• children;
  • elderly;
  • peripheral nerves;
  • reference values;
  • ultrasound

Introduction: Nerve cross-sectional area reference values have been reported for many nerves, but there have been few studies in pediatric and geriatric populations. This study was conducted to determine the influence of age on nerve cross-sectional area. Methods: Thirty-two children (3 months to 16 years) and 20 geriatric adults (67–92 years) without known neurologic conditions underwent bilateral ultrasound to measure the area of the following nerves: median at the wrist and forearm; ulnar at the wrist and elbow; radial in the spiral groove; sciatic in the distal thigh; fibular at the knee; tibial at the knee and ankle; and sural at the ankle. Results: In general, nerve cross-sectional area increased with age. Nerve size correlated most closely with age, but a correlation was also seen with body mass index. Conclusions: Nerve cross-sectional area increases with age, which is important to note when using ultrasound to evaluate children and geriatric patients. Muscle Nerve 47: 890–893, 2013