Transcranial direct current stimulation for upper extremity motor dysfunction in poststroke patients: A systematic review and meta-analysis.

Objective: To evaluate the efficacy and safety of transcranial direct current stimulation in poststroke patients with upper extremity motor dysfunction using a systematic review and meta-analysis.

Data Sources: We searched the Web of Science, Cochrane Library, EMBASE, and PubMed for randomized controlled trials investigating the effects of both active and sham stimulation up until January 27, 2024.

Review Methods: Efficacy, including the upper extremity Fugl-Meyer Assessment, Action Research Arm Test, Barthel Index, and safety, were assessed. The risk of bias was assessed using the Cochrane Risk of Bias 2 tool and the Physiotherapy Evidence Database Scale. Meta-analysis was performed using the RevMan 5.4 software.

Results: Forty-four studies with 1555 participants were included. Transcranial direct current stimulation proved effective in improving upper extremity motor function (standardized mean difference = 0.22, 95% confidence interval: 0.12-0.32,  < 0.001) and Barthel Index (mean difference = 4.65, 95% confidence interval: 2.82-6.49,  < 0.001). Subgroup analysis revealed the highest transcranial direct current stimulation efficacy in patients with subacute stroke. Both anodal and cathodal stimulation were effective against upper extremity motor dysfunction. C3/C4 was the most effective stimulus target. Optimal stimulation parameters included stimulus current densities <0.057 mA/cm for 20-30 min and <30 sessions. Adverse effects and dropouts during follow-up showed that transcranial direct current stimulation is safe and feasible.

Conclusions: Our findings suggest that both anodal and cathodal stimulation were significantly effective in subacute stroke patients, particularly when preceding other treatments and when C3/C4 is targeted.