title: Preservation of residual hearing with cochlear implantation: how and why.
abstract: CONCLUSIONS
  Hearing may be conserved in adults after implantation with the Nucleus Contour Advance perimodiolar electrode array. The degree of hearing preservation and the maximum insertion depth of the electrode array can vary considerably despite a defined surgical protocol. Residual hearing combined with electrical stimulation in the same ear can provide additional benefits even for conventional candidates for cochlear implantation.
  
  
  OBJECTIVE
  We present preliminary results from a prospective multicentre study investigating the conservation of residual hearing after implantation with a standard-length Nucleus Contour Advance perimodiolar electrode array and the benefits of combined electrical and acoustic stimulation.
  
  
  METHODS
  The subjects were 12 adult candidates for cochlear implantation recruited according to national selection criteria. A "soft" surgery protocol was defined, as follows: 1-1.2-mm cochleostomy hole anterior and inferior to the round window; Nucleus Contour Advance electrode array inserted using the "Advance-off-stylet" technique; and insertion depth controlled by means of three square marker ribs left outside the cochleostomy hole. These procedures had been shown to reduce insertion forces in temporal bone preparations. Variations in surgical techniques were monitored using a questionnaire. Pure-tone thresholds were measured pre- and postoperatively. Patients who still retained thresholds <90 dB HL for frequencies up to 500 Hz were re-fitted with an in-the-ear (ITE) hearing aid. Word recognition was tested in quiet and sentence perception in noise for the cochlear implant alone and in combination with an ipsilateral hearing aid.
  
  
  RESULTS
  Hearing threshold level data were available for 12 patients recruited from 6 of the centres. Median increases in hearing threshold levels were 23, 27 and 33 dB for the frequencies 125, 250 and 500 Hz, respectively. These median increases include the data for two patients who had total loss of residual hearing due to difficulties encountered during surgery. "Cochlear view" X-ray images indicated that the depth of insertion varied between 300 and 430 degrees, despite modest variations in the length of the electrode inserted (17-19 mm). The insertion angle had some influence on the preservation of residual hearing at frequencies of 250-500 Hz. Six of the 12 patients retained sufficient hearing for effective use of an ipsilateral ITE hearing aid (< or = 80 dB HL at 125 and 250 Hz; < or = 90 dB HL at 500 Hz). Word recognition scores in quiet were improved from 10% to 30% with the cochlear implant plus ipsilateral hearing aid in 3 patients who had at least 3 months postoperative experience. Signal:noise ratio thresholds for sentence recognition were improved by up to 3 dB. Patients reported that they experienced greatly improved sound quality and preferred to use the two devices together.
authors.affiliation: Service ORL, Hôpital Purpan, FR-31059 Toulouse, France. Chris.J.James@wanadoo.fr
authors.forename: Chris
authors.initials: C
authors.lastname: James
authors.forename: Klaus
authors.initials: K
authors.lastname: Albegger
authors.forename: Rolf
authors.initials: R
authors.lastname: Battmer
authors.forename: Sandro
authors.initials: S
authors.lastname: Burdo
authors.forename: Naima
authors.initials: N
authors.lastname: Deggouj
authors.forename: Olivier
authors.initials: O
authors.lastname: Deguine
authors.forename: Norbert
authors.initials: N
authors.lastname: Dillier
authors.forename: Michel
authors.initials: M
authors.lastname: Gersdorff
authors.forename: Roland
authors.initials: R
authors.lastname: Laszig
authors.forename: Thomas
authors.initials: T
authors.lastname: Lenarz
authors.forename: Manuel Manrique
authors.initials: MM
authors.lastname: Rodriguez
authors.forename: Michel
authors.initials: M
authors.lastname: Mondain
authors.forename: Erwin
authors.initials: E
authors.lastname: Offeciers
authors.forename: Angel Ramos
authors.initials: AR
authors.lastname: Macías
authors.forename: Richard
authors.initials: R
authors.lastname: Ramsden
authors.forename: Olivier
authors.initials: O
authors.lastname: Sterkers
authors.forename: Ernst
authors.initials: E
authors.lastname: Von Wallenberg
authors.forename: Benno
authors.initials: B
authors.lastname: Weber
authors.forename: Bernard
authors.initials: B
authors.lastname: Fraysse
mesh_terms: D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D019929:Cochlear Implantation; D003638:Deafness / Q000175:diagnosis* / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D017755:Prosthesis Fitting; D012720:Severity of Illness Index; D013067:Speech Perception; D013069:Speech Reception Threshold Test; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D014432:Tympanic Membrane / Q000601:surgery