Evolutionary medicine Carpal tunnel syndrome

Carpal tunnel syndrome (CTS) results from median nerve entrapment during increased intra-tunnel pressure that is often a product of swelling of the digital flexor tendon sheaths consequent to repetitive movements of the hand and wrist or by direct compression on the wrist. Individuals with CTS may experience pain, tingling, numbness and weakness in the palmar surface of the first three digits, small thumb and lateral two lumbrical muscles [1]. Occupational factors may exacerbate CTS, most notably, repetitive and forceful activities using the hand. Unfortunately, individuals affected with CTS may be unable to perform basic functions and cannot work. In 2014, the median number of days taken from work for CTS (32 days) was much greater than the average number of days taken off for other non-fatal illnesses (9 days) [2]. Measurements of the cross sectional area (CSA) of the proximal tunnel are effective in predicting CTS. In individuals presenting with CTS, the CSA of the median nerve is significantly larger than in unaffected individuals. Further, the nerve tunnel index (CSA median nerve/CSA tunnel) in affected individuals is much higher than in non-affected individuals. [3]. EVOLUTIONARY PERSPECTIVES