What causes Raynaud phenomenon?

The definite underlying cause of Raynaud's syndrome is still largely unknown to those in the medical field, especially when the condition is not associated with any other illness. A secondary form of Raynaud's can be traced back to specific underlying conditions or lifestyle habits that adversely affect the function of blood vessels and impact connective tissues.

Research studies point to abnormal nerve control of the diameter of blood vessels and a nerve sensitivity to cold temperature as the primary causes of the condition.

Some underlying problems associated with secondary Raynaud phenomenon include:

• Autoimmune / connective tissue conditions – rheumatoid arthritis, lupus, scleroderma or Sjogren’s disease.
• Conditions associated with hormone imbalances - Hypothyroidism or carcinoid tumours.
• Blood disorders - Cryoglobulinemia (excess proteins in the blood that become insoluble at lower temperatures) or polycythemia (elevated numbers of red blood cells in the blood).
• Medication use – beta-blockers and amphetamines are known to cause a narrowing of arteries. Birth control pills (oral contraceptives) are also known to influence blood flow. Other medications linked to Raynaud phenomenon include migraine drugs containing ergotamine or sumatriptan, as well as some chemotherapy, some ADHD (attention deficit hyperactivity disorder) medications, and over-the-counter cold remedy drugs.
• Atherosclerosis – a condition that occurs due to a hardening of the arteries (plaque build-up in the blood vessels).
• Other associated diseases of the arteries – Buerger’s syndrome (inflammation in the hands and feet) and primary pulmonary hypertension (high blood pressure which affects the arteries of the lungs and right side of the heart) can also lead to Raynaud-like symptoms.
• Carpal tunnel syndrome – Raynaud-like symptoms can develop as a result of pressure on the nerves connecting to the hand (median nerves). This can result in pain or numbness in the hands, priming them for more frequent Raynaud phenomenon attacks.
• Smoking (can narrow or constrict the arteries) and caffeine intake (may be a possible trigger)
• Bodily injury – fractures of the wrist or ankle, frostbite or following surgery.

For the most part, primary Raynaud phenomenon has no known or related cause. Both forms of the condition however, are similar in that comparable types of triggers result in symptomatic attacks.

Raynaud's syndrom triggers

The most common triggers include:

• Cold temperatures (exposure through air, placing a portion of the body in cold water or contact with ice)
• Intense emotions or emotional stress (even without exposure to cold temperatures)
• Using hand tools which emit vibrations (e.g. jackhammers can increase a person’s risk for vasospasm)
• Repetitive motion such as those used for playing a musical instrument (piano or guitar) or typing

Associated influences (which may be a combination of contributing factors) for Raynaud phenomenon include:

• Vascular mediators: Nitric oxide (a strong vasodilator that is more common in people with secondary Raynaud phenomenon), endothelin-1 (a strong vasoconstrictor / protein than is more common among those with primary Raynaud’s) and serotonin (a neurotransmitter which occurs in higher concentrations in those with Raynaud’s).
• Oxidative stress: An increase in free radicals may be associated with Raynaud phenomenon.
• Platelet activation: Components of blood which clump together in order to prevent bleeding has been noted as higher in those with Raynaud phenomenon.
• Fibrinolysis: This is a natural process which takes place to reduce clotting in the body (breaking down of clots). Some studies have suggested that those with Raynaud's have reduced levels of this process.