A randomized, double-blind, prospective pilot study of botulinum toxin injection for refractory, unilateral, cervicothoracic, paraspinal, myofascial pain syndrome.

STUDY DESIGN: In a randomized, double-blind study, two dosage strengths of botulinum toxin type A were compared with normal saline injected into symptomatic trigger points in the cervicothoracic paraspinal muscles.

OBJECTIVES: To compare the effect of botulinum toxin type A injections with that of normal saline to determine the former's usefulness in the management of neck pain and disability.

SUMMARY OF BACKGROUND DATA: The results of several studies have suggested that botulinum toxin type A may reduce pain associated with myofascial pain syndromes.

METHODS: Thirty-three participants were divided randomly to receive either 50 or 100 units of botulinum toxin type A, or normal saline. Patients were re-evaluated over a 4-month period by assessment of their pain and disability and pressure algometer readings, and then offered a second injection of 100 units of botulinum toxin type A.

RESULTS: All three groups showed significant treatment effects as measured by a decline in the scores on the Neck Pain and Disability Visual Analogue Scale and an increase in the pressure algometer scores. Group differences were apparent only when the authors considered the number of patients who were asymptomatic as a result of the injections.

CONCLUSIONS: Although no statistically significant benefit of botulinum toxin type A over placebo was demonstrated in this study, the high incidence of patients who were asymptomatic after a second injection suggests that further research is needed to determine whether higher dosages and sequential injections in a larger cohort might show a botulinum toxin type A effect.