Raynaud's phenomenon is the occurrence of ischemic episodes, characterized by changes in distal skin color as cyanosis or pallor followed by flushing. Raynaud's disease has nothing to do with the Raynaud’s phenomenon, but the Raynaud’s phenomenon is usually triggered by a disease.

First described by Maurice Raynaud in 1862, the phenomenon is often triggered by exposure to cold but can also be caused by emotional stress. It consists of the sequential development of pallor, cyanosis and flushing, usually well defined and usually confined to the fingers and toes. Pallor occurs during the ischemic phase phenomenon and is due to digital vasospasm.

During ischemia, arterioles, venules and capillaries dilate. Cyanosis is secondary to the presence of oxygen-depleted blood in these vessels. The pallor and cyanosis are accompanied by cold, swelling and paresthesia. With warmth, vasospasm resolves producing a reactive hyperemia which gives a reddening of the affected area sometimes with palpitations. These are some of the Raynaud’s disease symptoms. Subsequently, the color of the member returns to normal.

The precise causes of Raynaud's phenomenon are not known. Vasospasm may be an abnormal response to vasoconstrictor stimuli that normally produce only a modest contraction of smooth muscles of vessels and Raynaud's disease can cause obliteration of the arterioles.

Clinical picture - The crisis begins in the fingertips. Pallor, a few minutes' duration accompanied by stinging, numbness and coldness. Then the phase of cyanosis starts and coldness usually does not disappear spontaneously, but by applying heat. This is followed by the reactive hyperemia phase with the appearance of redness. Raynaud's disease (also called primary Raynaud's phenomenon) occurs more frequently in younger women than in men (from 3:1 to 5:1).

Diagnosis - Diagnosis is based on Raynaud’s disease symptoms, also known as the Allen and Brown criteria (1932): ischemic attacks of discoloration of the extremities; absence of functional arterial occlusions; bilateral distribution; trophic changes, should be present, are confined to the skin and in any case consists of gangrene; absence of other conditions or systemic diseases that can trigger Raynaud's phenomenon; duration of more than two years

There are several tests that can be used for diagnosis of Raynaud's phenomenon. The most accurate method is the measurement of digital blood pressure while cooling the body, although it is a laborious and difficult method. Angiography is generally not indicated except in patients with persistent digital ischemia secondary to arteriosclerosis, thromboangitis obliterans or hypothenary syndrome.

Treatment - Treatment should be individualized according to underlying causes of secondary Raynaud's phenomenon and the severity of symptoms.

Patients with Raynaud's disease require no treatment other than the advice to avoid exposure to cold and to use appropriate gloves and socks. Smoking cessation is recommended as the cutaneous vasoconstriction produced snuff. Biofeedback techniques can cause a reduction in the frequency and severity of vasospasm. Drugs seem to be effective in the treatment of Raynaud's phenomenon. These drugs are calcium antagonists and inhibitors of sympathetic nervous system.