Efficacy of repetitive transcranial magnetic stimulation for Tourette syndrome: A systematic review and meta-analysis

While previous studies have investigated the effect of repetitive transcranial magnetic stimulation (rTMS) in treating Tourette syndrome (TS), the results remain inconclusive.We aim to systematically review the existing literature related to the efficacy of rTMS in TS and synthesize the results through meta-analysis.We searched for PubMed, Embase, Cochrane Library, and ClinicalTrials.gov databases without language restriction through January 1, 2018, and included randomized-controlled and open-label trials that assessed the treatment effect of rTMS for tic symptoms. We used a random-effects model to pool effect sizes, which were expressed as Hedges' g and 95% confidence intervals (CIs). The outcomes include symptom improvement of tic, obsessive-compulsive (OC), and attention-deficit hyperactivity disorder. Distribution of sex, age, and differences of rTMS protocol were examined as potential moderators.Eight studies were included in the meta-analysis. rTMS significantly improved tic (g = -0.61; CI: -0.94 to -0.29) and OC (g = -0.48; CI: -0.83 to -0.14) symptoms in TS patients, compared to baseline. However, active rTMS was not effective in tic or OC symptoms among patients with TS when controlled for placebo. Furthermore, stimulation of the bilateral supplementary motor areas was more effective in tic symptoms than that of other areas (g = -0.70; CI: -1.11 to -0.30 vs. g = -0.36; CI: -0.84 to 0.14). Moreover, a younger age was associated with a better treatment effect (coefficient = 0.03, p = 0.027).Current study indicates that rTMS has a significant effect on tic and OC symptoms in TS patients.