Transcranial direct current stimulation in spinal cord-injured patients with neuropathic pain

Background & objective: Neuropathic pain (NP) is perhaps one of the most difficult to manage pain syndrome. Pharmacologic management is often not successful and various other pain management modalities have to be used. This study evaluated the effectiveness of transcranial direct current stimulation (tDCS) targeting the dorsolateral prefrontal cortex (DLPFC) for treating NP, which followed Spinal Cord Injury (SCI). Methodology: We enrolled 25 patients, 18-80 years old, from both genders, with NP, which followed SCI, From March 2023 to July 2024, in this retrospective study. Single-pulse transcranial magnetic stimulation (TMS) was used to locate the primary motor cortex (M1) and DLPFC regions before treatment. Patients received tDCS with the anode over the DLPFC and the cathode over the contralateral orbitofrontal (COF) region, with 2 mA current for 20 min daily, five days a week, for two weeks. Pain levels were assessed using Douleur Neuropathique 4 (DN4) and Numeric Rating Scale (NRS) before treatment, immediately after treatment, and then on monthly basis for three months. A responder was defined as a reduction of ≥ 2 points on the NRS or a 50% reduction in pain intensity. Additionally, side effects were diligently noted after each tDCS session. Results: DN4 scores decreased from 5.8 to 3.3 and VAS from 5.9 to 3.2 after two weeks (P < 0.05). This effect lasted for two months post-treatment. Common side effects included drowsiness and transient scalp tingling, while less frequent side effects like headache, dizziness, and fatigue were mild and self-resolving. Conclusion: tDCS stimulation on the DLPFC region can effectively alleviate NP symptoms after SCI in the short term, with no severe side effects. Further research is needed to optimize treatment regimens. Abbreviations: COF: contralateral orbitofrontal, DN4: Douleur Neuropathique 4, DLPFC: dorsolateral prefrontal cortex, NP: Neuropathic pain, SCI: Spinal Cord Injury, tDCS: transcranial direct current stimulation, TMS: transcranial magnetic stimulation Keywords: Neuropathic Pain; Spinal Cord Injury; Transcranial Direct Current Stimulation; Dorsolateral Prefrontal Cortex Citation: Nguyen AM, Do PT, Bui DHT, Le VT. Transcranial direct current stimulation in spinal cord-injured patients with neuropathic pain. Anaesth. pain intensive care 2025;29(3):480-484. DOI: 10.35975/apic.v29i3.2761 Received: February 23, 2025; Revised: March 04, 2025; Accepted: March 05, 2025