The Effectiveness of Transcranial Stimulation in Improving Swallowing Outcomes in Adults with Poststroke Dysphagia: A Systematic Review and Meta-analysis

Abstract

Background: In recent years, the use of brain stimulation in the rehabilitation of poststroke dysphagia has emerged. Transcranial stimulation, a non-invasive neuromodulation, offers an alternative therapy to improve the swallowing function in adults with post stroke dysphagia. Objective: This review aimed to examine the effectiveness of transcranial stimulation in adult stroke patients with poststroke dysphagia to improve swallowing function through synthesizing available evidence. Method: Six databases (PudMed, EMBASE, Cochrane, CINAHL and Scopus, Web of Science) were searched from commencement till 3 January 2021. RCTs on the use of Transcranial stimulation in adults who are above 18 years old with poststroke dysphagia to improve swallowing functions were included. Quality of studies were evaluated using ROB and GRADE. Meta-analysis was conducted using Review manager software where the random effects model with Inverse Variance method was used. Effect size and Z-statistics were used to evaluate overall effects. Heterogeneity was measured using I2 test and Cochran’s Q (𝜒2) and publication bias was evaluated using Egger’s test and funnel plot. Results: 665 studies were identified and 16 RCTs were included in qualitative synthesis and 13 were included for meta-analysis. Results showed small effect size favouring transcranial stimulation on swallowing function. Subgroup analysis suggested no difference between types of stimulation, stimulatory effects, number of sessions and concurrent therapy and site of stimulation in improving dysphagia. Overall quality of evidence by GRADE was low. Implication: Despite favourable outcomes, transcranial stimulation needs to be studied further to form definitive conclusions about the optimal stimulation protocol to yield the greatest improvement. Future trials should be of higher-quality with larger sample sizes to support the effectiveness of transcranial stimulation. Conclusion: Transcranial stimulation provides an opportunity for a more efficacious approach in PSD rehabilitation to mitigate dysphagia.