Intramuscular botulinum toxin in complex regional pain syndrome: case series and literature review.

BACKGROUND Pain associated with Complex Regional Pain Syndrome (CRPS) is frequently excruciating and intractable. The use of botulinum toxin for relief of CRPS-associated pain has not been well described. OBJECTIVES To assess whether intramuscular botulinum toxin injections cause relief of pain caused by CRPS, and to assess the risks of this treatment. STUDY DESIGN Retrospective chart review. SETTING Outpatient clinic. METHODS 37 patients with spasm/dystonia in the neck and/or upper limb girdle muscles. INTERVENTION EMG-guided injection of Botulinum Toxin - A (BtxA), 10-20 units per muscle. Total dose used was 100 units in each patient. Local pain score was measured on an 11-point Likert scale, 4 weeks after BtxA injections. RESULTS Mean pain score decreased by 43% (8.2 ± 0.8 to 4.5 ± 1.1, P < 0.001). 97% patients had significant pain relief. One patient had transient neck drop after the injections. LIMITATIONS This is a retrospective study, it lacks a control group and hence the placebo effect cannot be eliminated. This study does not provide information on the efficacy of this treatment after 4 weeks. CONCLUSIONS Intramuscular injection of botulinum toxin in the upper limb girdle muscles was beneficial for short term relief of pain caused by CRPS. The incidence of complications was low (2.7%).