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In medicine, Raynaud's (ray-NOHZ) Disease or Raynaud's Phenomenon is excessively reduced blood flow in response to cold or emotional stress, causing discoloration of the fingers, toes, and occasionally other areas. This condition may also cause nails to become brittle with longitudinal ridges. Named after French physician Maurice Raynaud (1834–1881), the phenomenon is believed to be the result of vasospasms that decrease blood supply to the respective regions. When the disorder's cause is idiopathic it is referred to as Raynaud's disease (also called Primary Raynaud's), If the syndrome is secondary to another disease such as systemic sclerosis, systemic lupus erythematosus, or other connective tissue disorders, it is correctly referred to as Raynaud's Phenomenon (Secondary Raynaud's).〔(【引用サイトリンク】url=http://www.nhlbi.nih.gov/health/health-topics/topics/raynaud/ )〕 If Raynaud's Phenomenon is suspected to be secondary to systemic sclerosis, one tool which may help aid in the prediction of systemic sclerosis is thermography. It is a hyperactivation of the sympathetic nervous system causing extreme vasoconstriction of the peripheral blood vessels, leading to tissue hypoxia. Chronic, recurrent cases of Raynaud phenomenon can result in atrophy of the skin, subcutaneous tissues, and muscle. In rare cases it can cause ulceration and ischemic gangrene. == Signs and symptoms == The condition can cause pain within the affected extremities, discoloration (paleness), and sensations of cold and/or numbness. This can often be distressing to those who are not diagnosed, and sometimes it can be obstructive. If someone with Raynaud's is placed into a cold climate, it could potentially become dangerous. # When exposed to cold temperatures, the blood supply to the fingers or toes, and in some cases the nose or earlobes, is markedly reduced; the skin turns pale or white (called pallor) and becomes cold and numb. # When the oxygen supply is depleted, the skin color turns blue (called cyanosis). # These events are episodic, and when the episode subsides or the area is warmed, the blood flow returns, and the skin color first turns red (rubor), and then back to normal, often accompanied by swelling, tingling, and a painful "pins and needles" sensation. All three color changes are observed in classic Raynaud's. However, not all patients see all of the aforementioned color changes in all episodes, especially in milder cases of the condition. Symptoms are thought to be due to reactive hyperemias of the areas deprived of blood flow. In pregnancy, this sign normally disappears owing to increased surface blood flow. Raynaud's has also occurred in breastfeeding mothers, causing nipples to turn white and become extremely painful. Nifedipine, a calcium channel blocker and vasodilator, was recommended to increase blood flow to the extremities and noticeably relieved pain in the breast in an extremely small study group. 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「Raynaud's phenomenon」の詳細全文を読む スポンサード リンク
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