Effects of Transcranial Direct Current Stimulation on Poststroke Dysphagia: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

OBJECTIVE:This review aimed to systematically evaluate the effect of transcranial direct current stimulation (tDCS) on poststroke dysphagia. DATA SOURCES:PubMed, Cochrane Library (CENTRAL), Web of Science, VIP, CNKI, and Wanfang databases were systematically searched up to June 2021. STUDY SELECTION:Randomized controlled trials (RCTs) on the effects of tDCS on poststroke dysphagia. DATA EXTRACTION:The extracted data included the author, country of publication, time of publication, key elements of bias risk assessment (such as RCTs and blind methods), sample size and basic information (age, course of disease, stroke location), intervention measures, treatment methods of tDCS (stimulation location, intensity, duration), relevant outcome indicators, and relevant data (SDs).The Cochrane Risk of Bias Assessment Tool and Physiotherapy Evidence Database Scale were used to assess the risk of bias. DATA SYNTHESIS:Sixteen RCTs were included in this meta-analysis. Overall, the results revealed a large and statistically significant pooled effect size (0.80; confidence interval [CI], 0.45-1.14; P<.001). The subgroup that explored the course of the disease yielded a large and significant effect size for the chronic phase group (0.80; CI, 0.43-1.16; P<.001). For the stimulation intensity, 1 mA and 1.6 mA showed a moderate and significant effect sizes (0.47; CI, 0.13-0.81; P=.006 vs 1.39; CI, 0.69-2.08; P<.001). In the subgroup analyses, the affected (0.87; CI, 0.26-1.48; P=.005) vs unaffected (0.61; CI, 0.23-0.99; P=.002) hemisphere showed a significant result, and stimulation of the affected hemisphere had a more obvious effect. Subgroup analysis of stroke location showed that tDCS was effective for dysphagia after unilateral hemispheric stroke, bulbar paralysis, and brainstem stroke but not for dysphagia after ataxic and basal ganglia stroke. However, the subgroup analysis of stroke location revealed a significant result (0.81; CI, 0.44-1.18; P<.001). CONCLUSIONS:This meta-analysis demonstrated the height and significant beneficial effect of tDCS on improving poststroke dysphagia.