Giant cell arteritis is a chronic inflammatory disease characterized by the progressive inflammation of many arteries of the body (panarteritis). Granular material and abnormally large cells (giant cells) accumulate in the elastic lining of the arteries. Chronic inflammation is sometimes confined to the different branches of the heart's main artery (aorta) and any large arteries can become inflamed. However, the temporal arteries of the head are most frequently affected (temporal arteritis). In rare cases, veins may also be affected by giant cell arteritis.
The symptoms of giant cell arteritis may include stiffness, muscle pain, fever, and/or headaches. The exact cause of this disease is not fully understood, although it is thought to be an autoimmune disease that occurs when the body's, own immune system attacks healthy tissue.
Giant cell arteritis is closely related to polymyalgia rheumatica, another inflammatory disorder. These two disorders have been described in the medical literature as possible variants of the same disease process. Some researchers believe they represent different ends of a disease continuum. The exact nature of the association is not fully understood.
The most common symptoms of giant cell arteritis are headaches and tenderness of the temples due to inflammation of the arteries on either side of the head (temporal arteries). This characteristic finding is why giant cell arteritis is sometimes called temporal arteritis.
Severe throbbing and stabbing pain on both sides of the head (temporal area) are frequently accompanied by redness, swelling, and/or tenderness on the scalp. Some affected individuals may feel rhythmic pulsations in the temporal arteries. The scalp may be tender in these reddened areas, and the temporal arteries may appear twisted and knotted under the scalp. Some people may also have trouble chewing. Other symptoms relate to difficulties with the eyes and visual impairment (retinal vessel disease). About 50 percent of people may experience a variety of visual symptoms, but only 10 percent of these people experience varying degrees of visual loss or blindness.
Additional symptoms of giant cell arteritis may begin gradually or suddenly and may resemble those of the flu. Symptoms may include low-grade fever, muscle pain (myalgia), low levels of circulating red blood cells (mild anemia), and/or severe stiffness, especially in the morning or after a period of inactivity (gel phenomenon). A few people with this disorder may experience respiratory symptoms including cough, sore throat, and/or hoarseness. These symptoms are often confused with other more common respiratory infections, making the diagnosis of giant cell arteritis difficult in some people.
Giant cell arteritis may be localized or widespread. When giant cell arteritis affects other medium or large arteries of the body (i.e., coronary, carotid, subclavian, pulmonary, renal, and mesenteric arteries), serious complications may develop. These may include blindness, stroke (cerebral vascular accident), blockage of the artery that carries blood from the heart (coronary artery occlusion), and/or the lack of fresh blood supply to the arms and legs (arterial insufficiency).
In approximately 50 percent of cases, individuals with giant cell arteritis develop symptoms related to polymyalgia rheumatica. Polymyaglia rheumatica is a rare form of arteritis, may affect the lower back, thighs, neck, shoulders, and/or hips. Symptoms may include stiffness that is most severe in the morning. Joint inflammation (synovitis), especially in the knees, is also common. There is some disagreement in the medical literature as to whether polymyalgia rheumatica and giant cell arteritis are actually part of a disease spectrum or whether they are related, but distinct disorders. (For more information on this disorder, choose “polymyalgia rheumatica” as your search term in the Rare Disease Database.)
The exact cause of giant cell arteritis is not known. The immune system has been implicated in some studies, but a direct relationship has not been positively established. Autoimmune disorders are caused when the body’s natural defenses against “foreign” or invading organisms (e.g., antibodies) begin to attack healthy tissue for unknown reasons.
Familial cases of giant cell arteritis have also been reported. Medical research indicates that some people with giant cell arteritis may have a genetic predisposition to the disease. A genetic predisposition means that a person may carry a gene for a disease but it may not be expressed unless something in the environment triggers the disease.
In giant cell arteritis, affected blood vessels become inflamed and swell. The cause for this reaction is not known. Inflammation of blood vessels causes the symptoms of giant cell arteritis such as headaches because of inflammation of the temporal arteries of the head. Swelling also causes narrowing of the blood vessels, which, in turn, results in diminished blood flow.
Giant cell arteritis is an inflammatory disease that affects twice as many females as males. It occurs in approximately 24 in 100,000 people over the age of 50 years. Giant cell arteritis is estimated to affect 110,000 individuals in the United States. The disease usually develops between the ages of 50 to 90 years. The average age of onset is about 70 years. Americans of European descent are more frequently affected than those of African or other ethnic heritage.
The diagnosis of giant cell arteritis is confirmed by a complete clinical evaluation, angiography, arterial biopsy, and blood tests. X-ray studies of the affected areas of the scalp are performed with a special contrast dye (angiography). These studies may show unusual areas of obstruction or narrowing (stenosis) in the temporal arteries. In some cases, a biopsy may be performed. Tissue samples are usually taken from the area of the artery that appears most twisted or knotted. Microscopic examination of tissue samples usually reveals the presence of abnormal giant cells, granular material (granulomatous inflammation), and tissue loss (focal necrosis). A specialized blood test, erythrocyte sedimentation rate (ESR), is usually elevated in people with giant cell arteritis.
The treatment of giant cell arteritis should start when the diagnosis is suspected. Prompt treatment may help to avoid serious complications such as blindness and coronary blockage (occlusion). High doses of corticosteroids (i.e., prednisone at 60 to 80 mg/day) may control initial local and systemic symptoms. This therapy is continued until symptoms subside and blood tests (e.g., erythrocyte sedimentation rate) have returned to normal, which generally occurs in about 2 to 4 weeks. Corticosteroid therapy is usually continued at gradually reduced doses for about 2 years or longer. This low dose therapy helps to reduce the risk of recurrence of giant cell arteritis.
The activity of giant cell arteritis can then be monitored by periodic blood testing of the sedimentation rate (ESR). A rise in the sedimentation rate along with the return of symptoms, especially headaches, usually signals a recurrence of the disease. Other treatment is symptomatic and supportive.
Some people with giant cell arteritis may not be able to tolerate high-dose corticosteroid drug therapy. For these individuals, other drugs such as azathioprine, methotrexate, and dapsone have been studied as possible treatment alternatives. More study is needed to determine the long-term safety and effectiveness of these drugs for the treatment of giant cell arteritis.
The drug infliximab is being studied as a potential treatment for individuals with giant cell arteritis. Further clinical study is necessary to determine the long-term safety and effectiveness of this potential treatment for individuals with giant cell arteritis.
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FROM THE INTERNET
Roque MR. Giant Cell Arteritis. Emedicine Journal, January 10 2006. Available at: http://www.emedicine.com/oph/topic254.htm Accessed on: May 2, 2007.
Mayo Clinic for Medical Education and Research. Giant Cell Arteritis. July 19, 2006. Available at: http://www.mayoclinic.com/health/giant-cell-arteritis/DS00440 Accessed On: May 2, 2007.
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