Section Information: Abstracts of Poster and Platform Presentations for the 2004 Combined Sections Meeting: Platform Presentations
K.F. Bjornson, R. Hays, C. Graubert, F. Won, R. Price, J.F. McLaughlin, V. Pinedo, Genetics/Development, Children’s Hospital & Regional Medical Center, Seattle, WA.
PURPOSE/HYPOTHESIS: To document the impairment and pathophysiologic level effects (NCMRR domains of science) of gastrocnemius BTX-A injections in children with spastic diplegic cerebral palsy.
NUMBER OF SUBJECTS: A sample of 33 children, with spastic diplegic cerebral palsy, who had mean ages of 5.5 years (range 3.0–11.9), of which 19 were male. GMFCS Levels were: I = 12, II = 15 &III = 6 recruited through a tertiary care childrens hospital.
MATERIALS/METHODS: All participants were randomized to receive either 12 units/kg BTX-A or placebo saline injections evenly distributed to bilateral gastrocnemius muscles in a randomized double masked placebo control trial. Outcomes were collected at baseline, 3, 8, 12 and 24 weeks after injections. Pathophysiologic outcomes were EMG electrical responses to maximal voluntary contraction (QEK). Impairment level outcomes were an electromechanical torque measure of spasticity (SMS), Ashworth scores, achilles deep tendon reflexes (DTR), clonus, ROM and maximum torque of the gastroc soleus muscle.
RESULTS: A significant effect (P = 0.05) of the treatment versus placebo group at 3 weeks post injection for the QEK. SMS total and elastic path-lengths were significantly lower for the treatment group at 8 weeks (P < 0.05). Ashworth scores were not significantly different at any time point. Achilles DTR (P < 0.03) and clonus (P = 0.05) were significantly decreased in the BTX-A group at 3 weeks. At 12 weeks, ankle dorsiflexion ROM was significantly greater for the treatment group (P = 0.05). Maximum voluntary torque was significantly greater in the treatment group at 24 weeks (P = 0.03).
CONCLUSIONS: The significant decrease in EMG activity at 3 weeks is consistent with the known pathophysiological effect of the intervention. Achilles DTR and clonus were significantly decreased in the treatment group also at 3 weeks. The significant difference in SMS at 8 weeks and subsequently the dorsiflexion ROM at 12 weeks may be due to changes in the visco-elastic properties of the muscle. The significant change in maximum voluntary torque at 24 weeks may be a direct response to the improved ROM.
CLINICAL RELEVANCE: The results of this study have implications for the effect of BTX-A injections to positively impact gastroc spasticity, range of motion and strength as well as acquisition of gross motor skills over a six month time period in children with spastic diplegic cerebral palsy.