Quantifying muscle activity in non-ambulatory children with spastic cerebral palsy before and after selective dorsal rhizotomy

Cerebral palsy is a condition that results in varying degrees of functional deficits. The goal of this study was to develop an objective measure of mu scle activity during a prescribed voluntary motor task in non-ambulatory ch ildren with spastic cerebral palsy. While performing a simultaneous hip/kne e flexion task from the supine position, followed by return to the starting position, electromyographic and kinematic data were obtained from the righ t leg of eight children before and after selective dorsal rhizotomy and com pared with eight age-matched controls. The electromyographic and kinematic data were combined to determine for each muscle of interest (tibialis anter ior, soleus, vastus lateralis, biceps femoris) the percentage of the moveme nt cycle for which the muscle was acting concentrically, eccentrically, iso metrically or was considered inactive. Averaged over the four muscles, isom etric activity decreased by 38% post-op and the time the muscles were inact ive increased by 37% following surgery. The percentages of concentric and e ccentric activity did not differ significantly between pre- and post-op con ditions. Post-operatively, the percentage muscle activity patterns of the c hildren with cerebral palsy more closely resembled that of the control chil dren: averaged across all muscles and contraction types, the difference bet ween the control children and the children with cerebral palsy was reduced by 50% following surgery. This measurement technique indicates promise as a method for quantifying muscle activity during voluntary motor tasks in non -ambulatory children with cerebral palsy. (C) 2001 Elsevier Science Ltd. Al l rights reserved.