Correlation of botulinum toxin dosage and GMFCS level in children with bilateral spastic cerebral palsy – An explorative cohortstudy

Introduction: Multi-level treatment with botulinum toxin type A (BoNT/A; Botox®) plays a central role within the integrative treatment strategy in children with cerebral palsy (CP). Goal of this study was to analyse the dosage/kg bodyweight (b.w.) in correlation to the severity of CP according to GMFCS level and to prove the hypothesis, that dosage is not severity dependent but correlates to the number of treated muscles.

Method: 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 BoNT/A specific parameters were assessed (age, gender, body weight; aetiology, severity, and type of CP; dosage/session, -/muscle, -/kg b.w., and number of treated muscles). Both cohorts were analysed separately for the GMFCS subgroups.

Results: In cohort A 466 sessions could be analysed versus 151 sessions in cohort B. Mean dosage/kg b.w. was 16.1 Units/kg b.w. versus 18.1 Units/kg b.w. in cohort B. Mean dosage/kg b.w. showed a peak in GMFCS levels III and IV in both cohorts (cohort A: GMFCS I: 11.4 U/kg b.w., GMFCS II: 13.6 U/kg b.w., GMFCS III: 17.6 U/kg b.w., GMFCS IV: 18.7 U/kg b.w., GMFCS V: 16.4 U/kg b.w.; cohort B GMFCS I:15.9 U/kg b.w., GMFCS II: 19.7 U/kg b.w., GMFCS III: 21.4 U/kg b.w., GMFCS IV: 21.4 U/kg b.w., GMFCS V:16.0 U/kg b.w.).

Conclusion: The distribution of dosage/kg b.w. supports the hypothesis, that dosage is not severity dependant, and patients with GMFCS levels III and IV require the highest dosages of BoNT/A to achieve an adequate multi-level treatment.