Greater Reliance on Cerebral Palsy-Specific Muscle Synergies During Gait Relates to Poorer Temporal-Spatial Performance Measures.

Yushin Kim,Diane L Damiano,Thomas C Bulea

doi:10.3389/fphys.2021.630627

Yushin Kim, Diane L Damiano + Show 1 more

Open Access

https://doi.org/10.3389/fphys.2021.630627

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Abstract

Children with cerebral palsy typically exhibit reduced complexity of muscle coordination patterns during walking; however, the specific patterns that characterize their gait abnormalities are still not well documented. This study aimed to identify the specific repertoire of muscle coordination patterns in children with CP during walking compared to same-aged peers without CP and their relationships to gait performance. To identify muscle coordination patterns, we extracted muscle synergies from 10 children with CP and 10 age-matched typically developing children (TD). K-mean clustering and discriminant analyses of all extracted synergies were used to group similar synergies. Then, weight-averaged z-scores were quantified for each cluster to determine their group-specific level. In this cohort, 10 of the 17 distinct clusters were largely CP-specific while six clusters were seen mainly in TD, and one was non-specific. CP-specific clusters generally showed merging of two TD synergies, excessive antagonist co-activation, decreased muscle activation compared to TD, and complex or atypical pattern. Significant correlations were found between weight-averaged z-scores and step length asymmetry, cadence asymmetry, self-selected treadmill speed and AP-COM displacement of the pelvis such that greater CP-specificity of muscle synergies was related to poorer performance, thus indicating that CP-specific synergies can influence motor dysfunction.

Highlights

Walking is an essential daily activity for many children with cerebral palsy (CP)
EMG data were split into windows of 20 gait cycles based on the heel contact, with 19 gait cycles of overlap between successive windows because we focused on relative contributions of each muscle and EMG normalization within each window
The mean number of synergies extracted from EMGo data set was slightly and significantly higher (t = −3.243, p = 0.009) in the typically developing children (TD) group (3.96 ± 0.12, range: 3.62–4.00) compared to CP (3.45 ± 0.48, range: 2.98–4.00)

Summary

Introduction

Walking is an essential daily activity for many children with cerebral palsy (CP). Their specific gait patterns are attributable to multiple factors such as weakness, spasticity, poor selective activation of muscles, abnormal spinal reflexes, and musculoskeletal changes (Damiano et al, 1995; Crenna, 1998). Research incorporating electromyography (EMG) analysis during walking in children with CP has shown alteration of muscle activation patterns such as reduced EMG amplitude, agonist-antagonist muscle co-activation, and altered activation timing (Berger et al, 1982; Crenna, 1998; Leonard et al, 2008). These altered patterns are considered a consequence of the disruption in brain development and maturation by the hallmark impairment in supraspinal control (Berger, 1998). EMG analyses indicate that children with CP have unique gait strategies with specific muscle activity patterns that typically developed children are unable to mimic (Romkes and Brunner, 2007)

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