Efficacy of Noninvasive Brain Stimulation on Pain Control in Migraine Patients: A Systematic Review and Meta-Analysis.

OBJECTIVE: To evaluate the efficacy of noninvasive brain stimulation (NIBS) on pain control in migraine patients.

BACKGROUND: Recent studies have used NIBS as an abortive and prophylactic treatment for migraine; however, its efficacy regarding meaningful clinical effects remains to be critically analyzed.

DESIGN: Systematic review of controlled clinical trials.

METHODS: Searches were conducted in six databases: MEDLINE (via PubMed), LILACS (via BIREME), CINAHL (via EBSCO), Scopus (via EBSCO), Web of Science, and CENTRAL. Two independent authors searched for randomized controlled clinical trials published through until January 2016 that involved the use of transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS) in migraineurs. Studies which met the eligibility criteria were assessed and methodological quality was examined using the Cochrane tool for assessing risk of bias. Information about pain intensity (primary outcome), migraine attacks, painkiller intake, and adverse effects were extracted.

RESULTS: Eight studies were included in the quantitative analysis with 153 migraine patients that received NIBS and 143 sham NIBS. In overall meta-analysis, we did not find significant results for pain intensity (SMD: -0.61; CI: -1.35 to 0.13; P = .11), for migraine attacks (SMD: -0.44; 95%; CI: -1.15 to 0.26; P = .22), and for painkiller intake (SMD: -0.57; 95% CI: -1.21 to 0.07; P = .08). However, subgroup analysis considering only tDCS effects have demonstrated a decrease for pain intensity (SMD: -0.91; 95% CI: -1.79 to -0.03; P = .04), migraine attacks (SMD: -0.75; 95% CI: -1.25 to -0.24; P = .004), and painkiller intake (SMD: -0.64; 95% CI: -1.21 to -0.07; P = .03). Subgroup analysis for TMS did not reveal significant effects for any outcome.

CONCLUSION: Low or very low quality of evidence suggests that our primary outcome evaluation failed to find support for the superiority of NIBS over sham treatment. Although, subgroup analysis reveals that tDCS have moderate to high effects and could be a promising nonpharmacological alternative to pain control, mainly for painkiller intake reduction. However, there is a need for larger controlled trials with methodological rigor, which could increase the power of result inference.