Long-term effect of repeated injections of botulinum toxin in children with cerebral palsy: a prospective study.

PURPOSE To prospectively evaluate long-term effects of repeated botulinum toxin A (BTX-A) injections in children with cerebral palsy (CP). METHODS Repeated injections of BTX-A were offered to children with CP, according to clinical indications, for a maximum of four injections within a period of two years. Injections were administered into lower extremity muscles of 26 consecutive children (age 3.7 +/- 1.2 years, 16 boys) with hemiplegic or diplegic CP. Clinical assessments before and one month following each injection included a gross motor function measure (GMFM), a modified Ashworth scale, and range-of-motion of knee extension and ankle dorsiflexion. RESULTS Twelve children received two injections, six received three injections, five received one injection, and three received four injections. The most common reason for discontinuing treatment was the need for orthopedic surgery (n = 17). A long-term effect was demonstrated by a significant increase of the GMFM score before the first injection compared with the last injection for each patient (P < 0.0001). There was no comparable change in the muscle tone or range-of-motion. The mean rate of GMFM change during the study was significantly higher than literature norms for CP children (13.2 vs. 5.37 per year, respectively, P < 0.01). The increase of the GMFM score before and one-month after injection (short-term effect) was significantly higher after the first injection than after the last injection (P < 0.05). Similar results were found for the Ashworth scale and popliteal angle. CONCLUSIONS Botulinum toxin A injections have a long-term effect on gross motor function in children with CP even though the effect on muscle tone is short-term. The effect apparently declines with repeated injections, with most children benefitting from 2 to 3 injections.