1. 2011;14;419-424Intramuscular Botulinum Toxin in Complex Regional Pain Syndrome: Case Series and Literature Review
   Retrospective Audit
   Prakash Ambady, MD, Yedatore S. Venkatesh, MD, Robert J. Schwartzman, MD, and Siddharth Kharkar, 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 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%)

INSTITUTIONAL REVIEW: This study was approved by the Institutional Review Board of the Drexel College of Medicine.