The investigators will recruit participants with CP requiring selective dorsal rhizotomy (SDR) surgery. During SDR, spastic dorsal roots are routinely identified by electrically stimulating each root at low frequency (1 Hz) and measuring the resulting muscle response via electromyography - a procedure called "clinical test stimulation." Dorsal roots that produce an abnormally large and widespread compound muscle action potential (CMAP) are classified as spastic. In this study, the investigators will superimpose higher-frequency dorsal root stimulation (40-5000 Hz) on top of this standard clinical test stimulation and assess whether it suppresses the abnormal large CMAP.
