Quantitative assessment for flexed-elbow deformity during gait following botulinum toxin A treatment

The effect of botulinum toxin A (BoNTA) injection on flexed-elbow deformity is usually evaluated using the Modified Ashworth Scale (MAS), but only with the muscle tone at rest. Some patients show the flexed-elbow deformity during gait despite low muscle tone at rest.

This study aimed to evaluate the effect of BoNTA injection on flexed-elbow deformity during gait using a three-dimensional motion analysis system.

Twenty stroke patients with spastic flexed-elbow deformity during gait received BoNTA injections into the upper limb muscles. The MAS score of the elbow flexors, passive elbow range of motion, comfortable overground gait velocity, and elbow flexion angle during treadmill gait were evaluated just before and 2, 6, and 12 weeks after the injection. Twenty-five healthy subjects were also recruited to provide a normal reference of the elbow flexion angle.

The MAS scores at 2, 6 and 12 weeks after the injection were significantly lower than that before the injection. Some patients showed no spasticity at rest but an obviously flexed elbow during gait. The elbow flexion angles during gait at 2 and 6 weeks after the injection were significantly lower than that before the injection.

BoNTA injections to the upper limb muscles reduced muscle tone at rest and flexed-elbow deformity during gait. However, the elbow flexion angle during gait returned to its pre-injection level sooner than the muscle tone at rest. We strongly recommend evaluating muscle tone during motion and at rest, preferably using three-dimensional motion analysis since it can objectively detect small changes.