A randomized controlled study of botulinum toxin A in the treatment of hemiplegic shoulder pain associated with spasticity

Objectives: To assess the effects of botulinum toxin A (BT-A) on hemiplegic shoulder pain associated with spasticity. Design: Randomized, double-blind, placebo-controlled study, Setting: Outpatient clinic of a rehabilitation department. Participants: Patients, more than three months post stroke, with hemiplegic shoulder pain associated with shoulder adductor and elbow flexor spasticity, randomly assigned to BT-A or placebo. Intervention: One-time injection of BT-A (500 units) into the pectoralis major and biceps brachii on the hemiplegic side. Main measures: Visual analogue scale of shoulder pain (0-10), shoulder adductor and elbow flexor tone using the Ashworth Scale and passive range of shoulder abduction. These were assessed at baseline, four weeks, eight weeks and 12 weeks post injection. Results: Seventeen patients were enrolled, eight in the BT-A group and nine in the placebo group. At baseline, the median visual analogue scale score for shoulder pain was 6, the median Ashworth Scale shoulder adductor and elbow flexor spasticity score was 2 and the median range of shoulder abduction 76 degrees. Subjects who received BT-A showed significantly greater improvements in median shoulder adductor and elbow flexor Ashworth Scale scores than placebo at week 4 (P < 0.01) but not at week 8 and 12. For shoulder pain and passive shoulder abduction range, all subjects showed postinjection improvements and no difference could be demonstrated between the two groups. Discussion: Possible reasons for the negative finding in this study include the small sample size and the presence of causes of shoulder pain not related to spasticity which could have confounded outcome.