Transcranial Magnetic and Direct Current Stimulation (TMS/tDCS) for the Treatment of Headache: A Systematic Review.

BACKGROUND: Headache is among the most prevalent causes of disability worldwide. Non-pharmacologic interventions, including neuromodulation therapies, have been proposed in patients who are treatment resistant or intolerant to medications. OBJECTIVE: To perform a systematic review on the use of transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) for the treatment of specific headache disorders (ie, migraine, tension, cluster, posttraumatic). METHODS: Data sources: Ovid MEDLINE, Cochrane Central Register of Clinical Trials, Embase, Scopus, PsycINFO. DATA EXTRACTION: All references were reviewed by 2 independent researchers (3039 abstracts, duplicates removed). Records were selected by inclusion criteria for participants (adults 18-65 with primary or secondary headaches), interventions (TMS and tDCS applied as headache treatment), comparators (sham or alternative standard of care), and study type (cohort, case-control, and randomized controlled trials [RCT]). Studies were assessed using the Cochrane Risk of Bias Tool and overall quality determined through the GRADE Tool. A structured synthesis was performed due to heterogeneity of participants and methods. RESULTS: Thirty-four studies were included: 16 rTMS, 6 TMS (excluding rTMS), and 12 tDCS. The majority investigated treatment for migraine (19/22 TMS, 8/12 tDCS). Quality of evidence ranged from very low to high. CONCLUSION: Of all TMS and tDCS modalities, rTMS is most promising with moderate evidence that it contributes to reductions in headache frequency, duration, intensity, abortive medication use, depression, and functional impairment. However, only few studies reported changes greater than sham treatment. Further high-quality RCTs with standardized protocols are required for each specific headache disorder to validate a treatment effect. Registration Number: PROSPERO 2017 CRD42017076232.