Deformation of the median nerve at different finger postures and wrist angles.

Ping Yeap Loh,Wen Liang Yeoh,Hiroki Nakashima,Satoshi Muraki

doi:10.7717/peerj.5406

Abstract

BackgroundThe objective of this study was to evaluate the changes of the median nerve cross-sectional area (MNCSA) and diameters of the median nerve at different finger postures and wrist angles.MethodsTwenty-five healthy male participants were recruited in this study. The median nerve at wrist crease was examined at six finger postures, and repeated with the wrist in 30° flexion, neutral (0°), and 30° extension. The six finger postures are relaxed, straight finger, hook, full fist, tabletop, and straight fist.ResultsThe main effects of both finger postures and wrist angles are significant (p < 0.05) on changes of the MNCSA. Different finger tendon gliding postures cause a change in the MNCSA. Furthermore, wrist flexion and extension cause higher deformation of the MNCSA at different finger postures.DiscussionThe median nerve parameters such as MNCSA and diameter were altered by a change in wrist angle and finger posture. The results may help to understand the direct biomechanical stresses on the median nerve by different wrist-finger activities.

Highlights

Carpal tunnel syndrome (CTS) is a compression neuropathy that affects the median nerve at the wrist region
The main effects of the finger postures (p < 0.05) and the wrist angles (p < 0.05) on the changes of median nerve cross-sectional area (MNCSA) were significant for both hands
The wrist angle in 30◦ flexion and 30◦ extension caused a greater change in the MNCSA when compared to the neutral wrist (0◦), similar deformation percentages were observed for the same finger posture at different wrist angles in compared to relaxed finger at neutral wrist (0◦)

Summary

Introduction

Carpal tunnel syndrome (CTS) is a compression neuropathy that affects the median nerve at the wrist region. It was observed that active differential finger motions among CTS patients cause a decrease of the median nerve cross-sectional area (MNCSA) and perimeter in contrast to the control group (Van Doesburg et al, 2012; Yoshii, Ishii & Sakai, 2013). The objective of this study was to evaluate the changes of the median nerve cross-sectional area (MNCSA) and diameters of the median nerve at different finger postures and wrist angles. Different finger tendon gliding postures cause a change in the MNCSA. Wrist flexion and extension cause higher deformation of the MNCSA at different finger postures. The median nerve parameters such as MNCSA and diameter were altered by a change in wrist angle and finger posture. The results may help to understand the direct biomechanical stresses on the median nerve by different wrist-finger activities

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Conclusion