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Cochlear implant - line diagrams

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Cochlear implant - line diagrams

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Cochlear implant - line diagrams

  1. 1. Cochlear implant - Line diagrams 22-06-2017 2.32 pm
  2. 2. Dr. N. Murali Chand MS (ENT ) DLO, FHM Fellowship in HIV medicine Websites = www.skullbase360.in & www.integratedmedicine.co.in Youtube = https://www.youtube.com/channel/UC3vRSTN8Rx46MQwq06XRJIA/playlists CELL = +919949677605
  3. 3. Updated further time to time – check www.skullbase360.in Dr. N. Murali Chand MS (ENT ) DLO, FHM Fellowship in HIV medicine Websites = www.skullbase360.in & www.integratedmedicine.co.in Youtube = https://www.youtube.com/channel/UC3vRSTN8Rx46MQwq06XRJIA/pl aylists CELL = +919949677605
  4. 4. The lecture of this PPT present in youtube video ( Cochlear implant surgery concepts ) https://www.youtube.com/watch?v=aRnKkjiJHn4&t=203 0s abnormal cochleas lecture videos present in https://www.youtube.com/playlist?list=PLZquE6mn0cym Eae9sQZK2N_1AVIFNjttd
  5. 5. OW = oval window ; RW = round window ; H = Helicotrema OW & RW & H forms 90 degree triangle Centre of OW roughtly corresponds to groove for tensor tympani
  6. 6. Below RW devided into 4 quadrants
  7. 7. In difficult conditions where finding RW is difficult try to identify FUSTIS , it leads to RW
  8. 8. In “ RW insertion ” technique , RW membrane is incised [ red mark ] at anterior inferior quadrant of RW membrane after drilling RW operculum – which leads to scala tympani
  9. 9. MC = Margin Cochleostomy ; Cf = Crista fenestrae ; OSL = Osseus spiral laminae ; OW = Owter wall of basal turn MARGIN COCHLEOSTOMY – in some patients Crista Fenestrae has to be drilled to expand round window to access scala tympani
  10. 10. ANTERO- INFERIOR COCHLEOSTOMY . When we devide round window into 4 quadrants , at anterior & inferior quadrant area if we make cochleostomy it becomes anterior-inferior cochleostomy
  11. 11. The round inferior to Antero-inferior cochleostomy is INFERIOR COCHLEOSTOMY , which is direct trajectory to scala tympani
  12. 12. cochleostomy made anterior to anterior & superior quadrant of RW is called SUPERIOR COCHLEOSTOMY – Which you are NOT supposed to do in CI surgery
  13. 13. If we drill between OW & RW it is SCALA VESTIBULAR COCHLEOSTOMY
  14. 14. If we drill 2 mm anterior to OW it is MIDDLE TURN COCHLEOSTOMY- Don’t drill more than 2 mm anteior to OW because there are chances of injuring the labyrinthine part of facial nerve in DANGEROUS TRIANGLE or PARISIER’S TRIANGLE .
  15. 15. Relation of middle turn cochleostomy in relation to dangerous triangle – explained further indetail
  16. 16. Osseus spiral laminae is seen through SUPERIOR COCHLEOSTOMY . The space above osseus spiral laminae is SCALA VESTIBULI & space below osseus spiral laminae is SCALA TYMPANI
  17. 17. SV insertion of CI electrode in basal turn stimulates SG of middle turn instead of SG of basal turn
  18. 18. Osseus spiral laminae is seen through SCALA VESTIBULAR COCHLEOSTOMY with angulation of microscope
  19. 19. hole at root of GSPN is SUPERIOR TURN COCHLEOSTOMY
  20. 20. 1. In middle cranial fossa approach – hole at root of GSPN leads to SUPERIOR TURN COCHLEOSTOMY 2. In middle ear appraoch - In the groove of Tensor Tympani also leads to SUPERIOR TURN COCHLEOSTOMY BOTH HOLES lie exactly at same level
  21. 21. AIC = antero-inferior cochleosomy IC = inferior cochleostomy SC = superior cochleosomy SVC = scala vestibular cochleosomy MTC = middle turn cochleostomy STC = superior turn cochleostomy FN = facial nerve IAC = internal auditory canal
  22. 22. SV ( Scala Vestibular ) Drilling has to be done in the same arch of ST ( Scala Tympani ) drilling & Middle turn drilling has to be done in the same arch of SV drilling – while drillouts we should not injure the OSL ( Osseus spiral laminae ) because neurons will damage
  23. 23. I will explain in future PPTs
  24. 24. Carotid relation to cochlea
  25. 25. Intratemporal Carotid & facial nerve – same parts – both have vertical & horizontal parts Vertical part of facial nerve bisects jugular bulb GSPN bisects V3 & petrous carotid
  26. 26. Infratemporal fossa anatomy line diagram in both anterior & lateral skull base ( Infratemporal fossa approach A, B, C , D )
  27. 27. PARS ( = PARTS ) of Cochlea
  28. 28. PARS ( = PARTS ) of Cochlea & Duodenum 1= pars inferior 2= pars ascendens 3 = pars superior 4 = pars inferior
  29. 29. 1. Supeior cochleostomy at root of GSPN from middle cranial fossa side & Superior cochleostomy in the groove for tensor tympani from middle ear – both reaches to almost superior turn 2. Pars ascendens associated with vertical part of intratemporal carotid where as Pars superior corresponds with labyrinthine part of facial nerve . 3. In literature it is not mentioned about where exactly the middle turn starts & basal turn ends – What I am understanding is if we draw a line from midpoint of stapes foot plate to groove for tensor tympani ( Green line ) , the turn above is ending of basal turn , the turn below is starting of middle turn .
