Transcranial direct current stimulation for upper limb neuropathic pain: A double-blind randomized controlled trial

While promising, there are mixed findings for the efficacy of transcranial direct current stimulation (tDCS) for the management of chronic pain. The goal of this study was to evaluate the effect of anodal tDCS on pain and function in people with upper limb neuropathic pain.

The study was a double-blinded, randomized controlled trial. Thirty participants were randomly allocated into active and sham tDCS groups. Baseline assessments of pain and function, as well as quantitative sensory testing (QST) to probe the function of the nociceptive system, were undertaken prior to participants receiving 5 days of active or sham anodal tDCS (1 mA) over the primary motor cortex. The outcome measures were re-assessed 1, 3 and 8 weeks following the intervention.

Group analyses revealed no significant improvement in pain, function, or QST measures over time in either group. However, there were significantly more individual responders (≥30% change in pain) in the active compared to the sham tDCS group at the final follow-up. In the active group, there was a significant correlation indicating those with higher baseline pain had greater pain relief.

On group analyses, no evidence was provided that 1 mA tDCS is beneficial for people with upper limb neuropathic pain, although it may provide lasting pain relief for some individuals.

At the group level, we found no evidence that 5 days of active 1 mA tDCS is effective for people with upper limb neuropathic pain. However, there were more individual responders in the active tDCS group compared to sham, and those who responded early after treatment experienced sustained pain relief.