title: Conductive component after cochlear implantation in patients with residual hearing conservation.
abstract: OBJECTIVE
  Changes in auditory thresholds following cochlear implantation are generally assumed to be due to damage to neural elements. Theoretical studies have suggested that placement of a cochlear implant can cause a conductive hearing loss. Identification of a conductive component following cochlear implantation could guide improvements in surgical techniques or device designs. The purpose of this study is to characterize new-onset conductive hearing losses after cochlear implantation.
  
  
  METHODS
  In a prospective study, air- and bone-conduction audiometric testing were completed on cochlear implant recipients. An air-bone gap equal to or greater than 15 dB HL at 2 frequencies determined the presence of a conductive component.
  
  
  RESULTS
  Of the 32 patients with preoperative bone-conduction hearing, 4 patients had a new-onset conductive component resulting in a mixed hearing loss, with air-conduction thresholds ranging from moderate to profound and an average air-bone gap of 30 dB HL. One had been implanted through the round window, 2 had an extended round window, and 1 had a separate cochleostomy.
  
  
  CONCLUSIONS
  Loss of residual hearing following cochlear implantation may be due in part to a conductive component. Identifying the mechanism for this conductive component may help minimize hearing loss. Postoperative hearing evaluation should measure both air- and bone-conduction thresholds.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Chole
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Hullar
authors.forename: Lisa G
authors.initials: LG
authors.lastname: Potts
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D001299:Audiometry; D001309:Auditory Threshold; D001844:Bone Conduction; D019929:Cochlear Implantation / Q000009:adverse effects / Q000379:methods; D005260:Female; D034381:Hearing Loss / Q000601:surgery; D006314:Hearing Loss, Conductive / Q000209:etiology*; D006319:Hearing Loss, Sensorineural / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies