Does Botulinum Toxin Injection Exacerbate Sarcopenia and Bone Mass in Individuals With Cerebral Palsy?

Background: Botulinum toxin (BoNT) causes sarcopenia and low bone mass in animal studies. Whether such effect exists in children and adolescents with spastic cerebral palsy (CP) is not clear yet. To investigate the influences of BoNT on grip strength (GS), skeletal muscle mass, and bone mineral density (BMD) in children and adolescents with spastic CP, we conducted this uncontrolled longitudinal study. Methods: The body composition of individuals with spastic CP were measured by dual-energy X-ray absorptiometry at preinjection and at 12 and 24 weeks after BoNT intervention. Sarcopenia was defined as meeting both decreased GS and low muscle mass. Twenty-five participants were enrolled (mean age 8.5 years). Results: Before BoNT intervention, four adolescents had sarcopenia and low bone mass. When the body composition was analyzed as four limbs, trunk, and head, the skeletal muscle mass of the injected limbs, appendicular skeletal muscle mass, and total body less head BMD increased significantly over 24-week follow-up period (P = 0.0117, 0.0032, 0.0229), whereas the GS remained unchanged. When the body composition was analyzed as segments derived from bilateral arms, forearms, hands, thighs, and lower legs, the skeletal muscle mass (P = 0.0113) but not BMD of the injected segments increased significantly over the 24 weeks. The prevalence of low muscle mass, decreased GS, sarcopenia, and low bone mass did not change over 24 weeks. Conclusions: The present study showed that BoNT does not exacerbate sarcopenia and low bone mass in individuals with spastic CP.