AUTHOR=Chen Joyce L. , Schipani Ashley , Schuch Clarissa Pedrini , Lam Henry , Swardfager Walter , Thiel Alexander , Edwards Jodi D. 

TITLE=Does Cathodal vs. Sham Transcranial Direct Current Stimulation Over Contralesional Motor Cortex Enhance Upper Limb Motor Recovery Post-stroke? A Systematic Review and Meta-analysis

JOURNAL=Frontiers in Neurology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2021.626021

DOI=10.3389/fneur.2021.626021

ISSN=1664-2295

ABSTRACT=During recovery from stroke, the contralesional motor cortex (M1) may undergo maladaptive changes that contribute to impaired interhemispheric inhibition (IHI). Transcranial direct current stimulation (tDCS) with the cathode over contralesional M1 may inhibit this maladaptive plasticity, normalize IHI, and enhance motor recovery. The objective of this systematic review and meta-analysis was to evaluate available evidence to determine whether cathodal tDCS on contralesional M1 enhances motor re-learning or recovery post-stroke more than sham tDCS. Following PRISMA guidelines, we searched OVID, Embase and EBM reviews for participants with stroke (greater than 1 week post-onset) with motor impairment, and who received cathodal or sham tDCS to contralesional M1 for one or more sessions. Outcomes included change in any clinically validated assessment of physical function, activity or participation, or change in a movement performance variable (e.g. time, accuracy). A meta-analysis was performed pooling 5 randomized controlled trials (RCTs) and comparing the change in Fugl Meyer Upper Extremity scores between cathodal and sham tDCS groups. Eleven studies met inclusion criteria. Qualitatively, 4 out of 5 cross-over design studies and 3 out of 6 RCTs reported a significant effect of cathodal versus sham tDCS. In the quantitative synthesis, cathodal tDCS (n=65) did not significantly reduce motor impairment compared to sham tDCS (n=67; standardized mean difference=0.33, z=1.79, p=0.07) with little observed heterogeneity (I-squared=5%). The effects of cathodal tDCS to contralesional M1 on motor recovery are small and consistent. Given the observed effect size, data from larger cohorts is required.