Determinants of responsiveness to botulinum toxin, casting, and bracing in the treatment of spastic equinus in children with cerebral palsy

Abstract

The objective was to determine whether specific intrinsic (age, pattern of cerebral palsy [CP], child's motivation) and extrinsic (number of treatments, parenting stress) characteristics were associated with responsiveness to botulinum toxin A (BoNT-A) injections in children with CP 3 months after injection into the gastrocnemius muscle. Children with hemiplegia or diplegia recruited from a BoNT-A programme were evaluated before and 3 months following injection of BoNT-A into the gastrocnemius. Outcome measures included muscle tone, range of motion, gait pattern, level of ambulation, gross motor function, and functional independence. Determinants of responsiveness to BoNT-A considered were age, number of treatments, distribution of CP, parenting stress, and motivation. Thirty-one children were recruited (17 males, 14 females)--22 with hemiplegia and nine with diplegia. Twenty-eight were classified at Gross Motor Function Classification System (GMFCS) level I and three at level III. The mean age was 6 years 4 months (SD 2y 11mo). Younger age (p=0.015) and fewer number (p=0.024) of BoNT-A treatments were associated with greater change in gross motor function. Child's motivation and parenting stress were significantly associated with improvements in muscle tone (p=0.006-0.017), passive range of motion (p=0.008-0.033), gait pattern (p=0.005-0.042), level of ambulation (p=0.001-0.043), and functional independence (p=0.004-0.027). The results indicate that child, family, and treatment characteristics influence the degree of responsiveness to BoNT-A treatment. The contribution of contextual factors (personal and environmental) on responsiveness may be underappreciated in children with CP.