Effects of transcranial direct current stimulation on experimental pain perception: A systematic review and meta-analysis

Objective: Many studies have examined the effectiveness of transcranial direct current stimulation (tDCS) on human pain perception in both healthy populations and pain patients. Nevertheless, studies have yielded conflicting results, likely due to differences in stimulation parameters, experimental paradigms, and outcome measures. Human experimental pain models that utilize indices of pain in response to well-controlled noxious stimuli can avoid many confounds present in clinical data. This study aimed to assess the robustness of tDCS effects on experimental pain perception among healthy populations. Methods: We conducted three meta-analyses that analyzed tDCS effects on ratings of perceived pain intensity to suprathreshold noxious stimuli, pain threshold and tolerance. Results: The meta-analyses showed a statically significant tDCS effect on attenuating pain-intensity ratings to suprathreshold noxious stimuli. In contrast, tDCS effects on pain threshold and pain tolerance were statistically non-significant. Moderator analysis further suggested that stimulation parameters (active electrode size and current density) and experimental pain modality moderated the effectiveness of tDCS in attenuating pain-intensity ratings. Conclusion: The effectiveness of tDCS on attenuating experimental pain perception depends on both stimulation parameters of tDCS and the modality of experimental pain. Significance: This study provides some theoretical basis for the application of tDCS in pain management. (C) 2021 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Automated summary

This study aimed to assess the robustness of tDCS effects on experimental pain perception among healthy populations. The results showed a significant tDCS effect on attenuating pain intensity ratings to suprathreshold noxious stimuli, while effects on pain threshold and tolerance were not significant. Moderator analysis suggested that stimulation parameters and experimental pain modality moderated the effectiveness of tDCS in reducing pain intensity ratings.