Associated reactions after stroke: A randomized controlled trial of the effect of botulinum toxin type A

Objective: To measure the impact of botulinum toxin A on associated reactions in patients following stroke. Design: Randomized placebo-controlled trial. Patients: Forty patients with spasticity in their paretic arm (median time since stroke: 2.7 years) were randomized to botulinum toxin A (Dysport (R); 1000 mouse units (MU) divided between elbow, wrist and finger flexors) or placebo. Methods: Associated reactions were measured using hand dynamometry. The effort used was measured using maximum voluntary grip in the unaffected arm. Measurements were recorded at 2 pre-treatment and 3 post-intervention times. Activities that patients felt caused associated reactions and activities that were affected by associated reactions were recorded. Results: Peak associated reactions force was reduced at week 6 with botulinum toxin A compared with placebo (mean group difference 19.0 N; 95% confidence interval (CI): 7.2, 30.9; p < 0.01) and week 2 (p = 0.005), with the effect wearing off by week 12 (p = 0.09). Thirty-one patients noted associated reactions on a regular basis and 24 said that these movements interfered with daily activities. Ten of 12 patients receiving botulinum toxin A and 2 of 12 receiving placebo reported reduction in interference with daily activities (p = 0.02). Conclusion: Botulinum toxin A reduces associated reactions and may be a useful adjunct to other rehabilitation interventions. The impact of associated reactions on daily activities may also be reduced.