Three weeks bilateral tDCS over auditory cortex significantly improves tinnitus: A double blinded randomized controlled clinical trial

Abstract

Abstract Background: Preliminary studies showed possible therapeutic efficacy of multisession transcranial direct current stimulation (tDCS) over auditory cortex (AC) for chronic tinnitus; however, the findings are controversial. Objective: To investigate the therapeutic effects of repeated sessions of bilateral tDCS over AC on tinnitus symptoms in chronic intractable tinnitus. Methods: A double blinded randomized placebo controlled parallel trial was conducted on 40 patients with chronic intractable tinnitus (> 2 years). Participants were randomly assigned into two groups of real tDCS (n=28), anode/cathode on left/right AC, or placebo treatment (n=28). Daily 20 min session of 2 mA current for 5 consecutive days per week and 3 consecutive weeks with 35 cm2 electrodes were applied. Tinnitus handicap inventory (THI) was assessed before and after intervention, and at one month follow-up. The tinnitus loudness and distress were assessed using a visual analogue scale (VAS) before intervention, and immediately, one hour, one week, and one month after last stimulation. Possible interaction between the disease features and treatment response was evaluated. Results: Ten sessions anodal tDCS significantly reduced THI after last session and after 1-month follow-up (P< 0.001), in 21 of 28 participants. In addition, significant reduced in distress VAS and loudness VAS were found (P< 0.001). The sham tDCS showed no statistically significant differences for any response variables. Age, sex, evolution time, laterality, basal THI, basal distress and basal loudness VAS showed no significant correlation with the treatment response. Conclusion: The repeated sessions of bilateral AC tDCS may serve as a potential therapeutic modality for chronic tinnitus. Research Category and Technology and Methods Clinical Research: 5. Other Transcranial Electrical Stimulation (tES) Keywords: Transcranial direct current stimulation, Chronic Tinnitus, Intractable, Treatment