Forearm Flexor Muscles in Children with Cerebral Palsy Are Weak, Thin and Stiff

Area of Science:

• Biomedical Engineering
• Pediatric Physical Therapy
• Neuromuscular Biomechanics

Background:

• Children with cerebral palsy (CP) often experience progressive loss of passive range of motion, particularly in the wrist.
• Skeletal muscle contracture is a primary suspected cause, altering joint biomechanics.
• Understanding forearm muscle mechanical properties in CP is crucial for targeted interventions.

Purpose of the Study:

• To investigate and compare the mechanical characteristics of forearm flexor muscles in children with and without CP.
• To determine if muscle weakness, stiffness, and viscosity differ between typically developing (TD) children and those with CP.
• To assess the relationship between muscle cross-sectional area, strength, and biomechanical properties.

Main Methods:

• Utilized the NeuroFlexor® apparatus to measure passive stiffness and viscosity of forearm flexors in 15 TD children and 9 children with CP.
• Measured grip strength using a Grippit® device.
• Assessed the cross-sectional area (CSA) of the flexor carpi radialis (FCR) muscle via ultrasound.

Main Results:

• Children with CP demonstrated significantly weaker grip strength (-65%) and smaller FCR muscle CSA (-43%) compared to TD children.
• Passive muscle stiffness was significantly increased (2-fold) in children with CP, while viscosity did not differ.
• In TD children, FCR CSA correlated with age, body weight, and grip strength; in CP, it correlated only with grip strength.

Conclusions:

• Children with CP present with forearm flexor muscles that are weaker, thinner, and stiffer than those in TD children.
• These altered biomechanical properties, specifically increased stiffness, likely contribute to the reduced range of motion observed in CP.
• Findings highlight the need for interventions addressing muscle contracture and mechanical properties in pediatric CP management.