Polyarteritis nodosa

What is it?

Polyarteritis nodosa is a rare, but potentially life threatening, inflammation of the blood vessels (vasculitis) that damages the walls of the body's small- and medium-sized arteries. This damage slows the supply of blood and nourishment to the arteries, causing nearby tissue in many parts of the body to be injured or even destroyed.

The disease most commonly affects the kidneys, the nerves of the arms and legs and the abdominal organs, although it can also involve the skin, joints, muscles, brain, heart, eyes and reproductive organs.

In individual organs, polyarteritis nodosa can have the following effects:

• Kidneys. Kidney failure and high blood pressure related to kidney injury
• Nervous system. Nerve injury in the arms or legs, which may cause numbness, tingling, or loss of sensation and movement caused by injury to one specific nerve bundle. In the brain, damage can trigger strokes, seizures or sudden alterations in brain function.
• Abdominal organs. Pain in the bowel, liver or pancreas, especially after eating, or even death of part of an organ caused by an interruption in blood supply. Arterial aneurysms, which are balloon-like swellings that develop along an artery in areas where vasculitis has weakened the arterial wall, may suddenly rupture. This can lead to life-threatening bleeding inside the abdomen, with severe abdominal pain.
• Heart. Heart attack, as well as inflammation of the lining of the heart (pericarditis). Congestive heart failure can make breathing difficult, as fluid backs up behind the heart into the lungs.
• Skin. Rashes, skin nodules, and a rash (purpura) caused by bleeding from damaged capillaries.

It is difficult to know exactly how many people have this illness because its symptoms can be confused with other diseases and other forms of vasculitis. One British study found that polyarteritis nodosa occurs in three or four of every 1 million people each year in the United Kingdom. In the United States, it may occur more often. According to one Minnesota study, it occurred in up to nine in every 1 million people.

Polyarteritis nodosa can affect people of all races and age groups, but most commonly strikes adults between the ages of 40 and 50. Men are affected about twice as often as women.

Although the cause of polyarteritis nodosa is unknown, some research has linked it to the presence of microscopic clumps of antibodies from the body's defense system, coupled with foreign proteins, such as portions of a virus. In some people with polyarteritis nodosa, the illness seems to be triggered by a viral liver infection, either hepatitis B or hepatitis C.

In some patients, researchers have found at least one autoantibody (an immune protein that attacks the body rather than a foreign invader) that appears to be related to the arterial damage of polyarteritis nodosa. This autoantibody, called antineutrophil cytoplasmic antibody, also has been found in the blood of patients with other vasculitic disorders, including granulomatosis with polyangiitis. However, most patients with polyarteritis nodosa do not have this antibody in their blood or tissues, and many experts do not believe this antibody plays an important role in this condition.

Symptoms

In most people, polyarteritis nodosa develops gradually over weeks to months. The first symptoms include fever, weight loss, weakness, a generally sick feeling (called malaise), muscle aches, headaches or abdominal pain. These complaints are called nonspecific, because many illnesses and diseases produce the same symptoms. Eventually, these symptoms are followed by specific signs of arterial damage to one or more organs. Depending on the location and severity of the damage, any of the following symptoms can occur:

• symptoms of high blood pressure or kidney failure, including severe headache, fluid retention, nausea and confusion
• nausea, vomiting or severe abdominal pain
• seizures, changes in mental function, numbness, tingling or weakness, slurred speech
• pain in muscles or joints
• skin rashes, nodules, hives, a red or purple rash (called purpura) caused by bleeding from damaged capillaries, or larger hemorrhages under the skin
• chest pain or shortness of breath
• pain in the testicles or pelvis.

Because polyarteritis nodosa can cause such a wide variety of symptoms, no two people experience it in exactly the same way.  And it can be difficult to diagnose quickly.

Diagnosis

Your doctor will review your medical history and medications you take. If your doctor suspects that you have polyarteritis nodosa, he or she will ask whether you have been immunized against hepatitis B. Your doctor may ask if you live a lifestyle that increases your risk of hepatitis infection, such as whether you share needles for drug injections or have unprotected sex.

