Peripheral nerve ultrasound in paediatric Charcot-Marie-Tooth disease Type 1A

Introduction Charcot-Marie-Tooth disease type 1A (CMT1A) is the most common cause of neuropathy in childhood. Peripheral nerve ultrasound provides a rapid, painless and non-invasive method of imaging the peripheral nervous system. Methods This cross-sectional, matched, case-control study evaluated differences in nerve cross-sectional area (CSA) measured by peripheral nerve ultrasound in children with CMT1A compared to healthy controls. Nerve CSA of the median, ulnar, tibial and sural nerves on the dominant side were measured. Correlations between nerve CSA and clinical severity (measured using the CMT Pediatric Scale) were explored. Results 29 children with CMT1A and 29 controls (matched for age and gender) were enrolled. Nerve CSA showed a strong positive linear correlation with age, height and weight in both the CMT1A and control groups. Nerve CSA was significantly increased in CMT1A – nerves were 2-3 fold larger in children with CMT1A compared to controls (p<0.001). The increase in nerve CSA with age was disproportionately greater in those with CMT1A (p<0.001), suggesting ongoing pathological nerve hypertrophy throughout childhood. Nerve CSA correlated with disease severity (r=0.63 for ulnar nerve). Conclusions Children with CMT1A have significantly greater nerve CSA compared to controls, and the increase in nerve CSA with age is disproportionately greater in CMT1A, suggesting ongoing pathological nerve hypertrophy throughout childhood. Nerve CSA correlates with neurology disability. These findings demonstrate the utility of peripheral nerve ultrasound as a diagnostic tool in paediatric neuropathies, and as an outcome measure in natural history studies and clinical trials in CMT1A.