Transcranial direct current stimulation for improving ambulation after stroke: a systematic review and meta-analysis

Achieving a sufficient level of functional ambulation remains to be a challenge to most stroke survivors. Different modes of transcranial direct current stimulation (tDCS) have been applied for improving various aspects of walking and mobility following stroke. However, systematic reviews before 2017 provided only general effects of tDCS on limited walking outcomes. Therefore, the aims of this study were to update the evidence of tDCS for improving walking and mobility after stroke with emphasis on individual outcomes and to delineate the effects of different modes of tDCS in subgroup analysis. The systematic search of PubMed, Medline, PEDro, Scopus, and Cochrane databases for studies published up to January 2019 identified 14 eligible reports. The PEDro scale indicated a good methodological quality of the included studies (score 6.8). The meta-analysis of primary outcomes revealed that active tDCS had no better effect than sham on walking speed [n = 7, standardized mean difference (SMD) = 0.189, P = 0.252] and 6-minute walking distance (n = 3, SMD = 0.209, P = 0.453). Among the secondary outcomes, significant positive effects were found on functional ambulation category (FAC) (n = 5, SMD = 0.542, P = 0.008), Rivermead Mobility Index (n = 3, SMD = 0.699, P = 0.008), and timed up and go test (TUG) (n = 5, SMD = 0.676, P = 0.001), whereas non-significant positive effects were found on Tinetti test (n = 3, SMD = 0.441, P = 0.062) and Berg Balance Scale (n = 2, SMD = 0.408, P = 0.177). In subgroup analyses, anodal tDCS had significant positive effects on FAC (n = 4, SMD = 0.611, P = 0.005) and dual-hemispheric tDCS on TUG (n = 2, SMD = 1.090, P = 0.000). The results provide up-to-date evidence of variable effects of tDCS on walking and functional mobility after stroke.