The Easy Handgrip Test as a Tool for Assessing Motor Fatigability in Children With Charcot-Marie-Tooth Disease Type...

Charcot-Marie-Tooth (CMT), the most common inherited neuromuscular disorder, causes progressive, symmetrical muscle weakness, often affecting distal extremities. Motor fatigability, characterized by a decline in maximal muscle force, is common in neuromuscular disorders but remains underexplored in children with CMT. This study aimed to evaluate the feasibility of a motor fatigability test using a bulb dynamometer in children and adolescents with CMT1A, assess test-retest reliability, and compare handgrip pressure, electromyographic parameters, perceived effort, and time to exhaustion between CMT1A and typically developing peers.

This observational cross-sectional study included 107 children (aged 8-16 years; 19 with CMT1A and 88 typically developing). Participants performed a handgrip motor fatigability test using a bulb dynamometer, involving repetitive maximum voluntary isometric contractions (MVICs) at one-second intervals until exhaustion, with simultaneous electromyographic monitoring. Test-retest reliability was assessed using Bland-Altman plots and the Intraclass Correlation Coefficient (ICC). For comparisons between groups and test phases, ANCOVA and linear mixed-effects models were adjusted for sex, age, height, and weight.

A hundred and four children completed the test. The protocol was feasible, with both groups reaching significant exhaustion in 4 min and showing a significant decline in handgrip pressure (p < 0.05). The decline in median power frequency observed during the fatigue test indicated reduced neural activation in both groups. The ICC was 0.824, indicating good test-retest reliability.

The protocol shows promise for monitoring disease progression and treatment effects in children with CMT1A, and may serve as a functional marker. Future studies should include other CMT types.