly developing signs of stimulation or destruction 
 of either the cochlear end-organ or the end-organs in 
 the static labyrinth, alone and not in combination, indi- 
 cate a retrolabyrinthine affection rather than endolaby- 
 rinthine disease. On the other hand, rapidly develop- 
 ing signs of stimulation or destruction of both the coch- 
 lear end-organ and the end-organs of the static laby- 
 rinth indicate endolabyrinthine disease rather than 
 retrolabyrinthine affections. 
 
 In the differentiation between labyrinthine disease 
 and affections of the eighth nerve, the bilateral simul- 
 taneous caloric and galvanic tests, as described by Eut- 
 tin, are of great value. By means of the caloric test we 
 determine the comparative susceptibility of the two 
 labyrinths, and, on the other hand, by the galvanic test 
 we compare the irritability of the two vestibular nerves. 
 Unfortunately the application of the galvanic current is 
 frequently very painful, so that it cannot be used in 
 every instance. 
 
 Those cases of polyneuritis in which both division^ 
 of the eighth, as well as the facial nerve, are involved, 
 are probably due to syphilis, and a positive Wasser- 
 mann reaction may be present. 
 
 If a diseased labyrinth is exenterated, the nystagmus 
 to the sound side, if any is present, will disappear in a 
 short time. If a nystagmus directed to the side of the 
 destroyed labyrinth develops after the labyrinth opera- 
 
202 THE LABYEINTH 
 
 tion, it indicates either disease of the opposite laby- 
 rinth, meningitis or cerebellar abscess. 
 
 By the functional tests disease of the opposite laby- 
 rinth can readily be excluded. If this, then, is normal, 
 and other signs of intracranial involvement are present, 
 incision of the dura in the posterior cranial fossa, per- 
 haps combined with exploration of the cerebellum, is 
 indicated. 
 
 When the labyrinth has been destroyed by disease, 
 but has not been operated upon, the diagnosis of laby- 
 rinthitis, to the exclusion of meningitis and cerebellar 
 abscess, is not always so simple. 
 
 With a meniagitis, however, the patient usually has 
 a higher temperature than if the labyrinthitis is uncom- 
 plicated. With meningitis there is also restlessness 
 and irritability, headache, rigidity of the neck muscles 
 and tenderness upon pressure over the cervical verte- 
 brae. Kernig's sign may be present, and there may be 
 paralysis of the ocular muscles, and disturbances in the 
 pulse rate and in respiration. The cerebro-spinal fluid 
 is turbid, may be under pressure and may contain a 
 large number of polynuclear leucocytes and bacteria. 
 A meningitis may be diagnosed early in its course by 
 means of the bio-chemical tests of the cerebro-spinal 
 fluid, as described by Kopetzky. 
 
 With a cerebellar abscess there is persistent, severe 
 headache, either frontal or occipital. There may be 
 ataxia of the cerebellar type, with a hemi-paresis on 
 the side of the lesion. The body may have a tendency 
 to fall toward the diseased side. The direction in 
 which the body falls is independent of the nystagmus, 
 if this is present, and does not change when the posi-* 
 
SYMPTOMS OF LABYEIKTHITIS 203 
 
 tion of the head is changed. The temperature may be 
 normal, subnormal or slightly elevated, but the pulse, 
 as a rule, is abnormally slow. The patient appears to 
 be severely ill. There may be nausea and changes in 
 the eye grounds. In cerebellar abscess the balance dis- 
 turbances do not diminish in severity, while in laby- 
 rinthitis the severity of the symptoms diminishes 
 almost from their inception. The duration of the 
 nystagmus, if this is present, may vary. 
 
 With a labyrinthitis the "pointing by" is in the di- 
 rection of the slow component of the nystagmus. With 
 a cerebellar abscess there is a loss of the normal reac- 
 tion movements, particularly in the arm of the affected 
 side. There is a destruction, centrally, of the tonus of 
 those muscles which tend to draw the arm of the af- 
 fected side inward, or toward the other side. Thus if 
 an abscess exists in the left lobe of the cerebellum, the 
 left arm will "point by" to the left spontaneously, and 
 independent of the nystagmus, if the latter is present. 
 
 If the pointing tests are made, after syringing the 
 right ear with cold water (causing nystagmus to the 
 left), the left arm will not deviate in the direction of 
 the slow component, i. e., to the right, because the cere- 
 bellar centre or centres that influence the movement of 
 the left arm inwards or to the opposite side have been 
 destroyed by the abscess. This loss of normal reaction 
 movements may not be confined to the shoulder joint, 
 but may extend to the elbow, wrist and lower extremity 
 as well. 
 
 As we have stated before, the vestibular nucleus of 
 either side is in relation with the central nuclei of the 
 muscles of both eyes. When an impulse from either 
 labyrinth reaches its nucleus, there arise in the latter, 
 
204 THE LABYBINTH 
 
 secondary impulses which extend to the nuclei of the 
 eye muscles. Those secondary impulses which result 
 in nystagmic movements of the eyes, directed toward 
 the side of the labyrinth in which the primary impulse 
 was aroused, are called homolateral, and those im- 
 pulses through whose influence a nystagmus in the op- 
 posite direction is aroused, are called heterolateral. 
 
 Through the medium of the cerebellum, the influences 
 of all the other sources of balance impulses, i. e., the 
 checks and balances, exercise a restraint upon the ves- 
 tibular impulses. Each cerebellar hemisphere exercises 
 this inhibitory influence upon those impulses whicH 
 emanate from the vestibular nucleus of its own side. 
 
 Let us assume, for instance, that the left labyrinth 
 has not been destroyed by disease, but that either a 
 tumor or an abscess has formed in the left lobe of the 
 cerebellum, in such a position that the restraining in- 
 fluences over the impulses from the left vestibular nu- 
 cleus are destroyed. If, then, a primary impulse is 
 aroused in the left labyrinth which produces chiefly 
 heterolateral secondary impulses (i. e., through cold 
 water irrigation), there will result a nystagmus di- 
 rected to the right, which will be uninfluenced by the 
 restraint exercised normally through the medium of 
 the cerebellum. Such a nystagmus would last, there- 
 fore, much longer than normal. To this phenomenon 
 Neumann has applied the term "enduring nystagmus," 
 and he states that it lasts from 2% to 15 minutes or 
 even longer. 
 
CHAPTER VI 
 TREATMENT OF LABYRINTHITIS 
 
 A large number of cases of labyrinthine disease re- 
 cover without treatment. Many get well as the result 
 of treatment, either operative or non-operative. A 
 small proportion die from intracranial complications. 
 Of the cases which recover, some have complete resto- 
 ration of function, while in others there is partial or 
 total loss of the functions of the internal ear. Of the 
 fatal cases, the vast majority are of the diffuse puru- 
 lent type. A few cases of fatal meningitis, complicat- 
 ing circumscribed purulent and diffuse serous laby- 
 rinthitis, have been reported. 
 
 Even cases of diffuse purulent labyrinthitis may heal 
 spontaneously. This is true particularly of those laby- 
 rinthitides which complicate scarlet fever. Many his- 
 tological examinations of the temporal bones of deaf- 
 mutes have shown that a purulent process in the laby- 
 rinth may heal, and. the intralabyrinthine spaces become 
 filled by new bone. Far more frequent, however, than 
 this spontaneous healing is the transition from the 
 acute to the chronic stage, which may last for years. 
 While in some instances no further trouble ensues, yet 
 in the majority of these cases, sooner or later, serious 
 complications develop. We must therefore consider 
 every labyrinthitis, even in the latent stage, an ex- 
 tremely serious condition. 
 
 We may lay down as a broad, general rule, that in 
 no case of circumscribed labyrinthitis should the inter- 
 
206 THE LABYRINTH 
 
 nal ear be operated upon. The circumscription of the 
 disease means that nature has been successful in erect- 
 ing a barrier against the spread of the infection. If w'e 
 operate in such a case, we may break down the barrier 
 which nature has erected, and thus cause the process to 
 extend into the cranial cavity. This is especially true 
 of incomplete operations on the labyrinth. In complete 
 labyrinth operations the breaking down of protective 
 adhesions and granulations does not possess the same 
 significance, because we provide for adequate drainage 
 here. 
 
 Perhaps the most frequent cause of the spread of a 
 labyrinthine infection to the intracranial contents is in- 
 complete operative interference. The fresher the 
 labyrinthine infection, i. e., the less time nature has had 
 to wall off the disease, the more certain is the spread 
 of the infection. In cases of manifest diffuse suppu- 
 rative labyrinthitis the radical mastoid operation 
 should never be performed alone. It is far better to 
 leave these cases entirely alone than to perform the 
 radical mastoid operation without, at the same time, es- 
 tablishing adequate drainage for the infected endo- 
 labyrinthine spaces. 
 
 Another reason for not opening the labyrinth, in cir- 
 cumscribed labyrinthine disease, is that by so doing we 
 destroy the remaining labyrinthine functions. 
 
 In our attitude toward diffuse serous labyrinthitis we 
 must also be influenced by the effect of our treatment 
 on the functions of the labyrinth, for in this type of in- 
 flammation there is usually restoration of function 
 after the disease has subsided. 
 
 It is of the utmost importance to positively establish 
 
TEEATMENT OP LABYRINTHITIS 207 
 
 our diagnosis before operating on a case of labyrinth- 
 ine disease. For to place a normal labyrinth into open 
 communication with an infected middle-ear cavity in- 
 vites certain infection of the labyrinthine contents. In 
 a diseased labyrinth, on the other hand, inflammatory 
 adhesions have, in most cases, shut off the infected laby- 
 rinth cavity from the intracranial lymph spaces before 
 operation. 
 
 Fortunately we are now enabled, as the result of 
 functional examination, to obtain a fairly accurate no- 
 tion of the presence and the extent of inflammatory 
 involvement of the internal ear. 
 
 Treatment of labyrinthitis may be of three kinds : 
 
 1. Non-operative treatment. 
 
 2. Operative treatment of the middle-ear spaces 
 alone. 
 
 3. Operative treatment of the middle-ear spaces com- 
 bined with the labyrinth operation. 
 
 The radical mastoid operation must, of course, pre- 
 cede the operation on the labyrinth. The two opera- 
 tions, however, may be performed at one sitting, or 
 there may be a considerable interval between them. 
 
