The effect of a multisite transcranial random noise stimulation (tRNS) on tinnitus loudness, distress, mismatch negativity response (MMN) and electroencephalography (QEEG) in subjects with chronic tinnitus

Objectives: investigating the effects of a multisite transcranial random noise stimulation (tRNS) on tinnitus loudness, distress, MMN response and electroencephalography in chronic tinnitus subjects. Design: it is an interventional, one phase, and randomized, single blinded study. We have two groups: the intervention group in which we will apply the (high frequency) hf-tRNS over the right DLPFC (Dorso Lateral Prefrontal Cortex) followed by (low frequency) lf-tRNS over the auditory cortex in one session. And the control group in which we will apply the lf-tRNS over the auditory cortex only. Each patient in these two groups will take a placebo (Sham stimulation) session before the active tRNS session. There is randomization in allocating patients in groups, but they will take the two treatment stages (placebo & active) without randomization. Patients will be randomly organized into the two groups, but they will take the two treatment stages (placebo & active) without randomization i.e in all cases we will begin with the Sham stimulation. The way of randomization is by drawing a number between 1-32 where numbers from 1 to 16 is referring to the intervention group while numbers from 17 to 32 is referring to the control group. The randomization will be done computerly using Matlab. Setting: After signing the consent form, Patients will be allocated randomly into the two groups. In each group, each patient blindly will undertake both Sham and tRNS simulations beginning with the Sham one. Each patient will complete the VAS-L and VAS-A (Visual Analogue Scale) before and immediately after each session. In addition, EEG and MMN recording will be taken before and immediately after each session. Our intervention is applying transcranial random noise electrical stimulation with two protocols (the multisite protocol (auditory and prefrontal), and the auditory cortex protocol). The placebo intervention is given by using the Sham stimulation mode; the current is switched off automatically after a ramp-in of 10 seconds and the session will be given in the same mentioned protocols in active interventions concerning electrode arrays and the time of the session which lasting for 20 minutes. Participants: all patients with chronic nonpulsatile tinnitus (>6 months) can participate in this study with the following entry criteria: age between 20 and 50 years, the behavioral pure-tone audiometry threshold levels of ≤20 dBHL in octave frequencies of 250–2000 Hz and not more than 40 dBHL in frequencies of 4000 -8000 Hz and the tinnitus intensity is moderate to severe. Patients will be excluded if they have a remarkable cognitive problems, a previous formal musical training, or having a history of otological, neurological, mental diseases, head trauma, psychiatric disorders, seizure and finally if they having a pacemaker or defibrillator. Main outcome measures: in this study we will analyze these variables as the primary variables of the study: tinnitus related loudness, tinnitus related annoyance (distress), MMN amplitude & MMN area under curve, Mean frequency of EEG waves, EEG absolute & relative powers and the EEG activity in ROIs (region of interest). As well as, we have the tinnitus pitch as a secondary variable.

Vice chancellor for research, Iran University of Medical Sciences