The effect of Transcranial Direct Current Stimulation in addition to Tinnitus Retraining Therapy for treatment of chronic tinnitus patients: a study protocol for a double-blind controlled randomised trial

BACKGROUND: Currently, there still is no treatment that eliminates tinnitus in all patients. Recent studies have shown that Tinnitus Retraining Therapy (TRT) significantly improves quality of life for tinnitus patients. Also, several studies have reported that transcranial Direct Current Stimulation (tDCS) has a positive effect on attention, working memory, long-term memory and other cognitive processes. The aim of this randomised placebo-controlled double-blind study is to evaluate the added effect of tDCS to TRT in chronic tinnitus patients. To our knowledge, this is the first study to combine both methods. METHODS: Patients with chronic, non-pulsatile tinnitus will be randomised in two treatment groups: TRT and real tDCS versus TRT and sham tDCS. Evaluations will take place at baseline before therapy starts, at the end of the TRT and 3 months after therapy starts. The Tinnitus Functional Index will be used as the primary outcome measurement. Secondary outcome measurements will be the Visual Analogue Scale of Loudness, Hospital Anxiety and Depression Scale (HADS), Hyperacusis Questionnaire, psychoacoustic measurements and Event-related potential (ERP). DISCUSSION: To our knowledge this is the first study to combine TRT and tDCS. The objective is to evaluate whether tDCS can provide faster and/or more relief from the annoyance experienced in chronic tinnitus patients’ daily lives. The advantage of the study is that it is double-blind and placebo-controlled. TRIAL REGISTRATION: The present study protocol was registered on 31 October 2014 at Clinicaltrials.gov: NCT02285803.