 In the treatment of certain forms of labyrinthitis 
 there is a unanimity of opinion. In other forms, how- 
 ever, particularly in the acute (manifest) diffuse puru- 
 lent form, there is still considerable difference of opin-. 
 ion as to the proper method of treatment. 
 
 The questions to decide are whether to operate and 
 how to operate. It must be decided whether to do a 
 radical mastoid operation or to do a labyrinth opera- 
 tion also ; whether to do the two operations at one sit- 
 ting or with an interval between them ; whether to open 
 
208 
 
 THE LABYRINTH 
 
 a portion or all of the labyrintMne spaces; "wliether 
 merely to open the labyrinthine spaces or exenterate 
 the entire labyrinth, with the portion of the petrous 
 pyramid in which it is embedded. Finally, we must 
 decide whether or not to explore the cranial cavity. 
 
 In cases of empyema of the labyrinth, where there is 
 no bone involvement, opening the labyrinthine spaces is 
 sufficient. When there is necrosis of a portion of the bony 
 capsule a labyrinthectomy should be done. That portion 
 of the petrous pyramid containing the labyrinth, from 
 the sigmoid sinus behind, to the carotid canal in front, 
 should be removed. In performing this operation the 
 canal containing the facial nerve must be left intact if 
 possible. When there are symptoms of intracranial in- 
 volvement, it may be necessary to explore both the pos- 
 terior and middle fossae of the skull. 
 
 Alexander believes that no extensive operation should 
 be done on the labyrinth without exposing the dura. 
 He says that "an extensive opening of the labyrinth, 
 without simultaneous exposure of the dura, is a very 
 dangerous procedure, which exposes the patient to the 
 possibility of a postoperative purulent meningitis." 
 He states further that we should always explore th6 
 dura in the region of the saccus endolymphaticus, i. e., 
 the posterior pyramidal wall between the sinus and the 
 internal auditory meatus, because extradural abscess, 
 without symptoms, is not at all uncommon in this 
 1-egion. 
 
 If during the labyrinth operation there is evidence 
 that the disease has spread in the direction of the mid- 
 dle fossa, the dura of the middle fossa should also be 
 exposed. If lumbar puncture shows a pathologically 
 
TREATMENT OF LABYRINTHITIS 209 
 
 changed cerebro-spinal fluid, and other signs of menin- 
 gitis are present, the labyrinth operation must be com- 
 bined with incision of the dura. 
 
 For the sake of convenience we will divide laby- 
 rinthitis into its clinical forms, and state the indica- 
 tions for treatment in each form. We will consider cir- 
 cumscribed labyrinthitis, diffuse serous labyrinthitis, 
 diffuse purulent manifest labyrinthitis and diffuse pur- 
 ulent latent labyrinthitis. 
 
 Circumscribed labyrinthitis is usually determined by 
 the ability to elicit a positive fistula test in the presence 
 of more or less of the labyrinthine function. Hearing 
 may or may not be present. The caloric test is usually 
 positive, and the rotation test normal. Complete deaf- 
 ness does not necessarily indicate a diffuse labyrinth- 
 itis, for the destructive changes in the end-organ or 
 nerve may be the result of toxic or degenerative 
 atrophic processes. 
 
 If the circumscribed labyrinthitis occurs during the 
 course of chronic suppurative middle-ear disease, as is 
 most commonly the case, a radical mastoid operation 
 should be done. There is no urgency in doing the op- 
 eration, as the labyrinthine disease may remain circum- 
 scribed indefinitely. But as these middle-ear suppur 
 rative conditions are usually complicated by cholestea- 
 toma, it is useless to treat them non-operatively. 
 
 On exposure of the middle-ear spaces, during the 
 radical mastoid operation, we usually see the fistula, 
 whose most common location is on the eminence of the 
 external semicircular canal. The fistula should neither 
 be probed nor curetted. 
 
 The patient should be watched very carefully after 
 
210 THE LABYEINTH 
 
 the operation for the possible development of a second- 
 ary diffuse serous or purulent labyrinthitis. The 
 trauma of the radical mastoid operation is sometimes 
 responsible for the transformation of a circumscribed 
 into a diffuse labyrinthitis. This extension usually 
 manifests itself on the second or third day following 
 the radical mastoid operation, and is recognized by loss 
 of hearing, vertigo, nausea and vomiting with a com- 
 bined rotatory and horizontal nystagmus in the direc- 
 tion of the sound ear. If a spontaneous nystagmus was 
 present before the operation, it was probably directed 
 toward the side of the diseased ear, or toward both 
 sides in accordance with the position of the eyes. 
 
 In order to determine whether the diffuse labyrinth- 
 itis is of the serous or the purulent type, a functional 
 examination must be made. In the serous form there is 
 usually some remnant of function left. 
 
 If the patient hears loud speech through the ban- 
 dage, the sound ear being excluded by the noise appa- 
 ratus, we can make a positive diagnosis of serous laby- 
 rinthitis. If he does not hear, even with the bandage 
 removed, we do a caloric test, using hot (112° F.) 
 sterile salt solution. If this does not neutralize or 
 reverse the spontaneous nystagmus, and if the fistula 
 test (which is made by placing a cup over the wound 
 and the auricle) is negative, we are dealing, in all prob- 
 ability, with a purulent labyrinthitis. Earely we have 
 complete destruction of function with diffuse serous 
 labyrinthitis, but such cases are treated as if they 
 were purulent. 
 
 These cases, particularly if there is any rise of tem- 
 perature, should be operated on immediately, the laby- 
 
TEEATMENT OP LABYEINTHITIS 211 
 
 rinth being opened wide, in order to prevent the spread 
 of the infection into the cranial cavity. 
 
 In cases of diffuse serous labyrinthitis, we do not 
 operate. These cases usually subside in a week or two. 
 Cases of induced serous labyrinthitis are also treated 
 without operation, but they must be carefully observed, 
 and if complete loss of function supervene during the 
 active stage, the labyrinth must be opened. 
 
 Sometimes a labyrinthine fistula refuses to heal after 
 the radical mastoid has been performed. The radical 
 cavity epidermatizes in its entire extent except for a 
 small spot at the fundus, which continues to granulate. 
 Such a condition is usually due to the presence of a ne- 
 crotic area in the bony capsule about the fistula. A 
 secondary radical may be performed and the necrotic 
 bone removed. A complete labyrinth operation, of 
 course, should not be done in such a case. 
 
 If the circumscribed labyrinthitis occurs during tKe 
 course of an acute middle-ear suppuration (which is 
 very uncommon) a simple mastoid operation is usually 
 sufficient to cure the condition. 
 
 The cases of diffuse manifest purulent labyrinthitis 
 are recognized by the occurrence of a spontaneous rota- 
 tory and horizontal nystagmus toward the sound ear, 
 vertigo, nausea and vomiting and a complete absence 
 of labyrinthine function. The patient is absolutely 
 deaf, and there is a negative caloric and fistula test. 
 
 There is still some difference of opinion in regard to 
 the treatment of this form of labyrinthitis. Neumann 
 and Ruttin believe that these cases must be operated on 
 at once, the labyrinth operation being done in one sit- 
 ting with the radical mastoid. Alexander, on the other 
 
212 THE LABYRINTH 
 
 hand, holds that they should be operated on only if 
 they show signs of beginning intracranial complica- 
 tions, such as sleeplessness, headache, fever and rigid- 
 ity of the neck. He believes that these symptoms ap- 
 pear as soon as the suppuration in the labyrinth has 
 become diffuse. In the cases without signs of endo- 
 cranial involvement, he advises complete rest in bed, 
 and conservative treatment of the middle-ear suppura- 
 tion. 
 
 Ruttin, on the other hand, believes that every case of 
 manifest purulent diffuse labyrinthitis, with complete 
 loss of function, should be operated on immediately ; for 
 in the absence of all labyrinthine function we have no 
 indicator to warn us of the progress of the infection. 
 
 Of 20 such cases of diffuse purulent manifest laby- 
 rinthitis, operated on at Urbantschitsch's clinic, and re- 
 ported by Ruttin, 12 recovered and 8 died. Of the 8 
 fatal cases 5 already had signs of meningitis at the 
 time of operation, i. e., they were either comatose or 
 had purulent cerebro-spinal fluid. This leaves 3 out of 
 20, or 15% in which the operation failed to prevent the 
 spread of the infection to the meninges. However, 
 there are cases which recover, despite the fact that 
 meningeal symptoms are already present at the time of 
 operation. 
 
 In the cases of latent diffuse purulent labyrinthitis, 
 there are no symptoms, except those of the chronic 
 middle-ear suppuration. But on examining such a case, 
 it is found that all of the labyrinthine functions have 
 been lost. There is no hearing. Caloric and fistula 
 tests are negative. 
 
 These cases are very treacherous. There may be no 
 
TREATMENT OP LABYEINTHITIS 213 
 
 symptoms for years. But at any time, as the result of 
 an acute exacerbation of the middle-ear suppuration, 
 or as the result of an operation on the middle ear or 
 mastoid, there is a sudden extension of the inflamma- 
 tion to the meninges. 
 
 In these latent cases there is usually no haste neces- 
 sary, but, if operated at all, a complete labyrinth opera- 
 tion must be done. A radical mastoid operation in such 
 a case is very dangerous. It is very apt to cause a light- 
 ing up of the labyrinthine infection, with extension 'to 
 the meninges. 
 
 In every ease of chronic suppuration of the middle 
 ear it is absolutely imperative to test the labyrinthine 
 functions before doing a radical mastoid. If it is found 
 that the labyrinthine functions have been destroyed, 
 either a labyrinth operation must be done or no opera- 
 tion at all. Of 25 cases of latent diffuse purulent laby- 
 rinthitis reported by Buttin, 21 recovered and 4 died. 
 
 Every case of chronic middle-ear suppuration with 
 loss of labyrinthine functions, is not necessarily a latent 
 labyrinthitis. We may be dealing with a healed laby- 
 rinthitis. Unfortunately we cannot be absolutely sure 
 whether the labyrinthine inflammation is latent or 
 healed. But there are certain points which help us con- 
 siderably in our decision. 
 
