Repeated sessions of transcranial direct current stimulation for treatment of chronic subjective tinnitus: a pilot randomized controlled trial

Abstract

Subjective tinnitus is an auditory phantom sensation characterized by the perception of sound in the absence of an identifiable external source. This distressing audiological symptom can severely affect the quality of life. Transcranial direct current stimulation (tDCS) is a noninvasive technique that can induce short-term relief in tinnitus in some patients. The purpose of this pilot double-blind randomized controlled trial was to investigate whether repeated application of anodal tDCS over left temporoparietal area could induce long-lasting relief in patients with chronic tinnitus. Twenty-two patients with chronic tinnitus for at least 6 months were randomly allocated into two groups and received five sessions of anodal (N = 11) or sham (N = 11) stimulation in five consecutive days. A current intensity of 2 mA for 20 min was used for anodal stimulation. Outcomes were assessed using Persian version of tinnitus handicap inventory (THI), loudness and distress visual analog scale (VAS) scores and clinical global impression (CGI) scale. The trial is registered at the Iranian Registry of Clinical Trials (IRCT) with the reference ID of IRCT2014082018871N1. No statistically significant difference was found between anodal and sham stimulation regarding either immediate or long-lasting effects over the 2 weeks follow-up period. Deterioration of symptoms and alteration in tinnitus characteristics were reported by a few patients. There were no significant long-term beneficial effects following tDCS of the left temporoparietal area.

Combined Bifrontal Transcranial Direct Current Stimulation and Tailor-Made Notched Music Training in Chronic Tinnitus

“…According to a recent report, 29.3% of the one nation population experiences tinnitus that interferes with daily life [1]. The suggested pathophysiologic mechanism of tinnitus includes maladaptive plastic changes in the brain due to the deafferentation of peripheral auditory input [2]. Thus, the phantom perception of sound is thought to be the manifestation of compensatory, persistent neural hyperactivity in the tonotopic cortical area [3].…”

“…Recently, a diverse array of neuromodulation techniques believed to alter cortical excitability has been introduced for the control of neuropsychiatric disorders such as depression, pain, epilepsy, and chronic tinnitus [2]. These techniques most famously include transcranial direct current stimulation (tDCS).…”

“…In addition, lasting after-effects of tDCS are associated with the modulation of gamma-aminobutyric acid-ergic (GABAergic) and glutamatergic synapses [4]. According to polarity, anodal tDCS results in an increase in cortical excitability by depolarizing neurons and cathodal tDCS decreases excitability by hyperpolarization [25]. The most frequently used settings for tDCS stimulation intensity, duration, and frequency are 1.0-2.0 mA for 10-30 minutes over 5-6 sessions, although these parameters differ between studies [23567].…”

The Effects of Acute Multisession Bifrontal Transcranial Direct Current Stimulation on Intractable Tinnitus and comorbid depression and anxiety: A Study Protocol for Randomized Controlled Trial

“…For the primary outcome (THI score) we will use the clinical improvement rather than statistical improvement so that a reduction ≥ 20 points in the THI score (Pre-treatment THI-Post-treatment THI ≥ 20) is defined as the treatment response. The 20 point cut-off value of THI is generally accepted as significant clinical improvement in tinnitus treatment 26,37,38 .…”

“…Therefore, the two main targeting sites in the tDCS studies on studies were AC and DLPFC [20][21][22][23] . In line with these hypotheses, several studies have investigated the effects of tDCS in different protocols and electrode montages on tinnitus 17,22,[23][24][25][26][27] . Findings of these studies were promising, though controversial.…”