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; 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.

Measuring movement irregularity in the upper motor neurone syndrome using normalised average rectified jerk.

Movement irregularity is a feature of the upper motor neurone (UMN) syndrome which is difficult to measure. Average rectified jerk (ARJ) has been proposed as a measure of this movement irregularity, but ARJ depends upon the duration of movement. Since movements may be slower in UMN patients, duration dependence compromises ARJ as a measure of irregularity. A normalisation technique is proposed that generates a measure of movement irregularity which is independent of movement duration: normalised average rectified jerk (NARJ). This paper presents a validation of NARJ in the UMN syndrome. Nine control subjects, nine left hemiparetic stroke patients and nine right hemiparetic stroke patients were studied. Test movements comprised elbow extension/flexion in the horizontal plane; these were recorded with an electro-goniometer and accelerometer. The effectiveness of the normalisation technique has been demonstrated using trajectories of various durations; some of these were artificially generated from participants' trajectories, in order to preserve the movement profile. The variability of NARJ and ARJ have been compared in a sample of control subjects. NARJ has been criterion validated by correlation with expert subjective rating of irregularity in a heterogeneous set of trajectories. Construct validity has been tested by discrimination between movements of control subjects, left hemiparetic stroke patients and right hemiparetic stroke patients. When comparing trajectories of identical profile but two-fold difference in movement duration, NARJ differed only 2.6% whereas ARJ differed 706%. NARJ was less reproducible in healthy participants than ARJ: median non-parametric coefficients of variation for repeated movements were 55% and 41%, respectively. Spearman rank correlation coefficient for NARJ and expert rating was 0.92 (p<0.01). NARJ measurements on right hemiparetic patients differ significantly from those made on the control group (p<0.02); corresponding ARJ measurements do not attain statistical significance. NARJ is a valid measure of movement irregularity in the UMN syndrome.