Effects of transcranial direct current stimulation over the right hemisphere on naming ability in patients with poststroke aphasia: A meta-analysis

Abstract

Transcranial direct current stimulation (tDCS) applied to language regions in the left hemisphere can promote language recovery in patients with poststroke aphasia (PSA), but the effect of tDCS over the right hemisphere is still unclear. We performed a meta-analysis to explore the effects of tDCS applied to the right hemisphere on naming ability in patients with PSA. An electronic database search was conducted up to July 2020. Four eligible studies involving 46 stroke patients that met our inclusion criteria were identified. In the overall analysis (real tDCS vs sham tDCS), there was a clinically significant real tDCS effect which indicated that real tDCS of right-hemispheric regions could improve naming accuracy in patients with PSA. Moreover, we found a clinically significant difference between the anodal tDCS groups and sham tDCS groups in a subgroup analysis. This meta-analysis proved that anodal tDCS over the right hemisphere is more likely to be a prospective approach for promoting language recovery in patients with PSA, and further randomized controlled trials (RCTs) studies with larger populations are required to ascertain the therapeutic effect of anodal tDCS and cathodal tDCS.