Purpose: The purpose of this proof of concept study is to demonstrate that electromyographic (EMG) activation patterns of leg muscles differ predictably among patients with predominantly spasticity, patients with predominantly dystonia, and typically developing control subjects during rest, volitional movement, and passively induced movement.
Methods: Eight control subjects, 6 subjects with dystonia, and 7 subjects with spasticity were recruited, ages 6-25 years. Surface EMG sensors were applied over 4 muscle groups of each leg. EMG recordings and video were obtained during rest, quick stretch, and volitional movement. The number of muscles active during 3 resting, 4 quick stretch, and 8 volitional movement items were averaged and compared across subject groups.
Results: Control subjects showed minimal numbers of muscles active during resting, quick stretch, or volitional movement activities. Spastic subjects showed multiple muscles responding with high amplitude to quick stretch but not to volitional movement activities. Dystonic subjects showed multiple muscles responding to volitional movement activities but not to quick stretch. Analysis with a Kruskal-Wallis test indicated significant differences between the three groups in numbers of muscles activated during quick stretch activities (p= 0.017) and volitional movement activities (p= 0.005).
Conclusion: EMG data collected with this protocol may be useful for distinguishing spastic from dystonic hypertonia.
Keywords: Cerebral palsy; dystonia; electromyography; hypertonia; spasticity.