Botox for cerebral palsy kids: muscle quality declines despite treatment
A new study finds that children with cerebral palsy experience increased fat infiltration in leg muscles within a year of starting botulinum toxin injections, the standard treatment for reducing muscle stiffness. The finding raises questions about long-term outcomes and could reshape how clinicians monitor therapy effectiveness and plan rehabilitation strategies.
Originaltitel: Muscle morphology and intramuscular fat after treatment-as-usual including botulinum neurotoxin A injections in children with cerebral palsy.
Botulinum-A-behandling är inte tillräcklig för att åtgärda muskelförändringar hos barn med cerebrala parese. En ny svensk studie visar att även efter ett år med behandling bibehålls muskelvolymen, men fettvävnad infiltrerar muskelfibrerna — ett tecken på försämrad muskelkvalitet trots stabila storlek. Forskarna från KTH och Karolinska institutet undersökte tio barn med spastisk cerebrala parese före och 12 månader efter första BoNT-A-injektionen med MR-avbildning. De jämförde muskelmorfologi i underbensmuskler mot friska barn. Medial gastrocnemius visade signifikant ökad fettvävnadsfraktion (p = 0,008) utan förändring i normaliserad muskelvolym. Barn med cerebrala parese hade redan vid start mindre tibialis anterior-volym än jämförgruppen. Resultatet förändrar förväntningarna på monoterapin. Multimodal träning eller tidiga interventioner innan fettvävnadsinfiltrationen blir etablerad kan bli nödvändiga för att bevara muskelkvalitet och långsiktiga motoriska funktioner.
AIM: To explore lower leg muscle morphology and intramuscular fat content changes using magnetic resonance imaging (MRI) after 12 months of treatment-as-usual (TAU), after the first botulinum neurotoxin A (BoNT-A) injection in children with cerebral palsy (CP) naive to muscle tone reduction treatment. METHOD: This prospective longitudinal study included 10 children with spastic CP (five female, median age 8 years 11 months, unilateral CP/bilateral CP 7/3, Gross Motor Function Classification System levels I/II 8/2) and 10 typically developing peers (seven female, median age 9 years 6 months). Children with CP received two MRI scans (before and 12 months after the first injection), typically developing peers received one. Muscle volume (normalized by product of weight and height), fascicle length (normalized by height), pennation angle, and intramuscular fat fraction (IFF) of medial gastrocnemius, lateral gastrocnemius, soleus, and tibialis anterior were quantified. RESULTS: After 12 months of TAU, normalized muscle volume remained unchanged while IFF increased (medial gastrocnemius: p = 0.008). Compared to typically developing peers, children with CP had smaller normalized muscle volume (tibialis anterior: p = 0.027) and similar IFF at pre-injection timepoint. INTERPRETATION: Although normalized muscle volume remained unchanged after the 12-month TAU, concurrent fat infiltration was evident in medial gastrocnemius.