Auditory Brainstem Implants

Summary: The development of cochlear implantation has al-lowed the majority of patients deafened after the development of language to regain significant auditory benefit. In a subset of patients, however, loss of hearing results from destruction of the cochlear nerves, rendering cochlear implantation ineffec-tive. The most common cause of bilateral destruction of the cochlear nerves is neurofibromatosis type 2 (NF2). The hall-mark of this genetic disorder is the development of bilateral acoustic neuromas, the growth or removal of which causes deafness in most patients. Patients with NF2 may benefit from direct stimulation of the cochlear nucleus. We describe the devel-opment, use, and results of the auditory brainstem implant (ABI), which is typically implanted via craniotomy at the time of tumor removal. Most patients with the implant have good appreciation of environmental sounds, but obtain more modest benefit with regard to speech perception. The majority of patients make use of the implant to facilitate lip reading; some can, to varying degrees, comprehend speech directly. We discuss future directions in cen-tral implants for hearing, including the penetrating ABI, the use of ABI in nontumor patients, and the auditory midbrain implant.Ke