Normal values of median nerve cross‐sectional area obtained by ultrasound along its course in the arm with electrophysiological correlations, in 100 Asian subjects

INTRODUCTION: The objective of this study is to obtain normative cross-sectional area (CSA) values for median nerve by ultrasound at predetermined sites and correlate them with electrophysiological variables in healthy Asian subjects. METHODS: The median nerve was examined ultrasonographically in 100 healthy volunteers, mean age 39 years (range, 18–75 years). CSA of the median nerve was measured at wrist, mid-forearm, mid-arm, and axilla. All subjects underwent simultaneous standardized nerve conduction studies. RESULTS: The mean median nerve CSAs ± SD at the distal wrist crease was 7.2 ± 1 mm2; mid-forearm 4.8 ± 0.9 mm2; mid-arm 6.1 ± 1 mm2; axilla 5.9 ± 0.9 mm2. The CSA at the wrist was the largest compared with other levels (P < 0.001), and it increased with advancing age (P < 0.002). CONCLUSIONS: These normative data show that median nerve CSA is not uniform along its length. There are differences between gender, and values increase with advancing age.