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. 2015 Feb 6;10(2):e0117930.
doi: 10.1371/journal.pone.0117930. eCollection 2015.

Effect of wrist angle on median nerve appearance at the proximal carpal tunnel

Ping Yeap Loh  1 , Satoshi Muraki  2
Affiliations

Effect of wrist angle on median nerve appearance at the proximal carpal tunnel

Ping Yeap Loh et al. PLoS One. .

Abstract

This study investigated the effects of wrist angle, sex, and handedness on the changes in the median nerve cross-sectional area (MNCSA) and median nerve diameters, namely longitudinal diameter (D1) and vertical diameter (D2). Ultrasound examination was conducted to examine the median nerve at the proximal carpal tunnel in both dominant and nondominant hands of men (n = 27) and women (n = 26). A total of seven wrist angles were examined: neutral; 15°, 30°, and 45° extension; and 15°, 30°, and 45° flexion. Our results indicated sexual dimorphism and bilateral asymmetry of MNCSA, D1 and D2 measurements. MNCSA was significantly reduced when the wrist angle changed from neutral to flexion or extension positions. At flexion positions, D1 was significantly smaller than that at neutral. In contrast, at extension positions, D2 was significantly smaller than that at neutral. In conclusion, this study showed that MNCSA decreased as the wrist angle changed from neutral to flexion or extension positions in both dominant and nondominant hands of both sexes, whereas deformation of the median nerve differed between wrist flexion and extension.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Ultrasound image of the median nerve at the proximal carpal tunnel.
A) median nerve cross-sectional area by tracing method; B) longitudinal diameter; C) vertical diameter.
Fig 2
Fig 2. Median nerve cross-sectional area at different wrist angles.
(A) Male dominant hand. (B) Male nondominant hand. (C) Female dominant hand. (D) Female nondominant hand. Extn = extension, Flex = flexion.
Fig 3
Fig 3. Median nerve longitudinal diameter (D1) at different wrist angles.
(A) Male dominant hand. (B) Male nondominant hand. (C) Female dominant hand. (D) Female nondominant hand. Extn = extension, Flex = flexion.
Fig 4
Fig 4. Median nerve vertical diameter (D2) at different wrist angles.
(A) Male dominant hand. (B) Male nondominant hand. (C) Female dominant hand. (D) Female nondominant hand. Extn = extension, Flex = flexion.
See this image and copyright information in PMC

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