Effectiveness of Non-invasive Brain Stimulation in Dysphagia Subsequent to Stroke: A Systemic Review and Meta-analysis

The objective of this study is to assess the efficacy and safety of non-invasive brain stimulation (NIBS) in patients with dysphagia subsequent to stroke. A systematic search of the literature published by Medline (January 1, 1976 through June 21, 2013), EMBASE (January 1, 1985 through June 21, 2013), and the Cochrane Library (January 1, 1987 through June 21, 2013) was conducted for all relevant articles related to NIBS, dysphagia, and cerebrovascular disorders (CVD). Two reviewers (S.N.Y and S.B.P) independently evaluated the eligibility of retrieved data according to the selection criteria and assessed methodological quality of the studies using the ‘assessing risk of bias’ table recommended in the Cochrane Handbook for Systematic Reviews of Interventions (version 5.0.2). Six randomized controlled trials (59 intervention groups and 55 placebo groups) were identified as addressing the use of NIBS for dysphagia after CVD and were included in the meta-analysis. The function scale score improvement of dysphagia in patients treated with NIBS was statistically significant compared with that of patients who underwent sham stimulation (standardized mean difference = 1.08, 95 % confidence intervals = 0.29–1.88, p = 0.008; I ² = 72 %). A subgroup analysis based on the type of intervention (three repetitive transcranial magnetic stimulation (rTMS) studies and three transcranial direct current stimulation (tDCS) studies) revealed a statistically significant beneficial effect of NIBS compared with sham stimulation in the rTMS group, but not in the tDCS group. When the results were examined based on intervention site (ipsilesional vs. contralesional site stimulation), no statistically significant difference was noted between two groups. No complications of NIBS were reported in this analysis.