title: Surgical and radiologic anatomy of a cochleostomy produced via posterior tympanotomy for cochlear implantation based on three-dimensional reconstructed temporal bone CT images.
abstract: OBJECTIVE
  In this study, we evaluated the surgical and radiologic anatomy of a cochleostomy produced via posterior tympanotomy for cochlear implantation (CI).
  
  
  METHODS
  Twenty computed tomography (CT) images of the temporal bone from patients aged between 20 and 60 years were selected. The inclusion criterion was a radiologically normal temporal bone CT scan. Three-dimensional (3D) reconstructed images were obtained using high-resolution axial temporal bone CT scans. Eight points were used to evaluate the surgical anatomy of the posterior tympanotomy and cochleostomy. The length of lines between the points and the angles between the lines were measured.
  
  
  RESULTS
  The mean length of line AB (superior-inferior length of the posterior tympanotomy for CI) was 6.48 ± 0.26 mm, while line AC (width of the chorda tympani and facial nerves) was 3.60 ± 0.2 mm. The mean angle of ABC (angle at which the chorda tympani nerve branched from the facial nerve) was 18.40° ± 1.05°. The mean length of line AD (distance from the facial ridge to the point of cochleostomy) was 9.58 ± 0.47 mm.
  
  
  CONCLUSIONS
  3D imaging of the facial recess and round window can be used to identify the facial recess before surgery. This may help to avoid injury to the chorda tympani nerve during posterior tympanotomy, and make it easier to insert the electrode array during CI by creating a large enough posterior tympanotomy to avoid injury to the facial nerve, which can cause immediate or delayed facial palsy.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, College of Medicine, The Catholic University of Korea, Uijeongbu St. Mary's Hospital, 65-1 Geumo-Dong, Uijeongbu, Gyeonggi-Do 480-717, Korea.
authors.forename: Eun-Ju
authors.initials: EJ
authors.lastname: Jeon
authors.forename: Beomcho
authors.initials: B
authors.lastname: Jun
authors.forename: Ji-Nam
authors.initials: JN
authors.lastname: Song
authors.forename: Ju-Eun
authors.initials: JE
authors.lastname: Kim
authors.forename: Dong Hee
authors.initials: DH
authors.lastname: Lee
authors.forename: Ki-Hong
authors.initials: KH
authors.lastname: Chang
mesh_terms: D000328:Adult; D019929:Cochlear Implantation / Q000379:methods*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D013506:Otologic Surgical Procedures / Q000379:methods; D011859:Radiography; D012189:Retrospective Studies; D012405:Round Window, Ear / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000601:surgery; D013701:Temporal Bone / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000601:surgery; D016896:Treatment Outcome; D014432:Tympanic Membrane / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery; D014433:Tympanoplasty / Q000379:methods; D055815:Young Adult