After checking your body temperature and blood pressure, your doctor will examine you. Depending on your symptoms, the doctor will pay special attention to your skin, abdomen and heart, and to any neurological symptoms or signs. After the exam, your doctor may send you for tests to look for evidence of arterial inflammation and organ damage, especially in your kidneys. These tests may include:

• complete blood count, looking for evidence of anemia (which is common in polyarteritis nodosa), or other abnormal blood counts (which may be found in infections or other conditions that can mimic polyarteritis nodosa)
• erythrocyte sedimentation rate or C-reactive protein, measures of body-wide inflammation that are commonly elevated in patients with vasculitis
• blood chemistry to measure levels of blood urea nitrogen and creatinine, two chemicals that reflect kidney function
• urinalysis, which is a microscopic examination of urine, to check for kidney damage or inflammation
• blood tests to check for hepatitis B or hepatitis C infection
• a blood test for the antineutrophil cytoplasmic antibody (ANCA) — although this test is usually negative in polyarteritis nodosa, it is often positive in other types of vasculitis that can cause similar symptoms.

Other blood tests may be performed to check for other explanations for your condition.

To confirm that you have polyarteritis nodosa, your doctor may recommend that a sample (a biopsy) of the involved tissue be obtained so that it can be examined under a microscope to see if an artery is inflamed. For example, a skin biopsy may help to confirm the diagnosis.

As an alternative, your doctor may send you for an X-ray procedure called angiography, which can pinpoint aneurysms or other areas of arterial damage in the affected area. This is less accurate than a biopsy but in some cases, a biopsy may not be possible; for example, major arteries cannot be sampled without causing excessive bleeding or other complications. In such cases, an angiogram may be the best way to show evidence of vasculitis. Sometimes an angiogram using CT scan or MRI can show changes in blood vessels suggestive of vasculitis. Although a positive blood test for the antineutrophil cytoplasmic antibody may support the diagnosis in some patients, this test alone is usually not enough to confirm polyarteritis nodosa.

Expected duration

Some people respond promptly to therapy and can taper off treatment over many months. Others require long-term treatment.

Prevention

There is no way to prevent most cases of polyarteritis nodosa.

Being vaccinated against hepatitis B, and avoiding activities that increase the risk of hepatitis, such as sharing needles during intravenous drug use or having unprotected sex, may prevent hepatitis-related polyarteritis nodosa.

Treatment

If you have no evidence of hepatitis and your symptoms are relatively mild, the doctor usually will begin your treatment with a steroid drug, such as prednisone, a powerful medication that suppresses the immune system and reduces inflammation. However, if you have more severe symptoms involving your heart, nerves or kidneys, if you don't improve with initial treatment or if you have relapses after initial treatment, prednisone may be combined with an additional immunosuppressant medication, such as cyclophosphamide (Cytoxan, Neosar) azathioprine (Imuran), methotrexate (Rheumatrex), mycophenolate mofetil (Cellcept) or rituximab (Rituxan). Full treatment usually takes at least one year.

Sometimes plasmapheresis (also called plasma exchange) is recommended along with one or more medications (as noted above). Plasmapheresis is a process in which plasma is separated from the blood, cleaned of abnormal antibodies, and then replaced. The overall benefit of plasmapheresis for polyarteritis nodosa induced by viral hepatitis is not clear.

If polyarteritis nodosa is related to hepatitis B or hepatitis C, you may be treated with antiviral medications alone to fight the liver infection. Or antiviral treatment may be combined with prednisone to control arterial inflammation.

When to call a professional

See your doctor if you develop any symptoms of polyarteritis nodosa. If you experience chest pain, difficulty breathing, severe abdominal pain or a combination of these symptoms, call or get to a hospital emergency room for an evaluation.

Prognosis

With proper treatment, at least 80% of people with polyarteritis nodosa survive for five years or more after diagnosis, often recovering completely. In one study, the risk of relapse after successful treatment was about 10%, although damaged blood vessels may cause problems, such as a heart attack, long after the inflammation has been treated. Without appropriate treatment, the prognosis is poor: only 10% of people survive for five years after they are diagnosed.

Additional info

National Institute of Arthritis and Musculoskeletal and Skin Diseases
https://www.niams.nih.gov/

American College of Rheumatology
https://www.rheumatology.org/

National Organization for Rare Disorders
https://www.rarediseases.org/