Electrical Stimulation of the Motor Cortex or Paretic Muscles Improves Strength Production in Stroke Patients: A Systematic Review and Meta-Analysis.

OBJECTIVE: Transcranial direct current stimulation (tDCS) and functional electrical stimulation (FES) are two widely applied methods of electrical stimulation for motor recovery among stroke patients. This systematic review and meta-analysis investigated the efficacy of tDCS and FES for strength production in stroke patients. LITERATURE SURVEY: Studies that explored the effects of tDCS or FES on the strength production of paralyzed muscles in stroke patient were retrieved on a comprehensive set of 3 databases: (1) Google Scholar, (2) PubMed, and (3) the Cochrane Database of Systematic Reviews until July 2019. METHODOLOGY: Systematic study retrieval led to the inclusion of 15studies that reported on strength production effects after tDCS and FES interventions among stoke patients. A sham control group and randomization were used in each study. The 15studies included 20 comparisons with sham controls, 7 of which involved tDCS and 13 of which involved FES. SYNTHESIS: Random-effects models showed that strength production was improved after tDCS (ES = 0.52, 95%CI = 0.35-0.69, P < 0.00001, Z = 6.05) and FES (ES = 0.47, 95%CI = 0.16-0.78, P < 0.003, Z = 2.99). Additionally, tDCS was shown to improve strength production in the acute (ES = 0.52, 95%CI = 0.24-0.80, P < 0.0003, Z = 3.65), subacute (ES = 0.85, 95%CI = 0.37-1.32, P < 0.0005, Z = 3.51), but not chronic (ES = 0.06, 95%CI = -0.47-0.60, P = 0.82, Z = 0.23) phases of stroke recovery. Out of the 13 studies involving FES, 12 investigated strength production in the chronic phase and one investigated in the acute phase, showing a positive effect in these two stages. CONCLUSIONS: The results of the meta-analysis showed that tDCS and FES successfully improved strength production in stroke patients. This article is protected by copyright. All rights reserved.