Carpal tunnel syndrome (CTS) is a median entrapment neuropathy that causes paresthesia, pain, numbness, and other symptoms in the distribution of the median nerve due to its compression at the wrist in the carpal tunnel. The mechanism is not completely understood but can be considered compression of the median nerve traveling through the carpal tunnel. It appears to be caused by a combination of genetic and environmental factors. Some of the predisposing factors include: diabetes, obesity, pregnancy, hypothyroidism, and heavy manual work or work with vibrating tools. There is, however, little clinical data to prove that lighter, repetitive tasks can cause carpal tunnel syndrome. Other disorders such as bursitis and tendinitis have been associated with repeated motions performed in the course of normal work or other activities. The main symptom of CTS is intermittent numbness of the thumb, index, long and radial half of the ring finger. The numbness often occurs at night, with the hypothesis that the wrists are held flexed during sleep. Recent literature suggests that sleep positioning, such as sleeping on one’s side, might be an associated factor. It can be relieved by wearing a wrist splint that prevents flexion. Long-standing CTS leads to permanent nerve damage with constant numbness, atrophy of some of the muscles of the thenar eminence, and weakness of palmar abduction (see ). Pain in carpal tunnel syndrome is primarily numbness that is so intense that it wakes one from sleep. Pain in electrophysiologically verified CTS is associated with misinterpretation of nociception and depression. Conservative treatments include use of night splints and corticosteroid injection. The only scientifically established disease modifying treatment is surgery to cut the transverse carpal ligament.