title: Effects of insertion depth of cochlear implant electrodes upon speech perception.
abstract: OBJECTIVE
  To investigate whether the insertion depth of a cochlear implant array affects postoperative speech perception.
  
  
  METHODS
  The subjects were 48 postlingually deaf adults who received either the Nucleus 22 or the Nucleus 24 cochlear implant with a straight array. A postoperative radiograph of the cochlear electrode was used to estimate insertion depth, as either the angle of the electrode tip (angle) or the intracochlear length of the electrode (length). Other estimates of insertion depth included the numbers of active electrodes and channels used by the speech processor. Electrode depth, together with the duration of deafness, hearing aid usage, pre-operative speech perception score and pre-operative pure-tone averages were independent variables in a forward stepwise multiple regression analysis, where the dependent variables were postoperative CNC words and CNC phonemes.
  
  
  RESULTS
  Duration of deafness and insertion depth (angle, insertion length or active electrodes) were the predictive variables for CNC words or CNC phonemes. Angle was the best 'depth-related' predictor of postoperative speech perception. An even clearer relationship was found between CUNY sentences in noise and angle, in a subset of 26 patients.
  
  
  CONCLUSIONS
  Depth of electrode insertion affects postoperative speech perception.
authors.affiliation: Department of Otolaryngology, University of Melbourne, Royal Victorian Eye and Ear Hospital, and CRC for Cochlear, Melbourne, Australia.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Yukawa
authors.forename: Lawrence
authors.initials: L
authors.lastname: Cohen
authors.forename: Peter
authors.initials: P
authors.lastname: Blamey
authors.forename: Brian
authors.initials: B
authors.lastname: Pyman
authors.forename: Viruch
authors.initials: V
authors.lastname: Tungvachirakul
authors.forename: Stephen
authors.initials: S
authors.lastname: O'Leary
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003051:Cochlea / Q000000981:diagnostic imaging; D019929:Cochlear Implantation / Q000379:methods / Q000592:standards*; D003054:Cochlear Implants; D003638:Deafness / Q000503:physiopathology / Q000601:surgery; D004567:Electrodes, Implanted; D005260:Female; D006310:Hearing Aids / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012044:Regression Analysis; D013063:Speech Discrimination Tests; D013067:Speech Perception; D016896:Treatment Outcome