Medial gastrocnemius volume and echo‐intensity after botulinum neurotoxin A interventions in children with spastic cerebral palsy

Abstract

first publication: reference 24 has been added and the ethical commission number has been corrected.] AIM This cross-sectional investigation evaluated whether recurrent botulinum neurotoxin A (BoNT-A) interventions to the medial gastrocnemius have an influence on muscle morphology, beyond Gross Motor Function Classification System (GMFCS) level.METHOD A cohort of typically developing children (n=67; 43 males, 24 females; median age 9y 11mo [range 7y 10mo-11y 6mo]), a cohort of children with spastic cerebral palsy (CP) naive to BoNT-A interventions (No-BoNT-A; n=19; 10 males, nine females; median age 9y 3mo [range 8y 5mo-10y 10mo]) and a cohort of children with spastic CP with a minimum of three recurrent BoNT-A interventions to the medial gastrocnemius (BoNT-A; n=19; 13 males, six females; median age 9y 8mo [range 7y 3mo-10y 7mo]) were recruited. Three-dimensional freehand ultrasound was used to estimate medial gastrocnemius volume normalized to body mass and echo-intensity.

Over 25 Years of Pediatric Botulinum Toxin Treatments: What Have We Learned from Injection Techniques, Doses, Dilutions, and Recovery of Repeated Injections?

“…The differences in muscle volume, fascicle length, or cross-sectional area were not significant between the single and multiple (three injections in one year) injection groups [115]. Both the GMFCS level, and the history of more than three BTXA injections were associated with increased echo-intensity and decreased medial GC volume, reflecting structural alterations in the muscles [116].…”

Comprehensive evaluation of gait, spasticity, and muscle morphology: A case report of a child with spastic paresis treated with Botulinum NeuroToxin‐A, serial casting, and physiotherapy

“…Moreover, the effects of repeated BoNT‐A treatment on muscle growth are controversial as after each injection muscles may atrophy and weaken which reduces their potential for adaptation . However, studies in cerebral palsy have been inconclusive on the long‐term effects of BoNT‐A on muscle volume . As muscles in children with SP are less developed (i.e., in this case ≈30% less volume of GM compared with that of typically developing children), it could also be that they may not be sensitive to atrophy any further.…”

“…5,39 However, studies in cerebral palsy have been inconclusive on the long-term effects of BoNT-A on muscle volume. 40,41 As muscles in children with SP are less developed (i.e., in this case ≈30% less volume of GM compared with that of typically developing children), it could also be that they may not be sensitive to atrophy any further. This would imply that muscle fibers had already reached the smallest possible cross-sectional area and could not atrophy any further without losing fibers.…”

Stretching Interventions in Children With Cerebral Palsy: Why Are They Ineffective in Improving Muscle Function and How Can We Better Their Outcome?

“…Additionally, it was shown that muscle volume decreased significantly after BoNT-A injections (Williams et al, 2013b), usually an unwanted outcome that could be counterbalanced with strength training (Williams et al, 2013a). Together with a reduction in normalized muscle volumes, alterations to muscle quality were shown by a reduction in echogenicity in a cohort of children with who had received BoNT-A injections compared to a cohort of children with CP who did not receive any BoNT-A injections (Schless et al, 2019). Although no difference could be shown between single and multiple BoNT-A injections (Barber et al, 2013), it seems unlikely that multiple BoNT-A injections would promote muscle growth, the desired outcome from the stretching interventions discussed in this review.…”