Effects of repetitive transcranial magnetic stimulation (rTMS) on chronic tinnitus

Abstract

Conclusions: Preliminary results indicate that repetitive transcranial magnetic stimulation (rTMS) can suppress tinnitus for some people. However, several procedural questions need to be addressed before the results of TMS studies can be interpreted or applied. For example, the placebo effect might be a significant factor because it is easy for patients to distinguish between real and sham stimulation. Objectives: This study was undertaken to determine the following: Can rTMS reduce patients’ perception of chronic tinnitus? Is ipsilateral or contralateral stimulation most effective at reducing patients’ perception of tinnitus? What is the extent and duration of the change in tinnitus following rTMS? Patients and methods: Fifteen subjects rated the loudness of their tinnitus on a 1–10 scale (1 = very quiet, 10 = very loud) before and after sham or real TMS. Participants wore foam ear plugs during the following procedures. After the patient's motor threshold was established, a figure-of-eight stimulating coil was positioned over the temporal region of the head at a location that corresponds to International 10–20 electrode position T3 (left) or T4 (right). ‘Sham’ rTMS was then delivered to this region of the head, first on the ipsilateral side, then on the contralateral side from where participants perceived tinnitus. Sham TMS consisted of an audio recording of actual TMS stimulus sounds. Actual rTMS was next delivered to each side of the head, starting with the side ipsilateral to tinnitus perception. Stimulation intensity was 100% of the resting motor threshold. A train of 30 pulses at 10 Hz was delivered every minute for 5 min. Results: Two subjects reported reductions in tinnitus loudness following sham stimulation. Actual TMS resulted in partial suppression of tinnitus for six subjects. The amount of suppression ranged from 19% to 86% (average 50%). The durations of tinnitus suppression for each of the six subjects were: 20 min, 30 min, 45 min, 60 min, and 1 and 4 days, respectively.