OBJECTIVETo evaluate the clinical application of intraoperative electrophysiological monitoring in lumbosacral selective posterior rhizotomy for spastic cerebral palsy.

METHODSTotal 372 dorsal roots of 89 patients underwent selective posterior rhizotomy at a single medical center. The dorsal roots from L3 to S1 were divided into rootlets and stimulated with a 1-second 50 Hz train. Motor responses were recorded by electromyography. Rootlets were assigned according to the extent of abnormal electrophysiological propagation, and grades of 3+ to 4+ were cut. If no electrical response was observed, the second criterion is the behavioral response (that is, muscle contraction in the legs or toes) assessed by the physical therapist, when rootlets were stimulated at the lowest threshold with a 1-second 50 Hz train.

RESULTSThe rootlets of 340 dorsal roots were assigned according to the extent of abnormal electrophysiological propagation, 324 (83.5%) roots were assigned the maximally abnormal response of grade 3+ (76, 22.4%) or 4+ (248, 72.9%) in EMG monitoring and were cut. For no electrical response was observed, according to the second criterion, 48 roots were partially cut. It was also be found that free running EMG occurred earlier than stimulus triggered EMG, and identified "abnormal" rootlets on free running EMG monitoring was more easily and quickly than on stimulus triggered EMG. During the postoperative 2 weeks in hospital, there was a significant decrease in lower-limb spasticity and an increase in range of movement in all patients, and no one case occurred obvious loss of muscle strength, abnormity of sensory, or deterioration of bladder/bowel control.

CONCLUSIONSThe spread of electromyography response to the contra lateral limb and/or upper extremity remains a valid criterion to define a "abnormal" posterior nerve rootlet that feeds into a disinhibited spinal circuit involved in uncontrolled spasticity. Intraoperative electrophysiological monitoring is reproducible and reliable for selection of "abnormal" rootlets.