RESUMO
OBJECTIVE: Although the prevalence and burden of tinnitus is high, none of the available tinnitus treatments has been proven to be effective for the majority of tinnitus patients so far. Neuromodulation is currently gaining more interest to explore as tinnitus treatment. Because noninvasive neuromodulation has been shown to be effective in some tinnitus patients in the short term, more invasive techniques have been applied with variable success and without clear clinical applicability. As new insights into the neuropathophysiology of tinnitus arise, it seems essential to recapitulate the current evidence of invasive neuromodulation for tinnitus, to assess the quality of the available studies and identify gaps in this research domain. DATA SOURCES: MEDLINE, Embase, Web of Science and Clinical Trial Register. MATERIALS AND METHODS: We conducted a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Studies since 2005 that reported on adult human subjects with chronic subjective tinnitus, who underwent some form of invasive neuromodulation, were included. Quality evaluation was performed using the modified Downs and Black checklist. RESULTS AND CONCLUSION: Twenty-one studies were included. Studies were often of low quality due to low sample sizes, lack of controlled designs, or investigating tinnitus as a secondary indication of neuromodulation. Current research results provide insufficient evidence to generally recommend invasive neuromodulation as an alternative treatment alternative for intractable tinnitus, although some promising effects are mentioned. Further research must be encouraged to gain more insight in this treatment including optimization of the technique, and standardization of tinnitus evaluation in subgroups.