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Cochlea cadaver dissection - part 2

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Cochlea cadaver dissection - part 2

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Cochlea cadaver dissection - part 2

  1. 1. Cochlea Cadaver Dissection- Part 2 18-04-2017 8.26 pm
  2. 2. Part-1 of this PPT present at weblink www.skullbase360.in
  3. 3. Middle cranial fossa approach for Cochlear implant
  4. 4. APICAL TURN / SUPERIOR TURN cochleostomy in middle cranial fossa approach So the indication of middle cranial fossa superior cochleostomy insertion is in infected cases after CWD + SP ( subtotal petrosectomy ) We can do redo by fat risnced in rifampacin . But if you want to go by sterile area middle cranial fossa superior cochleostomy & reverse insertion & reverse programming
  5. 5. Superior cochleostomy in middle cranial fossa is just below origin of GSPN Don't fear about carotid ( metal probe ) . Petrous carotid is 1 cm anterior to origin of GSPN
  6. 6. Superior cochleostomy in middle cranial fossa is just below origin of GSPN Don't fear about carotid ( metal probe ) . Petrous carotid is 1 cm anterior to origin of GSPN
  7. 7. Superior cochleostomy in middle cranial fossa is just below origin of GSPN Don't fear about carotid ( metal probe ) . Petrous carotid is 1 cm anterior to origin of GSPN
  8. 8. Probe in Superior cochleostomy in middle cranial fossa is just below origin of GSPN
  9. 9. Superior cochleostomy in middle cranial fossa is just below origin of GSPN
  10. 10. Superior cochleostomy in middle cranial fossa is just below origin of GSPN
  11. 11. See the probe inserted through superior cochleostomy from middle cranial fossa exactly corresponds to superior cochleostomy just below tensor tympani from middle ear
  12. 12. See the probe inserted through superior cochleostomy from middle cranial fossa exactly corresponds to superior cochleostomy just below tensor tympani from middle ear
  13. 13. See the probe inserted through superior cochleostomy from middle cranial fossa exactly corresponds to superior cochleostomy just below tensor tympani from middle ear
  14. 14. See the probe inserted through superior cochleostomy from middle cranial fossa exactly corresponds to superior cochleostomy just below tensor tympani from middle ear
  15. 15. Labyrinthine part of facial nerve in middle cranial fossa
  16. 16. Just now i fractured tegmen of middle ear with my finger nail … it is so thin …………..So identify ossicles of middle ear through very thin middle ear tegmen & then identify horizontal facial nerve & then 1st genu & then labyrinthine facial nerve ...... simplest way to decompress labyrinthine Or else if you come from medically you may injure cochlea or SSC
  17. 17. Note horizontal part of facial nerve through middle cranial fossa as continuation of GSPN
  18. 18. tegmen of middle ear is so thin …………..So identify ossicles of middle ear through very thin middle ear tegmen & then identify horizontal facial nerve & then 1st genu & then labyrinthine facial nerve ...... simplest way to decompress labyrinthine Or else if you come from medically you may injure cochlea or SSC
  19. 19. Note horizontal part of facial nerve through middle cranial fossa as continuation of GSPN
  20. 20. facial nerve in lateral part of IAC decompression is difficult even in middle cranial fossa. It is between two solid bones of cochlea & SSC
  21. 21. facial nerve in lateral part of IAC decompression is difficult even in middle cranial fossa. It is between two solid bones of cochlea & SSC
  22. 22. IAC [ Internal Auditory Canal ] Drilling
  23. 23. IAC conical tube present in angle of SSC crest & GSPN ( more than 50 % dehiscent )
  24. 24. IAC conical tube present in angle of SSC crest & GSPN ( more than 50 % dehiscent )
  25. 25. IAC has to be drilled from medial to lateral IAC first must be opened medially & then only tracked along the direction of IAC ( postero-laterally ) Unless you injure cochlea basal & medial turns
  26. 26. IAC has to be drilled from medial to lateral IAC first must be opened medially & then only tracked along the direction of IAC ( postero-laterally ) Unless you injure cochlea basal & medial turns
  27. 27. KAWASE APPROACH
  28. 28. The pit infront of cochlea & IAC is kawase approach
  29. 29. The pit infront of cochlea & IAC is kawase approach
  30. 30. Here I am expanding kawase approach . In few minutes I show you COA ( cochlear aperture)
  31. 31. Here I am expanding kawase approach . In few minutes I show you COA ( cochlear aperture)
  32. 32. Probing in middle turn
  33. 33. Observe metal probe in perisiers ( dangerous) triangle
  34. 34. Observe metal probe in perisiers ( dangerous) triangle
  35. 35. Observe metal probe in perisiers ( dangerous) triangle
  36. 36. Perisiers triangle corresponds to labyrinthine part of facial nerve
  37. 37. So the metal probe in perisiers triangle goes to the middle turn of cochlea & exactly corresponds to labyrinthine part of facial nerve So middle turn array of CI stimulates labyrinthine part of facial nerve causing twitchings in post-op . Then we have to switch off those electrodes in software programming .
