Carpal tunnel syndrome arises from compression of the median nerve that supplies the hand. Symptoms begin with numbness and/or tingling of the hand in the distribution of this nerve (the thumb, index, middle, and thumb side of the ring fingers). These symptoms are usually worse at night and may even awaken the sufferer from sleep. Symptoms can occur for a short time or may persist and become chronic. As the condition worsens, symptoms can include a burning or painful sensation, cramping, shooting pains in the forearm, or weakness of the hand. This results in a loss of grip strength. If the condition is chronic, there can be wasting of the muscles of the hand (atrophy).
Causes of carpal tunnel syndrome
In many cases, the cause of carpal tunnel syndrome is unknown. Any condition that leads to excess pressure on the median nerve at the wrist can cause carpal tunnel syndrome. These include obesity, pregnancy, hypothyroidism, arthritis, diabetes, and trauma. Tendon inflammation resulting from repetitive work, such as uninterrupted typing, has also been reported to cause carpal tunnel symptoms. Certain rare diseases can cause deposition of abnormal substances in and around the carpal tunnel, leading to nerve irritation.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.
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