  30. 30. Junction of pars superior & pars inferior is labyrinthine part of facial nerve
  31. 31. Pars ascendens associated with Pre-cochlear carotid [ vertical part of intra-temporal carotid ] Pars = Part
  32. 32. Just outside the outer wall of basal turn vertical part of intratemporal carotid present OR in other wards scala tympani is adjacent to vertical part of intratemporal carotid - so when carotid canal is dehiscent OR maltracked cochleostomy , there are chances of entering the CI electrode array into carotid canal . ST= Scala tympani ; SV = Scala vestibuli ; OSL = osseus spiral laminae ; OW = outer wall of basal turn
  33. 33. Middle cranial fossa drilling of cochlear turns Pars superior is seen through middle cranial fossa 1. Angle between SSC & GSPN is IAC 1. Angle between labyrinthine part of facial nerve & GSPN is COCHLEA ( Pars superior of basal turn )
  34. 34. In ST (scala tympani) drill outs we have to be very careful - vertical part of intratemporal carotid is just outside the outerwall of basal turn or scala tympani
  35. 35. Grades of ossification
  36. 36. Schematic presentation of Grade I (IA) ossification: only the area of the round window is affected. Grade I (IB) ossification: up to half of the scala tympani of the basal turn is affected.
  37. 37. Grade II: more than half up to whole of the scala tympani of the basal turn is affected. Grade II: the scala tympani of the basal turn is completely ossified; the scala vestibuli is less than half ossified, also grade II.
  38. 38. Grade III: both the scala tympani and scala vestibuli of the basal turn are ossified, while the middle and apical turns are patent. This can occur with the ascending part of the basal turn being accessible (IIIA) or inaccessible (IIIB)
  39. 39. Grade IV: totally ossified cochlea.
  40. 40. PARISIER'S TRIANGLE (DANGEROUS TRIANGLE) Perisier's triangle is very important triangle in cochlear implant surgery 1) Superior limb is formed by inferior part of HFN 2) The apex is formed by the geniculate ganglion 3) The base is formed by the anterior commissure (end) of oval window 4) Inferior limb is formed by tunning point of jocobson's nerve to the the geniculate ganglion.
  41. 41. Perisier's triangle is very important triangle in cochlear impalnt surgery 1) Superior limb is formed by inferior part of HFN 2) The apex is formed by the geniculate ganglion 3) The base is formed by the anterior commissure (end) of oval window 4) Inferior limb is formed by tunning point of jocobson's nerve to the the geniculate ganglion.
  42. 42. Wall of Parisier’s triangle is by “ wall of middle turn cochlea ” & cavity is by “ cavity of middle turn ” - & labyrinthine part of facial nerve stays above the middle turn cochlea which may be stimulated by CI electrode array causing facial twichings .
  43. 43. Relation of middle turn cochleostomy in relation to dangerous triangle
  44. 44. PARS ( = PARTS ) of Cochlea & Duodenum 1= pars inferior 2= pars ascendens 3 = pars superior 4 = pars inferior
  45. 45. Diagrammatic representation of the intracochlear electrode array (red) and the division of the cochlea into five segments. The beginning of segment 1 corresponded to the RW membrane, while that of segments 2 and 4 indicated the surface where the modiolus was no longer visualized. In the latter two segments, the electrode could be visualized in the transverse orientation.
  46. 46. So it is the 3rd part of the electrode/cochlea which is causing facial twistings . So in Programming we have to stop that electrode . Facial twistings commonly affects in pathological & abnormal cochleas like Otosclerosis & common cavity respectively . How it effects AVT [ Audio-verbal therapy ] I will explain in next slides .
  47. 47. • The surgical implications are 1) This triangle contains labyrinthine part of FN. 2) During transotic or transcochlear approaches surgeon should respect this triangle and drill carefully to avoid injury to FN. 3) Clinically labyrinthine part consists of two segments a meatal segment of nerve, labyrinthine part of nerve. total length of this nerve is 3 to 5 mm. Anteriorly we can see these parts clearly through this triangle. 4) 1st part of FN passes close to lower border of precochlear HFN towards anterior end of oval window in this triangle. 5) Irregular drilling of cochlea in this triangle damages FN That is why it is called DANGERS TRIANGLE. 6) During trans meatal endoscopic dissection of IAC, this triangle important for identification of nerves 7) Translabyrinthine approach visualises posterior surface of 1st part of FN, in transcochlear approaches the anterior surface of the nerve is exposed. In transottic approaches 270 to 320 degrees of 1 st part of FN is exposed. 8)Observe closely the labyrinthine part of FN there is a constriction of labyrinthine segment and meatal segment. Facial nerve key points 1) Facial nerve changes direction 5 times during its course from brain stem to styloid foramen. 2) No other nerve in body covers such a long distance in bony canal 3) facial nerve contains 10000 axons that are responsible for the innervation of the face musculature and also for the communications with other nerves human body 4) work with injured facial nerve requires lot of patience.
