Electrophysiologic studies in selective dorsal rhizotomy for spasticity in children with cerebral palsy.

A group of 20 children with spastic cerebral palsy underwent selective dorsal rhizotomy for alleviation of spasticity. Pre- and postoperatively, cortical somatosensory evoked responses (cSSEP), H reflex and F wave studies were done. Clinically there was dramatic reduction of tone without noticeable sensory loss. The electrophysiologic studies showed several findings: (1) many children have abnormal cSSEP preoperatively; (2) surgery seldom leads to a loss of cSSEP; (3) in many patients, there is a noteworthy improvement in the cSSEP wave form; (4) some children have electrophysiologic evidence of spinal cord dysfunction preoperatively and (5) Hmax/Mmax ratio decreases after surgery confirming decrease in tone.