Electrophysiological Changes after Botulinum Toxin Type A in Children with Cerebral Palsy

ABSTRACT

OBJECTIVE: To investigate the electrophysiological changes after botulinum toxin type A injection in children with cerebral palsy. METHOD: Sixteen children with spastic cerebral palsy enrolled in the study. Botulinum toxin type A (Dysport(R)) was injected into gastrocnemius muscles. Electrophysiological assessments included the compound motor action potential of the tibial nerve, the sensory nerve action potential of the sural nerve, the H-reflex and the T-reflex before injection, and at 2 weeks and 4 weeks after the injection. Modified Ashworth scale was used to evaluate spasticity before, 2 weeks and 4 weeks after the injection. RESULTS: Modified Ashworth scale of the ankle decreased at 2 weeks and 4 weeks after injection. The amplitude of the H-reflex and H(max)/M(max) ratio decreased significantly at 4 weeks. The amplitude of the T-reflex decreased at 2 weeks and 4 weeks. The correlation between changes in modified Ashworth scale of the ankle and the changes in electrophysiological parameters at 4 weeks after injection were not significant. CONCLUSION: The change in T-reflex is faster than the change of H-reflex and H(max)/M(max) ratio after botulinum toxin A injection in children with cerebral palsy. Electrophysiological tests could quantify the change in spasticity after botulinum toxin injection.