  48. 48. Perisier's triangle ( dangerous triangle ) which denotes labyrinthine part of facial nerve …… Corresponds exactly to middle turn drillout
  49. 49. Perisier's triangle ( dangerous triangle ) which denotes labyrinthine part of facial nerve…….. Corresponds exactly to middle turn drillout
  50. 50. Perisier's triangle ( dangerous triangle ) which denotes labyrinthine part of facial nerve…….. Corresponds exactly to middle turn drillout
  51. 51. RW = Round Window - Is the Human Round Window Really Round? Answer = NO
  52. 52. Different shapes of the human round window (medial views).
  53. 53. Prof. Proctor – variations of RW • • Fossula fenestrae rotundae lata • • Fossula fenestrae rotundae alta • • Fossula fenestrae rotundae ovalis • • Fossula fenestrae rotundae lateritia • • Fossula fenestrae rotundae quadrata • • Fossula fenestrae rotundae trapezoides • • Fossula fenestrae rotundae rhomboidea • • Fossula fenestrae rotundae semilunaris • • Fossula fenestrae rotunda rotundae • • Fossula fenestrae rotundae triangularis • • Fossula fenestrae rotundae semicircularis • • Fossula fenestrae rotundae dentata • • Fossula fenestrae rotundae spinosa • • Fossula fenestrae rotundae trabecularis
  54. 54. Fossula fenestrae rotundae lata
  55. 55. ROUND WINDOW REGION – studied/ discussed accordingly 1. Structures out side the Round window niche 2. Round window niche Variations & Grading 3. Peri – RW niche area 4. Round window membrane 5. HOOK region
  56. 56. RW niche NORMAL parts
  57. 57. Microscopic / ENDOSCOPIC anatomy of Operculum aio: anteroinferior overhang; po: postero-superior overhang; cf: crista fenestrae. Microscopic anatomy Endoscopic anatomy
  58. 58. Upper OW & lower RW t= tegmen - tegmen & anterior pillar & posterior pillar all together called as “ operculum ” by some CI surgeons . ap= Anterior pillar pp= Posteriror pillar Su=Subiculum f= Finicullus Fu= Fustis Scc= Sub cochlear canal leads to petrous apex CM = Comcomerata medialis CL = Comcomerata lateralis Anterior pillar continues as finicullus ; posterior pillar continues as Subiculum SCC [ Subcochlear canal ] present between two “F” words i.e., Fustis & Finicullus - CI surgeons mistakenly pass CI electrode array into this SCC .
  59. 59. RW niche [ = opening ] types - below is NORMAL t = tegmen [ = roof ] , pa = postis [ = door ] anterior , pp = postis [ = door ] posterior , f = fundus [ = floor ]
  60. 60. 1. Structures outside the niche which hide its entrance
  61. 61. Exostosis = The most frequent variation is exostosis near the entrance of the niche
  62. 62. jugular dome = A less frequent but clinically very important variation, the jugular dome can partially or even fully hide the round window niche
  63. 63. The thin bone separating the roof of the JF from the RW (<1 mm in 8%) highlights a potential risk of injury to the JB during cochleostomy placement.
  64. 64. trabeculae niche is protected by trabecules of varying sizes
  65. 65. 2. Round window niche Variations & Grading
  66. 66. Narrow Niche = When all the walls are thick, the niche becomes very narrow. Its surroundings show without exception a ‘cellfree’, compact bony surface without a fustis
  67. 67. Descending tegmen = The tegmen of the niche may stretch to varying degrees which results in a V- shaped transformation of the niche’s form
  68. 68. Anterior septum = The most frequent variation of the round window entrance is the lamellar growth of the postis anterior which covers the majority of the opening of the round window. The shape of the postis anterior shows a wide variability from a continuous plate to the trabecular form
  69. 69. Bony membrance = In the rarest variation the pseudomembrane is partially or completely ossified in the round window’s entrance and forms a thin bony plate
  70. 70. Open fudus = Lack of ossification lateral to the fustis results in the absence of bony tissue between the fustis and the anterior wall which occurs when the inferior wall remains incomplete
  71. 71. Round Window Grades - FOUR grades - through Facial recess approach
  72. 72. 3. Peri - RW area a. Fustis b. SCC = Subcochlear Canal
  73. 73. ENDOSCOPIC anatomy of Operculum aio: anteroinferior overhang; po: postero-superior overhang; cf: crista fenestrae.
  74. 74. Upper OW & lower RW t= tegmen - tegmen & anterior pillar & posterior pillar all together called as “ operculum ” by some CI surgeons . ap= Anterior pillar pp= Posteriror pillar Su=Subiculum f= Finicullus Fu= Fustis Scc= Sub cochlear canal leads to petrous apex CM = Comcomerata medialis CL = Comcomerata lateralis Anterior pillar continues as finicullus ; posterior pillar continues as Subiculum SCC [ Subcochlear canal ] present between two “F” words i.e., Fustis & Finicullus - CI surgeons mistakenly pass CI electrode array into this SCC .
  75. 75. FUSTIS & FINICULUS
  76. 76. Type A fustis. f fustis, sp styloid proeminence, st scala tympani, rw round window
  77. 77. Type B fustis. f fustis, sp styloid proeminence, st scala tympani, rw round window
  78. 78. FUSTIS • it is fustis a solid bony column connecting the retrotympanum to round window niche. So far this structure is neglected Microscopically it may not be clearly visible, but endoscopically it is seen clearly The surgical implications of this structure are 1) its origin is pylogenically different from other parts of that area hence it behaves differently 2) It contains enzymes which are resistant to cholesteatoma destruction 3) it prevents sinus cholesteatoma extending downwards.. 4) This structure is directed towards round window, in narrow round window niche by following its upper border, we can identify the round window membrane 5) It divides upper part of subtympanic sinus, concomerata into medialis and lateralis. C medialis is site for posterior ampullary nerve section. 6) Fustis regulates smooth out flow of sound waves from round window membrane.
