Reduced Cross-Sectional Muscle Growth Six Months after Botulinum Toxin Type-A Injection in Children with Spastic Cerebral Palsy.

Nathalie De Beukelaer,Jorieke Deschrevel,Julie Uytterhoeven,Britta Hanssen,Domiziana Costamagna,Anja Van Campenhout,Nicky Peeters,Karen Maes,Guido Weide,Ghislaine Gayan-Ramirez,Ines Vandekerckhove,Kaat Desloovere,Ester Huyghe,Marlies Corvelyn

doi:10.3390/toxins14020139

Abstract

Botulinum Neurotoxin type-A (BoNT-A) injections are widely used as first-line spasticity treatment in spastic cerebral palsy (SCP). Despite improved clinical outcomes, concerns regarding harmful effects on muscle morphology have been raised. Yet, the risk of initiating BoNT-A to reduce muscle growth remains unclear. This study investigated medial gastrocnemius (MG) morphological muscle growth in children with SCP (n = 26, median age of 5.2 years (3.5)), assessed by 3D-freehand ultrasound prior to and six months post-BoNT-A injections. Post-BoNT-A MG muscle growth of BoNT-A naive children (n = 11) was compared to (a) muscle growth of children who remained BoNT-A naive after six months (n = 11) and (b) post-BoNT-A follow-up data of children with a history of BoNT-A treatment (n = 15). Six months after initiating BoNT-A injection, 17% decrease in mid-belly cross-sectional area normalized to skeletal growth and 5% increase in echo-intensity were illustrated. These muscle outcomes were only significantly altered when compared with children who remained BoNT-A naive (+4% and −3%, respectively, p < 0.01). Muscle length growth persevered over time. This study showed reduced cross-sectional growth post-BoNT-A treatment suggesting that re-injections should be postponed at least beyond six months. Future research should extend follow-up periods investigating muscle recovery in the long-term and should include microscopic analysis.

Highlights

Starting from an early age, the medial gastrocnemius (MG) muscle morphology is impaired in children with spastic cerebral palsy (SCP) [1,2]
Absolute muscle atrophy was not determined, the current study revealed hampered medial gastrocnemius muscle growth six months post-botulinum neurotoxin type-A (BoNT-A) injection
The hampered muscle growth was primarily attributed to the cross-sectional muscle dimension, while growth in the longitudinal muscle dimension remained preserved

Summary

Introduction

Starting from an early age, the medial gastrocnemius (MG) muscle morphology is impaired in children with spastic cerebral palsy (SCP) [1,2]. The injection of botulinum neurotoxin type-A (BoNT-A) is widely used within the conventional management of spasticity. This treatment is already prescribed from the ages of two to four years, aiming to reduce focal muscle hyper-excitability [7]. Beneficial outcomes such as reduced muscle spasticity, increased ankle joint range of motion and improved gait have been described when BoNT-A injections are combined with concurrent therapies (e.g., serial casting, ankle–foot orthoses and physiotherapy) [8,9,10,11]

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