Deep Brain Stimulation for Refractory Tinnitus: Pilot Study Protocol for a Randomized Double-Blinded Crossover Trial

Abstract Background: Chronic tinnitus can have an immense impact on quality of life. Despite recent treatment advances, many tinnitus patients remain refractory to them. Preclinical and clinical evidence suggest that deep brain stimulation (DBS) is as a promising treatment to suppress tinnitus. The thalamic medial geniculate body (MGB) takes a key position in the tinnitus network, shows pathophysiological hallmarks of tinnitus, and is readily accessible using stereotaxy. This study will evaluate the safety and therapeutic effects of DBS in the MGB in severe tinnitus sufferers.Methods: Bilateral DBS of the MGB will be applied in six patients with severe and refractory tinnitus. A double-blinded, randomized 2x2 crossover design (stimulation ON and OFF) will be applied, followed by a period of six months open label follow-up. The primary focus is to assess safety and feasibility (acceptability). Secondary outcomes assess a potential treatment effect and include tinnitus severity measured by the Tinnitus Functional Index (TFI), tinnitus loudness and distress, hearing, cognitive and psychological functions, quality of life, and neurophysiological characteristics. Discussion: Whilst carefully balancing risks and benefits and taking ethical considerations into account, this study explores the safety and feasibility of DBS in severe refractory tinnitus, by extensive assessment of clinical and neurophysiological outcome measures. Additionally, important insights in the underlying mechanism of tinnitus and hearing function might be revealed. Trial registration: ClinicalTrials.gov NCT03976908 (June 6, 2019)