  38. 38. So the metal probe in perisiers triangle goes to the middle turn of cochlea & exactly corresponds to labyrinthine part of facial nerve So middle turn array of CI stimulates labyrinthine part of facial nerve causing twitchings in post-op . Then we have to switch off those electrodes in software programming .
  39. 39. So the metal probe in perisiers triangle goes to the middle turn of cochlea & exactly corresponds to labyrinthine part of facial nerve So middle turn array of CI stimulates labyrinthine part of facial nerve causing twitchings in post-op . Then we have to switch off those electrodes in software programming .
  40. 40. So the metal probe in perisiers triangle goes to the middle turn of cochlea & exactly corresponds to labyrinthine part of facial nerve So middle turn array of CI stimulates labyrinthine part of facial nerve causing twitchings in post-op . Then we have to switch off those electrodes in software programming .
  41. 41. So the metal probe in perisiers triangle goes to the middle turn of cochlea & exactly corresponds to labyrinthine part of facial nerve So middle turn array of CI stimulates labyrinthine part of facial nerve causing twitchings in post-op . Then we have to switch off those electrodes in software programming .
  42. 42. So the metal probe in perisiers triangle goes to the middle turn of cochlea & exactly corresponds to labyrinthine part of facial nerve So middle turn array of CI stimulates labyrinthine part of facial nerve causing twitchings in post-op . Then we have to switch off those electrodes in software programming .
  43. 43. So the metal probe in perisiers triangle goes to the middle turn of cochlea & exactly corresponds to labyrinthine part of facial nerve So middle turn array of CI stimulates labyrinthine part of facial nerve causing twitchings in post-op . Then we have to switch off those electrodes in software programming .
  44. 44. So the metal probe in perisiers triangle goes to the middle turn of cochlea & exactly corresponds to labyrinthine part of facial nerve So middle turn array of CI stimulates labyrinthine part of facial nerve causing twitchings in post-op . Then we have to switch off those electrodes in software programming .
  45. 45. So the metal probe in perisiers triangle goes to the middle turn of cochlea & exactly corresponds to labyrinthine part of facial nerve So middle turn array of CI stimulates labyrinthine part of facial nerve causing twitchings in post-op . Then we have to switch off those electrodes in software programming .
