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Churg-Strauss Syndrome

What is Churg-Strauss syndrome?

Churg-Strauss syndrome (CSS) is an extremely rare disease – there are only 2 to 5 new cases per year per 1 million people. CSS results from inflammation that occurs in certain types of cells in blood or in tissues. This inflammation causes injury to organ systems – the most commonly involved are the lungs, nose, sinuses, skin, joints, nerves, intestinal tract, heart, and kidneys. A main feature of CSS is that all patients have had a history of asthma and/or allergies.

Almost all people with CSS have increased numbers of "allergic type" blood cells called eosinophils. Eosinophils are a type of white blood cell. Normally, eosinophils make up 5% or less of the total white blood cell count. In CSS, eosinophils usually make up more than 10% of the total white blood cell count. In addition, most biopsies contain clusters of cells called "granulomas" that may or may not involve blood vessels. The granulomas often include eosinophils and are therefore called "allergic granulomas." In fact, another name for CSS is allergic granulomatosis. Some of the most serious manifestations of CSS are related to the presence of vasculitis.

What is vasculitis?

Vasculitis is a general medical term that refers to inflammation of the blood vessels. When blood vessels become inflamed, they can stretch, become thin-walled, or narrow in size. When they weaken and stretch in size, aneurysms can develop. (An aneurysm is an abnormal blood-filled expansion of a blood vessel.) When they thin, the walls can rupture and blood leaks into tissue. Vasculitis can also cause blood vessels to narrow to the point of closing. Organs can be damaged from the loss of oxygen and nutrients that were being supplied by the blood.

What are the symptoms of CSS?

Because many different organ systems may be involved, a wide range of symptoms are possible in CSS.

Patients who have CSS may feel generally ill and fatigued, have fevers, or have a loss of appetite and weight. Other specific symptoms depend on the organs or diseases involved. For example, patients may have:

  • shortness of breath from asthma or inflammation in the air sacs and blood vessels of the lung
  • chest pain from disease affecting the lungs or heart
  • rashes on the skin
  • muscle and/or joint pain
  • increased nasal discharge or facial pain from sinusitis
  • abdominal pain or blood in the stools occurring as a result of intestinal tract involvement
  • abnormal sensations followed by numbness or loss of strength and feeling as a result of nerve involvement

Any combination of these symptoms may be present.

Kidney disease caused by CSS often does not produce symptoms. Inflammation of the kidney may not be apparent to the patient until the kidneys begin to stop working. Therefore patients with any form of vasculitis must always have their urine examined.

What causes CSS?

The cause of CSS is unknown. CSS is not a form of cancer, it is not contagious, and it does not usually occur within families. The immune system plays a role in CSS. The immune system acts to protect the body against ‘foreign invaders’ – eg, germs, bacteria – that cause infections, disease, and other injuries to the body. Sometimes the immune system does not protect the body as it normally should.

Who is affected by CSS?

CSS can occur in people of all ages, from children to the elderly. The average age of diagnosis is between 35 and 50 years old. CSS appears to affect men and women equally.

How is CSS diagnosed?

Suspicion of CSS is based on information including:

  • Medical history - to look for the presence of CSS symptoms, especially the presence of asthma, allergies and other features suggestive of disease.
  • Physical examination - to detect sites of organ involvement and to exclude other illnesses that may have a similar appearance.
  • Blood tests - to look for abnormal blood counts with an increase in eosinophils.
  • Urinalysis - to detect excessive protein or the presence of red blood cells.
  • Imaging tests such as x-rays, including computed tomography (CT), to see any abnormalities in areas such as the lungs or sinuses.

Once the diagnosis of CSS is suspected, a biopsy (tissue sample) is often performed to try to confirm the presence of eosinophils, eosinophilic granulomas and/or vasculitis. Biopsies of suspected organs or other disease sites are only recommended when abnormal findings are seen in the exam, laboratory tests, or imaging tests. Biopsies are not required in all cases.

How is CSS treated?

Drugs that suppress the immune system are the foundation of treatment for CSS. A variety of immunosuppressive drugs are used to treat CSS. The severity of CSS is the most important factor in determining what drug to use. Disease severity can range from a more mild presence -- such as affecting the skin or joint -- to potentially life threatening.

Corticosteroids, such as prednisone or prednisolone, are the most common treatments. People who have a mild disease presence – those whose disease does NOT affect the nervous system, heart, kidneys, intestinal tract or show other features of severe disease -- might do extremely well on corticosteroid therapy alone. Once dramatic improvement is achieved, the drug dosage is reduced to the lowest amount that keeps the disease under control.

People with CSS who have critical organ system involvement are generally treated with corticosteroids combined with another immunosuppressive drug, such as cyclophosphamide (Cytoxan®), methotrexate, or azathioprine (Imuran®). These drugs are also used to treat other medical conditions. Azathioprine is used to prevent organ transplant rejection and is a treatment option for rheumatoid arthritis and lupus. High doses of cyclophosphamide and methotrexate are used to treat certain types of cancer. In cancer treatment, these drugs work by killing or slowing the growth of rapidly multiplying cancer cells. In vasculitis, these drugs are given at doses 10 to 100 times lower than that used to treat cancer. In vasculitis, these drugs’ primary effects are to suppress the immune system.

All immunosuppressive drugs can have side effects; and each drug can have side effects unique to it. To prevent or minimize side effects, watching for them is critical. A person with CSS may tolerate treatment when they first starting taking drugs; however, this does not guarantee that the same degree of tolerance will last over time. This makes ongoing monitoring essential, and in some instances, monitoring for long-term effects may be important even after the drug is stopped. Monitoring of blood tests is also used to evaluate the illness itself.

The goal of treatment is to stop all damage that results from CSS (a stage referred to as "remission"). Once it is apparent that the disease is improving, doctors slowly reduce the corticosteroid dose and eventually hope to discontinue it completely. Complete discontinuation may be particularly difficult if a person has significant asthma, as the airways can be very sensitive to corticosteroids. If cyclophosphamide is used for severe CSS, it is often only given until the time of remission (usually around 3 to 6 months), after which time the patient is switched to another immunosuppressive agent, such as methotrexate or azathioprine to maintain remission. The treatment duration of maintenance immunosuppressive drug may vary between individuals. In most instances, it is given for a minimum of 1 to 2 years before consideration is given to the possibility of slowly reducing the dosage to discontinuation.

What is the outlook for patients with CSS?

Because CSS is a rare disease, accurate statistics on overall outcome are only approximate. On average, after 5 years of illness, over 80% of people have survived the effects of CSS. How people with CSS do is strongly related to the severity of their illness. Although CSS can be a progressive and serious illness, many people with CSS do extremely well.

The best opportunity for minimal organ damage to occur comes when treatment has been promptly initiated and is carefully monitored by a physician who is knowledgeable about CSS. Even patients who have the most severe CSS can achieve remission when treated promptly and followed closely.

After achieving remission, it is possible for the CSS to recur (often referred to as a "relapse"). People with asthma or nasal allergies can frequently experience worsening of these symptoms that is independent of vasculitis. Relapses involving vasculitis occur in about 30% to 50% of people with CSS. Such relapses may be similar to what the person experienced at the time of their diagnosis or they may be different. The likelihood of experiencing a severe relapse can be minimized by prompt reporting of any new symptoms to the doctor, regular doctor follow-up, and ongoing monitoring with laboratory tests and imaging. The treatment approach for relapses is similar to that of newly diagnosed disease with achievement of remission again being possible for most people with CSS.


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This information is provided by Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition.

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