Prevalence of Nonauditory Stimulation from Auditory Brainstem Implantation

Auditory brainstem implants (ABIs) can be used to restore hearing in subjects with no functional auditory nerve. Not infrequently, channels on the ABI give rise to nonauditory stimulation. The aim of the present study was to explore the prevalence of side effects for different portions of the implant and to investigate the number of active channels.

Patients aged ≥ 15 years implanted with an ABI at Uppsala University Hospital were investigated. The number of active channels was extracted from the ABI programming software and reported side effects were extracted from the medical records.

Twenty-four patients were analyzed who were implanted with ABIs from Cochlear Ltd. (Lanecove, NSW, Australia; n = 20) and Med-El Ltd. (Innsbruck, Austria; n = 4). The most common side effect, independent of localization of the ABI electrode, was sensations in the ipsilateral leg. It accounted for 20% of reported side effects, followed by sensations in the throat (14%), ipsilateral side of the face (12%), ipsilateral side of the body (12%), and ipsilateral eye (12%). The number of active channels differed significantly statistically between initial and latest fitting (P = 0.027) for the Cochlear implants. The number of patients with Med-El Ltd. implants was too small to analyze statistically.

Side effects were reported on the ipsilateral side of the body. The most common side effect was sensory stimulation in the ipsilateral leg. Throat stimulation was most common for the horizontal-lateral portion of the implant. The number of active electrodes decreased significantly statistically over time.