I. Clinical classification
Raynaud’s syndrome is traditionally classified into two categories according to its etiology.
1. Raynaud’s disease: primary Raynaud’s disease, the most common type, occurs naturally in the absence of any underlying disease and often involves both limbs. It usually does not cause disability, but patients mostly experience significant pain and discomfort.
2, Raynaud’s phenomenon: that is, secondary Raynaud’s disease, relatively rare, with primary disease. Such as scleroderma, systemic lupus erythematosus, rheumatoid arthritis, arteriosclerosis, neurological diseases, pulmonary hypertension, certain drugs (such as B2 receptor antagonists), trauma, etc. Raynaud’s phenomenon is often the first symptom of many connective tissue diseases and predicts the severity of the disease, so early and accurate diagnosis is very necessary.
II. Epidemiology
It is generally believed that Raynaud’s syndrome has a low incidence, occurs mostly in women, has a male to female ratio of about 1:5, is often between the ages of 20-40, and occurs mostly in winter. However, in a recent 7-year follow-up study of 1525 healthy individuals in the Framingham, Massachusetts area, Suter et al. found a prevalence of 2.2% in women and 1.5% in men. The incidence of Raynaud’s phenomenon is related to geography and climate change. A Greek scholar investigated the staff of Ioannina University Hospital and found a prevalence of 5.2%. In the United Kingdom, researchers conducted a questionnaire survey on 12907 workers, and the incidence of Raynaud’s phenomenon reached 14.2%, of which 11.8% was caused by cold stimulation.
Third, the etiology and pathogenesis
The etiology of Raynaud’s disease is still not completely clear. Cold stimulation, emotional excitement or mental tension are the main triggering factors. Other triggers are infection, fatigue, etc.
Causes of Raynaud’s phenomenon include
Connective tissue diseases as well as vasculitis Almost all connective tissue diseases can be accompanied by Raynaud’s phenomenon and can appear years before other manifestations of connective tissue diseases. The incidence of Raynaud’s phenomenon is quite inconsistent across diseases, with scleroderma (70%-90%), mixed connective tissue disease (85%), rheumatoid arthritis (25%), systemic lupus erythematosus (20%), dermatomyositis, and dry syndrome in that order. Vascular lesions in these diseases are predominantly spastic in the early stages, and after repeated episodes they cause inflammation of the arterial wall, followed by thrombosis and lumen occlusion, and eventually tissue necrosis and ulceration.
1, chronic occlusive arterial disease: occlusive atherosclerosis, thrombo-occlusive vasculitis, arterial embolism, etc.
2, neurological diseases: including central and peripheral nervous system diseases, such as suboptic tumors, spinal cord tumors, myelitis and nerve injury.
3, pharmacological factors: ergot and other antitussive agents, beta-blockers, contraceptives, cyclosporine, heavy metal salts and discontinuation of nitroglycerin, etc.
4, occupational factors: such as repeated vibratory damage, small fish interferential hammer syndrome (ulcerative arterial thrombosis). Commonly found in carpenters, cast iron workers, mechanics, stone workers, typists, pianists, cold injury, etc.
5, blood disorders (intravascular coagulation or aggregation): cold agglutininemia and cold globulinemia, etc.
6, other: such as hypothyroidism, chronic renal failure, malignant tumor and pulmonary hypertension, etc.
The pathogenesis of Raynaud’s syndrome is not yet clear. Some studies suggest that genetic factors, adhesion molecules, vascular endothelial and blood flow factors are involved in the pathogenesis of Raynaud’s syndrome.
Genetic factors
Raynaud’s syndrome is influenced by certain genetic factors. a survey of a large family in the Netherlands by Tewindt et al. found that Raynaud’s disease occurred in 50 out of 289 family members (17.3%), while a study by Smyth et al. found a prevalence of 45.3% in people with a family history of Raynaud’s phenomenon attacks. These studies suggest a potential genetic predisposition for Raynaud’s syndrome.
Adhesion molecules
Increased levels of adhesion molecules may be associated with secondary Raynaud’s syndrome. in a study of 13 patients with primary Raynaud’s disease and 19 patients with secondary Raynaud’s phenomenon and one normal control, Brevetti et al. measured intercellular adhesion molecule-I (IAM-I), vascular cell adhesion molecule-I (VCAM-I), E-selectin (E-S ) and vW factor, the results showed that the four adhesion molecules were significantly higher in the group of patients with secondary Raynaud’s phenomenon than in the other two groups, while there was no difference in the group of patients with primary Raynaud’s phenomenon and controls.
Blood flow factors
Ziegler et al. suggested that blood flow factors play an important role in Raynaud’s phenomenon. They studied 38 patients and 137 controls. It was found that after cold stimulation of the skin at the extremity and then exposure to hot temperatures, the temperature of the fingers was lower in the affected group than in the controls, and the whole blood flow viscosity was highest at different cut rates. Thus, there is a relationship between vasospasm induced by cold stimulation and blood flow factors.