Comparison of the outcomes of repetitive transcranial magnetic stimulation to the ipsilateral and contralateral auditory cortex in unilateral tinnitus

Abstract

Transcranial magnetic stimulation (TMS) is a noninvasive method of activating or deactivating focal areas of the human brain. Repetitive TMS (rTMS) applied over the temporoparietal cortex has been reported to show therapeutic effects on tinnitus. We compared the effects of 1 Hz rTMS delivered either contralaterally or ipsilaterally to the symptomatic ear in patients with unilateral tinnitus. Forty patients with asymmetric hearing loss and non-pulsatile tinnitus localized to poorer ear of 6 months in duration or greater who were refractory to medication were enrolled in this study. Patients were assigned randomly to one of two treatment groups: with 1 Hz stimulation applied the temporoparietal junction either ipsilaterally (n = 21) or contralaterally (n = 19) to the symptomatic ear. The patients were given 600 pulses per session daily for 5 d. Changes in the tinnitus handicap inventory (THI) and self-rating visual analog scores (VAS) for loudness, awareness and annoyance were analyzed before, immediately after and 1 month after treatment. There was no significant difference in the rate of patients with marked improvement between ipsilateral and contralateral stimulation groups. In addition, there were no significant differences in the amount of decreases in THI scores and VAS between the two groups immediately or 1 month after rTMS. Finally, significant decreases in THI scores and most VAS were observed 1 month after rTMS in both groups compared to pretreatment. Daily treatment with 1 Hz rTMS ipsilaterally and contralaterally to the side of tinnitus both had significant beneficial effects. The laterality of stimulation with 1 Hz rTMS is not the decisive factor in relieving symptoms.