Under what circumstances would you consider a selective dorsal rhizotomy for treatment of lower extremity spasticity?

There are two basic categories to indicate a patient for SDR. The first category is ambulatory patients for whom we are looking to improve the quality of gait. These are generally patients around 3-8 years of age, GMFCS II-III, who have good ability to comply with PT instructions, good selective motor control, and adequate strength in the legs to withstand removal of their "support" from their spasticity. We often look for patients with CP with a history of prematurity and spastic diplegia with PVL on MRI of the brain. The second category is nonambulatory patients, GMFCS IV-V, who are being indicated for surgery to improve tone for quality of life alone. I generally do this with a combined ventral rhizotomy since the goal is significant ton...