Raynaud's phenomenon (RP) is a disorder that produces vasospasm, a particular series of discolorations of the fingers and toes after exposure to changes in temperature (hot or cold) or emotional events. Most people with RP are sensitive to cold. The skin discoloration occurs because an abnormal spasm of blood vessels cause decreased blood flow to local tissues. Initially, the involved digits turn white due to decreased blood flow.
Digits turn blue (cyanosis) due to prolonged lack of oxygen. Eventually, the blood vessels reopen, causing a local "reddening" phenomenon, which turns the digits red. This three-phase color sequence (white to blue to red), most often after exposure to cold temperatures, is characteristic of RP.
Raynaud's phenomenon affects women more often, especially in the second, third, or fourth decades of life. People can have Raynaud's phenomenon alone or as part of other rheumatic diseases. Raynaud's phenomenon in children is essentially identical to Raynaud's phenomenon in adults. When it occurs alone, it is known as " Raynaud's disease " or primary Raynaud's phenomenon. When it accompanies other diseases, it is called secondary Raynaud's phenomenon.
The causes of primary Raynaud's phenomenon and secondary Raynaud's phenomenon are unknown. Both abnormal nervous control of the diameter of the blood vessels and nervous sensitivity to cold exposure are suspected contributing factors. The characteristic color changes of the digits are in part related to the initial narrowing of the blood vessels due to spasm of the small muscles in the vessel wall, followed by a sudden opening (dilation), as described above. The small arteries in the fingers can have a microscopic thickness of their inner lining, which also leads to abnormal narrowing of the blood vessels.
Risk factors for Raynaud's phenomenon include freezing injuries and vibrating tools, medications (bleomycin, Blenoxane), propranolol (Inderal), ergotamine), and rheumatic autoimmune diseases such as scleroderma, systemic lupus erythematosus, Sjogren's syndrome, mixed tissue disease connective tissue, and rheumatoid arthritis.
