The effect of botulinum toxin type A on the functional ability of the child with spastic hemiplegia a randomized controlled trial.

It has been demonstrated that botulinum toxin type A (BTX-A) injections reduce spasticity and improve muscle growth in children with spasticity. It has been postulated that BTX-A allows the learning of more normal movement patterns. The aim of this study was to measure the effect of this treatment on functional ability, as measured by the Gross Motor Function Measure (GMFM), in children with spastic hemiplegic cerebral palsy. Children of 3--13 years and meeting the selection criteria were randomly allocated to the control or injection group using a matched pair design. A match constituted a child within 6 months of age with the same Modified Ashworth Score (MAS) for the gastroc-soleus and within 10% of the same goal scores on the Gross Motor Function Measure. Twelve matched pairs were enrolled. Outcomes were measured on enrolment and at 1, 3 and 6 months post injection. The time course of the response to BTX-A was assessed with measurements of the MAS, dynamic range of motion (R1) and static muscle length (R2). Motor function was assessed using the 88-item GMFM and parental satisfaction with a 10-point visual analogue scale. Within pair comparisons of the GMFM using the Wilcoxon signed rank test indicated that the treatment group made significantly greater gains than controls at 3 months (P=0.02) with even greater differences seen at 6 months (P=0.004). Using parametric statistics, the intrapair difference in proportional change of GMFM increased from 35% (4 to 65) at 3 months to 52% (17--87) at 6 months. Response to injection was confirmed by a decrease in MAS in the treatment group and very little change in controls. This difference was significant (P=0.002) at 3 months and was attenuated but still significant (P=0.016) at 6 months; the difference in proportional change decreased from 44% at 3 months to 22% at 6 months. Changes in R1 reflected those of MAS in the treatment group and deteriorated significantly over the study period in controls. Parents of children in the treatment group were more satisfied than controls, but satisfaction scores did not correlate with changes in function or technical outcomes suggesting that this may be a placebo effect. The changes in GMFM correlated with changes in technical outcomes at 3 months, suggesting a causal relationship. The intrapair differences in GMFM continued to increase even after the local response to injection had started to wane.