SPASTICITY AND STRENGTH CHANGES AS A FUNCTION OF SELECTIVE DORSAL RHIZOTOMY

Object. The goal of this investigation was to quantify changes in hams tring muscle spasticity and strength in children with cerebral palsy ( CP) as a function of their having undergone a selective dorsal rhizoto my. Methods. Nineteen children with CP (CP group) and six children wit h able bodies (AB group) underwent testing with a dynamometer. For the spasticity measure, the dynamometer measured the resistive torque of the hamstring muscles during passive knee extension at four different speeds. Torque-angle data were processed to calculate the work done by the machine to extend the knee for each speed. Linear regression was used to calculate the slope of the line of best fit for the work-veloc ity data. The slope simultaneously encompassed three key elements asso ciated with spasticity (velocity, resistance, and stretch) and was con sidered the measure of spasticity. For the strength test, the dynamome ter moved the leg from full knee extension to flexion while a maximum concentric contraction of the hamstring muscles was performed. Torque- angle data were processed to calculate the work done on the machine by the child. Hamstring spasticity values for the CP group were signific antly greater than similar values for the AB group prior to surgery; h owever, they were not significantly different after surgery. Hamstring strength values for the CP group remained significantly less than tho se for the AB group after surgery, but were significantly increased re lative to their presurgery values. Conclusions. The results of spastic ity testing in the present investigation agreed with those of previous studies, indicating a reduction in spasticity for the CP group. The r esults of strength testing did not agree with those in the previous li terature; a significant increase in strength was observed for the CP g roup.