  79. 79. • 7) It helps in creation of pressure difference between round and oval windows encourages acoustic coupling. 8) It gives support round window niche because both postis anticus and postis posticus contains cochlea and subcochlear portion that are hollow structures. 9) This structure modulates according to round window niche i. e, "V" shaped, square shaped, triangular gothic shaped, like that, to have a relation with RW 10) In absent sibiculum, the fustis gives support. 11) Fustis narrows the round window niche there by protects the round window membrane (rupture)normally. 12) embryologically fustis develops between periosteal layer of the labyrinthine capsule and the thin smooth plate of Pavementum Pyramidalis and it is ontogenically important structure. So surgeons, fustis is very important structure at outflow gate of sound in middle ear. In 1968 Bruce Proctor mentioned, Recently prof Presutti, Prof Marchioni and Prof Joao F Nogueira described this part. so surgeons please look this important but poor part while performing surgeries because it is present in all middle ears..
  80. 80. Right ear. Endoscopic view of fustis type B. ow oval window, st scala tympani, fu fustis, pe pyramidal eminence, rw round window
  81. 81. Right ear. The tool shows the scala tympani. ow oval window, st scala tympani, fu fustis, rw round window
  82. 82. Sometimes you may not appreciate fustis by Sinus tympani approach but for Veria technique fustis is very important.
  83. 83. between fustis & finiculus SCC ( subcochlear canal ) present
  84. 84. FUSTIS VARIATIONS – Prof. Proctor
  85. 85. SCC = Subcochlear Canal CI surgeons mistakenly pass CI electrode array into this SCC . Previously they used to call this SCC as “ Hypotympanic cell ” in older literature . Now with the advant of Endoscopy SCC is clearly defined which leads to petrous apex
  86. 86. (Right ears) a–d in these subjects a deep (Type A) “subcochlear canaliculus” is found between the fustis bone and the finiculus and has different dimensions pp posterior pillar, ap anterior pillar, pr promontory, rw round window, t tunnel of subcochlear canaliculus, ac area concamerata, f finiculus, su subiculum, fu fustis, su subiculum, sty styloid complex
  87. 87. (Right ears) Three types of conformations of the round window chamber related to the relationship between the fustis, area concamerata and the finiculus bone. Type A between the fustis and the finiculus a deep hole/tunnel is present with deep extension to the petrous apex cells lying below the cochlea; in these cases a CT scan in a sagittal view shows the presence of a well pneumatized temporal bone at the most inferior and medial portion of the petrous apex below the internal auditory canal. pp posterior pillar, ap anterior pillar, rw round window, red arrow tunnel of subcochlear canaliculus, ac area concamerata, f finiculus, su subiculum, fu fustis, su subiculum, sty stylod complex
  88. 88. Type B between the fustis and the finiculus a small hole is present, the connection between this hole and the apex is not recognizable endoscopically because of the dimensions of this area; in these cases a CT scan in a sagittal view shows the presence of a limited pneumatized bone below the cochlea. pp posterior pillar, ap anterior pillar, rw round window, red arrow tunnel of subcochlear canaliculus, ac area concamerata, f finiculus, su subiculum, fu fustis, su subiculum, sty stylod complex
  89. 89. Type C the fustis and area concamerata are fused with the finiculus and anterior pillar without any connection between the round window chamber and the petrous apex, in these cases no air cells are present at the most inferior and medial portion of the petrous apex on the CT scan in a sagittal view pp posterior pillar, ap anterior pillar, rw round window, red arrow tunnel of subcochlear canaliculus, ac area concamerata, f finiculus, su subiculum, fu fustis, su subiculum, sty stylod complex
  90. 90. (Right ear) Infracochlear approach in pediatric subjects affected by tympanic cavity cholesteatoma with involvement of the petrous apex through the tunnel of the subcochlear canaliculus. a a cholesteatoma matrix is endoscopically visible extending into the tunnel of the subcochlear canaliculus. b extension of the cholesteatoma into the depth of the subcochlear canaliculus, medially with respect to the internal carotid artery. c endoscopic infracochlear approach after cholesteatoma removal from the petrous apex conserving the cochlea. d endoscopic magnification of the petrous apex below the cochlea after cholesteatoma removal ch cholesteatoma, rw round window, t tunnel of subcochlear canaliculus, ca carotid artery, pr promontory, ow oval window, white arrow deep extension of the subcochlear canaliculus medially with respect to the internal carotid artery into the petrous apex
  91. 91. A. Original round window. B. Basilar membrane. C. Osseous spiral lamina. D. Reflection of perilymphatic fluid. E. Darker area of first curve of the basal turn of the scala tympani. F. Blood vessels. G. Modiolus. H. Removed bone of round window overhang.
