Long-Term Hearing Outcomes After Hybrid Cochlear Implantation

Objective: To examine long-term (>5 yr) low-frequency hearing preservation after hybrid cochlear implantation.

Study design: Retrospective cross-sectional study.

Setting: Tertiary care center outpatient clinic.

Patients: All patients older than 21 years implanted with a Cochlear Hybrid L24 device from 2014 to 2021.

Main outcome measure: Changes in low-frequency pure-tone average (LFPTA) were calculated at each of several time points relative to the date of implantation. The proportion of patients with preserved LFPTA at last follow-up and Kaplan-Meier estimates for loss of residual hearing were calculated in addition to hazard ratios for hearing loss according to patient- and surgery-specific factors.

Results: Thirty ears in 29 patients underwent hybrid cochlear implantation and were eligible for inclusion (mean age, 59 yr; 65% female). Mean preoperative LFPTA was 31.7 dB. Mean LFPTA across all implanted ears at first follow-up was 45.1 dB; no patient had experienced loss of residual hearing at first follow-up. Six patients had loss of residual hearing during the follow-up period, with Kaplan-Meier probability estimates of preserved hearing of 100% at 1 month, 90% at 12 months, 87% at 24 months, and 80% at 48 months. There was no association between loss of residual hearing and patient age, preoperative LFPTA, surgeon, or use of topical steroids intraoperatively (hazard ratios, 1.05 [0.96-1.15], 0.97 [0.88-1.05], 1.39 [0.20-9.46], 0.93 [0.09-9.74], respectively).

Conclusions: Long-term (>5 yr) outcomes after hybrid cochlear implantation demonstrate good preservation of low-frequency hearing, with only modest decline in the long-term postimplantation, and a low proportion of loss of residual low-frequency hearing.