The Easy Handgrip Test as a Tool for Assessing Motor Fatigability in Children With Charcot-Marie-Tooth Disease Type 1A

Background and Aims

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.

Methods

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.

Results

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.

Interpretation

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.