The Auditory Brainstem Implant (ABI) is a surgically implanted electronic device that provides auditory sensations in patients with anacusis due to sensorineural hearing loss, with cochlear or auditory nerve impairment that prevents the placement of a cochlear implant. The ABI uses technology similar to that of the Cochlear Implant, but the electrical stimulation occurs at the level of the brainstem rather than the cochlear level. It is not always possible to insert a cochlear implant, in which case a brainstem implant can be performed.

. Le cause per le quali non sempre si può applicare un cochlear implant, generally, are:

• the presence of cochlear ossifications (malformations, traumas, meningitis, ossifying otosclerosis);
• aplasia or hypoplasia of the auditory nerves or cochlea;
• neurofibromatosis type 2.

The brainstem implant bypasses both the cochlea and the nerve by acting directly on the auditory nuclei (ventral and dorsal). Patient selection is similar to that performed for the cochlear implant.

The surgical procedure through which the cochlear implant can be inserted is more complex compared to that for the cochlear implant. It is necessary to consider that in patients with neurofibromatosis type 2, it is possible to remove the neoplasm and insert the brainstem implant within the same procedure. The surgical approach can be, depending on the case, either via extended translabyrinthine or retrosigmoid approach.