Polyarteritis nodosa causes sections of the middle and outer layers of a blood vessel to swell and become inflamed. Eventually, the tissues of the vessel die. This most commonly occurs where a blood vessel branches into two or more vessels. The inflammation usually begins in the middle layer of medium-sized blood vessel and spreads to the outer and inner layers.
The inflammation and damage to the vessels can lead to the development of blood clots that can block the flow of blood through the artery, damaging organs and tissues. Damage to the blood vessel walls can also cause weak spots (aneurysms) that bulge from the pressure of the blood through the vessel and are at risk of bursting open. When the damaged areas heal, the blood vessel may be left with fibrous nodes in the outer wall of the vessel.
Polyarteritis nodosa mimics many diseases. Polyarteritis nodosa may be similar to hypersensitivity angitis, Churg-Strauss syndrome, Cogan's syndrome, Kawasaki's disease and complications associated with methamphetamine addiction, hepatitis B and C infections and other liver conditions.
The symptoms can vary widely. The disease may be acute with a fever and on-going for a long time; milder but fatal within several months; or appear as a chronic, debilitating disease.
Specific symptoms vary depending on where the affected areas of the arteries are, how severe they are, how much of the blood circulation they affect and what the impact is on various organs.
The most common symptoms are:
- Blood in the urine
- High blood pressure
- High levels of protein in the urine
- Numbness, tingling or weakness of the hands and feet
- Pain in the joints, especially the large ones
- Skin rash with raised reddish-purple patches and knobs that can be felt along affected arteries
- Stomach pain sometimes with nausea, vomiting and bloody diarrhea
- Weight loss
The vessels of the kidneys, liver, heart, stomach and intestines are most often affected.
Causes and Risk Factors
Currently, it is not known what causes polyarteritis nodosa. Various factors may be involved, including the body's defense or immune systems. Other factors include reactions to drugs such as penicillin, iodide and others; vaccinations; bacteria infections; and viral infections such as hepatitis, influenza and HIV.
While the disease can affect people of any age, it usually first appears in people between the ages of 40 and 50.
A doctor may suspect polyarteritis nodosa when a patient has unexplained fever, stomach pain, kidney failure or high blood pressure. The condition may also be suspected if a patient with nephritis or a heart condition has unexplained joint pain, muscle tenderness or weakness, nodes beneath the skin, purplish skin rashes, pain in the stomach, hands or feet or high blood pressure that develops suddenly.
A doctor will rule out other causes of a fever or a condition that affects more than one system of the body at a time. There is no specific test that can be done to confirm polyarteritis nodosa. A doctor will base his or her diagnosis on the symptoms and tests such as:
- A blood test
- A urine test
- Taking a sample of an artery lesion, nearby skin, muscles or nerves (a biopsy) for examination under a microscope
- Angiography that shows aneurysms on medium-sized blood vessels in the kidneys, liver and stomach region
- Electromyography, which measures the electrical impulses between nerves and muscles. This can help select a place for a biopsy
If the condition is acute or chronic, it is usually fatal without treatment. The condition often causes failure of the heart, kidneys or other vital organisms or a ruptured aneurysm.
Treatment may include:
- Eliminating drugs that may be causing reactions
- Using high-dose corticosteroids to prevent the condition from becoming worse. This can partly or completely make the condition go away for about one out of three patients with polyarteritis nodosa. The dosage has to be carefully balanced against side effects such as high blood pressure. This is especially so when a patient already has kidney damage. The dosage given is usually lowered as symptoms improve.
- Drugs that suppress the body's defense or immune system. These may be used alone or with corticosteroids
- Measures to address specific problems such as high blood pressure, fluid retention, etc.
- Surgery, which may be needed if there are intestinal or bowel complications