  92. 92. When you don’t have any landmark especially RW drill infra-cochlear cells & try to identify the outer wall of cochlea & make cochleostomy – Dr. Satish jain
  93. 93. Inside chitradurga fort – cochlea , RW , SCC , FUSTIS
  94. 94. Obavva story https://www.youtube.com/watch?v=tdNjRgW3hBk Inside red circle ( round window ) - Scala tympani yellow circle – Subcochlear tunnel
  95. 95. Yellow ring = subcochlear canal [ SCC ]
  96. 96. Inside Subcochlear tunnel - leads to petrous apex
  97. 97. RIGHT EAR PERI-RW AREA Inside red circle ( round window ) - Scala tympani yellow circle – Subcochlear tunnel
  98. 98. 4. RWM = Rouond Window Membrane
  99. 99. 1 Round window membrane 2 Crista semilunaris 3 Fustis 4 Horizontal bar 5 cavum posterior 6 Cavum anterior 7 vertical bar 8 Antero-inferior RWM 9 Postero-superiro RWM PS RWM = postero-superior round window membrane OR Horizontal part of RWM AI RWM = antero-inferior round window membrane OR Vertical part of RWM
  100. 100. 8 Antero-inferior RWM 9 Postero-superior RWM 8) Antero-inferior RWM always for sound vibration RWM vibration is evident at 1500 to 3000 hzs and at higher frequencies it vibrates irrigularly 9) Postero-superior RWM is always tor micromolecules diffusion in to inner ear ant it contains more melanocytes so for gentamycin instillation it is better to place fluid . In posterior part of RWM for better diffusion
  101. 101. . The posterosuperior overhang impedes visibility of the posterior portion of the round window membrane, aio: anteroinferior overhang; po: postero-superior overhang; cf: crista fenestrae. Both Operculum & RWM has postero-superior & antero-inferior parts.
  102. 102. Right RWM [ Round Window Membrane ] - the junction of PS RWM & AI RWM is anchored to Crista semilunaris PS RWM = postero-superior round window membrane OR Horizontal part of RWM AI RWM = antero-inferior round window membrane OR Vertical part of RWM
  103. 103. Area of vertical part of RWM [ AI RWM ] is more than horizontal RWM [ PS RWM ] - the ratio of the area of the horizontal part of the RW to the area of the vertical part is about 3 : 4
  104. 104. Sagittalsection of the right human cochlea. The anterior and posterior portions of the round window membrane form a right angle to each other. The posterior portion, hidden by the postero-superior overhang, lies very close to the osseous spiral lamina. The distance between the window membrane and the osseous spiral lamina is only 0.1 mm. at the posterior periphery of the round window, cf: crista fenestrae; set: scala tympani; pspl: primary spiral lamina; sspl: secondary spiral lamina; Rm: Reissner's membrane; hrwm: horizontal portion of window membrane; vrwm: vertical portion of window membrane; po: postero-superior overhang; * blind end of scala tympani.
  105. 105. Various distances between PS RWM & OSL ( actually secondary OSL ) – this various distances is Sinus tympani PS RWM = Postero-superior RWM ; OSL = Osseus spiral laminae
  106. 106. hrwm = PS RWM ; vrwm = AI RWM ST = = Scala tympani Coronal section Saggital section
  107. 107. After removing the RWM ( Round window membrane ) you can appreciate at posterior superior area Modiolus & OSL+BM + SL complex. & at antero-iferior area ST ( scala tympani )
  108. 108. 4 quadrants vital areas of right ear RW area Antero- Superior quadrant = OSL + BM + SL complex Postero-superior quadrant = Modiolus Antero-inferior quadrant = Scala tympani Postero – inferior quadrant = Scala tympani
  109. 109. Vital structures in each quadrant of Right ( Rt ) ear Round window 1. ASQ = Antero-superior quadrant - OSL+BM+SL complex 2. AIQ = Antero-inferior quadrant – Scala tympani ( ST ) 3. PSQ = Postero-superior quadrant – Modiolus ( M ) 4. PIQ = Postero-inferior quadrant – Scala tympani ( ST ) + Crista semilunaris ( CS ) 5. RED/BLUE PLUS is imaginary mental plus OSL = Osseus spiral laminae BM = Basillar membrane SL = Spiral ligament
  110. 110. 1. < 1mm gap present between postero-superior RWM & OSL+ BM + SL complex 2. Prof. Clark & Dr. Prahlad sir says we should not drill the postero-superior part of the operculum as it injures the OSL+BM+SL complex , we have to drill the only the antero-inferior part of the operculum & do the RWM insertion .
  111. 111. 5. HOOK Region
  112. 112. This plaster tape is my RW [ = round window ]
  113. 113. This paper strip is OSL ( inner ) + BM + SL ( outer ) OSL = osseus spiral laminae BM = basillar membrane SL = spiral ligament
  114. 114. Now this is OSL + BM + SL & round window unit
  115. 115. Now let me keep in anatomical position ; This is right ear ……. Now observe , superiorly & anteriorly OSL + BM + SL strip present in relation to RW
  116. 116. So conclusion is we should not drill superiorly & anteriorly , we may damage this OSL + BM + SL complex --- in hearing preservation technique even more important & in routine surgeries also endolymph & perilymph shouldn't mix
  117. 117. BOTH PHOTOS RIGHT ROUND WINDOW MEMBRANES - The right round window in a human temporal bone as seen from an endaural approach demonstrating the close relationship between the osseous spiral lamina and the posterior portion of the round window membrane. For better demonstration the postero-superior and the antero-inferior overhang have been removed, bm: basiliar membrane; spl: spiral lamina; set: scala tympani; rwm: found window membrane, cf: crista fenestrae
  118. 118. A microdissected left human temporal bone. The lower basal turn has been opened showing the position of the OSL [ Osseus spiral laminae ] . The SL [ Spiral ligament ] and its topographic relationship with the RW rim are depicted. A cochleostomy drilled anterior or superior to the RW rim may affect the SL [ Spiral ligament ] anatomy of the human round window (left ear-medial view). A, The RW is fan shaped and and even the OSL in this specimen. A, lateral view; B, surgical view.
