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

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; 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.