Q. My wife has been diagnosed with polymyalgia rheumatica. She's had aches and pains in her arms, shoulders and legs. Her doctor is treating her with prednisone, which has helped a lot. What is polymyalgia? We have been unable to find any information on it.

A. Polymyalgia rheumatica is a painful condition that mostly affects seniors. You can get relief with steroids such as prednisone, but you have to watch out for possible side effects.

Polymyalgia means multiple muscle pains; rheumatica refers to pain and stiffness around the joints. Polymyalgia rheumatica typically develops after age 50, with the average age around 70. It is twice as likely to affect women as men, and it is most common in whites of northern European ancestry.

Doctors don't know what causes polymyalgia rheumatica, but it seems to be triggered by a reaction in the immune system. The condition usually first shows up as pain and stiffness, especially in the neck, shoulders and hips. Other symptoms might include fatigue, low-grade fever and weight loss.

Polymyalgia rheumatica is a chronic condition, meaning that once it starts it tends to last for months, even years. Its onset is usually sudden; the time from first mild ache to full-scale pain and stiffness is usually about two weeks. On the other hand, if you just have an occasional ache or pain, polymyalgia rheumatica is unlikely to be the cause.

The condition can be difficult to recognize. A patient or doctor might mistakenly blame the aches and pains on some other condition, such as arthritis, bursitis, tendinitis or just "getting old." And it is possible that you might have one or more of these problems, in addition to the polymyalgia, and not think of a second cause of shoulder pain, for example.

Once your doctor suspects polymyalgia rheumatica, there are a couple of things that can be done to pin down the problem. The first is a blood test known as an erythrocyte sedimentation rate (ESR). Polymyalgia rheumatica is one of several conditions that will cause high readings on this test. In some cases, however, the test will yield a reading in the normal range even in a person with the condition.

A doctor might also try steroid treatment as a test. In people who have polymyalgia rheumatica, the response to steroid pills is typically so dramatic that it is seen as evidence that the condition is responsible for symptoms.

For treatment, there are a couple of options. You may start with non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen. If these don't do the trick, you will probably want to try steroid pills, such as prednisone. Long-term use of steroids can have serious side effects, including osteoporosis, fractures, susceptibility to infection, stomach ulcers, high blood sugar and cataracts.

To lower your risk of side effects, your doctor might try to use the lowest dose that relieves symptoms. You might start at a higher dose, such as 20 milligrams (mg) a day, but gradually taper it down to 5 mg or less. It's hard to predict how long you'll need to take it, but a year or two is not unusual. And after finally stopping the prednisone, you're at risk of the condition coming back.

For more information, contact the Arthritis Foundation, 1330 West Peachtree St., Atlanta, GA 30309. The foundation can be reached by telephone at 800-283-7800 or on the Web at http://www.arthritis.org.

Jay Siwek, chairman of the department of family medicine at Georgetown University Medical Center, practices at the Fort Lincoln Family Medicine Center and Providence Hospital in Northeast Washington.