Polyarteritis Nodosa

Polyarteritis nodosa is a disorder in which segments of medium-sized arteries become inflamed and damaged, reducing the blood supply to certain organs and tissues.

Polyarteritis nodosa most often develops at 40 to 50 years of age but can occur at any age. Men are 3 times more likely than women to develop this type of vasculitis.

Its cause is unknown but sometimes appears to be a reaction to certain drugs and vaccines. Viral infections (such as hepatitis B infection) and bacterial infections (such as streptococcal or staphylococcal infections) sometimes appear to trigger the inflammation, but most often no initiating event or substance can be found.

Symptoms

The disorder can be mild at first but can worsen rapidly and be fatal within several months, or it can develop subtly as a chronic debilitating disease. Any organ or combination of organs in the body can be affected (except the lungs); the symptoms depend on which organs are affected. Because vasculitis is often associated with inflammation of connective tissue, joints are often affected. Muscle and joint pain is common, and joint inflammation (arthritis) may occur.

A fever is a common early symptom. Abdominal pain, numbness and tingling in the hands and feet, weakness, and weight loss can also develop early. Three fourths of people who have polyarteritis nodosa develop kidney damage (because blood vessels supplying the kidneys are affected), which can cause high blood pressure, swelling from water retention, and decreased production of urine.

When blood vessels in the digestive tract are affected, areas of this tract can become perforated, causing an abdominal infection (peritonitis), severe pain, bloody diarrhea, and a high fever. When blood vessels to the heart are affected, chest pain and heart attacks can result. Damaged blood vessels in the brain can cause headaches, seizures, and hallucinations. Damaged blood vessels in the liver can cause extensive liver damage. Blood vessels near the skin may feel bumpy and irregular to the touch, and occasionally ulcers form on the skin over the blood vessels.

Diagnosis and Treatment

No blood test can confirm the diagnosis of polyarteritis nodosa. Doctors suspect the disease when the combination of symptoms and laboratory test results cannot be explained any other way. For instance, they may suspect it when fever and evidence of nerve damage, such as patchy numbness, tingling, or paralysis, develop in a previously healthy middle-aged man. The diagnosis can be confirmed by a biopsy of an affected blood vessel. A biopsy of the liver or kidney may also be needed. X-rays taken after a radiopaque dye, which is visible on x-rays, is injected into the arteries may show bulges (aneurysms) in the walls of affected arteries.

Without treatment, only 33% of affected people survive for 1 year; 88% die within 5 years. Aggressive treatment can delay or prevent death from this disorder.

Any drugs that may have precipitated the disease are discontinued. Any other possible triggering factors, such as an infection, are treated.

High doses of a corticosteroid, such as prednisone, can prevent the disease from worsening and induce a symptom-free period in about one third of the people. Because long-term treatment with a corticosteroid is usually needed and because such long-term treatment can produce significant side effects, doctors reduce the dose once symptoms have subsided. If corticosteroids do not reduce the inflammation adequately, they may be replaced with or accompanied by drugs that suppress the immune system, such as cyclophosphamide. Other treatments, such as those used to control high blood pressure, are often needed to prevent damage to internal organs.

Even with treatment, several vital organs may fail or a weakened blood vessel may rupture. Kidney failure is a common cause of death. Potentially fatal infections may occur because the long-term use of corticosteroids and immunosuppressive drugs reduces the body's ability to fight infections.