Multichannel auditory brain stem implant: case studies comparing fitting strategies and results

Area of Science:

• Neurosurgery
• Biomedical Engineering
• Audiology

Background:

• Bilateral auditory nerve tumors, often caused by neurofibromatosis-2, lead to deafness.
• Auditory brainstem implants (ABI) offer a potential solution for hearing restoration in such cases.
• The multichannel auditory brain stem implant has been used since 1992.

Purpose of the Study:

• To evaluate the efficacy of a new 8-electrode auditory brain stem implant.
• To assess auditory sensations and speech perception in patients with neurofibromatosis-2.
• To compare outcomes between patients with varying electrode usage and processing strategies.

Main Methods:

• Twelve patients with neurofibromatosis-2 received the multichannel auditory brain stem implant.
• Processor fitting involved electrode-specific pitch scaling, ranking, and non-auditory sensation determination.
• Speech perception performance was assessed in two representative patients with different experiences and electrode counts.

Main Results:

• Eleven out of twelve patients reported useful auditory sensations.
• An inexperienced patient using two electrodes and the "Speak" strategy performed comparably to an experienced patient with six electrodes using an older processor.
• This suggests the effectiveness of newer processing strategies even with limited electrode engagement.

Conclusions:

• The 8-electrode auditory brain stem implant provides useful auditory sensations for individuals deafened by bilateral auditory nerve tumors.
• Advanced speech-processing strategies can enhance outcomes, even in patients with fewer functional electrodes.
• Auditory brain stem implantation is a viable option for hearing restoration in neurofibromatosis-2.