Definition:

Raynaud syndrome (RS) is characterized by episodic digital ischemia induced by cold or emotional stress. Pathophysiologic mechanisms include temporary vasospasm and fixed digital artery obstruction. Although the underlying pathophysiological mechanism is unclear, alterations in activity of the peripheral adrenoceptor have been implicated, specifically an enhanced smooth muscle contraction due to overexpression or hyperactivity of postsynaptic alpha 2 receptors. RS can occur as an isolated entity, historically referred to as Raynaud disease or now primary RS, or in association with other conditions, most frequently the connective tissue diseases (eg, scleroderma [DS:H01492], systemic lupus erythematosus [DS:H00080], rheumatoid arthritis [DS:H00630], and Sjogren's syndrome [DS:H01502]), often referred to as Raynaud phenomenon or secondary RS. The diagnosis is mainly clinical, based on patient descriptions of skin changes. Therapy has been focused on the use of general vasodilation strategies.