Effectiveness of transcranial direct current stimulation in the treatment of neuropathic pain following spinal cord injury — The Association Specialists
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Effectiveness of transcranial direct current stimulation in the treatment of neuropathic pain following spinal cord injury (278)

Leigh N McIndoe 1 , Paul J Wrigley 1 2 , Sylvia M Gustin 3 , Rosemary J Chakiath 1 , Luke A Henderson 3 , Philip J Siddall 2 4
  1. Kolling Inst.,University of Sydney, St Leonards, NSW, Australia
  2. Sydney Medical School - Northern, University of Sydney, Sydney, NSW, Australia
  3. Department of Anatomy and Histology, University of Sydney, Sydney, NSW, Australia
  4. Department of Pain Management, HammondCare, Greenwich Hopsital, Greenwich, NSW, Australia

Background
Neuropathic pain is a frequent and debilitating consequence of spinal cord injury (SCI) with no treatments currently available that provide consistent or satisfactory pain relief. Brain stimulation using transcranial direct current stimulation (tDCS) has been proposed to be an effective non-invasive treatment.

Aims
To determine the analgesic efficacy of tDCS in patients with SCI neuropathic pain.

Methods
Ten participants with complete SCI and neuropathic pain received both anodal and sham tDCS using a cross-over design. tDCS was applied over the primary motor cortex at 2mA for 20 mins, over 5 consecutive days. The order of conditions was randomized with a 4-week ‘wash-out’ period between.
Data were collected during baseline, treatment and follow-up (to 6-months). Pain intensity and unpleasantness were the primary outcomes measured by an 11-point numerical rating scale. Other variables assessed were mood (a potential confounder), side-effects and subjects blinding.

Results
We found that neither treatment nor sham tDCS had a significant effect on ongoing pain intensity or pain unpleasantness ratings. At the completion of the tDCS treatment phase, only 1 subject reported a significant (>50%) decrease in ongoing pain intensity.
Subjects in this study were unable to predict accurately the treatment order and there was no appreciable change in mood after either treatment or sham. There was no statistically significant difference in the proportion of side-effects experienced in the active vs sham group.

Discussion
Contrary to previous reports our data show that in individuals with longstanding neuropathic SCI pain, tDCS focused over the primary motor cortex does not provide pain relief. Long injury duration (>20years) was felt to be a potential reason for this profoundly negative trial. Further research needs to asscertain whether tDCS is an effective analgesic in individuals with relatively recent injuries and pain (less than 5 years).

The results of this trial have been recently published[1] 

  1. Wrigley PJ, Gustin SM, McIndoe LN, Chakiath RJ, Henderson LA, Siddall PJ. Longstanding neuropathic pain after spinal cord injury is refractory to transcranial direct current stimulation: A randomized controlled trial. Pain 2013;154(10):2178-2184.