Noninvasive brain stimulation for dysphagia after acquired brain injury : a systematic review

The purpose of this study was to review the best available evidence of noninvasive brain stimulation, including repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) for dysphagia after acquired brain injury. We searched randomized controlled trials that compared noninvasive brain stimulation with control used to improve dysphagia after acquired brain injury. We assessed dysphagia severity rating scales and penetration-aspiration scale as outcomes immediately after intervention. We calculated the pooled estimate of the standardized mean difference (SMD) to combine individual results. We included 8 published studies. Two heterogenous trials of 48 patients showed that rTMS was associated with a significant improvement in the dysphagia severity rating scale score (SMD 2.95). Three homogeneous trials of 88 patients showed a significant effect of rTMS on the penetration-aspiration scale score (SMD 0.77). Two homogeneous trials of 34 patients showed that tDCS was associated with a significant improvement in the dysphagia severity rating scale score (SMD 1.20). The review provided low-quality evidence for the effectiveness of noninvasive brain stimulation in improving dysphagia after acquired brain injury. Further trials of larger sample sizes are needed to determine the most appropriate noninvasive brain stimulation protocol.