• Peripheral nervous system
• Median nerve
• Ultra-high-frequency ultrasound

Abstract

Objective: The objective of this study was to utilize a newly approved ultrahigh-resolution ultrasound device with a frequency of 70 MHz to gather data from healthy individuals. The aim was to establish reference values for the digital branches of the median nerves in the hand.
Methods: The ultrasound probe equipped with a 70 MHz linear array transducer, was employed to measure various parameters, including the cross-sectional area of the median nerve at the wrist (CSAw) and digital branches (CSAf), as well as the sizes of the largest and smallest fascicles. Additionally, the number of fascicles (Nfasc), fascicle density (FD), flattening ratio (FR), and CSAw/CSAf ratio were assessed.
Results: Data were collected from 15 healthy subjects, encompassing both hands. The median nerve and its digital branches were accurately identified without any anatomical abnormalities. No significant differences were observed between the right and left hands. In the dominant hand, CSAw measured 8.12 mm2 (range: 5.37–11.67), while Nfasc was 25 (range: 18–34). The values for FD and FR were 3.04 (range: 2.28–4.05) and 3.32 (range: 1.51–5.64), respectively.
Conclusion: Conventional ultrasound devices often struggle to visualize the distal branches of the median nerve. The UHFUS technology enables visualization of the median nerves at the wrist, their internal structure, and the smaller branches extending to the fingers. It offers both qualitative and quantitative assessments, enhancing capability to detect and measure the smaller structures of the nerve, thereby assisting in clinical practice. The reference values obtained from this study serve as preliminary data based on a healthy sample.