Botulinum toxin type A treatment in children with spastic cerebral palsy: documentation of the short-term effect with general motor function-measure (GMFM)

Objective: Botulinum toxin type A (BTX-A) has gained widespread acceptance during the last years as an adjunctive therapy for the management of children with spastic cerebral palsy (CP). The Gross Motor Function Measure (GMFM) evaluates quantitative (and at a lesser degree qualitative) motor changes in children with CP over a certain time frame (age at administration: 6 months –16 years).

Method: In a prospective study, the effect of BTX-A injection was studied in 52 patients with spastic CP (34 males, 18 females) 18–150 months old (56.1±29.3). 9 patients had a spastic diplegia, 32 had spastic tetraplegia and 11 had spastic hemiplegia. The grade of the motor function involvement was classified according to the Gross Motor Function Classification System (GMFCS). Patients with spastic diplegia received selectively injections in muscles of the lower extremities (gastrocnemius and adductors) while patients with either spastic tetraplegia or hemiplegia received additional injections in muscles of the upper extremities (biceps and ulnar flexors). The mean dose for both was 16.5 ÉU/kg/bw and 43.5 ÉU/kg/bw (BOTOX and DYSPORT, respectively). All patients were receiving BTX-A for the first time and all were evaluated with GMFM from 3 different observers and videotaped the day before as well as 6 weeks after the injection.

Results: The evaluation of all three observers demonstrated similar results (intra-observer agreement; F=0.9999 & p=0.996; one way ANOVA), while there was a statistically significant difference between the scores before and after the BTX-A injection (35.85±32.44 vs. 38.17±33.11; p<0.001, paired t-test). Similar statistically significant differences could be demonstrated in 4 out of the 5 GMFM dimensions (B-E) (p<0.001, p=0.002, p=0.004 and p=0.001, for sitting (dimension B), crawling and kneeling (dimension C), standing (dimension D) and walking, running and jumping (dimension E), respectively), except for dimension A (lying and turning; p=0.089). Similar differences were found in 41 out of the 52 patients who were reevaluated by 2 different examiners. Only 3 patients demonstrated mild and totally reversible side effects (hypotonia of the shoulder muscles Í=1, dysphagia Í=1 and pain at injection’s site Í=1).

Conclusion: The GMFM is a standardised and validated tool, which can also document the short-term effect of BTX-A therapy in children with spastic CP.

Keywords: botulinum toxin type A, GMFM, cerebral palsy