Introduction:
Polyarteritis nodosa or PAN is a rare systemic condition that occurs when inflammation of a blood vessel disrupts the blood supply to the concerned organ, ultimately resulting in organ damage. Polyarteritis is a type of vasculitis. It typically affects medium-sized vessels and mostly in vessel bifurcation. It can affect nerves, the intestinal tract, and joints. It can even affect the blood supply to the kidney resulting in high blood pressure and kidney damage.
It presents as an aneurysm, thinning, or rupture of a blood vessel, which causes hemorrhage or organ failure due to disruption in blood supply.
The disease was first described in 1886 by Kussmaul and Maier. They identified the disorder to consist of focal, inflammatory, arterial nodules. That is, it had a specific focus, and the nodule was the result of inflammation. They initially named it periarteritis nodosa as the inflammation was seen around the blood vessel; it was renamed polyarteritis nodosa, as the inflammation was throughout the arterial wall, not solely around it. This is one of the major features of the disease. It is also referred to as systemic necrotizing vasculitis, but that term may cause confusion due to a lack of specificity, as other forms of vasculitis may also be necrotizing.
What Is Vasculitis?
Vasculitis or vascular inflammation is the inflammation of blood vessels. The inflamed blood vessel may become weak or stretch. It can present as an aneurysm, thinning of the vessel, or ultimately complete occlusion. Thinning may lead to rupture, causing bleeding into the tissue. Occlusion of the blood vessel will result in organ failure as the oxygen supply to the organs is completely cut off.
What Causes PAN?
The exact cause of polyarteritis nodosa has not been found. It is not a form of malignancy (cancer); it is non-communicable and non-hereditary. However, research has found a relation between PAN and the immune response of the body, considering it is an inflammatory response, causing blood vessels and tissue damage. Most research suggests that PAN is an autoimmune disease. An autoimmune disorder is when the body attacks itself for an unknown reason as a defense mechanism.
There has been some association between hepatitis B and polyarteritis nodosa. Patients with hepatitis B may develop polyarteritis nodosa within six months of being infected. The introduction of the hepatitis vaccine and the decline of polyarteritis nodosa further strengthen the correlation between the diseases.
Some bacterial infection is also considered to trigger the immune response, thereby causing polyarteritis nodosa. The primary cause for PAN is mostly considered idiopathic (without a proper cause), whereas secondary cases of PAN (rare in occurrence) are mostly seen in association with hepatitis B and C.
Who Is Susceptible to Polyarteritis Nodosa?
The disease is mostly seen affecting men twice more than women. It usually presents in the age group of 40 to 50 years. Hepatitis B patients are also susceptible to developing the disease. It is a rare disease affecting one in 100,000 people.
How to Identify Polyarteritis Nodosa?
Symptoms include fatigue, fever, skin lesions, weight loss, and abdominal pain. Damage to the affected arteries may cause an increase in blood pressure. Joint, muscle, and testicular pain may also occur. If the blood supply to the kidney is affected, it may lead to kidney failure. Patients may also report nausea, vomiting, and diarrhea. It may also present as burning, tingling, or numbness in the hands and feet.
Symptoms Related to Skin - Skin abnormalities are a common symptom in polyarteritis nodosa. It may include purpura, ulcers, nodules or gangrene.
Lesions in the skin may be tender, red (erythematous) nodules. Like other forms of vasculitis, it may also be associated with palpable purpura. The skin lesions are usually found in the lower extremities and may be painful.
Symptoms Related to Nerve - Decreased nerve stimulation may occur two to three years after the onset of PAN. This may occur in the hands, arms, feet, and legs. It may worsen and lead to seizures and cognitive dysfunction.
Symptoms Related to Blood Vessels - Aneurysms, thinning of blood vessels, and even occlusion are the characteristic features of PAN.
The damage to the blood vessels may lead to an increase in blood pressure.
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Aneurysms - The ballooning of an arterial wall.
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Thrombosis - Formation of clots.
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Occlusion - Obstruction of blood supply to organs and tissues.
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Necrosis - Loss of blood supply in certain areas.
Symptoms Related to Abdomen - Patients may experience abdominal pain, also described as intestinal angina. It consists of continuous or intermittent pain, often after meals.
How Does the Disease Progress?
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The thinning of blood vessels leads to decreased or no blood supply to tissues and organs, which leads to necrosis.
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If the kidney is involved, this will lead to increased blood pressure.
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Long-standing increased blood pressure leads to the involvement of coronary (heart) arteries leading to heart failure.
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Inflammation not only leads to narrowing of the vessels but also to complete necrosis which can manifest as a multi-system failure, such as kidney, skin, neurological, cardiac, and muscular.
How to Diagnose Polyarteritis Nodosa?
There is no single blood or laboratory test that can identify the disorder. The diagnosis is mainly based on physical examination of symptoms and by elimination of other likely disorders.
It is done by:
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Checking medical history.
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Physical examination.
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Blood tests suggest inflammation. Some may show elevated ESR.
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Urinalysis and creatinine tests.
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Imaging tests such as magnetic resonance imaging (MRI) and computed tomography (CTs) to locate lesions.
Once PAN is suspected or narrowed down cases, a biopsy may be done to confirm. Biopsy of the kidney and liver may also be required.
What Are the Complications of Polyarteritis Nodosa?
Untreated PAN is usually fatal. Mostly due to kidney failure, heart attack, or intestinal complications.
The complications include the following:
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Skin lesions and ulcers.
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Infarction.
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Kidney failure.
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Intestinal bleeding.
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Numbness.
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Gangrene of extremities.
How to Treat Polyarteritis Nodosa?
Treatment is based on the severity of the disease.
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Treatment mostly consists of immunosuppressive drugs- those that help reduce the immunological response of the body and relieve inflammation.
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Mild Form - Those with symptoms but normal kidney function are considered to have a mild form of the disease, with no sign of necrosis or organ failure.
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These cases may be treated with glucocorticoids, most commonly Prednisone.
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Immunosuppressive medications will have side effects, so proper long-term monitoring of the patient has to be done. Side effects include other infections.
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Patients with secondary cases, such as PAN due to hepatitis B or C infection, may be treated with antivirals first. This is shown to have better results.
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Patients with increased blood pressure may require medications to reduce it.
Even with proper care, PAN has high rates of relapse. Without treatment, the disease is fatal, and patients may not survive more than three months. But with proper care, there is at least a five-year survival rate. The prognosis is best for patients with only skin involvement.
Conclusion:
Polyarteritis nodosa, although a rare disorder, is one with severe systemic manifestations and complications. The best prognosis is for those patients where the disease has been identified and treated promptly. Long-term monitoring of the patient is also of utmost importance. These interprofessional treatments and monitoring can significantly increase the survival rate of the individual.
