Multi-scale complexity analysis of muscle coactivation during gait in children with cerebral palsy

Wen Tao; Xu Zhang; Xiang Chen; De Wu; Ping Zhou

doi:10.3389/fnhum.2015.00367

Multi-scale complexity analysis of muscle coactivation during gait in children with cerebral palsy

Front Hum Neurosci. 2015 Jul 22:9:367. doi: 10.3389/fnhum.2015.00367. eCollection 2015.

Authors

Wen Tao¹, Xu Zhang¹, Xiang Chen¹, De Wu², Ping Zhou³

Affiliations

¹ Neuromuscular Control Laboratory, Department of Electronic Science and Technology, University of Science and Technology of China Hefei, China.
² Department of pediatrics, First Affiliated Hospital of Anhui Medical University Hefei, China.
³ Neuromuscular Control Laboratory, Department of Electronic Science and Technology, University of Science and Technology of China Hefei, China ; Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, TIRR Memorial Hermann Research Center Houston, TX, USA.

Abstract

The objective of this study is to characterize complexity of lower-extremity muscle coactivation and coordination during gait in children with cerebral palsy (CP), children with typical development (TD) and healthy adults, by applying recently developed multivariate multi-scale entropy (MMSE) analysis to surface electromyographic (EMG) signals. Eleven CP children (CP group), eight TD children and seven healthy adults (considered as an entire control group) were asked to walk while surface EMG signals were collected from five thigh muscles and three lower leg muscles on each leg (16 EMG channels in total). The 16-channel surface EMG data, recorded during a series of consecutive gait cycles, were simultaneously processed by multivariate empirical mode decomposition (MEMD), to generate fully aligned data scales for subsequent MMSE analysis. In order to conduct extensive examination of muscle coactivation complexity using the MEMD-enhanced MMSE, 14 data analysis schemes were designed by varying partial muscle combinations and time durations of data segments. Both TD children and healthy adults showed almost consistent MMSE curves over multiple scales for all the 14 schemes, without any significant difference (p > 0.09). However, distinct diversity in MMSE curve was observed in the CP group when compared with the control group. There appears to be diverse neuropathological processes in CP that may affect dynamical complexity of muscle coactivation and coordination during gait. The abnormal complexity patterns emerging in the CP group can be attributed to different factors such as motor control impairments, loss of muscle couplings, and spasticity or paralysis in individual muscles. This study expands our knowledge of neuropathology of CP from a novel point of view of muscle co-activation complexity, which might be useful to derive a quantitative index for assessing muscle activation characteristics as well as motor function in CP.

Keywords: cerebral palsy; electromyography; gait analysis; multi-scale analysis; multivariate sample entropy.