Twenty-five years of auditory brainstem implants: perspectives.

The auditory brainstem implant (ABI) provides auditory sensations, recognition of environmental sounds and aid in spoken communication in more than 300 patients worldwide. It is no more a device under investigation but it is widely accepted for the treatment of patients who have lost hearing due to bilateral tumors of the vestibulocochlear nerve. Most of these patients are completely deaf when the implant is switched off. In contrast to the cochlear implants (CI), only few of the implanted patients achieve open-set speech recognition without the help of visual cues. In the last few years, patients with lesions other than tumors have also been implanted. Auditory perceptual performance in patients who are deaf due to trauma, cochlea aplasia or other non-tumor lesions of the cochlea or the vestibulocochlear nerve turned out to be much better than in NF2 tumor patients. Until recently, the target region for ABI implantation has been the ventral cochlear nucleus (CN). The electrodes are implanted via the translabyrinthine or retrosigmoid approach. Currently, new targets along the central auditory pathways and new, minimally invasive techniques for implantation are under investigation. These techniques may further improve auditory perceptual performance in ABI patients and provide hearing to a variety of types of central deafness.