Residual spasticity after selective posterior rhizotomy.

The technique used in performing selective posterior rhizotomies to treat spastic cerebral palsy remains controversial. One hundred nine children who had undergone selective posterior rhizotomies were studied 6 months after their surgery. Their residual spasticity was correlated to the number of roots and whether or not abnormally responding roots were left, in order to validate the surgical technique used to treat spastic cerebral palsy at most neurosurgical centers in North America. The children were divided into three groups (group A: children who had their L2-S1 roots tested and selectively lesioned, n = 15; group B: children who had their L2-S2 roots tested and selectively lesioned, n = 62; group C: children who had their L2-S2 roots tested and whose lesioning was directed both by the response to the stimulation and mapping of the S1-S3 dorsal roots for afferent pudendal nerve activity, n = 32). Clinically significant residual spasticity was present in the gastrocnemius in 33% of the group A children, 11% of the group B children, and 6% of the group C children. We found that there was no significant increase in residual spasticity in the group C children when abnormally responding roots were not cut in order to preserve pudendal nerve activity. This study shows that the inclusion of the S2 roots decreases the amount of residual spasticity (P < 0.01). It also shows that leaving abnormally responding S2 roots to preserve pudendal nerve activity does not affect the incidence of postoperative spasticity (P > 0.1).