Definition and Overview
Raynaud's syndrome is a condition in which excessive vasospasm occurs in peripheral arteries and arterioles in response to cold or emotional stress. The fingers are most commonly affected, but the toes, ears, nose, and lips may also appear.
It occurs in approximately 3-5% of the world's population, and is approximately 5-9 times more common in women than in men. It is especially common in young women aged 15 to 30. It is divided into primary Raynaud's phenomenon (formerly 'Raynaud's disease') and secondary Raynaud's phenomenon with an underlying disease.
Triphasic skin color changes
A triphasic color change in skin color that occurs during Raynaud's attack is characteristic.
Pallor: When local blood flow is interrupted due to vascular spasm, the skin turns white. Cyanosis: Stagnant blood turns blue as oxygen saturation decreases. Redness (erythema/rubor): As blood vessel spasm is relieved, blood flows rapidly and becomes red. The recovery period may be accompanied by burning pain.
The three stages may not be clearly visible in all patients, and biphasic changes directly leading to redness after pallor are also common.
Mechanism of occurrence
The mechanism of occurrence of Raynaud's syndrome is complex.
Sympathetic nerve hyperactivity and alpha-2 receptor hypersensitivity are the key. When cold is stimulated, norepinephrine is secreted from sympathetic nerve terminals, and alpha-2C receptors in vascular smooth muscles recognize this and constrict blood vessels. In Raynaud's patients, this receptor is hypersensitive or has increased expression in blood vessels. The mechanism by which alpha-2C receptor movement to the cell surface increases in a low-temperature environment was also confirmed.
Vascular endothelial dysfunction is also involved. The production of nitric oxide (NO) and prostacyclin, which induce normal vasodilation, decreases, and the secretion of vasoconstrictor substances (endothelin-1) increases, resulting in a decrease in vasodilation ability.
In secondary Raynaud's phenomenon, vascular structural damage caused by an autoimmune mechanism additionally occurs. Systemic sclerosis is accompanied by structural vascular stenosis in addition to functional vasospasm due to damage to vascular endothelial cells and fibrosis of the vascular wall.
Distinguish between primary and secondary
Diseases that cause secondary Raynaud's phenomenon include connective tissue diseases (systemic sclerosis, systemic lupus erythematosus, mixed connective tissue disease, rheumatoid arthritis, Sjögren's syndrome), occupational factors (use of vibrating tools, repetitive trauma), drugs (beta blockers, ergotamine, anticancer drugs), vascular occlusive diseases (thrombosis, arteriosclerosis), endocrine diseases (hypothyroidism), and neurological diseases.
Tests that may be helpful in differential diagnosis include nailfold capillaroscopy, antinuclear antibody (ANA), anti-CCP antibody, complement, rheumatoid factor, and complete blood count. If abnormal capillaries (dilatation, loss, bleeding) are observed under a capillary microscope, it suggests an association with connective tissue disease.
treatment
Non-pharmacological treatment
Insulation is the most basic. Minimize exposure to cold environments and use thick gloves and hot packs. Keeping your whole body warm is more effective than keeping just your fingers warm. Quitting smoking is important. Nicotine constricts blood vessels, causing or worsening Raynaud's attacks. Relaxation therapy, biofeedback, and cognitive behavioral therapy for stress management may be helpful.
medication
Calcium channel blockers are the first-line drugs. In a meta-analysis, long-acting dihydropyridine calcium channel blockers such as amlodipine and nifedipine were reported to reduce the frequency of Raynaud's attacks by about 30-40%.
If you have finger ulcers or are at high risk for secondary Raynaud's phenomenon, phosphodiesterase-5 inhibitors (sildenafil), intravenous prostacyclin (iloprost), and endothelin receptor blockers (bosentan) are used.
Sympathetic nerve blockade (stellate ganglion blockade, intrafatty sympathetic nerve blockade) is attempted to control vasospasm in severe secondary Raynaud's phenomenon.