Auditory Brainstem Implants 34 CHAPTER

The auditory brainstem implant (ABI) for patients was originally developed for patients with neurofibromatosis type 2 (NF2) in order to electrically stimulate the cochlear nucleus complex. Drs. William House and William Hitselberger first used the ABI in such a patient in 1979, who continues to use it daily. Patients with NF2 usually have bilateral vestibular schwannomas (VS) necessitating tumor removal, which often results in profound deafness, and cochlear implants (CIs), which electrically activate peripheral neural processes within the cochlea, are usually not an option for patients with NF2 because of their loss of integrity of the auditory nerve. The ABI is introduced into the lateral recess of the fourth ventricle and placed over the area of the ventral and dorsal cochlear nuclei after tumor removal. The ABI is similar in design and function to multichannel CIs, except for differences in the design of the stimulating electrode arrays. Multichannel CIs and ABIs were developed to capitalize on the frequency tuning of neurons in the human cochlea and cochlear nucleus complex, respectively. The programming of ABI devices, however, differs in several important aspects from CI programming. In multichannel CIs, the electrode is placed into the cochlea. Consistent placement of the electrode carrier and its depth of insertion are assured in normal cochleas. However, in ABI recipients, anatomical landmarks that are used in electrode array placement may be altered or obscured due to the presence of tumors making electrode Eric P Wilkinson, Steven R Otto, Marc S Schwartz, Derald E Brackmann Auditory Brainstem Implants 34 CHAPTER Author Query: 1. Please update the ref. 22.