Noninvasive Brain Stimulation for Poststroke Dysphagia: A Meta-Analysis for Randomized Controlled Trials

BACKGROUND: Past research has indicated that repetitive transcranial magnetic stimulation (rTMS) on the pharyngeal motor cortex may be beneficial to poststroke dysphagic patients. In addition, some studies have supported that transcranial direct current stimulation (tDCS) over the pharyngeal motor cortex can improve swallowing function in poststroke dysphagia. However, some studies showed that rTMS and tDCS show no effect on poststroke dysphagia. This study aims to make a meta-analysis to investigate the therapy effect of rTMS and tDCS on poststroke dysphagia in randomized controlled trials (RCTs). METHODS: We searched for studies published before March 2021 in databases (PubMed, Web of Science, MEDLINE, EMBASE, and Google Scholar). Meta-analysis was made to compute the results of included studies using STATA 12.0 software. RESULTS: The present study shows a significant increase in the swallowing function in poststroke dysphagia given rTMS compared to those given sham rTMS (standardized mean difference [SMD] = 1.08, 95% confidence interval [CI] = 0.37-1.80, I2 = 81.2%, p < 0.001). In addition, the study shows a significant increase in the swallowing function in poststroke dysphagia given tDCS (combined or not combined with conventional swallowing therapy), compared to those given sham tDCS (combined or not combined with conventional swallowing therapy) (SMD = 1.43, 95% CI = 0.73-2.13, I2 = 77.6%, p < 0.001). CONCLUSIONS: The study demonstrates that rTMS and tDCS over the pharyngeal motor cortex show therapy effects on poststroke dysphagia. Many more large-scale, blinded RCTs are essential to investigate the effect of rTMS and tDCS on poststroke dysphagia.