Auditory Brainstem Implant in Bilateral and Completely Ossified Cochleae

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Abstract
To report and evaluate the results of auditory brainstem implantation in a case of postmeningitis hearing loss with totally ossified cochleae on both sides. Case report. Tertiary referral center. A 49-year-old man was referred to the authors' department for bilateral total hearing loss subsequent to bacterial meningitis 2 years earlier. Pure tone audiometry, auditory brainstem response tests, and promontory tests did not reveal any cochlear activity. Computed tomography showed bilateral and totally ossified cochleae. Magnetic resonance imaging confirmed the diagnosis by showing no cochlear signal on T2-weighed images and ruled out brainstem and cerebellopontine angle abnormalities. A left auditory brainstem implantation was performed through a translabyrinthine route, using a Nucleus 22-channel device. Word and sentence recognition tests in sound-only and sound plus vision modes. No postoperative complication was observed. Twelve electrodes could be activated, and their tonotopy was defined. Nine other electrodes were inactivated because of an absence of auditory response (4 electrodes) or paresthesia (5 electrodes). At the last follow-up visit, 26 months after the implantation, 50% of disyllabic word scores and 60% of sentence scores were achieved using auditory brainstem implant sound only. These scores reached 80% and 93%, respectively, with lip-reading. Auditory brainstem implantation is an efficient means of auditory rehabilitation in cases of bilateral total hearing loss with totally ossified cochleae. It should be considered in cases of predictable failure in cochlear implantation.