  119. 119. Plaster tape is right ear ; below photo is left ear – compare both
  120. 120. Crista fenestera is intracochlear inferior border of RW and Crista Semilunaris is inferior bony attatchment of RW which is removed before insertion .
  121. 121. HOOK region – the narrowest point of Crista fenestrae & Crista Semilunaris & Initial turn of OSL is called HOOK region
  122. 122. View of the round window from a posterior tympanotomy in a right human temporal bone. The posterosuperior overhang impedes visibility of the posterior portion of the round window membrane, aio: anteroinferior overhang; po: postero-superior overhang; cf: crista fenestrae.
  123. 123. a & b are width & height of Crista fenestrae ( Cf ) a = width = 1.6 ± 0.20mmSD b = height = 2.0 ± 0.28mmSD
  124. 124. Facial recess view – View of same OSL ( Osseus spiral laminae ) , modiolus , crista fenestrae , crista semilunaris & outer wall of basal turn
  125. 125. A tangential insertion along the outer wall of the basal turn is possible after removal of the crista fenestrae. cf: crista fenestrae; spl: spiral lamina; ow: outer wall of basal turn.
  126. 126. MC = Margin Cochleostomy ; Cf = Crista fenestrae ; OSL = Osseus spiral laminae ; OW = Owter wall of basal turn MARGIN COCHLEOSTOMY – in some patients Crista Fenestrae has to be drilled to expand round window to access scala tympani
  127. 127. Amount of drilling is somuch in INFERIOR cochleostomy to some extent in ANTERO- INFEIROR cochleostomy – due to crista fenestrae drilling Cf = Crista fenestrae ; OSL = Osseus spiral laminae ; OWC = Owter wall of basal turn ; IC = inferior cochleostomy ; AIC = antero-inferior cochleostomy
  128. 128. Amount of drilling is somuch in INFERIOR cochleostomy to some extent in ANTERO- INFEIROR cochleostomy – due to crista fenestrae drilling Cf = Crista fenestrae ; OSL = Osseus spiral laminae ; OWC = Owter wall of basal turn ; IC = inferior cochleostomy ; AIC = antero-inferior cochleostomy
  129. 129. Amount of drilling is somuch in INFERIOR cochleostomy – due to crista fenestrae drilling
  130. 130. Amount of drilling is somuch in INFERIOR cochleostomy – due to crista fenestrae drilling
  131. 131. • The crista fenestrae forms the anteroinferior sharp bony margin of the round window. This margin of the round window lies closer to the modiolus and the osseous spiral lamina than the outer wall of the scala tympani in the basal turn of the cochlea. When the crista fenestrae is left in place only the medial portion of the scala tympani gives room for the electrode insertion. The narrow space between the crista fenestrae and the modiolus can cause friction, and the electrode cannot be led tangentially along the outer wall of the basal turn right from the start . A good view along the basal turn of the cochlea is achieved when the antero-inferior overhang and the crista fenestrae are removed. Only after the removal of the crista fenestrae can the whole width of the scala tympani in the basal turn be seen and this gives enough space for the electrode insertion. It is important to preserve the osseous spiral lamina anatomically and thus prevent a reduction of the nerve fibre population. When attention is paid to the above particular features of the round window at surgery, damage to the osseous spiral lamina should not occur, and a deep electrode insertion will be possible.
  132. 132. A post-mortem view of the hook region of the osseous spiral lamina (osl) in a cat cochlea as seen through the round window. For the purposes of this figure, the round window membrane and all the perilymph has been removed. The basilar membrane is visible as the medium gray crescent (black arrows) below the margin of the round window. The extreme basal end of the cochlear spiral is toward the right. The scala tympani spirals counterclockwise and away into the basal turn at the bottom left of the round window. The modiolus (large asterisk) is toward the bottom. The white arrow indicates a 1-mm spiral ganglion lesion. The lesion is visible due to extravasated blood in Rosenthal's canal, which can be seen as a light gray crescent (small asterisk) in the osseous spiral lamina.
  133. 133. Relation of OSL [ = Osseus spiral laminae ] & RW niche [ = opening ]
  134. 134. OSL= Osseus spiral laminae ; SV = Scala vestibuli ; ST = Scala tympani ; F = Fustis Cochleostomy drilled anterior or superior [ SC = SUPERIOR COCHLEOSTOMY ] to the RW rim may affect the OSL anatomy .
  135. 135. Dissected temporal bone specimen. The view is through the facial recess to the RW area of the promontory. The promontory inferior and anterior to the RW has been drilled down to show the close relation of the osseous spiral lamina and basilar membrane to the anterior RW membrane. ST/scala tympani; SV/scala vestibuli; OSL/osseous spiral lamina; RWM/RW membrane; LSCC/lateral semicircular canal.
  136. 136. The right round window in a human temporal bone as seen from an endaural approach demonstrating the close relationship between the osseous spiral lamina and the posterior portion of the round window membrane. For better demonstration the postero-superior and the antero-inferior overhang have been removed, bm: basiliar membrane; spl: spiral lamina; set: scala tympani; rwm: found window membrane, cf: crista fenestrae.
