Anticipatory postural adjustments associated with a loading perturbation in children with hemiplegic and diplegic...

Area of Science:

• Neuroscience
• Motor Control
• Pediatrics

Background:

• Anticipatory postural adjustments (APAs) are crucial for maintaining stability during voluntary movements and in response to external perturbations.
• Cerebral palsy (CP) is a group of disorders affecting movement and posture, with hemiplegic (HEMI) and diplegic (DIPL) forms presenting distinct motor challenges.
• Understanding APA deficits in children with CP is essential for developing targeted interventions to improve balance and functional mobility.

Purpose of the Study:

• To investigate and compare anticipatory postural adjustments (APAs) in children with typically developing (TD), hemiplegic (HEMI), and diplegic (DIPL) cerebral palsy.
• To quantify differences in muscle activation onset and magnitude, and center of pressure (COP) displacement during a predictable loading task.
• To elucidate distinct postural control strategies employed by children with HEMI and DIPL CP compared to TD peers.

Main Methods:

• Twenty-seven children (9 per group: TD, HEMI, DIPL) participated in the study.
• Participants stood and caught a dropped load, while leg and trunk muscle electrical activity and center of pressure (COP) displacements were recorded.
• Analysis focused on quantifying APA onset, magnitude, and COP displacement patterns prior to the perturbation.

Main Results:

• All groups generated APAs, but HEMI and DIPL groups exhibited smaller magnitudes and delayed onset of APAs in dorsal (agonist) postural muscles compared to TD.
• HEMI and DIPL groups also activated antagonist postural muscles during APAs, unlike the TD group.
• Anticipatory backward COP displacement differed significantly from baseline only in TD and HEMI groups; HEMI showed diminished agonist APAs, while DIPL had increased background activity and diminished agonist APAs.

Conclusions:

• Children with HEMI and DIPL cerebral palsy demonstrate altered anticipatory postural adjustments, characterized by delayed and diminished agonist muscle activation and unique muscle recruitment strategies.
• Distinct postural control strategies were observed between HEMI and DIPL groups, suggesting different underlying motor control impairments.
• These findings underscore the importance of considering these specific APA differences when designing rehabilitation programs aimed at enhancing posture and movement control in children with cerebral palsy.