Impacts of Typing on Different Keyboard Slopes on the Deformation Ratio of the Median Nerve

Carpal tunnel syndrome is a symptomatic compression neuropathy of the median nerve as it travels through the wrist. Several factors such as wrist angle and finger posture cause a change of the intra-carpal tunnel pressure. Carpal tunnel syndrome is one of the most commonly reported work-related musculoskeletal disorders. Computer users are at higher risk of upper extremity musculoskeletal symptoms and work-related musculoskeletal disorders, since time spent on the computer is associated with a higher incidence of musculoskeletal disorders. Objective: to investigate the impact of typing at two keyboard slopes (0° and +20°) on the median nerve deformation ratio. Fifteen healthy young men (24.8 ± 2.3 years) were recruited to type using both 0° and +20° inclined keyboards. The participants performed four 30-min blocks of computer typing at 0° and +20° keyboard inclinations. The left wrist median nerve was examined with an ultrasound machine after each 30-min typing block. Two-way repeated analysis of variance was performed to examine any differences in the deformation ratio of the median nerve cross-sectional area. The four time blocks and two keyboard slope conditions (0° and +20° inclination) were used as factors. Continuous typing activity causes a significant increase in the median nerve cross-sectional area deformation ratio (p < 0.05). Ultrasonography examination of the median nerve following computer typing can be used to generate absolute measurements and deformation ratios. These measurements help provide a better understanding of the impact of typing tasks on the median nerve.