Raynaud’s phenomenon is a change in the color of the fingers and toes, and sometimes the nose and ears, in response to cold or strong emotion or stress. Blood vessel spasms cause a lack of blood flow, turning the digits or appendages white, blue, and then red again as blood flow is restored. The medical term for this manifestation is pallor and cyanosis. The phenomenon is named for the doctor who first described it, Maurice Raynaud. Raynaud’s phenomenon can occur as a primary disorder, which is suspected to be due to abnormal nerve activity according to Dr. William Shiel, Jr. at MedicineNet, but it also occurs secondary to a number of diseases, particularly autoimmune diseases.
Systemic diseases associated with Raynaud’s phenomenon
Systemic diseases are diseases that affect the whole body. The cold phenomenon is seen in some forms of arthritis, cryoglobulinemia, and some autoimmune diseases. Cryoglobulinemia is the presence of immune molecules, specifically immunoglobulin (Ig) proteins, that precipitate at low temperatures. In autoimmune diseases, antibodies are produced against the body’s own tissues or cells. According to Medscape the most common autoimmune disorder associated with Raynaud’s phenomenon is systemic sclerosis, a connective tissue disease also known as scleroderma. Approximately 90 percent of patients with systemic sclerosis experience the phenomenon, and 85 percent of patients with mixed connective tissue disease experience it. The phenomenon is also seen in systemic lupus erythematosus (SLE, or lupus).
The phenomenon as a manifestation of disease
As a secondary disorder, Raynaud’s phenomenon is a manifestation of the underlying disease’s effect on blood flow to the fingers and toes. The phenomenon is thought to occur because of an overreaction of the small blood vessels. The role of vascular damage in this process is exemplified by what has to come to light about systemic sclerosis (see a review). Over the course of the autoimmune disease, the blood vessels undergo structural alterations and dysfunction, including enhanced vascular permeability. These changes in the integrity of the vessels lead to an imbalance in vasoconstriction and vasodilation, leading to the dysregulation of the contractile response (i.e. spasms) that cause Raynaud’s. Over time, the ischemia and reperfusion caused by the vasospasms, which manifests as the pallor and cyanosis of Raynaud’s phenomenon, further damage the small vessels.
A different mechanism may be in play in cryoglobulinemia - according to research the immune proteins aggregate and cause blockages in the small blood vessels. These blockages cause the ischemia and cyanosis of Raynaud’s. In contrast to other forms of secondary Raynaud’s, the cold and pallor in this form is associated with numbness and pain and can include more of the extremity than just the digits. The aggregates can cause tissue damage, not just vessel damage.
Using it as an indicator for treatment
Because secondary Raynaud’s phenomenon is a manifestation of an underlying disease, the appearance of its symptoms can be used as an indicator for treatment. After testing for underlying causes and determining the reason for vessel damage, doctors can treat patients to prevent further complications of their systemic disease, such as ulceration in systemic sclerosis using endothelin receptor antagonists. Other treatments include relaxing the vessels with phosphodiesterase inhibitors (for example, sildenafil, known by the brand name Viagra), ACE inhibitors, or calcium channel blockers, and modulating vascular signaling with adrenoceptor blockade. Some researchers think that the cold, blue digits are just an outward indicator of problems with the vasculature of the organs. So recognizing Raynaud’s phenomenon in the digits allows the diagnosis of potentially systemic problems.