Kinematic aiming task: measuring functional changes in hand and arm movements after botulinum toxin-A injections in children with spastic hemiplegia.

OBJECTIVE

To describe different aspects of a kinematic aiming task (KAT) as a quantitative way to assess changes in arm movements within 2 wks after botulinum toxin-A (BTX-A) injections in children with spastic hemiplegia.

DESIGN

Intervention study randomized clinical trial; follow-up within 4 wks after baseline measurement.

RESULTS

The KAT gave a high intraclass correlation on movement time, spread of end points (END), and index of performance effective (IP-E). After BTX-A, a significant increase of END and IP-E was shown if precision demand in the KAT was high, whereas the inverse occurred when speed was more important. These functional changes coincided with a significant decrease of the maximum voluntary contraction of the flexor muscles of the forearm. Muscle tone measured with the Ashworth scale did show a nonsignificant decrease of muscle tone, as did the stretch restricted angle and the active and passive ranges of motion of the elbow and wrist.

CONCLUSIONS

Muscle force decreased immediately after BTX-A, showing the direct effect of BTX-A. The KAT is an adequate, reproducible way to quantify functional changes after BTX-A in the upper limb. BTX-A has an inverse effect in the precision task when accuracy is important, and it has a positive effect when speed prevails.