 It has been found by Ruttin that after complete de- 
 struction of the labyrinthine contents of one ear, fol- 
 lowed by fibrous or bony healing, the rotation test be- 
 haves peculiarly. The after-nystagmus toward the side 
 of the diseased ear is as long as that toward the oppo- 
 site side, but both are shorter than normal. This he 
 calls the compensation symptom. 
 
214 THE LABYEINTH 
 
 If in a chronic suppurative middle-ear condition, tlie 
 functional examination shows complete destruction of 
 the labyrinth, and the presence of the compensation 
 symptom, and there are evidences of new bony growth 
 on the inner tympanic wall, especially in the region of 
 the external semicircular canal, then we are, in all prob- 
 ability, dealing with a healed labyrinth, and not a latent 
 labyrinthitis. In such a case, it would naturally be un- 
 necessary to open the labyrinth. 
 
 In cases of suspected latent labyrinthitis, Neumann 
 is guided by the character of the bone in the petrous 
 pyramid, and the conditions found in the posterior cra- 
 nial fossa. If the petrous pyramid shows marked 
 pneumatization of the bone, or if there is a deep extra- 
 dural abscess in the posterior cranial fossa, he con- 
 cludes that there is a suppuration in the labyrinth. 
 
 Politzer is guided largely by the behavior of the 
 wound after a radical mastoid. If there are persistent 
 exuberant granulations on the inner tympanic wall, 
 after the radical mastoid operation, he assumes the 
 presence of a labyrinthitis. 
 
 The occurrence of a facial paralysis in the course of 
 a chronic middle-ear suppuration, when the functional 
 tests show a non-functionating labyrinth, is positive 
 evidence of a latent labyrinthitis. 
 
 A typical labyrinth operation for all cases of laby- 
 rinthitis is impracticable. We may divide the opera- 
 tions on the labyrinth into two groups. In one group, 
 the operation is limited to an opening of the labyrinth- 
 ine spaces, or labyrinthotomy. In the second group, 
 the operation consists of the removal of the entire laby- 
 rinth, as far as practicable, with the adjacent portions 
 
TREATMENT OF LABYEINTHITIS 215 
 
 of the petrosa. This latter type of operation may be 
 called labyrinthectomy. In the former class belong 
 Richards', Hinsberg's and Bourguet's operations, and 
 in the latter class, Jansen's and Neumann's. In the 
 first type of operation, the great danger is injury to 
 the facial nerve, and in the second class, injury to the 
 dura. 
 
 A simple enlargement of a labyrinthine fistula is of 
 no value for draining an infected labyrinth. A wide 
 opening of the labyrinthine spaces behind and in front 
 of the facial canal is indicated in empyema of the laby- 
 rinth, with intact bony capsule. When there is involve- 
 ment of the bony capsule, we must do a labyrinthec- 
 tomy, with removal of that portion of the petrous pyra- 
 mid which contains the labyrinth. When there are 
 signs of intracranial involvement, the posterior fossa 
 of the skull must be explored, and sometimes the middle 
 fossa. 
 
 The question as to whether the cochlea should be 
 opened together with the vestibule, in every case in 
 which the labyrinth is operated on, is still the subject 
 of discussion. But since we open the labyrinth only in 
 cases of diffuse labyrinthitis, it seems but rational that 
 the cochlea should be opened as well as the vestibule, 
 in every case. It is usually unnecessary to do more than 
 to uncover the lower half of the basal whorl of the coch- 
 lea. This can be done with one stroke of the chisel, and 
 if a reasonable amount of care is exercised, is a per- 
 fectly safe procedure. In addition to draining the coch- 
 lea, this procedure helps to drain the vestibule. 
 
 In sequestration of a large portion of the labyrinth, 
 the sequestrum is removed, and the remaining portions 
 
216 THE LABYEINTH 
 
 of the labyrinth left intact, in order not to destroy the 
 protective granulation-zone set up by nature. 
 
 In regard to the treatment of injuries to the laby- 
 rinth during the performance of a radical mastoid op- 
 eration, there is some difference of opinion. Alexander' 
 believes that if the labyrinthine cavity is opened acci- 
 dentally during the radical operation, the entire laby- 
 rinth should be widely opened, for the same reason that 
 a small accidental tear in the dura should be widely 
 opened. He believes that such injuries to the labyrinth, 
 if left untreated, almost always end fatally. Jansen, 
 on the other hand, believes that these cases should be 
 left alone. He has found that most of the cases get 
 well. 
 
 The most rational course to pursue, it seems to us, 
 is to treat the ease expectantly, until signs of a diffuse 
 purulent labyrinthitis have supervened, and then to 
 operate on the labyrinth. Of the cases of operative in- 
 jury to the labyrinth seen by the writers, the cases of 
 injury to the semicircular canals have gotten well with- 
 out operation on the labyrinth. Of three cases of dislo- 
 cation of the stapes, one recovered, without operation, 
 and two died in spite of operation on the labyrinth. 
 
 In tuberculous labyrinthine disease, operation is in- 
 dicated only when the formation of a sequestrum de- 
 mands it. 
 
 In meningogenic labyrinthitis, opening the labyrinth 
 is only of value to preserve hearing. Whether it ever 
 does this is problematical. 
 
 Non-operative treatment of labyrinthitis consists 
 principally of rest in bed, to minimize the unpleasant 
 subjective symptoms. The patient usually finds the 
 
PLATE XX. 
 
 Fig. 71 
 
 Hixsberg's Operatiok on the Labyrixtii 
 
 Oval window is enlarged downward 
 Vestibule is entered behind facial ridge, through anterior limb of 
 external semicircular canal 
 
TKEATMENT OF LABYEINTHITIS 217 
 
 most comfortable position for himself. It is the posi- 
 tion in which nystagmus and vertigo are least marked, 
 and is usually on the side of the sound ear. The pa- 
 tient should be left in bed as long as there is any ver- 
 tigo. This may be anywhere from three or four days 
 to several weeks. Best in bed may be of some value to 
 prevent the spread of a labyrinthine infection. 
 
 Galvanization has been employed to relieve the ver- 
 tigo. One electrode is placed in front of each ear. If 
 the spontaneous nystagmus is to the right, the kathode 
 is placed in front of the left ear, and the anode before 
 the right ear. A current of 4 to 12 milliamperes is 
 usually sufiScient to stop the nystagmus and the accom- 
 panying vertigo. 
 
 Bromides and other sedatives may have some value. 
 
 During this time there should be no manipulative in- 
 terference with the middle ear. It may be irrigated 
 with warm antiseptic solutions. 
 
 HINSBERG'S OPERATIOX 
 
 Of the various operations on the labyrinth which 
 have been described up to the present, the most con- 
 servative is that of Hinsberg. His operation consists 
 of the removal of the outer wall of the vestibule, in 
 front of and behind the facial canal, and in this way 
 establishing drainage. The semicircular canals are not 
 touched, except that portion of the external semicircu- 
 lar canal which must be removed in order to reach the 
 vestibule. The cochlea is drained by removing the 
 outer wall of the lower half of its basal whorl (Fig. 71, 
 Plate XX). 
 
218 THE LABYEINTH 
 
 The steps of the operation are as follows : 
 
 First a radical mastoid operation is done, the pos- 
 terior canal wall being shaved down as far as possible 
 without jeopardizing the integrity of the facial nerve. 
 The posterior canal wall is removed as far as is neces- 
 sary to make the oval window easily accessible. 
 
 If the stapes is present, it is removed. The oval win- 
 dow is now enlarged at the expense of its lower margin. 
 This may be done either by means of a chisel placed 
 across the bridge of bone between the oval and round 
 windows, or with a burr. When a chisel is used it is 
 directed downward, and removes the bridge of bone 
 between the oval and round windows. When a burr is 
 used, it is placed against the lower margin of the oval 
 window, care being taken not to injure the inner ves- 
 tibular wall. The posterior margin of the oval window 
 must not be touched, in order to avoid injuring the fa- 
 cial nerve. The oval window may be enlarged to twice 
 its normal size. 
 
 Sometimes Hinsberg removes the promontory. This 
 exposes the lower half of the basal whorl of the cochlea. 
 
 The external semicircular canal is then opened. 
 Hinsberg prefers to use a drill for this work. The am- 
 pullated end of the external semicircular canal is 
 nearer to the antrum than is the small end. The point 
 where the outer wall of the external semicircular canal 
 is thinnest, according to Hinsberg, and where it is eas- 
 iest to enter, is in the region vertically above the fenes- 
 tra ovalis. From here, the anterior limb of the external 
 canal is followed in an inward and forward direction, 
 until the vestibule is reached. In order to determine 
 when the vestibule has been opened, a bent probe is 
 
TBEATMENT OF LABYBINTHITIS 219 
 
 passed through the enlarged oval window. Its end will 
 appear in the cavity behind the facial ridge. 
 
 In cases where there is a deep overhanging middle- 
 fossa, it is difficult to open the external semicircular 
 canal at its anterior part. In these cases, Hinsberg 
 advises opening the vestibule from behind, after the 
 manner of Jansen. 
 
 RICHARDS' OPERATION 
 
 Richards first opens, and then removes all three 
 semicircular canals, and opens the vestibule behind the 
 facial nerve, through the solid angle. He then opens 
 up the entire cochleal cavity, and removes the apex of 
 the modiolus. The operation is best described in his 
 own words. 
 
 "A Schwartse-Stacke operation is done, by which we 
 secure the maximum amount of working room, and in 
 which we exenterate the bony angle included between 
 the groove of the sinus knee and the under surface of 
 the middle fossa, which better enables us to work in the 
 axis of the petrous pyramid. We lower the facial ridge 
 to its absolute limit, remove the fringe of bone on the 
 anterior aspect of the facial ridge back to the descend- 
 ing limb of the facial nerve, remove the outer wall of 
 the hypotympanum, and lower the level of the canal 
 floor, securing by these steps the maximum exposure 
 of the outer wall of the vestibule, and the dome of the 
 jugular bulb should it rise high. 
 
 ''As exploration of the cochlea may be necessary, it 
 is important that we see the exact position of the caro- 
 tid artery by the exposure of its canal. In consequence 
 
220 THE LABYRINTH 
 
 we shave down the convexity of the anterior wall of 
 the auditory canal, remove the lip of bone over- 
 tanging the mouth of the tube and evulse the tensor 
 tympani. 
 
