Associated reactions after stroke: a randomized controlled trial of the effect of botulinum toxin type A.
To measure the impact of botulinum toxin A on associated reactions in patients following stroke. Randomized placebo-controlled trial. Forty patients with spasticity in their paretic arm (median time since stroke: 2.7 years) were randomized to botulinum toxin A (Dysport; 1000 mouse units (MU) divided between elbow, wrist and finger flexors) or placebo. 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. 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). 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.