A Cochrane review [Abstract] 1 included 5 RCTs with 233 participants with tinnitus. Each study used a different repetitive transcranial magnetic stimulation (rTMS) device, delivering different waveforms at different frequencies. A statistically significant improvement in Tinnitus Handicap Inventory (THI) scores at 4 months follow-up was seen in one trial (n=66), when low-frequency rTMS was compared with a sham control treatment ('partial improvement' measured as THI reduction of 21% to 80%: RR 12.00, 95% CI 1.76 to 81.74). However, no statistically significant improvement was demonstrated by another two studies (n=71) that evaluated rTMS at the same frequency. When studying tinnitus severity and disability after 4 months follow-up between 'lower' low-frequency rTMS (1 Hz) and 'higher' low-frequency rTMS (10 Hz, 25 Hz), a statistically significant difference between rTMS with a frequency of 1 Hz and the sham group was seen ('partial' improvement: RR 12.00, 95% CI 1.76 to 81.74). However, no statistically significant difference was demonstrated between 10 Hz and 25 Hz rTMS and the sham control group. When considering tinnitus loudness in patients undergoing rTMS, a statistically significant reduction in tinnitus loudness was seen when the results of two studies were pooled (RR 4.17, 95% CI 1.30 to 13.40, n=95). No serious adverse effects were reported in any of the trials.
Comment: The quality of evidence is downgraded by inconsistency (heterogeneity in interventions) and imprecise results (few patients and wide confidence intervals).
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