 ' ' This exposes the tube to curettement, by which we 
 relieve the field of blood, and it gives the maximum 
 width to the apex of the cavity. Should the consistency 
 of the bone permit, the arches of the semicircular canals 
 should be delineated. This enables us to work with 
 accuracy. The cavity should be cleansed; the tube 
 packed with adrenalin gauze ; the field rendered blood- 
 less ; the instruments and hands resterilized. 
 
 "We next remove the prominence of the horizontal' 
 semicircular canal; it is a treacherous structure (Fig. 
 72, Plate XXI). The cutting edge of the chisel is 
 placed at a point below the summit, but well above the 
 level of the fallopian canal, for this prominence sepa- 
 rates along definite planes of cleavage, and as the outer 
 lip of this semicircular canal is intimate with the fallo- 
 pian, a fissure in the former may extend out into the 
 latter. Should the plane of cleavage be on a level with 
 or below the fallopian canal, the facial nerve may either 
 be exposed by having its roof removed, or else com- 
 pletely undermined, under which circumstances we may 
 definitely expect paralysis, for it will ensue. The stroke 
 should be made in a direction corresponding to the 
 plane of the canal. The remaining canals are next un- 
 capped, and the condition of the interior is noted. It 
 will be found that the interior of the external semicir- 
 cular canal most frequently of all shows pathological 
 change. In opening the superior canal a curved gouge 
 should be xised. It permits the stroke to be made in the 
 
ri.AlE XXI. 
 
 Fig. 
 
 ElCIIAKDS' OrEI!.\TIOX OX THE LabYRIX'TII 
 
 Kadical ma.stnid o]iPiatinn lias lieen done. The three seiiiieiicular canals 
 have been outlined, and nncajiiied, (ipening nji their lumina 
 
PLATE XXII. 
 
 Fig. 73 
 
 EiCHARDs' Opeisatiox ox the Labykinth 
 
 Seniicii'cular canals have been removed, and vestibule opened from 
 
 behind, leaving; the ridge containing the facial nerve intact. 
 
 Probe has entered the vestilnile thi-ough the oval window 
 
TBEATMBNT OF LABYRINTHITIS 221 
 
 direction of safety. The danger arises from the non- 
 support of this canal by solid bony structure. 
 
 ' ' Owing to the contrast between the dark interior of 
 the canals and the brilliantly illuminated white bone 
 surrounding them, the labyrinthine fluid may appear 
 dark and be mistaken for blood or granulations; we 
 should not be deceived by this illusion. 
 
 "We next enter the vestibule through the solid angle 
 of the semicircular canals by creating at this point a 
 conical pit with its apex directed inward and grad- 
 ually lowered until it enters the vestibule (Fig. 73, 
 Plate XXII). As it is necessary to remove the inner 
 lip of the horizontal semicircular canal, during this step 
 the chisel should be held perpendicular to the plane of 
 cleavage, and under no circumstances should it impinge 
 upon the outer lip, which is intimately associated with 
 the fallopian canal, together with which it is left as a 
 bridge carrying the nerve which spans the vestibule. 
 
 ' ' The opening in the vestibule is now enlarged until a 
 full exposure is obtained of this portion of the cavity. 
 Its inner wall should be searched for fistulas. In enlarg- 
 ing this cavity no pressure should be made upon the 
 bridge. For this reason a curette is a dangerous in- 
 strument. A small sharp gouge is safer. 
 
 "Owing to widespread necrosis, it is necessary in 
 some instances to sacrifice the bridge of bone carrying 
 the facial nerve. To accomplish this without injury to 
 the facial, we select a curette with its cutting edge 
 turned backward, utilize the superior rim of the bone 
 cavity as a fulcrum and shave off from above downward 
 in a direction parallel to the course of the nerve, the 
 roof of the fallopian canal, thus leaving the nerve ex- 
 
222 THE LABYEINTH 
 
 posed in its gutter of bone, from whicli it may be sepa- 
 rated and lifted without injury. Any filaments given 
 off from the nerve should be cut and not torn from this 
 structure, as unnecessary traumatism is committed. 
 We next remove such portions of the bridge as are ne- 
 crotic, but no more, for the nerve here represents a 
 curve, and should it lose the entire support of its bony 
 gutter, it apparently elongates, and consequently sags 
 or kinks, and, becoming enmeshed in this vicious posi- 
 tion by the granulations, has its functions interfered 
 with later. 
 
 "In this condition the nerve stretches as an exposed 
 structure from its point of emergence low down on the 
 facial ridge, across the cavity of the vestibule to its 
 entry into the inner wall of the tympanum, correspond- 
 ing to a point above and anterior to the original site 
 of the oval window. 
 
 "In knocking out the inner edge of the bony ridge, 
 which corresponds to the upper inner wall of the tym- 
 panum, the stroke of the chisel should not be made from 
 behind forward in a direction parallel to the course of 
 the nerve, but from above downward, or, from before 
 backward; i. e., in a direction perpendicular to the 
 course of the nerve and to the fallopian canal. 
 
 "The reason for this is that the bone at this point 
 tends to separate when struck from behind forward, 
 along a plane of cleavage which crosses the fallopian 
 canal, causing its fracture; as the fallopian canal at 
 this point represents the greater portion of an exposed 
 cylinder, its fracture results in the facial nerve being 
 encompassed by a little annulus or cylinder of bone, 
 which may be slid up and down upon the nerve, just as a 
 
TBEATMENT OF LABYEINTHITIS 223 
 
 ring upon a finger. This complication is — so far as the 
 integrity of the nerve is concerned — a formidable one, 
 and it requires the greatest patience to remove the lit- 
 tle annulus without causing injury to the facial. To 
 accomplish it, we steady the annulus with mouse-tooth 
 thumb forceps and with a pair of rongeurs — the jaws of 
 which are accurately apposed — crush it in a direction 
 parallel to the course of the nerve. 
 
 "To avoid this complication, it is only necessary be- 
 fore attempting the removal of the upper portion of 
 the bony ridge that the fallopian canal should have been 
 thoroughly converted into a gutter, by shaving off its 
 roof, as mentioned, and by making the stroke in the 
 direction indicated. Should the accident now occur, the 
 nerve can be easily freed from the little mass of bone 
 by slipping it through the open side of the annulus, 
 or cylinder. 
 
 "Should we have to expose the nerve as mentioned, 
 no attempt should be made to retract it or draw it to 
 one side for the sake of gaining room for manipula- 
 tion, as this is unnecessary; for the fallopian canal at 
 the points at which the nerve emerges from and enters 
 the bone is represented by sharp, serrated margins, 
 against which if the nerve is drawn it may be lacerated 
 at its fixed points. The sharp spicules should be re- 
 moved so that the margin of the canal at these respect- 
 ive points is represented by an even rim. 
 
 "The next step is to expose the anterio-inferior cav- 
 ity of the vestibule by removing the posterior aspect of 
 the promontory and the outer vestibular wall. We se- 
 lect a gouge, the width of which corresponds to the dis- 
 tance between the round and oval windows. The cut- 
 
224 THE LABYRINTH 
 
 ting edge straddles the little bridge of bone separating 
 these two openings, and the stroke — ^which is slight, for 
 the posterior aspect of the promontory is brittle and 
 fractures easily — is directed from above, downward and 
 forward in the direction of the first eochleal turn. We 
 must at this step think of the possible position of the 
 dome of the jugular bulb. 
 
 ' ' The greatest care should be taken that the cutting 
 edge of the chisel does not cross the cavity of the ves- 
 tibule and impinge upon its inner wall, for the inner 
 wall at this point bulges outward and is separated from 
 the internal auditory meatus by a brittle partition of 
 bone not more than H2 of an inch in thickness. Should 
 the inner wall be fractured, we lose cerebro-spinal fluid 
 and aside from the inconvenience caused by this acci- 
 dent, the infected operative cavity is placed in direct 
 communication with the intracranial cavity and the pa- 
 tient's life is jeopardized; meningitis will probably 
 result. 
 
 "As the cerebro-spinal fluid is under pressure and is 
 of low specific gravity, gauze does not act as an efficient 
 plug to the rent ; sterile wax is preferable. 
 
 ' ' By enlarging this opening we secure, with the pre- 
 vious steps, the full exposure of the vestibular cavity 
 and the beginning of the first eochleal whorl. Should 
 we now find that the disease has invaded the cochlea, 
 we must continue the exploration of the cochlea until 
 we have followed the diseased process to its legitimate 
 end. 
 
 "We next remove the roof of the first eochleal whorl 
 from behind forward, exposing its interior to a point 
 just short of the carotid eminence (Fig. 74, Plate 
 
PLATE XXIII. 
 
 Fic. 74 
 
 RicnAKDS' Operation on the Labykintii 
 
 A portion of the pioniontoiy has been removed, exposing the beginning 
 
 of the linsal whorl of the cochlea 
 
 Fic. 75 
 
 Richards' Operation on the LABYr.iNTii 
 
 Exposure of lower half of basal whorl and second whorl of the cochlea 
 
TBEATMENT OF LABYBINTHITIS 225 
 
 XXIII). The instrument of preference is a thin, sharp 
 gouge with no shoulder, the width of which is slightly- 
 greater than that of the cochleal whorl. Four struc- 
 tures are to be avoided; the dome of the jugular bulb 
 below, the eminence of the carotid canal in front, the 
 base of the modiolus and the internal auditory meatus 
 internally. The danger to the first two is slight; to 
 the second two it is imminent, and injury to these struc- 
 tures is to be avoided only with the exercise of care. 
 
 "By confining the removal of the cochleal shell en- 
 tirely to the roof of its first whorl and not allowing the 
 gouge to impinge upon the inner wall of the cochleal 
 turn these last dangers may be averted. From the 
 carotid artery in front, the cavity of the first cochleal 
 turn is separated by a hard cuff of bone which serves 
 the purpose of an efficient bumper; though thin this 
 partition is sufficient. 
 
