Somatosensory evoked potentials following functional posterior rhizotomy in spastic children.

Ten children with cerebral palsy and severe lower limb spasticity were treated by functional posterior rhizotomy (FPR). Somatosensory evoked potential recordings were performed preoperatively, intraoperatively (directly on the surface of the spinal cord) and 6 months after surgery, to evaluate the effects of FPR on lower limb somatosensory function. Before surgery, 7/10 patients showed abnormal cortical responses after tibial stimulation. In all patients, intraoperative recordings showed a reduction in the amplitude of segmental responses (N22) (50 +/- 25% of reference value) after the section of a mean 50% of L2-S2 dorsal rootlets. The modifications of segmental responses (N22) were maintained 6 months after surgery, whereas reduction of cortical responses (P39) did not reach the significance level when compared with preoperative recordings.