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In 1862, Maurice Raynaud described episodes of discoloration of the skin of the digits on exposure to cold, and he thought this was due to increased sensitivity of the sympathetic nervous system. This condition, which is limited to the skin, usually accompanied by cyanosis, rubor, pain or paresthesia, and associated gangrene, came to be termed Raynaud's disease.(1) More than a century later, the pathogenesis, diagnosis, and treatment are still unclear.(2)
An episode typically begins when one or more of the digits appear white as the patient is exposed to cold environment or touches a cold object. This blanching or pallor is considered the ischemic phase, and is caused by vasospasm of the digital arteries. The arterioles and venules dilate following the vasospasm, causing a cyanotic appearance, due to the deoxygenated blood in these vessels. This phase is often accompanied by sensations of cold or numbness or paresthesia. Upon rewarming, the vasospasm resolves and blood flow returns dramatically to the affected area. This phase is sometimes accompanied by a painful, throbbing sensation, and the digits may turn bright red as warmth returns.
The event, or series of events, described is known as Raynaud's phenomenon, which is broadly classified into two categories. The idiopathic variety, termed Raynaud's disease, is applied when secondary causes of Raynaud's phenomenon have been ruled out. The secondary variety is associated with other disease states or other known causes of vasospasm.
Over 50 percent of patients with Raynaud's phenomenon have Raynaud's disease. Women are affected about five times more often than men, and the age of presentation is usually between 20 and 40 years.(3) One interesting group of patients with Raynaud's symptoms comprises those whose occupations involve routine use of vibratory equipment, or frequent exposure to cold temperatures. From 40 to 90 percent of loggers and 50 percent of miners using vibratory equipment have been diagnosed with Raynaud's disease. Heredity may also play a role in the development of this disease.(2) Frequency also seems to be increased in pianists and typists, and electric shock injury or frostbite may also predispose a later development of Raynaud's phenomenon. Raynaud's phenomenon occurs in 80-90 percent of patients with systemic sclerosis (scleroderma) and is the presenting symptom in 30 percent. It may be the only symptom of scleroderma for many years.(3)
Other causes of secondary Raynaud's phenomenon include atherosclerosis of the extremities, (frequently seen in men over age 50), collagen vascular diseases, arterial occlusive diseases, pulmonary hypertension, neurogenic lesions such as carpal tunnel syndrome or thoracic outlet syndrome, and certain blood dyscrasias.
Several drugs have been implicated to cause Raynaud's phenomenon. These include beta-blockers, ergot preparations, methysergide, amphetamines, imipramine, bromocriptine, clonidine, cyclosporin, cocaine, and the chemotherapy drugs; bleomycin, vincristine, and cisplatin.
Two theories of the cause of digital artery vasospasm in primary Raynaud's disease are an increased activity of the sympathetic nervous system, and a local fault in the digital arteries.(4) In general, persons with Raynaud's disease seem to have a milder form than those with secondary Raynaud's phenomenon.
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