 "If we now find that the limit of the disease has not 
 been reached, we must explore the remaining cochlea. 
 This constitutes by far the most difficult and dangerous 
 step of the procedure ; for the cochlea, which represents 
 an extremely small cavity encased in a brittle shell of 
 bone, is hemmed in on all sides by structures which we 
 cannot afford to injure. In front is the carotid artery, 
 below the dome of the jugular bulb, behind the internal 
 auditory meatus, above and behind in immediate prox- 
 imity to the second half of the first cochleal turn, the 
 knee of the facial nerve. A circle a quarter of an inch 
 in diameter could be so placed as to pass through the 
 majority of these structures. 
 
 "Were the above factors the only ones to be con- 
 sidered it would be comparatively easy to select a point 
 
226 THE LABYRINTH 
 
 on the cocMeal shell which from dead house work we 
 had found to be a safe one, and open its cavity. But 
 the difficulty lies in the fact that within this shell of 
 bone is contained a structure which from its position is 
 exposed to injury, and which from a surgical stand- 
 point is the most treacherous of the internal ear; I 
 refer to the modiolus. 
 
 "Before approaching the cochlea it will be well to 
 consider certain anatomical features of the modiolus 
 which are of surgical importance. The modiolus rep- 
 resents a small pyramid of bone seated upon the in- 
 ternal auditory meatus, decreasing in size from base to 
 apex. Its apex is its weakest point, but the next weak- 
 est point is not immediately below its apex, but at the 
 extreme base ; for its base is excavated by the internal 
 auditory meatus, and the pyramid consequently rests 
 upon a mere rim of thin, brittle bone. If the chisel is 
 applied to the pyramid well above its base and a stroke 
 made, the fracture does not take place at the point of 
 applied violence but at its base; when this occurs the 
 pyramid fractures completely round the circumference 
 of its base and separates as a single piece of bone. The 
 internal auditory meatus is consequently opened 
 throughout its entire circumference, and as the diam- 
 eter of the base of the pyramid or the rim of bone upon 
 which it rests is about % of an inch, the loss of cerebro- 
 spinal fluid is rapid. The failure to appreciate the sur- 
 gical importance of this anatomical feature of the modi- 
 olus resulted in the death of the first patient. 
 
 "If we now examine the modiolus with a strong con- 
 vex lens we see that the pyramid has an outer casing 
 of brittle bone and a core which is porous, made so by 
 
TEEATMENT OP LABYEINTHITIS 227 
 
 canals running from base toward apex for the passage 
 of various structures. These canals are not completely 
 filled by the structures which they contain, and this per- 
 mits the cerebro-spinal fluid to penetrate out into the 
 modiolus. 
 
 "During the second operation in which the modiolus 
 had been removed well down toward its base it was 
 noticed that a sepage of cerebro-spinal fluid took place 
 through its stump; the intracranial cavity had been 
 placed in gross communication with the infected cavity 
 in an altogether unexpected way through the aforemen- 
 tioned channels, and the failure to appreciate the sig- 
 nificance of this structural character of the modiolus 
 resulted in the death of the second patient. In this 
 case the infection could be traced along the cochlear 
 branch of the auditory nerve. It now became impor- 
 tant to determine how far down from the apex toward 
 the base the pyramid could be removed without putting 
 the intracranial and operative cavities in gross commu- 
 nication; for in dealing with the anterior half of the 
 cochleal cavity it is absolutely necessary to get rid of 
 a portion of the modiolus. 
 
 "It can be shown upon increasing the tension of the 
 intracranial fluid in a cadaver by injection, or in the 
 living subject by pressure over the internal jugular 
 vein, under which circumstances the cerebro-spinal 
 fluid win penetrate as far out as possible into the modi- 
 olus (i. e., grossly), that the pyramid may be removed 
 from the apex toward its base, down to a point corre- 
 sponding to the termination of the first cochleal whorl 
 without causing the loss of cerebro-spinal fluid; i. e., 
 without placing the operative and intracranial cavities 
 
228 THE LABYBINTH 
 
 in gross communication. As will be shown later, this 
 suffices for the complete exploration of the anterior 
 half of the cochleal cavity. 
 
 "In approaching, therefore, the cochlea, we must re- 
 move its shell in such a way as not to injure the modio- 
 lus. We select a point in the cochleal shell correspond- 
 ing somewhat to the apex of the cochleal cavity, and 
 with a thin sharp gouge shave it down until the dark 
 interior of a cochleal whorl shows through the thin la- 
 mella of bone (Fig. 75, Plate XXHI). The stroke 
 should be made from above downward and forward in 
 a direction corresponding to that of a cochleal whorl. 
 
 "Not infrequently the shell of the cochlea is scal- 
 loped and the position of the cochleal turns roughly in- 
 dicated. In this way a window is created in the coch- 
 leal shell, and we now enlarge this window, completely 
 exposing the upper portion of the cavity. 
 
 "In enlarging this window the small gouge is the in- 
 strument of preference ; an attempt to insinuate a very 
 fine curette beneath the opening in the cochleal shell 
 causes its back to impinge or press upon the modiolus, 
 which sticks up as a little tent pole in the cavity, and 
 this may result in the fracture of the pyramid at its 
 base. The gouge merely removes the shell without en- 
 dangering the pyramid. 
 
 "To expose the second half of the first cochleal whorl 
 it is necessary to remove the apex of the pyramid down 
 to a point corresponding to the termination of the first 
 cochleal whorl (Fig. 76, Plate XXIV). This done, we 
 can look down over the stump of the pyramid, upon the 
 roof the second half of the first whorl, and with a small 
 gouge carefully break through its roof from above, ex- 
 
PLATE XXIV. 
 
 Fig. 70 
 
 Eicii.\nD,s' Operatiok on riiio Labyiiixtii 
 Lower half of basal wlioii. middle wlioil. and cupola of eoelilca e.xposed 
 
PLATE XXV. 
 
 Fig. 
 
 Richards' Operation on the Labyrinth 
 Exposure of the entire coehleal cavity 
 
PLATE XXVI. 
 
 MsJ 
 
 Fig. 78 
 
 Richards' Operation ok the Labyrikth 
 
 Complete exenteration of the cochlea. The stump of the auditory nerve 
 is seen at the bottom of the cochleal cavity 
 
TREATMENT OF LABYBINTHITIS 229 
 
 posing in this way the entire interior of the cavity of 
 the cochlea (Fig. 77, Plate XXV) . In breaking through 
 the roof over the last portion of the first whorl, we are 
 in direct relation to the facial nerve and the internal 
 auditory meatus, both of which must be avoided." 
 (Fig. 78, Plate XXVI). 
 
 THE JANSEX OPERATION 
 
 Jansen operates within the temporal bone, except 
 where a diagnosis of disease in the posterior cranial 
 fossa has been made. In the latter case, he exposes the 
 dura of the posterior fossa, and removes the posterior 
 surface of the petrous pyramid. The former method 
 is called the semicircular canal or tympanal method, 
 and the latter the endocranial method. 
 
 The Neumann operation is just like Jansen's endo- 
 cranial operation, except that Neumann continues the 
 removal of the posterior pyramidal surface until the 
 posterior wall of the internal auditory canal has been 
 removed, and the auditory and facial nerves lie exposed 
 in the canal. Neumann believes that the internal au- 
 ditory canal should be opened in every operation on the 
 labyrinth, on account of the frequency with which an 
 abscess is found at the fundus of this canal. 
 
 Jansen's semicircular canal or tympanal method is 
 as follows; with a chisel or burr he removes the emi- 
 nence of the external semicircular canal. The upper 
 wall of the anterior limb of the external semicircular 
 canal is then removed. Great care must be exercised 
 not to injure the lower wall of this canal, as immedi- 
 ately below it lies the facial nerve. He then removes 
 
230 THE LABYRINTH 
 
 the entire posterior limb of the external semicircular 
 canal, together with the underlying bone, in a down- 
 ward and backward direction, being careful not to in- 
 jure the facial nerve in front. By following the an- 
 terior and posterior limbs of the external semicircular 
 canal, the vestibule is reached. A bent probe passed 
 into the vestibule through the oval window is a valu- 
 able guide during the operation. 
 
 After reaching the vestibule, he enlarges the open- 
 ing into it until the entire outer vestibular wall, behind 
 the facial nerve, is gone. He removes the outer wall, 
 in a downward direction, until the ampuUary orifice of 
 the posterior semicircular canal is seen ; backward, until 
 the orifice of the common limb is seen; and upward, 
 until the ampuUary orifice of the superior semicircular 
 canal is exposed. 
 
 He does not follow up the semicircular canals. He 
 believes that the disease in the canals is usually slight, 
 and that after exposure of their orifices into the ves- 
 tibule they are very likely to heal. 
 
 In cases of narrowing of the vestibule and oblitera- 
 tion of the semicircular canals, resulting from the 
 formation of new bone, he penetrates the vestibule be- 
 hind and parallel to the facial ridge, inward downward 
 and forward, in the direction of the fenestra ovalis. 
 
 Jansen believes that while the chisel gives one a bet- 
 ter idea of the contents of the labyrinthine spaces, as 
 the canals do not fill up with bone-dust, the burr, on the 
 other hand, is less dangerous to the integrity of the 
 facial nerve. He uses the chisel as a plane, thus taking 
 off successive shavings of bone. 
 
PLATE XXVII. 
 
 LS 
 
 Fig. 
 
 Jansen-Neumann Operation on the Labyrinth 
 
 The inner table has been removed over the anterior portion of the lateral 
 
 sinus and cerebellum, as far forward as the labyrinthine capsule 
 
 Position of chisel in removing posterior surface of petrous pyramid 
 
 is indicated 
 
 L8 — Lateral sinus 
 
 C — Cerebellar dura 
 
TBEATMENT OF LABYRINTHITIS 231 
 
 THE JAXSEN- NEUMANN OPERATION 
 
 The endocranial Jans en-Neumann operation is done 
 as follows; first a complete Schwartze-Stacke opera- 
 tion is done. Then by means of a broad flat chisel the 
 inner table over the anterior portion of the lateral sinus 
 is removed (Fig. 79, Plate XXVII). From this point the 
 inner table is removed in a forward direction until the 
 labyrinthine capsule is reached. This exposes a tri- 
 angular area of the cerebellar dura in front of the lat- 
 eral sinus. The base of the triangle is directed upward 
 and corresponds to the angle between the middle and 
 posterior fossae of the skull. The posterior margin of 
 the triangle corresponds to the anterior border of the 
 lateral sinus, and the anterior margin of the triangle 
 corresponds to that portion of the petrous pyramid 
 which contains the labyrinth. 
 
