Botulinum Toxin A: A Novel Therapeutic Modality for Upper Extremity Chronic Regional Pain Syndrome.

[BACKGROUND] Complex regional pain syndromes (CRPS) is a disease that is poorly understood. It is a chronic pain syndrome characterized by sympathetic disruptions as well as CNS sensitization. Botulinum Toxin-A has been shown to have efficacy in Raynaud's as well as other neuropathic pain disorders. Perhaps BTX-A warrants experimentation in the treatment of CRPS.

[METHODS] Patients with CRPS refractory to 2 or more regional sympathetic nerve blocks in 2007 were included in the study. Patient's were asked to rank their initial pain on a visual analog scale of 0 to 10 (10 being the worst pain). "Tenderness maps" were marked on patient's areas of most pain in 1 by 1 centimeter grids. Each box on the grid was injected with 10 IU of BTX-A after nerve blocks with 1% lidocaine. Treatment sessions occured on a monthly basis with VAS pain scores being re-assessed immediately before the new treatment. Test, linear regression, and Cohen's D-test were used to analyze the correlation of the data.

[RESULTS] Study sample was 20 patients. Etiology of CRPS was 6 amputations, 4 crush injuries, 4 penetrating injuries, and 2 lacerations. Average pain reduction on VAS scale achieved was 2.05 points. Average percentage pain reduction was 22.94%. Cohen's D Test also showed a meaningful difference with a score of 1.01. Linear regression R2 = 0.491. Maximum pain reduction, on average, was achieved by treatment 9.

[CONCLUSION] Despite the esoteric etiology of CRPS, BTX-A has a well-demonstrated mechanism of effect. BTX-A should be further explored as a treatment modality for CRPS.