A sham-controlled, phase II trial of transcranial direct current stimulation for the treatment of central pain in traumatic spinal cord injury

TLDR

Motor cortical stimulation, both invasive and non‑invasive, has previously been shown to relieve central pain, possibly via secondary modulation of thalamic nuclei activity. The study aimed to evaluate the effect of transcranial direct current stimulation on pain control in patients with central pain after traumatic spinal cord injury. Patients were randomized to receive 5 days of 2‑mA, 20‑minute motor‑cortex tDCS or sham, with pain assessed by VAS, CGI, and PAG, and safety monitored via neuropsychological testing and depression/anxiety measures. Active anodal tDCS produced significant pain relief that was not observed with sham, was not confounded by changes in depression or anxiety, and did not alter cognitive performance, indicating that this cortical stimulation approach can effectively control pain in spinal cord injury patients.

Abstract

Past evidence has shown that motor cortical stimulation with invasive and non-invasive brain stimulation is effective to relieve central pain. Here we aimed to study the effects of another, very safe technique of non-invasive brain stimulation – transcranial direct current stimulation (tDCS) – on pain control in patients with central pain due to traumatic spinal cord injury. Patients were randomized to receive sham or active motor tDCS (2 mA, 20 min for 5 consecutive days). A blinded evaluator rated the pain using the visual analogue scale for pain, Clinician Global Impression and Patient Global Assessment. Safety was assessed with a neuropsychological battery and confounders with the evaluation of depression and anxiety changes. There was a significant pain improvement after active anodal stimulation of the motor cortex, but not after sham stimulation. These results were not confounded by depression or anxiety changes. Furthermore, cognitive performance was not significantly changed throughout the trial in both treatment groups. The results of our study suggest that this new approach of cortical stimulation can be effective to control pain in patients with spinal cord lesion. We discuss potential mechanisms for pain amelioration after tDCS, such as a secondary modulation of thalamic nuclei activity.