Safety of botulinum toxin treatment in children with cerebral palsy in correlation to GMFCS level

Introduction: Botulinum toxin (BoNT/A, Botox®) treatment plays a central role within the multi-modal treatment strategy in children with cerebral palsy (CP). Although it is well tolerated, the reason for development of adverse events (AE) remains unclear. The goal of this study was to differentiate AE in correlation to severity of CP according to GMFCS level and to look for special riscfactors for the occurrence of AE. Methods: Retrospective data analysis from January 2000– March 2003 (cohort A: Duisburg, Wedau clinics), prospective data analysis from April 2003– November 2005 (cohort B: Munich, Dr. v. Hauner's Chidren's Hospital, University of Munich). Demographic, disease related and AE specific parameters were assessed (age, gender, body weight, aetiology, severity, and type of CP, duration, severity and type of AE). Both cohorts were analysed separately for the GMFCS subgroups. Additionally sessions with AE were assessed separately from the total subgroup. Results: in cohort A 466 sessions could be analysed versus 151 sessions in cohort B. The highest incidence of AE in cohort A was seen in 11/10 (10%) sessions of subgroup GMFCS III [GMFCS I: 3/81 (3.7%), GMFCS II: 7/110 (6.4%), GMFCS IV: 9/110 (8.2%), GMFCS V: 3/55 (5.5%)]. In cohort B the highest incidence of AE was seen in 8/37 (21.6%) sessions of subgroup GMFCS I [GMFCS II: 4/31 (12%), GMFCS III: 6/42 (14.3%), GMFCS IV: 2/25 (8.0%), GMFCS V: 1/13 (7.7%]. Within both cohorts the age of children with AE was lower than in the total cohort (cohort A with AE 70 vs. 91 months; cohort B: 66 vs. 78 months). Conclusion: The occurrence of AE seems to be more likely in younger patients with CP. Taking both cohorts together, the risk for the occurrence of AE is the highest (11.2%) in children with GMFCS level III.