P 49. Change in cross-sectional area of the median nerve with age in neonates, infants and children analyzed by high-resolution ultrasound imaging

Abstract

Aim. To analyze age dependencies in the cross-sectional area (CSA) of the median nerve during early childhood. Method. A total of 43 participants (32 of whom were children younger than 2 years) were included in this cross-sectional study to analyze the age dependency of the CSA of the median nerve at three locations (wrist, forearm and upper arm) using high-resolution ultrasound images. Results. A strong and highly significant correlation was found between age and CSA (p < 0.001). When plotted, the relationship followed a logarithmic curve (p < 0.001) with a growth rate that decreases with age. Based on the regression analysis, a temporally similar increase in CSA for all three locations was found. The nerve reaches 70% of its final CSA by 2 years of age at all three locations. Interpretation. Similar to the nerve conduction speed, the increase in CSA is greatest during the first 2 years of life. Then, the rate gradually and synchronously slows at the proximal and distal locations. Measurement of the CSA in the clinical setting might offer a new method to assess the maturation of the nervous system in infants with minimal interference Figs. 1 and 2. Fig. 1. Typical ultrasound images for all three locations from three participants ages 26 days to 775 days. Arrowheads point in the direction of the nerve. The nerve is located at the intersection of the two direction. The scale bar on the lower left applies to all images of Location 1, and the scale bar on the lower right applies to all images of Locations 2 and 3. Fig. 2. (A) Location 1:wrist; (B) Location 2: forearm; (C) Location 3: upper arm The measured CSA is plotted against age (green dots: righy arm; red dots: left arm). Panels A.1 to C.1 cover the whole age range of the study (main study group and comparison group). Panels A.2 to C.2 focus on the main study group. The logarithmic regression curve is plotted in each panel as a grey line, with the limits of the lower and upper 95% confidence intervals plotted as dotted lines above and below.