 This plate of bone can be removed either by means 
 of a chisel or with a rongeur. 
 
 The dura is now carefully separated from that por- 
 tion of the posterior surface of the petrous pyramid 
 which contains the labyrinth, either with a narrow 
 straight periosteal elevator or with a pair of dressing 
 forceps. This separation must be done very carefully, 
 as the posterior surface of the petrous bone contains 
 numerous small depressions, into which processes of 
 the dura extend. In attempting to separate the dura 
 it is very easy to tear through the membrane at these 
 points.. 
 
 With a straight chisel placed parallel to the posterior 
 surface of the petrous pyramid, the bone is now re- 
 moved in thin shavings, the strokes being directed from 
 
232 THE LABYRINTH 
 
 the base toward the apex of the petrous pyramid. In 
 this way, that portion of the petrosa containing the 
 semicircular canals is removed. It is very important 
 that the strokes should be parallel to the posterior sur- 
 face of the pyramid. A deviation of the strokes up- 
 ward would endanger the superior petrosal sinus. A 
 deviation downward would endanger the jugular bulb. 
 A deviation outward would endanger the facial 
 nerve. 
 
 After the first few strokes of the chisel there appears 
 a small curved portion of one of the semicircular 
 canals (Fig. 80, Plate XXVIII). It is on a level with the 
 round window, and a little less than half an inch behind 
 it. This is the convexity of the posterior semicircular 
 canal. On thinning down the bone a little further, there 
 appear two round openings, about a quarter of an inch 
 apart (Fig. 81, Plate XXIX). The lower opening is on 
 a level with the lower margin of the round window, and 
 is the lower limb of the posterior semicircular canal. 
 The upper opening is on a level with the lower part of 
 the oval window, and is the common limb of the su- 
 perior and posterior canals. A narrow probe passed 
 through this upper opening in a forward direction, 
 enters the vestibule. 
 
 Soon a third opening appears, midway between the 
 first two openings, and somewhat more superficial 
 (Fig. 82, Plate XXX). This is the posterior limb of 
 the external semicircular canal. A probe passed 
 through this canal in a forward direction reaches the 
 vestibule very readily. This last canal is now followed 
 up with the chisel-strokes in a forward direction. It 
 becomes oval in shape, then becomes an elongated 
 
PLATE XXVIII. 
 
 PS 
 
 Fig. 80 
 
 jAXSEX-NEUMArs'X OPERATION 
 
 Showing beginning of removal of posterior surface of petrous pyramid 
 PS — Posterior semieireular canal 
 
PLATE XXIX. 
 
 Fig. 81 
 
 Jansen-Xeumann Operation 
 
 C — Common limb of superior and P — Inferior linili of posterior semi- 
 posterior semicireu- circular canal 
 
 lar canals 
 
PLATE XXX. 
 
 c 
 
 E 
 
 D 
 P 
 
 Fig. 82 
 
 Jansen-Neumakk Opekation 
 Probe passed through external semioircuhir canal into vestibule 
 
 C — Common limb of superior and D — Process of dura going into de- 
 
 posterior semicircu- pression on posterior sur- 
 
 lar canals face of petrous pyramid 
 
 E — Probe in external semicircular P — Inferior limb of posterior 
 
 canal semicircular canal 
 
PLATE XXXI. 
 
 Fig. 83 
 
 Jaksex-Neumann Operation 
 
 T — Vestibule containing probe P — Inferior limb of posterior semi- 
 
 eular canal 
 
PLATE XXXII. 
 
 V 
 
 N 
 
 Fig. 84 
 Neuma^^n Opekation 
 
 F — Vest ibule 
 
 A' — Seventh and eighth nerves in 
 internal auditory canal. 
 The lower half of the first 
 turn of the cochlea is ex- 
 posed 
 
TEEATMENT OF LABYBINTHITIS 
 
 233 
 
 canal, and finally the vestibule appears (Fig. 83, 
 Plate XXXI). 
 
 In following up the external semicircular canal, care 
 must be taken to leave its external wall intact. The 
 external semicircular canal is undermined by the chisel, 
 removing only the inner wall of this canal, and the 
 petrosa internal to and in front of it. In this way 
 injury to the facial nerve is readily avoided. 
 
 We can assure ourselves that we have really opened 
 the vestibule by passing a bent probe through the oval 
 window in a backward direction. The end of the probe 
 will emerge through the opening in the posterior wall 
 of the vestibule. 
 
 At this point of the operation Jansen usually stops. 
 Neumann, however, continues to remove the petrous 
 pyramid beyond the vestibule until he has removed the 
 posterior wall of the internal auditory canal, and laid 
 bare the seventh and eighth nerves, as they lie in this 
 canal (Fig. 84, Plate XXXII). 
 
 Each chip of bone, as it is cut loose with the chisel, 
 should be carefully extracted with a pair of dressing- 
 forceps, care being taken not to tear the dura. If the 
 chip is firmly fastened to the dura at its deeper end, it 
 should be carefully separated with a periosteal ele- 
 vator. If the dura is accidentally torn, the opening 
 should be enlarged. Only small tears in the dura are 
 dangerous. 
 
 The lower half of the basal whorl of the cochlea is 
 then exposed, by chipping off the promontory. This is 
 done with one stroke of the chisel, starting at the oval 
 window, and directing the cut downward and forward. 
 
 When the cochlea is a mass of sequestra, pus and 
 
234 THE LABYRINTH 
 
 granulations, it can easily be scooped out with a 
 curette. 
 
 AFTER-TREATMENT 
 
 After doing a radical mastoid, in the presence of a 
 circumscribed labyrinthitis, the posterior wound may 
 be left open, so as to be ready to do a labyrinth opera- 
 tion if a diffuse suppurative labyrinthitis supervene. 
 
 If a labyrinth operation has been done, the wound 
 should be left open until all danger of intracranial ex- 
 tension is past, when the posterior wound is closed and 
 a meatal flap made. The flap is made just as in an or- 
 dinary radical mastoid operation, and the dressings are 
 done in the usual way. 
 
 In cases of labyrinthine empyema, where a laby- 
 rinthotomy has been done, the radical cavity heals just 
 as quickly as in an uncomplicated middle ear suppura- 
 tion. In labyrinthine empyema with superficial para- 
 labyrinthitis, a labyrinthotomy is apt to be followed 
 by a granulating spot on the inner tympanic wall, which 
 lasts for an indefinite time. 
 
 "When a resection of the labyrinth is done, the rapid- 
 ity of the healing depends upon the thoroughness of 
 the removal of diseased bone in the petrous pyramid. 
 
BIBLIOGRAPHY 
 
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236 THE LABYBINTH 
 
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 Baeth. 
 
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bibliogbaphy 237 
 
 Bbeueb. 
 
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 zimgsber., part III, 1903, vol. CXII, p. 353. 
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 Bbextee und Kbeidl, 
 
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 Bbyant, W. S. 
 
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 Cheatle, a. 
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 Day, E. W. 
 
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 Dench. 
 
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 EWALD, J. R. 
 
 "Untersuchungen fiber das Endorgan des Nervus 
 
 Octavus. ' ' 
 "Eine neue Hortheorie." 
 
238 the labyrinth 
 
 Fbeystadtl, B. 
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 mus." Monats. f. Ohrenh., 1909. 
 
 Fbiedeich, E. p. 
 
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 GOEBKE, M. 
 
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 Arch, f . OFrenh., 1909, vol. 80. 
 "Die Vorhofswasserleitung und ihre EoUe bei Laby- 
 
 rintheiterungen. ' ' 
 
 Geay. 
 "Anatomy." 
 
 Gbay, a. a. 
 Jour, of Anat. and Physiol., 1900, vol. XXXIV. 
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 "The Labyrinth of Animals." 
 
 GEliNBBEG, K. 
 
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 ungen. ' ' Zeitsch. f . Ohrenh., 1909, 
 
 Heine. 
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 Woehenschr., 1907. 
 
 Helmholtz, H. 
 "Die Lehre von den Tonempfindungen." 
 
 Heezog. 
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 HiNSBEEG, V. 
 
 "Ueber Labyrintheiterungen. " Zeitsch. f. Ohrenh., 
 1901, vol. 40. 
 
BIBLIOGBAPHY 239 
 
 "Eeferat iiber Labyrintheiterungen. " Verhandl. d. 
 Deutsch. Otol. Gesell., 1906. 
 
 Jansen, a. 
 
 "Labyrintlioperatioiien." In Blau's Encyklop. d. 
 
 Obrenb., 1900. 
 "Ueber eine haufige Art der Betbeiligung des Laby- 
 
 rinthes bei den Mittelohreiterungen." Arcb. f. 
 
 Obrenh., vol. XLV. 
 ' ' Treatment of Infective Labyrintbitis. ' ' Trans, of 
 
 Amer. Lar., Rbin. & Otol. Soc, 1908. 
 
 Kalischeb, 0. 
 
 Arch, f . Anat. nnd Pbysiol., 1909. 
 
 Kebbison, p. D. 
 
 "Tbe Pbenomena of Vestibular Irritation in Acute 
 Suppurative Labyrintbitis." Trans, of tbe Amer. 
 Lar., Ebin. & Otol. Soc, 1909. 
 
 KiPBOFF. 
 
 "Quantitative Messung des kaloriscben Nystagmus 
 bei Labyrinthgesunden." Passow's Beit., 1909, 
 vol. 2. 
 
 KOPETZKY, S. J. 
 
 "Meningitis— Nature, Cause, Diagnosis, and Princi- 
 ples of Surgical Eelief." Trans, of Amer. Lar., 
 Ebin. & Otol. Soc, 1912. 
 
 KtTBO. 
 
 "Ueber die vom Nervus Acusticus ausgelosten Au- 
 genbewegungen. " Pfliiger's Arcb. vol. CXV. 
 
240 the labyrinth 
 
 Keamm. 
 
