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

Abstract

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.

Effects of Bilateral Repetitive Transcranial Magnetic Stimulation on Post-Stroke Dysphagia

“…Moreover, depending on the site of stimulation, recent systematic reviews and metaanalyses reported different results regarding the effect of NIBS. For instance, Yang et al [12] reported no significant difference according to stimulation sites; by contrast, Pisegna et al [13] found a significantly better effect size resulting from the contralesional stimulation as compared to the ipsilesional stimulation. The latter review even included one study that applied a combined method for 5 Hz rTMS over the contralesional hemisphere with the pharyngeal electrical stimulation [14].…”

“…Moreover, depending on the stimulating site, previous systematic reviews reported different results regarding the effect of non-invasive brain stimulation (NIBS). Specifically, one review reported no significant difference according to the stimulation site [12], while another review found a significantly better effect size resulting from the contralesional stimulation as compared to the ipsilesional stimulation [13]. The latter review included a combined brain and peripheral stimulation study, which applied 5 Hz rTMS over the contralesional hemisphere in combination with the pharyngeal electrical stimulation [14].…”

The Use of Brain Stimulation in Dysphagia Management

“…A systematic review and meta-analysis of non-invasive brain stimulation (NIBS) published in 2015 by Yang et al pooled the data of many of the aforementioned studies. 6 randomised control trials met the inclusion criteria for this meta-analysis of which 3 were studies using rTMS and 3 were studies using tDCS [43]. All 6 trials compared the intervention with sham stimulation.…”

“…However, when analysing the specific intervention, it was found that only the rTMS intervention resulted in a statistically significant improvement compared with sham stimulation. The tDCS group did not have a statistically significant improvement compared with the sham stimulation group [43]. …”

“…Confidence intervals overlapped between the two groups of stimulation and differences were not statistically significant. From this, Yang et al concluded that it is not yet possible to determine which stimulation is more effective [43]. …”