Wrist Kinematics and Ultrasound Measures of the Median Nerve During Computer Keyboarding

Carpal tunnel syndrome (CTS) is a common, costly problem in the general population and particularly in manual workers [1–3], with as many as 3 million individuals experiencing its symptoms and signs, including pain, tingling, numbness, fatigue and weakness in the hands and fingers [4]. Treatment of CTS is estimated to cost over one billion dollars a year [5]. The most prevalent theory for the pathogenesis of CTS is compression of median nerve in the carpal tunnel [6]. Although this theory is widely accepted, the cause of the compression in the carpal tunnel is not fully understood. Epidemiological research has identified several occupational risk factors associated with the development of CTS in general industry including: force, repetition, awkward/static postures, localized mechanical compression, and vibration [7]. Several studies have found greater prevalence of carpal tunnel syndrome in workers with highly repetitive manual jobs [8]. Keyboarding is a highly repetitive daily task, and its association with musculoskeletal disorders of the upper extremity has been a public health concern since the 1980s [1]. However, there are controversial results regarding the association between computer keyboarding and CTS which indicate that we have an insufficient understanding of an association between keyboarding and upper limb neuropathy. Using ultrasonographic techniques, our laboratory was able to explore acute changes in the median nerve following a one-hour keyboarding task [9].