Is Electrical Stimulation Beneficial for Improving the Paralytic Effect of Botulinum Toxin Type A in Children with Spastic Diplegic Cerebral Palsy?

PURPOSE The purpose of the present study was to investigate whether electrical stimulation (ES) improves the paralytic effect of botulinum toxin type A (BTX-A) and evaluate the differences between low frequency (LF) and high frequency (HF) ES in children with spastic diplegic cerebral palsy (CP). MATERIALS AND METHODS Twenty-three children with spastic diplegia CP who had BTX-A injections into both gastrocnemius muscles were assessed. Following the toxin injection, electrical stimulation was given to 1 side of the injected muscles and a sham-stimulation to the other side for 30 min a day for 7 consecutive days [HFES (25Hz) to 11 children, LFES (4Hz) to 12 children]. The compound motor action potentials (CMAP) from the gastrocnemius muscle were assessed before injection and at 5 time points (days 3, 7, 14, 21, and 30) after injection. The clinical assessments of spasticity were performed before and 30 days after injection. RESULTS The CMAP area became significantly lower in both LFES and HFES sides from 3 days after injection compared to baseline values. In other words, the CMAP area of the sham-stimulated side showed a significant decrease at 7 or 14 days after injection. However, there were no significant differences in clinical assessment of spasticity between the stimulated and sham-stimulated sides. CONCLUSION Short-term ES in both LF and HF to the spastic muscles injected with BTX-A might induce earlier denervating action of BTX-A. However, it does not necessarily lead to clinical and electrophysiological benefits in terms of reduction of spasticity.