Penn Otorhinolaryngology – Head and Neck Surgery is one of only a handful of institutions now offering auditory brainstem implantation (ABI) for patients with total deafness as a consequence of severely damaged or absent auditory nerves.
ABI is indicated for individuals 12 years of age or older with neurofibromatosis type 2 (NF2) undergoing first- or second-side vestibular schwannoma resection. NF2 is an inherited condition most commonly identified with bilateral vestibular schwannomas (acoustic neuromas). Schwannomas are benign nerve sheath tumors that typically infiltrate neural tissue to such a degree that removal of the tumors involves resection of the nerve, as well. Severing the nerve eliminates the communication between the inner ear and brain resulting in deafness in the affected ear or ears.
In addition to NF2, ABI has been used in investigational settings for traumatic avulsion of the bilateral cochlear nerve, severe cochlear ossification and cochlear malformations not amenable to cochlear implantation.
How does it work?
ABI involves an external microphone and transmitter and a surgically implanted receiver and electrode array that transmits auditory information directly to the brainstem.
Essentially, the ABI attempts to re-establish auditory perception by replacing the function of the inner ear and auditory nerve. The code is then translated internally into rapid electrical impulses, and these signals are distributed to an electrode array within a silicone paddle placed at the brainstem surface. ABI devices are generally activated a month or more after implantation, and patients return for testing and calibration regularly thereafter.
Hearing Improvement with ABI
Generally, post-procedural hearing among patients having ABI is comparatively improved for both awareness of environmental sounds and face-to-face communication. Some levels of speech recognition are also possible, even among patients with NF2 who’s anatomy has been distorted by the tumor.
At Penn Medicine, the ABI team includes neurosurgeon John Y.K. Lee, MD; Douglas Bigelow, MD, and Jason Brant, MD, from the Penn ENT Division of Otology/Neurotology; and specialists from Penn Audiology and Electrophysiology.
“For these patients who previously had no other effective course of treatment available,” Dr. Brant says “we are particularly proud to be able to offer this revolutionary option.”