Transcranial Magnetic Stimulation as a Therapy for Migraine: An Overview of Systematic Reviews.

Introduction: This overview of systematic reviews (SRs) systematically collected, evaluated, and combined the evidence for migraine treatment with transcranial magnetic stimulation (TMS). Methods: We conducted a systematic literature search in various databases, such as PubMed, The Cochrane Library, Web of Science, Embase, the China National Knowledge Infrastructure, Wanfang, VIP, and China Biomedical Literature. Two reviewers independently assessed the methodological quality, risk of bias, reporting quality, and strength of evidence of the included studies using AMSTAR-2, ROBIS, the PRISMA checklist, and the GRADE system. Results: We performed an overview of 7 relevant SRs, of which 4 were of moderate quality and 3 were of low quality according to AMSTAR 2. All SRs had low risk of bias in Phase 1 (Assessing relevance), Domain 1 (Study eligibility criteria), and Domain 4 (Synthesis and findings) as evaluated by ROBIS. In Domain 2 (Identification and selection of studies), 4 SRs (57.1%) had low risk of bias, while in Domain 3 (data collection and study appraisal) and Risk of Bias in the Review Phase 3, 4 SRs (57.1%) had low risk of bias. The PRISMA reporting standards were generally comprehensive, but some limitations were observed in the assessments, pooled results, evidence reliability, registration and protocols, and funding sources. The GRADE levels ranged from moderate to low, with 10 outcomes of moderate quality and 6 outcomes of low quality. The main reason for the low quality of evidence was the small sample size and high heterogeneity of the available studies. Conclusion: TMS may improve migraine severity and frequency, but the evidence is limited due to methodological flaws and heterogeneity. Future studies should standardize use, assess side effects, and compare with other treatments.