Enhancement of muscle activity by electrical stimulation in cerebral palsy: a case-control study.
The objectives of this study were to compare the effects of low-intensity electrical stimulation of the quadriceps muscle in children with cerebral palsy in the following 2 modes: reconditioning by long-term training of the muscle versus real-time assist to the muscle during motion. To evaluate the force enhancement in the assist mode, we developed a method to dissociate the volitional and the induced components from the total electromyographic signal. The study group, including 5 children with cerebral palsy (mean age, 3.3 years; 0.4 SD), underwent 2 testing sessions: 1 before and 1 after 3-month training by electrical stimulation. Each session included 2 series of trials: 1 with electrical stimulation, as an orthotic assist, and 1 without electrical stimulation. The tests included flexion-extension movements of the knee at a self-selected pace. The results showed that, compared to before training, there was a significant increase in the average motion velocity and a decrease in motion jerk and in knee torque after training in both the electrical stimulation- assisted and -unassisted modes. Of special interest was the significant decrease in quadriceps-hamstrings co-contraction following training by electrical stimulation but not during electrical stimulation-assisted motion. The results obtained for the group with cerebral palsy were statistically different from those of the control group, but this difference decreased after long-term training by electrical stimulation. It was concluded that, in children with cerebral palsy, electrical stimulation is more beneficial in long-term training than when used as a real-time motion assist. Although muscle strength is not affected, more centrally controlled attributes such as co-contraction are improved.
Katz
Amir
A
Department of Biomedical Engineering, Israel Institute of Technology, Haifa.
Tirosh
Emanuel
E
Marmur
Rachel
R
Mizrahi
Joseph
J
D001696:Biomechanical Phenomena; D002547:Cerebral Palsy / Q000628:therapy*; D002675:Child, Preschool; D004599:Electric Stimulation Therapy / Q000379:methods*; D004576:Electromyography; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D009048:Motor Skills / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D009989:Orthotic Devices; D052097:Quadriceps Muscle / Q000503:physiopathology*; D012016:Reference Values; D013710:Tendons / Q000502:physiology