RaynaudÆs phenomenon:
A condition resulting in discoloration of fingers and/or toes when a person is exposed to changes in temperature (cold or hot) or emotional events. Skin discoloration occurs because an abnormal spasm of the blood vessels causes a diminished blood supply. Initially, the digits involved turn white because of diminished blood supply, then turn blue because of prolonged lack of oxygen and finally, the blood vessels reopen, causing a local "flushing" phenomenon, which turns the digits red. This three-phase color sequence (white to blue to red), most often upon exposure to cold temperature, is characteristic of RaynaudÆs phenomenon. Named for the French physician Maurice Raynaud (1834-1881).
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