Residual hearing conservation and electroacoustic stimulation with the nucleus 24 contour advance cochlear implant.
OBJECTIVE
To assess the conservation of residual hearing in recipients of the Nucleus 24 Contour Advance cochlear implant (CI) and the benefits of combined electrical and acoustic stimulation.


METHODS
Prospective multicenter study.


METHODS
CI clinics in Western Europe.


METHODS
Adult candidates for conventional cochlear implantation with a minimum preoperative word recognition score of 10% in the ear to be implanted.


METHODS
"Soft-surgery" protocol, including a 1- to 1.2-mm anterior and inferior cochleostomy hole with the electrode array, inserted 17 mm using the "advance-off-stylet" technique. Patients with postoperative pure-tone hearing threshold levels (HTLs) of 80 dB hearing loss or less at 125 and 250 Hz and 90 dB hearing loss or less at 500 Hz were refitted with an in-the-ear hearing aid for combined ipsilateral electrical and acoustic (El-Ac) stimulation.


METHODS
A questionnaire to collect information regarding surgery. Pure-tone HTLs measured at intervals. Word recognition tested in quiet and sentence recognition tested in noise at 10 and 5 dB signal-to-noise ratio (SNR). HEARING CONSERVATION RESULTS: HTL data were available for 27 patients. HTLs were conserved within 20 dB of preoperative levels for 33, 26, and 19% of patients for 125, 250, and 500 Hz, respectively. However, the recommended soft-surgery protocol was strictly followed in only 12 of 27 patients. For these 12 patients, hearing thresholds were conserved within 20 dB for 50, 50, and 33% of patients. Median threshold increases were 40 dB (range, 250-500 Hz) for the whole group and 23 dB for the strict surgery group. Ten patients retained sufficient HTLs to enter the El-Ac user group. SPEECH RECOGNITION RESULTS: Group mean recognition scores for nine El-Ac users for words presented at 65 dB sound pressure level were 45% for CI alone and 55% for CI + ipsilateral hearing aid (p < 0.05, paired t). For sentences presented in noise at 5 dB SNR, mean word scores were 46% CI alone and 56% CI + ipsilateral hearing aid (p < 0.01, paired t).


CONCLUSIONS
Hearing was conserved for conventional candidates for cochlear implantation where the recommended soft-surgery protocol was strictly adhered. Combined ipsilateral electrical and acoustic stimulation provided considerable benefits for speech recognition in noise, equivalent to between 3 and 5 dB SNR, compared with CI alone.
Fraysse
Bernard
B
Hôpital Purpan, Toulouse, France. fraysse.b@chu-toulose.fr
Macías
Angel Ramos
AR
Sterkers
Olivier
O
Burdo
Sandro
S
Ramsden
Richard
R
Deguine
Olivier
O
Klenzner
Thomas
T
Lenarz
Thomas
T
Rodriguez
Manuel Manrique
MM
Von Wallenberg
Ernst
E
James
Chris
C
D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D003051:Cochlea / Q000000981:diagnostic imaging / Q000601:surgery; D019929:Cochlear Implantation / Q000379:methods; D003054:Cochlear Implants; D004558:Electric Stimulation / Q000379:methods; D004867:Equipment Design; D034381:Hearing Loss / Q000601:surgery*; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D011859:Radiography; D013069:Speech Reception Threshold Test; D011795:Surveys and Questionnaires; D016896:Treatment Outcome