Transcranial Direct Current Stimulation for the Management of Neuropathic Pain: A Narrative Review

BACKGROUND: Neuropathic pain (NP) is common and often resistant to conventional analgesics. Among different types of noninvasive brain stimulation techniques, transcranial direct current stimulation (tDCS) has been widely used to mitigate pain in patients with NP. OBJECTIVE: The aim of this study was to review the effects of tDCS on the management of various types of NP. STUDY DESIGN: Narrative review. METHODS: A PubMed search was conducted for articles published until October 1, 2020, using tDCS to treat NP. The key search phrase, transcranial direct current stimulation and pain, was used to identify potentially relevant articles. The following inclusion criteria were applied for article selection: (1) studies involving patients with NP and (2) studies that used tDCS to treat NP. Review articles were excluded from the analysis. RESULTS: A total of 524 potentially relevant articles were identified. After reading the titles and abstracts and assessing eligibility based on the full-text articles, 34 publications were included in our review. Overall, our results suggest that tDCS induced pain reduction in patients with NP due to stroke or spinal cord injury, multiple sclerosis, or trigeminal neuralgia. There is insufficient evidence to validate the efficacy of tDCS for treating other painful conditions, such as complex regional pain syndrome, phantom pain, or NP of various origins. LIMITATIONS: The review did not include studies indexed in databases other than PubMed. CONCLUSION: The results of the included studies suggest that tDCS may be beneficial in treating patients with NP due to stroke, spinal cord injury, multiple sclerosis, and trigeminal neuralgia. Further studies are recommended to validate the efficacy of tDCS in treating other types of NPs. KEY WORDS: Transcranial direct current stimulation, neuropathic pain, central post-stroke pain, spinal cord injury, multiple sclerosis, complex regional pain syndrome, phantom pain, trigeminal neuralgia