Soussi andВ Otto published a study with patients who were implanted with an ABI for the indication of hearing loss. 11 Several clinical studies have also shown a positive effect of ABI implantation on tinnitus. Also, hyperactivity in the DCN might be modulated by direct stimulation of the neuronal circuit and interrupt pathways of hyperactivity to higher regions, such as the inferior colliculus, or it may induce a masking effect. 11 This effect might be explained by the possibility that stimulation of DCN compensates the loss of peripheral input caused by noise damage and thereby restores the disturbed balance between excitatory and inhibitory processes. 10 Thus, electrical stimulation of the cochlear nucleus in rats led to suppressed behavioural evidence of tinnitus. 9 In an animal model, it was demonstrated that there is behavioural evidence of tinnitus in conditions of increased hyperactivity in the DCN. For example, as a result of increased noise exposure, hyperactivity, expressed as an increased spontaneous activity, can be found in DCN this in turn reduces residual inhibition and increases excitability. It is thought that the dorsal cochlear nucleus (DCN) plays an important role in modulation and generation of tinnitus. 7 8 The implant hardware is comparable to that of the CI however, the ABI was specifically designed to bypass both the cochlea and the auditory nerve to directly stimulate the cochlear nucleus in the brainstem.

In 1979, the first ABI was implanted by House and Hitselberger for the purpose of restoring hearing in a patient with neurofibromatosis type II (NF2). To fill this gap, the auditory brainstem implant (ABI) might be an option. This means that CI is not an option for the large group of tinnitus patients who still have usable hearing. Therefore, CI is only indicated in cases where there is severe to profound hearing loss. 6 However, insertion of an electrode into the cochlea often leads to mechanical damage of intracochlear structures and subsequent, additional hearing loss. In a prospective study, CI implantation in patients with single-sided deafness and tinnitus resulted in significantly reduced tinnitus loudness in the long-term. 4Дuring the ongoing search for causal treatment methods, it has been demonstrated that a cochlear implant (CI) may be a potential treatment option. 4 5 However, not all patients benefit from these treatments and there is a remaining group of patients with severe tinnitus for whom there is no conventional treatment modality available. 1вЂ“3 Conventional treatment methods, for example, sound generators and cognitive behavioural therapy, seem not to reduce the loudness of tinnitus, but may improve related depression and quality of life. 1 It is a very common condition (prevalence 5%вЂ“18% in Western population) and, in a subgroup of patients, it causes extreme distress with far-reaching consequences for daily activities and quality of life. Tinnitus, which literally means вЂringing in the earsвЂ™, is defined by the perception of sound or noise in the absence of an external physical sound source.

Auditory brainstem implant