Muscle synergies during walking in very young children with cerebral palsy

Cerebral palsy (CP) is a developmental motor disorder, caused by non‐progressive lesions in an immature brain, which affects the development of walking. Coordinated muscle activation during walking can be decomposed into muscle synergies, i.e. groups of muscles activated at the same time. The number of muscle synergies in typically developing children increases throughout the motor development from two (during neonate stepping) to four (in toddlers when they start to walk independently). We hypothesized that the muscle synergies in children with CP are different from the ones observed in typically developing children, even in this early stage of motor development.

Patients and method
To test this hypothesis, we recorded full‐body kinematics and bilateral electromyography (EMG) (14–28 muscles) during treadmill and over‐ground walking in five children with CP and five typically developing children (age range: 6–46mo). Patients were included based on high‐risk of developing CP with abnormalities in brain magnetic resonance imaging. To quantify the muscle synergies underlying bilateral muscle activations, we applied non‐negative matrix factorization to EMG envelopes pooled across steps. We compared the number of muscle synergies between children with CP and typically developing children based on the same age and similar walking experience.

Results
Our analysis revealed fewer muscle synergies in children with CP versus typically developing children.

Conclusion
These preliminary results suggest that children with CP use a different motor control strategy during gait than typically developing children.