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Published on: January 9, 2019
Effects of Asymmetric Auditory Deprivation in Sequential Cochlear Implant
Eduardo S Farinazzo1, Rubens V de Brito Neto2, Elisabete H Yamaguti1
1Cochlear Implant Section and Department of Otolaryngology, Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo, Bauru, Brazil.
Objective:
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).
Study Design:
Retrospective study.
Setting:
A tertiary referral center.
Methods:
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.
Results:
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.
Conclusion:
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.