Dysfunction of a single nerve group, such as the distal median nerve, is classed as mononeuropathy. Mononeuropathy implies a local cause of the nerve damage, although occasionally systemic disorders may cause isolated nerve damage (such as the damage that occurs with mononeuritis multiplex). Distal median nerve dysfunction occurs when the nerve is injured by trauma, entrapment, or inflammation. Entrapment involves pressure on the nerve where it passes through a narrow structure. Wrist fractures may injure the median nerve directly or may present a risk for entrapment of the nerve later on. The nerve can also be compressed at the wrist by tendonitis, arthritis, or conditions that affect connective tissue or cause deposits in the tissues (such as multiple myeloma, pregnancy, acromegaly, and hypothyroidism). These mechanical factors may cause nerve disease, blocking blood flow to the area. In some cases, no detectable cause can be identified. Carpal tunnel syndrome, a form of median nerve dysfunction, is one of the more common localized peripheral neuropathies. Carpal tunnel syndrome may be associated with entrapment of the nerve following prolonged or repeated pressure on the wrist area (such as may occur with repetitive wrist movements such as those made when typing or using a computer). This is a fairly common occupational or recreational injury.
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