Short- and long-lasting tinnitus relief induced by transcranial direct current stimulation

Abstract

A significant proportion of the population suffers from tinnitus, a bothersome auditory phantom perception that can severely alter the quality of life. Numerous experimental studies suggests that a maladaptive plasticity of the auditory and limbic cortical areas may underlie tinnitus. Accordingly, repetitive transcranial magnetic stimulation (rTMS) has been repeatedly used with success to reduce tinnitus intensity. The potential of transcranial direct current stimulation (tDCS), another promising method of noninvasive brain stimulation, to relieve tinnitus has not been explored systematically. In a double-blind, placebo-controlled and balanced order design, 20 patients suffering from chronic untreatable tinnitus were submitted to 20 minutes of 1 mA anodal, cathodal and sham tDCS targeting the left temporoparietal area. The primary outcome measure was a change in tinnitus intensity or discomfort assessed with a Visual Analogic Scale (VAS) change-scale immediately after tDCS and 1 hour later. Compared to sham tDCS, anodal tDCS significantly reduced tinnitus intensity immediately after stimulation; whereas cathodal tDCS failed to do so. The variances of the tinnitus intensity and discomfort VAS change-scales increased dramatically after anodal and cathodal tDCS, whereas they remained virtually unchanged after sham tDCS. Moreover, several patients unexpectedly reported longer-lasting effects (at least several days) such as tinnitus improvement, worsening, or changes in tinnitus features, more frequently after real than sham tDCS. Anodal tDCS is a promising therapeutic tool for modulating tinnitus perception. Moreover, both anodal and cathodal tDCS seem able to alter tinnitus perception and could, thus, be used to trigger plastic changes.

Transcranial Electrical Stimulation: Methodology and Applications

“…Vanneste, Focquaert, Van de Heyning, and De Ridder (2011) found that responders to tDCS had elevated amplitude in the gamma frequency of the EEG in the right primary and secondary auditory cortex, as well as in the right parahippocampal area. Others (Garin et al, 2011) have found a reduction in tinnitus symptoms with anodal (but not cathodal) stimulation of the left temporo-parietal area.…”

Neuromodulation for the Treatment of Tinnitus

“…A comparatively long-lasting impact on tinnitus perception, lasting up to a few days, was observed in a recent double-blind, sham-controlled study conducted by Garin et al [18] using tDCS for 20 minutes with 1 mA current intensity. Anodal tDCS produced more favorable effects compared with cathodal or sham tDCS.…”

“…Anodal tDCS produced more favorable effects compared with cathodal or sham tDCS. Vanneste and colleagues [19] explored whether tDCS of DLPFC would suppress tinnitus and used a slightly higher current intensity (1.5 mA) than other authors [18,23]; they reported a 29.9% positive response rate with bifrontal tDCS using an anode on the right DLPFC and cathode on the left DLPFC. However, a review of studies conducted since 1998 using tDCS in humans under various clinical conditions showed that no studies used a current intensity greater than 2 mA [24].…”

“…Anodal tDCS of the LTA has led to transient suppression of tinnitus in 42% [23] and 35% [18] of participants. A comparatively long-lasting impact on tinnitus perception, lasting up to a few days, was observed in a recent double-blind, sham-controlled study conducted by Garin et al [18] using tDCS for 20 minutes with 1 mA current intensity.…”

“…Synaptic activity controls the changes in intracortical inhibition or facilitation and can affect the results of tDCS [17]. Anodal tDCS of the left temporoparietal area (LTA) and dorsolateral prefrontal cortex (DLPFC) are potentially the most favorable polarity and stimulation sites for tinnitus relief [18][19][20][21]. tDCS of LTA results in more widespread diffused impact on cortical areas beyond the target region.…”