  46. 46. Probing in basal turn
  47. 47. Probe in basal turn opens into basal turn cochleostomy in middle cranial fossa
  48. 48. Probe in basal turn opens into basal turn cochleostomy in middle cranial fossa
  49. 49. Probe in basal turn opens into basal turn cochleostomy in middle cranial fossa
  50. 50. Probe in basal turn opens into basal turn cochleostomy in middle cranial fossa
  51. 51. Probe in basal turn opens into basal turn cochleostomy in middle cranial fossa
  52. 52. Probe in basal turn opens into basal turn cochleostomy in middle cranial fossa
  53. 53. Probe in basal turn opens into basal turn cochleostomy in middle cranial fossa
  54. 54. Probe in basal turn opens into basal turn cochleostomy in middle cranial fossa
  55. 55. See all the turns of cochlea from middle fossa
  56. 56. SVN & FN converge
  57. 57. Superior Vestibular nerve ( SVN ) & facial nerve separatedby bills bar , that I drilled . Observe here SVN & FN converge . Where as IVN & cochlear nerve diverge ……….. This convergence of SVN & FN very useful in MRI reading
  58. 58. See horizontal Septum in IAC below SVN & FN ; I cut superior Vestibular nerve ( SVN ) & FN
  59. 59. IVN & CN diverge
  60. 60. Observe here the IVN & cochlear nerve diverge ( not so clear in cadaver )
  61. 61. Observe here the IVN & cochlear nerve diverge ( not so clear in cadaver )
  62. 62. Observe here the IVN & cochlear nerve diverge ( not so clear in cadaver )
  63. 63. Observe here the IVN & cochlear nerve diverge ( not so clear in cadaver )
  64. 64. COA [ Cochlear aperture ]
  65. 65. Observe here cochlear nerve fibres going through the cibriform area ( entry point of modiolus ) In COA ( cochlear aperture )
  66. 66. Observe in this one COA is 2.5 to 3 mm roughtly. If COA less than 1.5 mm it is cochlear nerve aplasia
  67. 67. Cochlear implant after Translabyrinthine approach
  68. 68. PSC is deeper than LSC & SSC is deeper than PSC
  69. 69. Intact facial canal technique of Skull base . If you transpose grade 3 facial palsy comes .
  70. 70. Ampulla of PSC bisects vertical part of facial nerve exactly at midpoint
  71. 71. See probe coming to Sinus tympani So while clearing Sinus tympani PSC exposed ... becareful
  72. 72. CI after LABYRINTHECTOMY Only two is enough for CI – one is cochlea & another cochlear nerve – so even in vestibular schwannoma excision by translabyrinthine exposure we can do CI & patient hears
  73. 73. Bills bar between FN & SVN
  74. 74. Labyrinthectomy done to enter Posterior cranial fossa
  75. 75. VA [ Vestibular Aqueduct ]
  76. 76. https://drive.google.com/file/d/0B7F_FcpOJCfpS2lJa3NBNkVDeV E/view?usp=sharing
  77. 77. IAC & VA are two eyes of baby in temporal boone
  78. 78. IAC & VA are two eyes of baby in temporal boone
  79. 79. Endolymphatic duct & Vestibular aqueduct both are same or not ........ I have to refer . ....... but clearly there is duct from vestibule to endolymphatic sac area . If it is more than 1.5 mm it is " dilated Vestibular aqueduct " Another 1.5mm is ........, if COA ( cochlear aperture ) less than 1.5mm it is cochlear nerve aplasia.
  80. 80. Mario sanna book mention >1.5 mm VA dilated . For mnemonic sake 1.5 mm is there at both VA & COA . One is more & one is less respectively
  81. 81. Radiologically if the width of the Vestibular aqueduct is more than the width of the PSC, then it is dilated. -----Satish jain sir says >2mm VA dilated in any section .
  82. 82. In HRCT Temporal bone Vestibular aqueduct ( VA )is seen parallel to PSC ( Posterior semi circular canal ) Here also after drilling PSC we are seeing VA
  83. 83. anatomically also after drilling PSC we are seeing VA .... so radiologically also both sizes same [ my mnemonic & philosophy ] ..... if VA more than PSC it is dilated
  84. 84. Abnormal cochleas dissection photos added later in few days Essence of abnormal cochleas 1. IP 2 is exactly like normal cochlea 2. IP 3 - wide cochleostomy & precurved electrode 3. cochlear hypoplasia -- outcomes depends on how many number of electrodes inserted . Minimum 10 electrodes insertion should be there to get better outcome 4. IP 1 - lateral wall electrode 5. common cavity - lateral wall electrode 6. CHARGE - still try CI , not working then ABI. 7. michel - ABI directly In all abnormalities see cochlear nerve aplasia .... even absent in MRI , do EABR & keep CI
  85. 85. Part-1 of this PPT present at weblink www.skullbase360.in

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