Transcranial Direct Current Stimulation for the Treatment of Chronic Tinnitus: A Randomized Controlled Study

•We investigated the efficacy of 5 sessions of tDCS for the treatment of tinnitus.•TDCS applied to the auditory and prefrontal cortices is safe.•Repeated sessions of tDCS did not improve tinnitus as assessed by outcome measures.

BackgroundTinnitus is an often disabling condition for which there is no effective therapy. Current research suggests that tinnitus may develop due to maladaptive plastic changes and altered activity in the auditory and prefrontal cortex. Transcranial direct current stimulation (tDCS) modulates brain activity and has been shown to transiently suppress tinnitus in trials.ObjectiveTo investigate the efficacy and safety of tDCS in the treatment of chronic subjective tinnitus.MethodsIn a randomized, parallel, double-blind, sham-controlled study, the efficacy and safety of cathodal tDCS to the auditory cortex with anode over the prefrontal cortex was investigated in five sessions over five consecutive days. Tinnitus was assessed after the last session on day 5, and at follow-up visits 1 and 3 months post stimulation using the Tinnitus Handicap Inventory (THI, primary outcome measure), Subjective Tinnitus Severity Scale, Hospital Anxiety and Depression scale, Visual Analogue Scale, and Clinical Global Impression scale.Results42 patients were investigated, 21 received tDCS and 21 sham stimulation. There were no beneficial effects of tDCS on tinnitus as assessed by primary and secondary outcome measures. Effect size assessed with Cohen's d amounted to 0.08 (95% CI: −0.52 to 0.69) at 1 month and 0.18 (95% CI: -0.43 to 0.78) at 3 months for the THI.ConclusiontDCS of the auditory and prefrontal cortices is safe, but does not improve tinnitus. Different tDCS protocols might be beneficial.