Botulinum toxin type A for neuropathic pain in patients with spinal cord injury.

[OBJECTIVE] To evaluate the analgesic effect of botulinum toxin type A (BTX-A) on patients with spinal cord injury-associated neuropathic pain.

[METHODS] The effect of BTX-A on 40 patients with spinal cord injury-associated neuropathic pain was investigated using a randomized, double-blind, placebo-controlled design. A 1-time subcutaneous BTX-A (200U) injection was administered to the painful area. Visual analogue scale (VAS) scores (0-100mm), the Korean version of the short-form McGill Pain Questionnaire, and the World Health Organization WHOQOL-BREF quality of life assessment were evaluated prior to treatment and at 4 and 8 weeks after the injection.

[RESULTS] At 4 and 8 weeks after injection, the VAS score for pain was significantly reduced by 18.6 ± 16.8 and 21.3 ± 26.8, respectively, in the BTX-A group, whereas it was reduced by 2.6 ± 14.6 and 0.3 ± 19.5, respectively, in the placebo group. The pain relief was associated with preservation of motor or sensory function below the neurological level of injury. Among the responders in the BTX-A group, 55% and 45% reported pain relief of 20% or greater at 4 and 8 weeks, respectively, after the injection, whereas only 15% and 10% of the responders in the placebo group reported a similar level of pain relief. Improvements in the score for the physical health domain of the WHOQOL-BREF in the BTX-A group showed a marginal trend toward significance (p = 0.0521) at 4 weeks after the injection.

[INTERPRETATION] These results indicate that BTX-A may reduce intractable chronic neuropathic pain in patients with spinal cord injury.