Efficacy of transcranial direct current stimulation for disorders of consciousness: an updated systematic review and meta-analysis based on sham-controlled randomized trials

Abstract

Background Transcranial direct current stimulation (tDCS) may improve behavioral signs of consciousness in patients with disorders of consciousness (DoC), but evidence from randomized controlled trials (RCTs) and previous meta-analyses has remained inconsistent. We evaluated the efficacy and safety of tDCS in patients with DoC and explored potential effect modifiers. Methods PubMed, Embase, Scopus, Web of Science, and the Cochrane Library were searched for RCTs comparing active tDCS with sham stimulation. For crossover trials, only first-period data were extracted. The primary outcome was the change in Coma Recovery Scale–Revised (CRS-R) score. Mean differences (MDs) with 95% confidence intervals (CIs) were pooled across studies. Subgroup analyses were performed according to baseline level of consciousness, etiology, disease duration, stimulation target, and total stimulation dose. Results Fourteen trials including 330 patients were included. Active tDCS was associated with greater improvement in CRS-R change scores than sham stimulation (MD = 1.02, 95% CI 0.43–1.60; p < 0.001). A significant subgroup interaction was observed for etiology (p < 0.001), with significant improvements in patients with traumatic brain injury and cerebrovascular accident, but not in hypoxic–ischemic brain injury. Other analyses suggested trends toward improvement in minimally conscious state, left dorsolateral prefrontal cortex stimulation, and higher total stimulation dose, without significant between-subgroup differences. No definite tDCS-related serious adverse events were reported. Conclusion tDCS may improve the level of consciousness in patients with DoC, with no definite tDCS-related serious adverse events identified. Treatment response may differ by etiology, but this finding requires confirmation because multiple subgroup comparisons were performed. Systematic review registration Identifier CRD420261370518.