Muscle Synergies During Walking in Children With Cerebral Palsy: A Systematic Review.

Annike Bekius,Nadia Dominici,Ralph De Vries,Marjolein M Van Der Krogt,Annemieke I Buizer,Margit M Bach

doi:10.3389/fphys.2020.00632

Annike Bekius, Nadia Dominici + Show 4 more

Open Access

https://doi.org/10.3389/fphys.2020.00632

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Abstract

Background: Walking problems in children with cerebral palsy (CP) can in part be explained by limited selective motor control. Muscle synergy analysis is increasingly used to quantify altered neuromuscular control during walking. The early brain injury in children with CP may lead to a different development of muscle synergies compared to typically developing (TD) children, which might characterize the abnormal walking patterns.Objective: The overarching aim of this review is to give an overview of the existing studies investigating muscle synergies during walking in children with CP compared to TD children. The main focus is on how muscle synergies differ between children with CP and TD children, and we examine the potential of muscle synergies as a measure to quantify and predict treatment outcomes.Methods: Bibliographic databases were searched by two independent reviewers up to 22 April 2019. Studies were included if the focus was on muscle synergies of the lower limbs during walking, obtained by a matrix factorization algorithm, in children with CP.Results: The majority (n = 12) of the 16 included studies found that children with CP recruited fewer muscle synergies during walking compared to TD children, and several studies (n = 8) showed that either the spatial or temporal structure of the muscle synergies differed between children with CP and TD children. Variability within and between subjects was larger in children with CP than in TD children, especially in more involved children. Muscle synergy characteristics before treatments to improve walking function could predict treatment outcomes (n = 3). Only minimal changes in synergies were found after treatment.Conclusions: The findings in this systematic review support the idea that children with CP use a simpler motor control strategy compared to TD children. The use of muscle synergy analysis as a clinical tool to quantify altered neuromuscular control and predict clinical outcomes seems promising. Further investigation on this topic is necessary, and the use of muscle synergies as a target for development of novel therapies in children with CP could be explored.

Highlights

Walking is the most common form of locomotion adopted by humans and limbed animals, and it requires the activation of numerous muscles
The studies varied in sample size, from 3 to 549 children with cerebral palsy (CP) and 8 to 84 typically developing (TD) children
The majority of studies found that children with CP recruit fewer synergies than TD children, and differences in both spatial and temporal structure of synergies were found

Summary

Introduction

Walking is the most common form of locomotion adopted by humans and limbed animals, and it requires the activation of numerous muscles. It has been shown that the number of muscle synergies in post-stroke individuals during walking is reduced compared to unimpaired individuals due to merging of the “mature synergies” observed in healthy adults (Clark et al, 2010). These findings correlate with the degree of motor impairment which might reflect a simplified control strategy of the central nervous system in moderate to severely impaired post-stroke individuals. The early brain injury in children with CP may lead to a different development of muscle synergies compared to typically developing (TD) children, which might characterize the abnormal walking patterns

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