Audiometry results in adult cochlear implant patients according to the electrode array.

Objective: To assess audiological outcome in adult (>18years) cochlear implant (CI) users with a straight (SA) or perimodiolar electrode array (PMA).

Material And Methods: Between 2017 and 2021, medical records of patients in 2 French centers who received a Cochlear™ SA (CI522/CI622) or PMA (CI532/CI632) CI were retrospectively analyzed according to the STROBE guidelines. Air-conduction pure-tone audiometry and disyllabic speech audiometry were recorded over a minimum 3-year follow-up. Only patients with thresholds above 90dB at low frequencies (500Hz) before surgery were considered to have residual hearing (RH). Surgery-related complications (e.g., vertigo, peripheral facial palsy, meningitis) were assessed. The significance threshold was set at P<0.005.

Results: We included 185 adult patients: 94 SA and 91 PMA. Median age at CI was 64.5±11.5years for SA and 60.9±12.2years for PMA. Preoperative unaided pure-tone averages (PTA) were comparable between SA and PMA (100 and 102dB, respectively; P=0.32), as were postoperative aided free-field air-conduction PTAs at 3months (30.9±6.0 and 31.3±8.8dB, respectively; P=0.68). Percentage correct dissyllabic word responses at 60dB HL did not significantly differ between SA and PMA before CI (P=0.483), or 1year (P=0.775), 2years (P=0.441) or 3years (P=0.785) post-CI, although there was a significant difference at 3months post-CI (P=0.001) in favor of PMA. Fifty-one patients (21 SA, 30 PMA) had RH prior to surgery; after 12months' CI experience, 14.2% of these had RH in the SA group and 13.3% in the PMA group. One peripheral facial palsy occurred in the SA group but resolved completely (P>0.99). Twenty patients experienced transient postoperative vertigo (10 SA [10.6%], 10 PMA [10.9%]; P=0.93). No meningitis was noted.

Conclusion: CI with straight or perimodiolar electrodes provided similar improvement in audiological performance.