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). Ninetyseven 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%)
Key words: Complex regional pain syndrome, botulinum toxin, spasm, dystonia
Botulinum Toxin A for Treatment of Allodynia of Complex Regional Pain Syndrome: A Pilot Study
