AUDITORY MIDBRAIN IMPLANTS: A WINDOW TO STIMULATE THE CENTRAL AUDITORY SYSTEM

Cochlear implant (CI) is considered to be the most successful neural prosthesis till date which works by integrating an electronic device to the central nervous system thereby restoring the lost special sense of hearing. In situations where the cochlea or cochlear nerve is aplastic and when cochlea is fully ossified, there is an option of auditory brainstem implantation (ABI). This has shown reasonable success by stimulating the cochlear nucleus to restore auditory perception. The auditory midbrain implant (AMI) is a recent experimental auditory prosthesis designed for stimulating the inferior colliculus of the midbrain in individuals who cannot benefit from CI and ABI. Candidates with neurofibromatosis type 2 (NF2) who develop neural deafness due to distortion of brainstem because of growth and/or surgical removal of bilateral acoustic neuromas are most suitable for AMI, since this stimulates the auditory midbrain proximal to the damaged cochlear nucleus thereby providing auditory spectral cues to the central auditory cortex. There is sparse literature on AMI and very few centers have experience with this type of Implant. The focus of this work is to review the literature regarding the development and translation of this new type of central auditory prosthesis and derive a rational conclusion based on the cumulative evidence for defining its current status and its future implications on clinical practice.