1. 2011;14;311-316Intramuscular Botulinum Toxin A (BtxA) in Complex Regional Pain Syndrome
   Retrospective Review
   Siddharth Kharkar, MD, Prakash Ambady, MD, Venkatesh Yedatore, MD, and Robert J. Schwartzman, MD.

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%)