Early surgical results of auditory brainstem implantation in nontumor patients

An auditory brainstem implant (ABI) that stimulates the cochlear nucleus in the brainstem was initially designed for patients with neurofibromatosis type-2. Recently, promising surgical outcomes after ABI have been reported in nontumor patients with sensorineural hearing loss including those with cochlear nerve aplasia or ossified cochlea. We herein describe the surgical results and auditory outcomes of ABI in nontumor patients.

Retrospective case series at a tertiary hospital.

Eleven deaf patients who received ABI from 2008 to 2010 were included in this study. The first group included eight patients with narrow internal auditory canals (IACs) and the second group consisted of three postlingually deaf adults with cochlear ossification. Pulsar CI100 ABI (Med-El Co., Innsbruck, Austria) was implanted via the suboccipital approach.

All eight patients with narrow IACs clearly demonstrated behavioral responses following initial stimulation using an ABI. The category of auditory performance (CAP) scores were progressively improved to reach auditory performances of CAP 4 in three patients, CAP 3 in two patients, CAP 2 in two patients, and CAP 1 in one patient. The three patients with ossified cochlea also reported auditory sensations when the ABI was activated. Two of them showed an auditory performance of CAP 4 or 5, but the third patient could not use the device due to nonauditory stimulation.

Based on our experience, ideal nontumor candidates for ABI include congenitally deaf children who experienced failure after cochlear implantation owing to cochlear nerve deficiency and postlingually deaf adults with severe cochlear ossification.