Auditory brainstem implants: past, present and future prospects

The purpose of the auditory brainstem implant (ABI) is to directly stimulate the cochlear nucleus complex and offer restoration of hearing in patients suffering from profound retrocochlear sensorineural hearing loss. Electrical stimulation of the auditory pathway via an ABI has been proven to be a safe and effective procedure. The function of current ABIs is similar to that of cochlear implants in terms of device hardware with the exception of the electrode array and the sound-signal processing mechanism. The main limitation of ABI is that electrical stimulation is performed on the surface of the cochlear nuclei, thereby making impractical the selective activation of deeper layers by corresponding optimal frequencies. In this article, we review the anatomical, and experimental basis of ABIs and the indications, and surgical technique for their implantation. To the best of our knowledge, we describe the first pathology images of the cochlear nucleus in a patient who had received an ABI.