 "Ueber die Diagnose des Empyems des Saccus Endo- 
 lymphaticus." Passow's Beitr., vol. I. 
 
 Langb, "W. 
 
 "Beitrage zur pathologischen Anatomie der vom 
 Mittelohr ausgehenden Labyrinthentziindungen. " 
 Passow's Beit,, vol. 1. 
 
 Lee, F. S. 
 
 "A Study of the Sense of Equilibrium in Fishes." 
 Jour, of Physiol., vol. XV, p. 311, and vol. XVII, 
 p. 192. 
 
 Leidleb. 
 "Ein Fall mit fehlendem Drebungsnystagmus. " 
 Zeits. f. Ohrenh., 1908. 
 
 Lewandowsky, M. 
 
 "Die Funktionen des Zentralen Nervensystems." 
 
 Mach. 
 
 " Grrundlinien der Lehre von den Bewegungsemp- 
 findungen." 
 
 Mabx, H. 
 
 "Untersuehungen liber Kleinbirnveranderungen 
 
 nach Zerstorung des bautigen, etc." Areb. f. d. 
 
 gesamt. Physiol., 1907, vol. XX. 
 "Betrag zur vergleiehenden patbol. Anatomie der 
 
 Labyrinthitis." Zeits. f. Ohrenh., 1910. 
 "Ueber den galvaniscben Nystagmus." Zeits. f. 
 
 Ohrenh., 1911. 
 
bibliogbaphy 241 
 
 Maybe, 0. 
 "Zur Entstehung der sogenannten Labyrinthitis 
 serosa im Verlaufe akuter Mittelohrentzundun- 
 gen." Monats. f. Ohrenh., 1909. 
 
 Neumann, H. 
 
 "Cerebellar Abscess." 
 
 * ' Labyrintheiterung. ' ' Monats. f . Ohrenh., vol. XLI. 
 
 "Atate Labyrintbeiterimg. " Monats. f. Ohrenh., 
 vol. XL. 
 
 * * Labyrinthitis Circumscripta. ' ' Monats. f . Ohrenh., 
 vol. XLI. 
 
 "Heilung einer Facialislahmung nach Labyrinth- 
 operation." Monats. f. Ohrenh., vol. XLI. 
 
 "Zwei Falle von zirkumskripten Labyrintheiterun- 
 gen." Monats. £. Ohrenh., vol. XLI. 
 
 "Ueber Circnmscripte Labyrinthitis." Deutsch. 
 Otol. GeseU., 1907. 
 
 "Ueber Infektiose Labyrintherkrankungen. " Mo- 
 nats. f . Ohrenh., 1911. 
 
 Panse, E. 
 "Pathologische Anatomie des Ohres." Leipzig, 
 1912. 
 
 POLITZEB, A. 
 
 "Diseases of the Ear." 
 
 QUAIN. 
 
 "Anatomy." 
 
 ElCHABDS, J. D. 
 
 "Surgery of the Labyrinth." Trans, of the Amer. 
 Lar., Ehin. & Otol. Soc, 1907. 
 
242 THE LABYRINTH 
 
 KOSBNPELD, M. 
 
 "Das Verhalten des kalorisclien Nystagmus in der 
 CMoroform-Aether Narkose und im Morphium- 
 Skopolamin ScMaf." Neurolog. ZentralbL, 1911. 
 
 ElTTTIN, E. 
 
 "Klinische Studien zur Differential-diagnose der 
 Labyrinthitis, der Meningitis und des Kleinhim- 
 abscesses." Monats. f. Obrenh., 1911. 
 
 "Zur Differentialdiagnose der Labyrinth.- und Hirn- 
 nervenerkrankungen." Zeits. f. Ohrenh., vol. 
 LVIL 
 
 "Paralabyrinthitis mit Fistelbildung am horizon- 
 talen Bogengang und abgelaufener seroser Laby- 
 rinthitis." Oester. Otol. Gesell., 1909. 
 
 "Akute Otitis mit akuter Labyrintheiterung imd 
 Meningitis." Oester. Otol. Gesell., 1909. 
 
 "Beginnende Labyrinthsequestration bei erhaltener 
 kalorischer Erregbarkeit. ' ' Ibid. 
 
 "Fistel im ovalen Fenster bei erhaltenen Horver- 
 mogen und erhaltener Eeaktion. ' ' Ibid. 
 
 "Zur Differentialdiagnose der Erkrankungen des 
 Vestibularendapparates und seiner zentralen 
 Bahnen." Deutsch. Otol. Gesell., 1909. 
 
 " Schlaf enlappenabscess und Nystagmus." Monats. 
 f. Ohrenh., vol. XLII. 
 
 "Klinik der Serosen und Eitrigen Labyrinth-Ent- 
 ziindungen." Wien, 1912. 
 
 "Klinische und pathologisch-histologisehe Beitrage 
 zur Frage der Labyrinthfistel." Monats. f. 
 Ohren., 1909. 
 
 "Zur Frage der Ektasie des Ductus Cochlearis." 
 Verhandl. d. Deutsch. Otol. Gesell., 1908. 
 
BIBLIOGBAPHY 243 
 
 "Beitrage zur Histologie der Labyrintheiterungen." 
 Passow's Beitr,, vol. I. 
 
 SCHWABTZE. 
 
 ' ' Olirenlieilkiinde. ' ' 
 
 Shambaugh, G. E. 
 Arcli. of Otol., vol. XXXVn, No. 6. 
 "The Physiology of the Cochlea." Annals of Otol., 
 
 Ehinol. and LaryngoL, 1910. 
 "A Eestudy of the Minute Anatomy of the Cochlea, 
 
 etc. ' ' Amer. Jour, of Anat., 1907. 
 Trans, of the Ninth Intemat. Otol. Cong., 1912. 
 
 Smith, S. MacC^ 
 "Indications for Operation in Suppurative Disease 
 of the Labyrinth." Pennsylv. Med. Jour., April, 
 1912. 
 
 Stbngeb. 
 " Topographische Anatomie des Gehororgans, in 
 Katz, Preysing & Blumenf eld's "Handbuch der 
 SpezieUen Chirurgie des Ohres und der Oberen 
 Luftwege." 
 
 VoN Stein, S. 
 
 "Ueber Gleichgewichtsstonmgen bei Ohrenleiden." 
 
 Zeits. f. Ohrenh., 1895. 
 "Ueber Gleichgewichtsstorungen bei Ohrenleiden." 
 
 (Sammelreferat.) Internat. Centralbl. f. Ohrenh., 
 
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 Voss, 0. 
 "Wodureh entsteht der Nystagmus bei einseitiger 
 
244 THE LABYBINTH 
 
 Labyrintliverletzung. " Verhandl. d. Deutsch. 
 
 Otol. Gesell., 1907. 
 "Klinische Beobachtungen iiber nicbt eitrige Laby- 
 
 rinthentzimdungen im Verlauf akuter und chro- 
 
 nischer Mittellohreiterungen." Verhandl. d. 
 
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 "Treten bei doppelseitiger Zerstorung der Vestibu- 
 
 larapparate Grleichgewichtsstorungen als Ausfalls- 
 
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 GeseU., 1909. 
 
 Wanneb. 
 
 "Fall von Labyrintheiterung mit Sequesterbildung 
 bei Otitis media acuta mit funktionellem Befund." 
 Deutsch. Otol. Gesell., 1909. 
 
 The Copyrights of this Book, in all English-speaking Countries, are 
 owned by Rebman Company, New York. 
 
LIST OF AUTHORS 
 
 Alexander, 34, 154, 162, 
 174, 175, 191, 208, 211, 216 
 
 AscH 53 
 
 aspissoff 129 
 
 Barant 48, 52, 57, 60, 62, 
 68, 73, 99, 113, 115, 
 
 126, 133, 138, 141, 188 
 
 Baetels 71, 100 
 
 Baeth 84 
 
 Bechteeew 45 
 
 Beck 127 
 
 BlELSCHOFSKY 28 
 
 Bloch 129 
 
 boettchee 37 
 
 BOTHE 53 
 
 bouequet 215 
 
 Beeuee 23, 54, 56, 58, 62, 
 
 64, 133 
 
 Beown-Sequaed 59 
 
 Beuehl 28 
 
 Beuenings 113, 119, 122, 
 
 126, 131 
 Betant, W. S 86 
 
 Cajal 28, 43, 46, 64, 66 
 
 Claeke 50 
 
 COHN 115 
 
 Cton 59 
 
 Deit 48 
 
 Deetfuss 53 
 
 EWALD 53, 65, 68, 83, 135 
 
 Flechsig 50 
 
 Ploueens 54, 58 
 
 Peiedeich 167 
 
 Feoehlig 53 
 
 GOBEKE 166,168, 177 
 
 GoLTZ 54, 59 
 
 GOWERS 50 
 
 Geat, a. a 34 
 
 Geuenbeeg 162 
 
 Habbemaktn 175 
 
 Haedestt 84 
 
 Hasse 82, 84 
 
 Held 41 
 
 Helmholtz 80, 82 
 
 Hensen 82, 115 
 
 Herzog 175 
 
 HiNSBBEG. .167, 198, 215, 218 
 Hoegtes 71 
 
 HOESLEY 45 
 
 jA]srssBN..168, 215, 219, 
 
 229, 231, 233 
 
 Kabo 58 
 
 KiPEOFP 127 
 
 KiSHi 37, 84 
 
 KOELLICKEE 43 
 
 KOHNSTAMM 43, 45 
 
 KoLMBE 28, 64 
 
 kopetzkt 202 
 
 Keamm 177 
 
 Lange.40, 159, 163, 170, 
 
 175, 177 
 
 Lee 58 
 
 Lewandowski 41, 76 
 
 loewenbbeg 59 
 
 Mach 56 
 
 Maechi 43 
 
 Maex 39 
 
 Mat 45 
 
 Matee 159, 162 
 
246 
 
 THE LABYRINTH 
 
 Nagee 159 Scott 
 
 Neumann.. 74, 181, 196, 
 198, 211, 214, 229, 231, 233 
 
 PoLiTZEE. . 14, 38, 54, 163, 
 
 175, 214 
 Probst 41 
 
 35 
 
 Shambadgh 63, 84 
 
 SlEBBNMANN. . .37, 80, 84, 86 
 
 Stacks 219, 231 
 
 Stein, von 84, 146 
 
 Steinbeueggb 175 
 
 Stilling 50 
 
 QuENSEL 45 TJebantschitsch 115, 212 
 
 Eeisner 
 
 Eetzius 
 
 ElCHAEDS 29, 215, 
 
 EiNNE 
 
 Eosenthal 
 
 eutherford 
 
 EUTTIN....74, 139, 155, 
 161, 194, 198, 
 
 SCHMIEDBKAM 
 
 SOHOENEMANN 
 
 Sohwabach 
 
 SCHWARTZE 219, 
 
 33 Van Eossbm 74 
 
 82 Voss 159, 188 
 
 219 VuLPLiN 59 
 
 148 
 30 
 85 
 
 211 
 
 115 
 
 17 
 
 149 
 
 231 
 
 Wagener 177 
 
 Weber 148 
 
 WlLGEROTH 53 
 
 Winkler 39 
 
 W1TTMAACK..39, 56, 80, 
 
 86, 172, 186, 190 
 
 YOSHII. 
 
