Intramuscular botulinum toxin a (BTXA) in complex regional pain syndrome

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: Patients: 37 patients with spasm/dystonia in the neck and/or upper limb girdle muscles. Intervention: Electromyography-guided injection of botulinum toxin A (BtxA), 10-20 U per muscle. Total dose used was 100 U in each patient. Measurement: Local pain score 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). Ninety-seven percent of the 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 therefore the placebo effect cannot be eliminated. This study does not provide information on the efficacy of this treatment after 4 weeks. Conclusion(s): Intramuscular injection of botulinum toxin A in the upper limb girdle muscles was beneficial for short term relief of pain caused by CRPS in this retrospective case series. The incidence of complications was low (2.7%).