The development of
cochlear implantation has allowed 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 ineffective. The most common cause of bilateral destruction of the cochlear nerves is
neurofibromatosis type 2 (NF2). The hallmark 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 development, 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 central implants for hearing, including the penetrating ABI, the use of ABI in nontumor patients, and the auditory midbrain implant.