RELATIONSHIP OF INTRAOPERATIVE ELECTROPHYSIOLOGICAL CRITERIA TO OUTCOME AFTER SELECTIVE FUNCTIONAL POSTERIOR RHIZOTOMY

At British Columbia's Children's Hospital, the criteria used in select ive functional posterior rhizotomy (SFPR) evolved in three distinct ph ases. In Phase 1 the electrophysiological criteria for abnormality inc luded a low threshold to a single stimulation, a sustained response to 50-Hz stimulation, and spread outside the segmental level being stimu lated. In Phase 2 the electrophysiological criteria were unchanged, bu t fewer L3-4 nerve roots were cut. Tn Phase 3, fewer L3-4 nerve roots were cut, as in Phase 2, but based on the results of posterior nerve r oot stimulation in nonspastic controls, the only electrophysiological criterion used was contralateral and suprasegmental spread. The presen t study examined the relationship between the criteria used in each ph ase and patient outcome. The records of 77 consecutive children who un derwent SFPR and had a minium follow-up period of 1 year were reviewed , comprising 25, 19, and 33 patients in Phases 1, 2, and 3, respective ly. Outcome parameters included quantitative assessments of lower-limb spasticity and range of motion, and qualitative assessments of lower- limb function. In Phase 3, 52% of the nerve roots were cut, compared t o 66% in Phases 1 and 2. In all three phases there was a significant d ecrease in lower-limb spasticity and an increase in range of movement, with the smallest decrease in spasticity in Phase 3. Over 90% of chil dren in each phase improved with respect to lower-limb function, and e xcluding independent walkers and quadriplegics confined to a wheelchai r, improvement in the level of ambulation occurred in 87.5%, 71.4%, an d 73.7% of patients, in Phases 1, 2, and 3, respectively.