Botulinum Toxin A for Treatment of Allodynia of Complex Regional Pain Syndrome: A Pilot Study

Objective. To investigate the efficacy and tolerability of Botulinum toxin A (BoNT-A) in allodynia of patients with complex regional pain syndrome. Design. A total of 14 patients were studied. Eight patients were participants of a randomized, prospective, double-blind, placebo-controlled protocol. Six patients were studied prospectively in an open-label protocol. Patients were rated at baseline and at 3 weeks and 2 months after BoNT-A administration. Ratings included brief pain inventory, McGill pain questionnaire, clinical pain impact questionnaire, quantitative skin sensory test, sleep satisfaction scale, and patient global satisfaction scale. BoNT-A was injected intradermally and subcutaneously, five units/site into the allodynic area (total dose 40-200 units). Results. None of the patients with allodynia showed a significant response after treatment. The treatment was painful and poorly tolerated. Conclusion. Intrademal and subcutaneous administration of BoNT-A into the allodynic skin of the patients with complex regional pain syndrome (CRPS) failed to improve pain and was poorly tolerated.