  137. 137. Human temporal bone specimen drilled to simulate the typical trans- mastoid, trans-facial recess approach to the inner ear. The buttress has been taken down and the incus removed. The view shows the authors’ preferred cochleostomy site, just inferior to and extending into the RW. This allows visual control of the basal turn prior to implantation.
  138. 138. FUSTIS continues as ( points to ) CRISTA SEMILUNARIS white arrow = Crista Semilunaris ; f = Fustis ; t = tegmen ; pa = Postis anterior ; pp = Postis posterior ; OSL= Osseus spiral laminae ; SV = Scala vestibuli ; ST = Scala tympani ; F = Fustis
  139. 139. Coronal diagrams of the RW region of a right cochlea. Note the change in orientation of the osseous spiral lamina from (a) vertical to (b, c) a more oblique position deeper within the basal turn. At the same time, the scala tympani gains cross-sectional depth. st = scala tympani ; sv = scala vestibuli ; osl = osseous spiral lamina ; M = modiolus ; SL= spiral ligament ; V =vestibule ; S = Subiculum ; OC = otic capsule ; PS RWM = Postero-superior Round window membrane
  140. 140. Compare Subiculum in both diagrams t= tegmen - tegmen & anterior pillar & posterior pillar all together called as “ operculum ” by some CI surgeons . ap= Anterior pillar pp= Posteriror pillar Su=Subiculum f= Finicullus Fu= Fustis Scc= Sub cochlear canal leads to petrous apex CM = Comcomerata medialis CL = Comcomerata lateralis Anterior pillar continues as finicullus ; posterior pillar continues as Subiculum
  141. 141. total paper can be get at - http://sci- hub.cc/10.1016/j.aanat.2005.09.0 06 Development of the bony round window niche from the 16th fetal week (A) to newborn (F). The first ossification centers of the otic capsule appear around the round window, but the inferior wall of the niche does not begin to ossify until the 17th fetal week (B). The first sign of the crest of round window can be seen in the 18th week (C) and it develops rapidly up to the 23rd week (D). The walls of the niche show intensive growth during the entire prenatal period but its typical appearance is not complete until the eighth fetal month (E). f – fustis, pa – postis anterior, pp – postis posterior, t – tegmen of the round window, arrow – crest of the round window.
  142. 142. Left ear - medial view [ Looking from inside of scala tympani to RW ] from paper http://sci-hub.cc/10.1097/MAO.0000000000000332 CA = Cochlear aqueduct is immedialy behind the Crista Semilunaris [ Here we are looking from inside of scala tympani ] t = tegmen [ = roof ] , pa = postis [ = door ] anterior , pp = postis [ = door ] posterior , f = fundus [ = floor ]
  143. 143. CA = Cochlear aqueduct is immedialy behind the Crista Semilunaris RED RING = Crista semilunaris
  144. 144. Anatomy of the human round window (left ear-medial view). A, The RW is fan shaped and conical and opens into the RW niche (*). CA, cochlear aqueduct; ST, scala tympani. B, A CI electrode array has been inserted through the RW. The electrode rides on the crista fenestrae. – from paper title “Is the Human Round Window Really Round? An Anatomic Study With Surgical Implications”
  145. 145. Various distances between PS RWM & OSL ( actually secondary OSL ) – this various distances is Sinus tympani PS RWM = Postero-superior RWM ; OSL = Osseus spiral laminae
  146. 146. Round Window Grades - FOUR grades - through Facial recess approach
  147. 147. Intracochlear trauma GRADES
  148. 148. INTRACOCHLEAR TRAUMA CLASSIFICATION = VERY IMPORTANT --- Eshraghi et al. OSL = Osseus spiral lamine ; BM = Basillar Membrane ; SL = Spiral laminae grade 0, no trauma; grade 1, elevationof the basilar membrane; grade 2, rupture of the basilarmembrane; grade 3, dislocation of the electrode array to thescala vestibuli; and grade 4, severe trauma such as fracture ofthe osseous spiral lamina, modiolus, or stria vascularis.
  149. 149. grade 0, no trauma; grade 1, elevationof the basilar membrane; grade 2, rupture of the basilarmembrane; grade 3, dislocation of the electrode array to thescala vestibuli; and grade 4, severe trauma such as fracture ofthe osseous spiral lamina, modiolus, or stria vascularis.
  150. 150. CI Radiology
  151. 151. Indetail HRCT temporal bone videos – click YouTube link https://www.youtube.com/playlist ?list=PLZquE6mn0cynJF47j2PZjEBKv q1GqU446
  152. 152. Comprehensive HRCT temporal bone – click YouTube weblink https://www.youtube.com/watch?v=iJp9ZLNMad0&index=9&list =PLZquE6mn0cynJF47j2PZjEBKvq1GqU446&t=226s
  153. 153. PARS [ = Parts ] of cochlea & HRCT temporal bone – histological study
  154. 154. Diagrammatic representation of the intracochlear electrode array (red) and the division of the cochlea into five segments. The beginning of segment 1 corresponded to the RW membrane, while that of segments 2 and 4 indicated the surface where the modiolus was no longer visualized. In the latter two segments, the electrode could be visualized in the transverse orientation.
  155. 155. So it is the 3rd part ( pars superior ) of the electrode/cochlea which is causing facial twistings . So in Programming we have to stop that electrode . Facial twistings commonly affects in pathological & abnormal cochleas like Otosclerosis & common cavity respectively . How it effects AVT [ Audio-verbal therapy ] I will explain in next slides .
