(See also Overview of Vasculitis.)
Polymyalgia rheumatica occurs in people over age 55. Women are affected more often than men. The cause of polymyalgia rheumatica is unknown. Polymyalgia rheumatica may occur before, after, or at the same time as giant cell (temporal) arteritis. Some experts think that the two disorders are variations of the same abnormal process. Polymyalgia rheumatica seems to be more common.
Symptoms of polymyalgia rheumatica may develop suddenly or gradually. Severe pain and stiffness occur in the neck, shoulders, upper and lower back, and hips. The stiffness and discomfort are worse in the morning and after periods of inactivity and are occasionally severe enough to prevent people from getting out of bed and from doing simple activities. People may feel weak, but the muscles are not damaged or weak. People may also have a fever, feel generally unwell or depressed, and lose weight unintentionally.
Doctors base the diagnosis of polymyalgia rheumatica on symptoms and the results of a physical examination. Doctors do other tests, such as blood tests, to distinguish polymyalgia rheumatica from other disorders. Blood tests usually include the following:
Erythrocyte sedimentation rate (ESR), C-reactive protein levels, or both: In people with polymyalgia rheumatica, results of both tests are usually very high, indicating active inflammation.
Complete blood count: This test is done to check for anemia.
Thyroid-stimulating hormone (TSH): This test is done to rule out hypothyroidism, which can cause weakness and sometimes pain of the shoulder and hip muscles.
Creatine kinase: This test is done to check for muscle tissue damage (myopathy), which can cause weakness and pain of the shoulder and hip muscles. If the level of creatine kinase in the blood is elevated, muscle damage is likely. In people with polymyalgia rheumatica, muscle damage is absent, so the creatine kinase level is normal.
Rheumatoid factor and anti-cyclic citrullinated peptide antibodies testing: These antibodies are present in up to 80% of people with rheumatoid arthritis but not in those with polymyalgia rheumatica. This test helps doctors distinguish between the two.
The diagnosis is also supported by how people respond to corticosteroids because most people with polymyalgia rheumatica feel much better very quickly when treated with low doses of corticosteroids.
Taking a low dose of prednisone, a corticosteroid, usually causes dramatic improvement. If people also have giant cell arteritis, a higher dose is prescribed to reduce the risk of blindness. As the symptoms subside, the dose is gradually reduced (tapered) to the lowest effective dose. Many people can stop taking prednisone in about 2 years. However, some people need to take a low dose for several years.
Corticosteroids commonly cause side effects in older people (see Spotlight on Aging: Giant Cell Arteritis and Polymyalgia Rheumatica).
Giant cell arteritis may develop at the start of polymyalgia rheumatica or much later, sometimes even after people appear cured of the disorder. Therefore, all people should immediately tell their doctor if they have headache, muscle pain during chewing, unusual cramping or fatigue of the arms or legs with exercise, or vision problems.
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