Comparison of Treatment Effects Between Children With Spastic Cerebral Palsy Under and Over Five Years After Botulinum Toxin Type A Injection

Objective To evaluate whether age influences a change in the spasticity of the ankle plantar flexor after botulinum toxin type A (BTA) injection in children with spastic cerebral palsy (CP). Methods Sixteen children with spastic CP were enrolled in the study. Seven children (group 1) were under 5 years of age, and nine (group 2) were over 5 years of age. They all received BTA injection in the gastrocnemius muscle (GCM) under ultrasound guidance. Passive range of motion (PROM) of ankle dorsiflexion, Modified Ashworth Scale (MAS) of the ankle plantar flexor, Gross Motor Function Measure (GMFM) and median red pixel intensity (RPI) of the medial GCM on real-time sonoelastography were measured at baseline (pre-injection) and 1-, 3-, and 6-month post-injection. Results In both groups, the mean PROM, MAS, and RPI were significantly improved after injection until 6-month post-injection. The change of PROM of ankle dorsiflexion in group 1 was significantly greater than that in group 2, until 6-month post-injection. The change in the MAS and GMFM between baseline and 6-month post-injection in group 1 was greater than that in group 2. The changes in the median RPI between baseline and 3- and 6-month post-injections were greater in group 1 than in group 2. Conclusion Our pilot study demonstrated the different changes in spasticity of the ankle plantar flexor after BTA injection based on age. Therefore, age may be considered when establishing a treatment plan using BTA injection for children with spastic CP.