  156. 156. (a) Identification of segments 1 and 4. The modiolus is located deeper than the bone surface..
  157. 157. (b) Identification of segments 1, 3, and 5. The modiolus is now visible on the surface of the bone. This defines the beginning of segments 3 and 5.
  158. 158. (c) Visualization of segments 1 and 3 and the modiolus.
  159. 159. (d) Visualization of the beginning of segment 2. The modiolus can no longer be visualized.
  160. 160. In the lap of basal turn middle turn present & in lap of middle turn superior turn present . So in both cranial most & caudal most axial cuts of HRCT Temporal bone you will see basal turn only . Don't confuse that in cranial most axial of HRCT you will see superior turn
  161. 161. Samples of corrosion casts from the temporal bone collection in Uppsala showing variations in the anatomy of the human cochlea. The collection contains 324 human inner-ear molds. Both methacrylate and silicon were used as material for casting. --- from paper http://sci- hub.cc/10.1179/146701011X13001035752174
  162. 162. Letter W in axial HRCT temporal bone
  163. 163. Facial nerve variations
  164. 164. Click this video link to get lecture of facial nerve variations https://www.youtube.com/watch? v=7s1dGND7W7A
  165. 165. Variations of vertical part of facial nerve Variations of horizontal part of facial nerve
  166. 166. Trajectory of cochlear implant electrode array
  167. 167. Trajectory of electrode array – I will explain in future PPTs - Prof. House says multichannel electrodes hits the spiral ligament at 7mm . So he made short electrode of 6 mm AIC = Antero-inferior cochleostomy ; IC = Inferior cochleostomy ; OW = outer wall of basal turn ; OSL = Osseus spiral laminae ; RW = round window
  168. 168. Microscopic details of CI
  169. 169. Figure 3–4. Cochlear dissection showing veins associated with the modiolus. The osseous lamina and basilar membrane have been removed to view the floor of scala tympani (ST) and modiolar wall (MW). The white arrow indicates a vein coursing down the modiolar wall to join the posterior spiral vein (black arrows). These superficially positioned vessels are vulnerable to injury by perimodiolar electrode arrays. Reproduced with permission from Roland PS,Wright CG. Surgical aspects of cochlear implantation: mechanisms of insertional trauma. Adv Otorhinolaryngol. 2006;64:11–30. --- from book Cochlear Implants and Other Implantable Hearing Devices
  170. 170. Figure 3–2. A. Cochlear cross-section showing the lower portion of the spiral ligament (SL) facing scala tympani (ST). The curved arrow indicates a venule coursing through the spiral ligament toward the floor of scala tympani. The straight arrow indicates the portion of the spiral ligament seen in B. The ligament and its vasculature are vulnerable to trauma by electrode arrays positioned against the lateral wall of scala tympani. Scale bar = 100 microns. B. Scanning electron micrograph of the surface of the spiral ligament in the area immediately below the attachment of the basilar membrane. The site of attachment of the basilar membrane to the lateral wall tissues is indicated by the dotted line. Note the highly porous, meshlike structure of the spiral ligament surface, which is susceptible to electrode array penetration and injury. Scale bar = 20 microns. Reproduced with permission from Roland PS, Wright CG. Surgical aspects of cochlear implantation: mechanisms of insertional trauma. Adv Otorhinolaryngol. 2006;64:11–30.
  171. 171. A modiolar cross section showing a vein (arrow) located on the side of the modiolus and covered only by a thin layer of bone. This blood vessel is quite similar to one illustrated in the dissected specimen shown in figure 11. SG Spiral ganglion. -- http://sci-hub.cc/10.1159/000094642
  172. 172. Prof.House single channel electrode paper
  173. 173. Abnormal cochleas
  174. 174. For Video click YouTube link https://www.youtube.com/watch? v=6NFaxi8IOn8&t=382s
  175. 175. Common cavity
  176. 176. “Uncoiled” electrode array has to be used as the cochlear neurons present at outer wall of common cavity my fingers = cochlear nerve fibres ; hand = cochlear nerve
  177. 177. “Uncoiled” electrode array has to be used as the cochlear neurons present at outer wall of common cavity my fingers = cochlear nerve fibres ; hand = cochlear nerve
  178. 178. “Uncoiled” electrode array has to be used as the cochlear neurons present at outer wall of common cavity my fingers = cochlear nerve fibres ; hand = cochlear nerve
  179. 179. “Uncoiled” electrode array has to be used as the cochlear neurons present at outer wall of common cavity my fingers = cochlear nerve fibres ; hand = cochlear nerve
  180. 180. “Uncoiled” electrode array has to be used as the cochlear neurons present at outer wall of common cavity my fingers = cochlear nerve fibres ; hand = cochlear nerve
  181. 181. IAC
  182. 182. right IAC when we are seeing from inside the cranium to IAC CN & IVN diverges ; FN & SVN converges – all the 4 cranial nerves must be confirmed in saggital MRI
  183. 183. I will explain in further PPTs
  184. 184. VERIA exit point
  185. 185. VERIA exit point
  186. 186. VERIA exit point
  187. 187. Updated further time to time – check www.skullbase360.in Dr. N. Murali Chand MS (ENT ) DLO, FHM Fellowship in HIV medicine Websites = www.skullbase360.in & www.integratedmedicine.co.in Youtube = https://www.youtube.com/channel/UC3vRSTN8Rx46MQwq06XRJIA/pl aylists CELL = +919949677605

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