WHAT: Raynaud's phenomenon. Raynaud's Phenomenon: the paroxysmal constriction of the small arteries and arterioles of the hands or feet, usually precipitated by cold or emotional upset, resulting in pallor and cyanosis of the fingers or toes following a characteristic pattern. WHY: Raynaud's phenomenon may occur in mixed connective tissue disease, systemic lupus erythematosus, progressive systemic sclerosis, poly- myositis/dermatomyositis, and rheumatoid arthritis associated with Sjogren's syndrome. HOW: In Raynaud's phenomenon there are three classic color changes of the fingers or toes. First, vasoconstriction results in a white blanching of the fingertips. Second, vasodilatation with sludging of vascular flow follows and results in blue, cyanotic digits. Finally, with recovery, there is increased blood flow with resulting erythema of the fingers. With observation of two of the three color changes, Raynaud's phenomenon is considered present. Local body cooling (by placing the hands in ice cold water) may demonstrate Raynaud's phenomenon, but some cases require general body cooling before the characteristic color phases occur. Permanent tissue damage can be induced by this testing, which therefore must be done only when absolutely necessary. If the digits show persistent cyanosis or there is evidence of pre-existing necrosis, performing this test is especially hazardous. One or more digits may be involved in Raynaud's phenomenon, and this involvement may be unilateral. REFS: 1) Spittell, JA: "Raynaud's phenomenon and allied vasospastic disorders". In Juergens, JL et al. (eds.): Peripheral Vascular Diseases, pp. 555-83. Philadelphia: W.B. Saunders Co., 1980. 2) Porter, JM; Snider, RL; Bardana, EJ; Rosch, J and Eidemiller, LR: The diagnosis and treatment of Raynaud's phenomenon. Surgery 77:11, 1975. DN19300-3.