Median nerve deformation and displacement with forceful gripping and wrist deviation

We explored median nerve (MN) deformation and displacement during forceful gripping to better understand injury mechanisms underlying work-related carpal tunnel syndrome. 12 participants performed a chuck grip in 3 wrist positions (15° radial deviation, 0° neutral, 30° ulnar deviation) and 2 force levels (10%, 40% of maximal voluntary effort) while transverse images of the carpal tunnel were collected with ultrasound. MN circularity increased with greater finger force in 0° and 30° ulnar deviation, but not in 15° radial deviation. Anterior (palmar) displacement of the MN also increased in 30° ulnar deviation. Our results link changes in MN deformation and displacement with forceful gripping and non-neutral wrist positions, in support of an injury mechanism related to contact stress.