 .80, 86 
 
INDEX 
 
 A 
 Aditus, 18 
 
 Aqueductus cochleae, 33, 34 
 Attic, 18 
 
 B 
 
 Barany's theory of galvanic 
 
 nystagmus, 133 
 Blickfixator, 113 
 Bourguet's operation, 315 
 Bruning^ optimum position 
 
 for caloric test, 119, 130 
 
 C 
 
 Caloric test, 115 
 
 Calorie test with hot water, 133 
 
 Caloric test with cold air, 139 
 
 Canalis reuniens, 34, 33 
 
 Canalis spiralis of Rosenthal^ 
 30 
 
 Canalis utriculo-saccularis, 34 
 
 Caries of labyrinthine capsule, 
 164 
 
 Cells of Claudius, 36 
 
 Cells of Deiters, 36 
 
 Cells of Eensen, 36 
 
 Cerebellum, 76 
 
 Cerebellar abscess, 303 
 
 Cholesteatoma as cause of laby- 
 rinthitis, 168 
 
 Circumscribed labyrinth- 
 itifi, 193 
 
 Circumscribed labyrinth- 
 itis, treatment of, 309 
 
 Cisterna perilymphatica vesti- 
 buli, 33 
 
 Clarke's column, 50 
 
 Cochlea, 38, 37 
 
 Cochlear nerve, central con- 
 nections of, 41 
 
 Compensation symptom, 313 
 
 Crista ampullar is, 34 
 
 Crista, distribution of nerves 
 
 to, 64 
 Crista vestibuli, 16 
 Cupula, 38 
 Cupula, direction of movement 
 
 of, influencing strength of 
 
 reaction, 65 
 Cupula, extent of movement 
 
 of, 60 
 
 D 
 
 Destruction disharmony, signs 
 of, 180 
 
 Diffuse latent purulent laby- 
 rinthitis, treatment of, 313 
 
 Diffuse manifest purulent laby- 
 rinthitis, treatment of, 311 
 
 Diffuse serous labyrinthitis, 
 symptoms of, 194 
 
 Diffuse serous labyrinthitis, 
 treatment of, 311 
 
 Diffuse suppurative labyrinth- 
 itis, symptoms of, 198 
 
 Disease of Eighth Nerve, 301 
 
 Ductus endolymphaticus, 31 
 
 Duration of nystagmus, rela- 
 tionship between it and dura- 
 tion of peripheral stimula- 
 tion, 63 
 
 E 
 Ectasia of ductus cochlearis, 
 
 161 
 Eighth nerve, 38 
 Eighth nerve, roots of, 38 
 Eminentia areuata, 19, 30 
 Empyema of labyrinth, treat- 
 ment of, 308 
 
248 
 
 THE LABYBINTH 
 
 Enduring nystagmus, 304 
 
 External semicircular canal, 
 14, 17, 18 
 
 External semicircular canal, as 
 guide in operations, 19 
 
 Ewald's experiments on pig- 
 eons with pneumatic ham- 
 mer, 135 
 
 Ewald's theory of hearing, 83 
 
 F 
 Facial nerve, 18 
 Facial paralysis in labyrinth- 
 itis, 182 
 Fever in labyrinthitis, 183 
 Fistula, 157 
 Fistula test, 135- 
 Flechsig's tract, 50 
 Fossa subarcuata, 20 
 
 G 
 
 Galvanic fistula test, 134 
 Galvanic test, 139 
 Gowers' tract, 50 
 
 H 
 
 Hair-cells, 35 
 
 Hearing in labyrinthitis, 181 
 
 Helicotrema, 31 
 
 Eelmholtz' theory of hearing, 
 
 85 
 Hinsb erg's operation, 217 
 Hysteria, differential diagnosis 
 
 of, 200 
 
 Injuries of labyrinth, treat- 
 ment of, 216 
 Internal auditory artery, 37 
 Internal auditory canal, 32 
 Internal auditory canal, patho- 
 logical changes in, 175 
 
 Jansen operation, 229 
 
 Jansen-Neumann operation, 
 234 
 
 K 
 
 Kataphoresis, 131 
 
 Labyrinthine capsule, 21 
 Labyrinth, after-treatment of, 
 
 234 
 Labyrinthitis, circumscribed, 
 
 152, 156 
 Labyrinthitis, diffuse, 153, 158 
 Labyrinthitis, diffuse, puru- 
 lent, 163 
 Labyrinthitis, diffuse, serous, 
 
 162 
 Labyrinthitis, induced, 159 
 Labyrinthitis, non-operative 
 
 treatment of, 316 
 Labyrinthitis, primary, 166 
 Labyrinthitis, results of, 173 
 Labyrinthitis toxica, 160 
 Labyrinthitis, traumatic, 171 
 Labyrinthectomy, 215 
 Labyrinthotomy, 214 
 Lamina spiralis ossea, 31 
 Ligamentum spirale, 33 
 Localization of function in 
 cerebellar cortex, 142 
 
 M 
 Macula cribrosa media, 16 
 Macula cribrosa posterior, 16 
 Macula cribrosa superior, 16 
 Maculae, gliding hypothesis of, 
 
 56 
 Macula sacculi, 23 
 Macula utriculi, 23 
 Membrana basilaris, 33, 37 
 Membrane of Reissner, 33 
 Meningitis, 202 
 
 Meningogenic labyrinthitis, 167 
 Metastatic labyrinthitis, 153 
 Modiolus, 29 
 
INDEX 
 
 249 
 
 Nausea and vomiting in laby- 
 rinthitis, 181 
 
 Necrosis of labyrinth, 165 
 
 New formed bone in labyrinth, 
 173 
 
 Noise apparatus, 147 
 
 Nystagmus during unconscious 
 state, 68 
 
 Nystagmus, dependence upon 
 rapidity of, 69 
 
 Nystagmus in galvanic test, 
 130 
 
 Nystagmus, pathways of, 78 
 
 Nystagmus to both sides, cause 
 of, 190 
 
 
 
 Operative interference, incom- 
 plete, 206 
 
 Organ of Corti, degenerative 
 changes in, 172 
 
 Otocalorimeter, 123 
 
 Otogoniometer, 125 
 
 Otolith membrane, 28 
 
 Oval window, changes in, 169 
 
 Panlabyrinthitis, 152 
 
 Paralabyrinthitis, 152, 167 
 
 Pathways of infection to laby- 
 rinth, from meninges, 153 
 
 Pathways of infection to laby- 
 rinth, from middle ear, 153 
 
 Pathways of infection from 
 labyrinth to cranial cavity, 
 173 
 
 Perilabyrinthitis, 152, 157 
 
 Perilymph space, 24 
 
 Portals of entry of infection 
 into labyrinth, 169 
 
 Posterior semicircular canal, 
 14, 16, 20 
 
 Primary fistulas, 170 
 
 Purhinje's cells, 52 
 
 Quantitative tests for static 
 labyrinth, 91 
 
 E 
 
 Eeaction movements, 73, 138 
 
 Reaction movements of body, 
 143 
 
 Eeaction movements of ex- 
 tremities, 141 
 
 Reaction movements in laby- 
 rinthitis, 182 
 
 Reaction movements, pathways 
 of, 48, 78 
 
 Recessus ellipticus, 15 
 
 Recessus sphericus, 15 
 
 Richards' operation, 319 
 
 Rinne test, 148 
 
 Rods of Corti, 36 
 
 Rotation, manner in which it 
 stimulates semicircular ca- 
 nals, 61. 
 
 Rotation test, 92 
 
 Round window, 32 
 
 Ruhetonus, 60 
 
 S 
 
 Saccule, 22 
 
 Saccus empyema, 176 
 
 Saccus endolymphaticus, 21 
 
 Scala tympani, 31 
 
 Scala vestibuH, 16, 31 
 
 Scarlatinal labyrinthitis, 168 
 
 Sea-sickness, 58, 75 
 
 Secondary fistulse, 170 
 
 Semicircular canals, planes of, 
 17 
 
 Sequestration of cochlea, treat- 
 ment of, 215 
 
 Sequestrum of cochlea, 166 
 
 Similarity of symptoms of 
 labyrinthitis to those of de- 
 struction of the labyrinth, 
 185 
 
 Solid angle, 20 
 
250 
 
 THE LABYEINTH 
 
 Spiral ganglion, 36 
 
 Spontaneous nystagmusin 
 labyrinthitis, 183 
 
 Stillmg's columns, 50 
 
 Stimulation disharmony, signs 
 of, 179 
 
 Subjective noises in labyrin- 
 thine disease, 180 
 
 Superior semicircular canal, 
 14, 16, 19 
 
 T 
 
 Tectorial membrane, 34 
 Thrombi in labyrinthine ves- 
 sels, 178 
 
 Utricle, S3 
 
 U 
 
 Vertigo and disturbances of 
 eqiiUibrium in labyriathitis, 
 181 
 
 Vestibule, 13 
 
 Vestibule, openings into, 14, 15 
 
 Vestibular artery, 37 
 
 Vestibular nerve, central con- 
 nections of, 46 
 
 Vestibular nerve, central nu- 
 clei of, 43 
 
 Yon Stein's tests, 146 
 
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