Peripheral Nerve Cross-Sectional Area in Healthy Thai Children: Reference Values for Clinical Neuromuscular...

Ultrasonography of the nerve cross-sectional area (CSA) is increasingly used to support the diagnosis of peripheral neuropathies. However, normative CSA reference values in children, particularly in Southeast Asian populations, are limited.

Ultrasonographic nerve CSA measurements were conducted in 164 healthy Thai children aged 1 to 18 years at King Chulalongkorn Memorial Hospital, Thailand. Participants were classified into six age groups. CSA was measured in 10 peripheral nerves at 34 anatomical sites and bilateral cervical roots (C5-C7), and the median CSAs were calculated. Correlations between CSA and body weight, height, and age were calculated using Spearman and Pearson correlation coefficients. Intraobserver and interobserver reliability were evaluated in a subset of participants using intraclass correlation coefficients.

Normative CSA values were established for all examined nerves and sites. Most nerves demonstrated proximal-to-distal tapering in CSA, with the median nerve exhibiting a unique pattern of larger CSA at the wrist and mid-upper arm. C7 root was the largest cervical root measured (median CSA up to 7.0 mm 2 in older adolescents). CSA demonstrated moderate-to-strong correlations with anthropometric variables, including weight, height, and age ( r = 0.36-0.78). The tibial, sciatic, and median nerves showed the strongest correlations (all P < 0.001). Intraobserver and interobserver reliability were good-to-excellent across the selected nerves.

Nerve CSA is influenced by age, weight, height, and location in this Southeast Asian population. These normative reference values may serve as a reference for distinguishing normal from pathological findings and aid clinical decision making in pediatric neurophysiological practice.