title: Predicting basal cochlear length for electric-acoustic stimulation.
abstract: OBJECTIVE
  To assess the feasibility and accuracy of predicting electrode insertion depth necessary in cochlear implantations for electric-acoustic stimulation by means of preoperative high-resolution computed tomography (HRCT).
  
  
  METHODS
  Human temporal bone study with evaluation of cochlear dimensions.
  
  
  METHODS
  Tertiary care medical center.
  
  
  METHODS
  Eight fresh human temporal bones were scanned, and basal cochlear structures were reconstructed and measured. Standard cochlear implantations with a free-fitting array were performed, and the bones then underwent histologic analysis using a technique that allows sectioning of undecalcified bones. After embedding, all bones underwent conventional radiologic analysis with further insertion measurements. Preimplantation HRCT data were compared with radiologic and histologic data.
  
  
  RESULTS
  Preimplantation HRCT-based measurements correlated very well with postimplantation radiologic data. A mean failure of 0.3 mm was found. Mean values for the first 360 degrees ranged from 18.8 to 22.0 mm.
  
  
  CONCLUSIONS
  Preimplantation HRCT-based prediction of cochlear implant insertion depths is both feasible and accurate. It is especially useful when aiming for hearing preservation, where insertion depths of 360 degrees are necessary.
authors.affiliation: Department of Otorhinolaryngology, J.W. Goethe University, Frankfurt am Main, Germany. adunka@em.uni-frankfurt.de
authors.forename: Oliver
authors.initials: O
authors.lastname: Adunka
authors.forename: Marc H
authors.initials: MH
authors.lastname: Unkelbach
authors.forename: Martin G
authors.initials: MG
authors.lastname: Mack
authors.forename: Andreas
authors.initials: A
authors.lastname: Radeloff
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Gstoettner
mesh_terms: D000328:Adult; D003051:Cochlea / Q000033:anatomy & histology*; D019929:Cochlear Implantation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D013701:Temporal Bone / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed