Effects of transcranial direct current stimulation on neuropathic pain: A systematic review with meta-analysis and meta-regression

Background The effects of transcranial direct current stimulation (tDCS) have been well reported in populations with chronic pain in the literature. However, in neuropathic pain (NP), results remain contrasting, with previous studies showing small effect sizes and some factors that may influence the efficacy of tDCS. Objective To evaluate the effects of tDCS on pain intensity, disability, and psychological aspects in individuals with chronic NP, and to determine the predictive effect of characteristics of individuals, study design, and intervention parameters. Design and Setting Systematic review with meta-analysis and meta-regression. Methods A literature search was conducted in the databases MEDLINE, CINAHL, EMBASE, and CENTRAL, in July 2025. Controlled clinical trials involving individuals with chronic NP treated with tDCS were included. The standardized mean difference (SMD) with a 95% confidence interval (CI) was calculated. Meta-regression was performed to investigate potential moderators of the treatment effect. Results Eighteen studies were included with a pooled sample of 482 individuals. Moderate level of evidence indicated that tDCS was superior to sham for improving pain (SMD = −0.47; 95% CI: −0.75; −0.19), and low level of evidence indicated that tDCS was not superior to sham in improving disability, anxiety, and depression. Meta-regression analyses demonstrated that duration of pain is negatively correlated with effect size. In addition, stimulation target, randomization, and study design significantly contributed to variability. Conclusion Moderate level of evidence indicated that tDCS may have beneficial effects on pain intensity. Symptom duration, tDCS application site, and methodological quality are moderators of tDCS effects. Future studies are required to enhance the quality of evidence.