Effects of Asymmetric Auditory Deprivation in Sequential Cochlear Implant.

Abstract

To evaluate the influence of auditory deprivation on sequential cochlear implants in postlingual patients, comparing the ear with shorter deprivation (ESAD), longer deprivation (ELAD), and the bilateral condition (BIL). Retrospective study. A tertiary referral center. Postlingually deafened patients who underwent sequential bilateral implantation between 1990 and 2021. Auditory performance was assessed over 24 months after activation of each implant. Outcomes included free-field pure-tone average (PTA), speech detection threshold (SDT), and sentence recognition in quiet and in noise at +10 dB SNR. Secondary variables were interimplant interval, duration of preimplant hearing aid use, etiology, and electrode insertion depth. ESAD outperformed ELAD in quiet (73% [IQR 44-92] vs 37% [IQR 0-87]) and in noise (27% [IQR 0-62] vs 0% [IQR 0-45]) at 24 months (P < .001). BIL achieved superior results to both monaural conditions in quiet (97% [IQR 72.5-100], P < .001) and in noise (57% [IQR 23-86.5], P = .008), regardless of ESAD experience. Interimplant interval correlated positively with BIL performance (r = 0.450; P < .001). Longer hearing aid use was negatively associated with ESAD (r = -0.293; P = .020) and BIL performance (r = -0.312; P = .018). Partial electrode insertion in ELAD was linked to poorer BIL outcomes in quiet (P = .045). No correlations were found for age or etiology. Shorter auditory deprivation and interimplant intervals are associated with better outcomes. Bilateral stimulation enhances performance even with long deprivation in 1 ear, and auditory experience with the first implant improves results. Complete insertion favors the more deprived ear, whereas prolonged ineffective hearing aid use may compromise outcomes.