title: Effect of surgical technique on electrode impedance after cochlear implantation.
abstract: OBJECTIVE
  We compare the evolution of electrode impedance values (IVs) following either conventional cochlear implantation or implantation by the soft surgery (SS) technique.
  
  
  METHODS
  We performed a retrospective chart review of 20 consecutive adult patients who underwent implantation with the Nucleus CA 24 device between 2004 and 2007. Five patients with preoperative residual hearing at the frequencies 256, 512, and 1,024 Hz underwent implantation by an SS cochlear implantation technique (SS group), and the 15 other patients underwent a conventional implantation technique (conventional cochleostomy [CC] group). The active electrodes were classified as distal (17 to 22), middle (10 to 16), or proximal (3 to 9) according to their position in relation to the tip of the electrode array. Their IVs were collected at 1, 3, 12, 24, and 36 months after implantation. Changes in auditory thresholds at 3 and 24 months were reported for patients in the SS group.
  
  
  RESULTS
  The postoperative IVs of both the CC and SS groups decreased significantly between 1 and 3 months after implantation (p < 0.05) and then remained stable. The IVs after 12 months were significantly lower (p < 0.05) in the SS group than in the CC group.
  
  
  CONCLUSIONS
  Patients who underwent the SS technique displayed lower long-term electrode IVs than did their counterparts in the CC group. If electrode IVs are indeed an indirect representation of cochlear fibrosis, the use of the SS technique in lieu of the CC technique could reduce fibrotic development.
authors.affiliation: Ear, Nose, and Throat Department and Cochlear Implant Center, Gui de Chauliac, University Hospital, Montpellier, France.
authors.forename: Huan
authors.initials: H
authors.lastname: Jia
authors.forename: Frédéric
authors.initials: F
authors.lastname: Venail
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Piron
authors.forename: Charlène
authors.initials: C
authors.lastname: Batrel
authors.forename: Pierfrancesco
authors.initials: P
authors.lastname: Pelliccia
authors.forename: Françoise
authors.initials: F
authors.lastname: Artières
authors.forename: Alain
authors.initials: A
authors.lastname: Uziel
authors.forename: Michel
authors.initials: M
authors.lastname: Mondain
mesh_terms: D000328:Adult; D000368:Aged; D001309:Auditory Threshold; D002921:Cicatrix / Q000209:etiology / Q000517:prevention & control; D019929:Cochlear Implantation / Q000009:adverse effects / Q000379:methods*; D003054:Cochlear Implants; D017097:Electric Impedance; D004868:Equipment Failure; D005260:Female; D034381:Hearing Loss / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult