Median nerve imaging using high-resolution ultrasound in healthy subjects

Although electroneuro- and electromyography are still the leading diagnostic methods for investigation of peripheral nerve function, they do not provide information on their morphology. This study was conducted to evaluate the suitability of ultrasonography in visualization of median nerve in healthy volunteers. Twenty-five asymptomatic volunteers (17 women and 8 men), age range 21-47 years, participated in the study. Body height was measured and handedness ascertained, as well as average time spent daily working on a computer. The device used was Aloka Prosound Alpha10 Premier with a 13-MHz probe, using custom preset for musculoskeletal sonography. The following dimensions of median nerve at the pisiform bone level were measured bilaterally: cross-sectional area (CSA), circumference, and longer and shorter diameter. Using the latter values, the flattening ratio (FR) was calculated. Median nerve and the surrounding soft tissue structures were easily depicted in all study subjects. The mean median nerve CSA was 9.70 mm2 (range 5-15 mm2, SD 2.25 mm2), mean FR (longer/shorter diameter) 4.04 (range 2.16-6.08), and median height 172.72 cm. Only one subject was left-handed. The mean time spent daily working on a computer (overall mean of 3.2 h/day) did not correlate with either CSA or FR for the dominant hand. In four subjects, an aberrant artery accompanying median nerve was visualized. High-resolution sonographic imaging is a fast and noninvasive method for assessment of various morphological properties of median nerve and can be used to enhance diagnostic efficiency.