The relative benefit of ipsilateral, contralateral, and bilateral repetitive
transcranial magnetic stimulation (rTMS) for
tinnitus treatment remains unclear, especially for patients with lateralized
tinnitus. In this study, we compared outcomes after 10 sessions of 1-Hz rTMS at 110% of resting motor threshold over a two-week period. In total, 104 right-handed patients with lateralized
subjective tinnitus were randomly divided into four groups according to rTMS treatment: Left (n = 29), Right (n = 23), Bilateral (
n = 30), and
Sham stimulation (n = 22). Outcomes included estimates of
tinnitus severity, psychological state, and psychoacoustic measures. Patients with left- or right-sided
tinnitus were similarly distributed across treatment groups. There were no significant changes in outcome measures for the Right or
Sham treatment groups. For the Left and Bilateral groups,
tinnitus severity was significantly lower
after treatment (p < 0.05). The reduction in
tinnitus severity was largest for ipsilateral treatment in the Left group. The overall response rate was 56.1% for the Left group, 46.7% for the Bilateral group, 8.3% for the Right group, and 8.3% for the
Sham group. For the Left and Bilateral groups, the response rate was larger for patients with left- than right-sided
tinnitus. Changes in
tinnitus severity were best predicted by changes in anxiety, depression, and the loudness of the
tinnitus. The results suggests that rTMS on the left temporoparietal cortex is more effective for patients with left-sided than with right-sided
tinnitus.