title: Assessment of electrode placement and audiological outcomes in bilateral cochlear implantation.
abstract: OBJECTIVE
  The goal of this study was to use highly accurate nonrigid algorithms to locate the position of cochlear implant (CI) electrodes and correlate this with audiological performance.
  
  
  METHODS
  After obtaining institutional review board approval, adult patients who had bilateral CIs were identified, and those with preoperative temporal bone computed tomographic scans were asked to return for a postintervention computed tomography. Sixteen adult patients agreed. Demographics, cause of deafness, length of auditory deprivation, and audiological performance were recorded.
  
  
  METHODS
  Using a nonrigid model of the shape variations of intracochlear anatomy, the location of the basilar membrane was specified in relationship to the electrode array. The number of electrodes within each compartment of the cochlea was correlated with hearing in noise and consonant-noun-consonant scores for the known confounding variable: length of deafness.
  
  
  RESULTS
  Mann-Whitney U tests of differences were used to compare the hearing performance resulting from implants completely in the scala tympani (ST) versus those not completely in the ST.
  
  
  RESULTS
  Of all implants, 62.5% were fully inserted in the ST; 34.4% were partially inserted into the ST and 3.1% was fully inserted in the scala vestibuli. Controlling for the known contributing variable of length of auditory deprivation, our results show that the location of electrodes in relationship to the scala is not predictive of audiological performance.
  
  
  CONCLUSIONS
  We have assessed electrode placement and correlated it with audiological outcome. The presence of the electrodes solely in the ST was not predictive of outcome. We estimate that it would take analyzing data of thousands of CI patients before any valid correlations can be made.
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, Medical Center, Vanderbilt University, Nashville, Tennessee 37232-8605, USA. george.wanna@vanderbilt.edu
authors.forename: George B
authors.initials: GB
authors.lastname: Wanna
authors.forename: Jack H
authors.initials: JH
authors.lastname: Noble
authors.forename: Theodore R
authors.initials: TR
authors.lastname: McRackan
authors.forename: Benoit M
authors.initials: BM
authors.lastname: Dawant
authors.forename: Mary S
authors.initials: MS
authors.lastname: Dietrich
authors.forename: Linsey D
authors.initials: LD
authors.lastname: Watkins
authors.forename: Alejandro
authors.initials: A
authors.lastname: Rivas
authors.forename: Theodore A
authors.initials: TA
authors.lastname: Schuman
authors.forename: Robert F
authors.initials: RF
authors.lastname: Labadie
mesh_terms: D000328:Adult; D000368:Aged; D001299:Audiometry; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D005260:Female; D006312:Hearing Loss, Bilateral / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012533:Scala Tympani / Q000601:surgery*; D013701:Temporal Bone / Q000601:surgery; D016896:Treatment Outcome