Abstract:
Tinnitus is a symptom of disease that can make a significant impact on an individual’s quality of life. Recent attention has focused on the use of neuromodulation techniques to modify the maladaptive neural activity in auditory and non-auditory areas that lead to the perception of tinnitus. Transcranial random noise stimulation (tRNS) is an innovative technique of non-invasive electrical stimulation that uses a weak oscillatory current, and has shown neuromodulatory effects in transiently reducing the perception of tinnitus. This study explores the effectiveness of tRNS for tinnitus suppression through comparing two scalp locations, the dorsolateral prefrontal cortex (DLPFC), and the left temporoparietal area (LTA), comparing tRNS to a placebo, and examining the relationship between tRNS for tinnitus suppression with the adaptation level theory (ALT) framework. Twelve subjects participated in this double blind placebo controlled randomised study. Each participant received four separate sessions that involved two sessions, one real and one sham, over the LTA, and two sessions, one real and one sham, over the DLPFC. The real stimulation used a 2mA current for 20 minutes, and the sham had no stimulation for 20 minutes. Rating scales were used to measure participants’ tinnitus loudness and annoyance every 5 minutes during stimulation. There was a significant difference over time for tinnitus loudness (p=0.003) and annoyance (p=0.027), but this difference was not significant between the sham stimulation and the real tRNS stimulation. There was a significant difference between the DLPFC and LTA for decreasing tinnitus annoyance (p=0.047), but not tinnitus loudness. The interpretation within the ALT framework is difficult due to the minimal difference between the real tRNS and sham. However, a strong placebo effect is not inconsistent with tinnitus magnitude being modulated through top-down processes. Overall, these results show that tRNS can be a potential tool for the suppression of tinnitus, but it requires further investigation of the optimal parameters for tinnitus suppression.