Long-term use of botulinum toxin type A in children with cerebral palsy: treatment consistency.

At the University Hospital of Pellenberg (Belgium), more than 1000 patients have been treated with Botulinum toxin type A (BTX-A) over the last decade. Ten percent of these patients (n=106) received multiple (at least four times), multi-level, high-dosage treatments. The aim of this study was to evaluate the stability of dosage and treatment intervals in long-term, multi-level, high-dosage treated children with cerebral palsy and to evaluate the evidence for a safe and stable response to this treatment. Data on disease, age, dosage and target muscles were extracted for each treatment session of 106 patients who received multiple BTX-A treatment sessions. Patients had a follow-up of 4y 6mo (range 1y 8mo-8y 9mo) on average and received 4 to 12 BTX-A treatments within the period of January 1996 and December 2005. Patients received a mean dosage of 23.5+/-5.2U/kgbw at first treatment with stable subsequent values. Mean dosages for children with diplegia, hemiplegia and quadriplegia were 24.5+/-4.7U/kgbw, 15.9+/-3.7U/kgbw and 22.0+/-4.8U/kgbw, respectively. Mean age at first treatment was 4y 6mo (range 1y 11mo-18y 10mo) with a majority of patients (76.4%) first treated within 2 and 4y of age. Treatment intervals of approximately 1y remained stable within four, five and six subsequent treatments. Long-term, high-dosage, multi-level BTX-A applications can be considered as a safe and stable treatment option for children with cerebral palsy and the formation of antibodies, responsible for secondary non-response, can be indirectly precluded.