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Carpal tunnel syndrome (CTS) is a medical condition in which the median nerve is compressed as it travels through the wrist at the carpal tunnel and causes pain, numbness and tingling, in the part of the hand that receives sensation from the median nerve. Pain may extend up the arm leading to discomfort extending to the shoulder and forearm. The mechanism of injury is compression; there are a variety of contributing factors.〔〔http://www.ninds.nih.gov/disorders/carpal_tunnel/detail_carpal_tunnel.htm#227043049〕 Some of the individual predisposing factors include: diabetes, obesity, pregnancy, hypothyroidism, and a narrow-diameter carpal tunnel. CTS may also result from an injury that causes internal scarring or mis-aligned wrist bones. Occupational causes involve use of the hand and arm, such as heavy manual work, work with vibrating tools, and highly repetitive tasks even if they involve low force motions. The main symptom of CTS is intermittent numbness of the thumb, index, and middle (long) fingers and the radial (thumb) side of the ring finger. The numbness often occurs at night, with hypothesized reasons related to sleep position, such as the wrists being held flexed during sleep or sleeping on one's side. 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. ==Signs and symptoms== People with CTS experience numbness, tingling, or burning sensations in the thumb and fingers, in particular the index and middle fingers and radial half of the ring finger, because these receive their sensory and motor function (muscle control) from the median nerve. Less-specific symptoms may include pain in the wrists or hands, loss of grip strength, and loss of manual dexterity.〔(【引用サイトリンク】date=December 28, 2010 )〕 Some suggest that median nerve symptoms can arise from compression at the level of the thoracic outlet or the area where the median nerve passes between the two heads of the pronator teres in the forearm, although this is debated. Numbness and paresthesias in the median nerve distribution are the hallmark neuropathic symptoms (NS) of carpal tunnel entrapment syndrome. Weakness and atrophy of the thumb muscles may occur if the condition remains untreated, because the muscles are not receiving sufficient nerve stimulation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Carpal tunnel syndrome」の詳細全文を読む スポンサード リンク
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