Axonal-demyelinating differences in functional change in pediatric Charcot–Marie–Tooth and related neuropathies

Abstract

Background: Charcot–Marie–Tooth disease and related neuropathies (CMTR) are heterogeneous inherited neuropathies with variable progression, yet data on pediatric disease progression by neurophysiological subtype are limited. We evaluated 1-year clinical and functional changes in children with CMTR and compared axonal versus demyelinating trajectories. Methods: We conducted a prospective cohort study of 20 Thai children with CMTR who were aged 3–20 years. Participants were assessed at baseline and after 1 year using the Rasch-modified Charcot–Marie–Tooth Examination Score (CMTES-R), Charcot–Marie–Tooth Pediatric Scale (CMTPedS), manual muscle testing (MMT), Foot Posture Index, and muscle length testing. Within-subject changes in clinical outcomes over time were assessed using appropriate paired statistical tests. Results: Thirteen patients had axonal forms and seven had demyelinating forms; the patients’ mean age was 13.0 ± 4.9 years. The axonal variants involved MFN2 (n = 3), GDAP1 (n = 2), and GAN, GJB1, IGHMBP2, KIF1A, PRDM12 (n = 1 each); 3 axonal variants were genetically undiagnosed. The demyelinating variants comprised MPZ (n = 2), PMP22 duplication (n = 2), EGR2 (n = 1), NEFL (n = 1), and PMP22 deletion (n = 1). At both time points, 85% of the patients were ambulatory, 15% used a wheelchair, and 65% used an ankle-foot orthosis. CMTPedS increased by 1.0 ± 3.4 points over 1 year (p = 0.271), with a larger change in axonal versus demyelinating cases (+ 1.1 ± 3.2 vs. + 0.7 ± 4.0). CMTES-R changed minimally (median + 0.5), and MMT showed stable strength. Conclusion: The clinical progression in pediatric CMTR was heterogeneous and differed by neurophysiological subtype, with more pronounced 1-year functional decline in axonal disease. These findings support vigilant longitudinal monitoring of pediatric CMTR, particularly where genetic testing access is limited.