Raynaud's Phenomenon

Raynaud's phenomenon is an exaggerated, temporary constriction of the small arteries supplying the fingers or toes. Cold exposure is the usual trigger; emotional stress can produce the same sympathetic vasoconstriction. Blood flow falls abruptly during an attack, so the digits may become white or pale. As stagnant, deoxygenated blood remains in the tissue, the colour may progress to blue. Rewarming restores flow, producing redness, warmth, tingling, throbbing, or burning. The classic sequence is white → blue → red, but an individual episode may show only one or two phases. The diagnostic clue is not the exact colour sequence; it is a reproducible, trigger-linked attack that improves when the trigger is removed and the digit is rewarmed. Primary Raynaud's occurs without an identified underlying disease and usually affects both sides symmetrically. Between attacks, the digits generally look and feel normal, and tissue loss is not expected. Secondary Raynaud's results from another process, often a connective-tissue disease, and deserves closer investigation because vasospasm may be more painful, asymmetric, prolonged, or severe enough to cause digital ulcers, infection, or gangrene. This distinction changes...