Longstanding neuropathic pain after spinal cord injury is refractory to transcranial direct current stimulation: A randomized controlled trial

• Published in: Pain (Amsterdam) Vol. 154; no. 10; pp. 2178 - 2184
• Main Authors: Wrigley, Paul J., Gustin, Sylvia M., McIndoe, Leigh N., Chakiath, Rosemary J., Henderson, Luke A., Siddall, Philip J.
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Elsevier B.V 01-10-2013; Lippincott Williams & Wilkins, Inc; Elsevier
• Subjects: Adult; Aged; Below-level neuropathic pain; Biological and medical sciences; Clinical trial; Cross-Over Studies; Female; Follow-Up Studies; Fundamental and applied biological sciences. Psychology; Humans; Male; Medical sciences; Middle Aged; Nervous system involvement in other diseases. Miscellaneous; Neuralgia - diagnosis; Neuralgia - epidemiology; Neuralgia - therapy; Neurology; Neuropathic pain; Pain Management - methods; Pain Measurement - methods; Randomised controlled trial; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Spinal Cord Injuries - diagnosis; Spinal Cord Injuries - epidemiology; Spinal Cord Injuries - therapy; Spinal cord injury; Thoracic Vertebrae; Time Factors; Transcranial direct current stimulation; Transcranial Magnetic Stimulation - methods; Treatment Outcome; Vertebrates: nervous system and sense organs; Below-level neuropathic pain; Clinical trial; Spinal cord injury; Transcranial direct current stimulation; Randomised controlled trial; Neuropathic pain; Spinal cord; Central nervous system; Controlled therapeutic trial; Stimulation; Lesion
• ISSN: 0304-3959; 1872-6623
• DOI: 10.1016/j.pain.2013.06.045

In a randomized sham-controlled crossover study, transcranial direct current stimulation over the primary motor cortex did not provide relief for long-standing neuropathic spinal cord injury pain.
Neuropathic pain remains one of the most difficult consequences of spinal cord injury (SCI) to manage. It is a major cause of suffering and adds to the physical, emotional, and societal impact of the injury. Despite the use of the best available treatments, two thirds of people experiencing neuropathic pain after SCI do not achieve satisfactory pain relief. This study was undertaken in response to a recent clinical trial reporting short-term, clinically significant reductions in neuropathic SCI pain with primary motor cortex transcranial direct current stimulation (tDCS). In this investigation, we aimed to build on this previous clinical trial by extending the assessment period to determine the short-, medium-, and long-term efficacy of tDCS for the treatment of neuropathic pain after SCI. We found that, contrary to previous reports, after 5 tDCS treatment periods, mean pain intensity and unpleasantness rating were not significantly different from initial assessment. That is, in this trial tDCS did not provide any pain relief in subjects with neuropathic SCI pain (n=10). A similar lack of effect was also seen after sham treatment. Because the injury duration in this study was significantly greater than that of previous investigations, it is possible that tDCS is an effective analgesic only in individuals with relatively recent injuries and pain. Future investigations comparing a range of injury durations are required if we are to determine whether this is indeed the case.