Transcranial direct current stimulation combined with peripheral stimulation in chronic pain: a systematic review and meta-analysis.

Introduction: The combination of Transcranial Direct Current Stimulation (tDCS) with peripheral stimulation may optimize their effects and bring positive results in treatment of people with chronic pain.

Areas Covered: A systematic review with meta-analysis of randomized and non-randomized trials was performed to investigate the combination of tDCS with peripheral stimulation in adults with chronic pain. The primary outcome was pain intensity. Six studies were included in this review (sample of 228 participants), which investigated the combination of tDCS and transcutaneous electrical nerve stimulation, peripheral electrical stimulation, breathing-controlled electrical stimulation and intramuscular electrical stimulation. The conditions studied were knee osteoarthritis, spinal cord injury, chronic low back pain, and neurogenic pain of the arms. Pain intensity, measured by visual analog scale or numerical rating scale, was reduced in all included studies when at least one of the interventions was active, regardless they were combined or alone, with or without tDCS. However, meta-analysis showed superiority of tDCS used in combination with peripheral stimulation.

Expert Opinion: This systematic review and meta-analysis suggests positive effects of tDCS combined with peripheral stimulation in chronic pain conditions. However, the evidence of the primary outcome was classified as low quality due to the limited number of studies.