Polymyalgia Rheumatica

Polymyalgia rheumatica (PMR) is a type of arthritis that affects the muscles.  It does not affect bones or joints, but causes muscles to become stiff, tender and very sore (inflammation).  Even though the muscles are sore they do not become weak.  PMR affects the muscles of the neck, shoulders, lower back, hips and thighs, and the pain is believed to be caused by the swelling of blood vessels in the muscles.

PMR is a clinical syndrome that can be a manifestation of many pathological processes, including rheumatoid arthritis, cancer, and Giant Cell Arteritis (GCA).  GCA is a condition associated with polymyalgia rheumatica and sometimes occurs in people who suffer from PMR.  The two disorders often overlap in clinical presentation, and classification may sometimes present a problem.

Incidence

PMR usually affects persons older than 50 years, and women are affected twice as often as men.

Signs and Symptoms

The disorder may have either an acute or insidious onset.  Fatigue, depression, weight loss, and fever may also occur.

Diagnosis and Tests

The differential diagnosis includes rheumatoid arthritis, polymyositis, occult malignant disease, infectious disease, myofascial pain syndromes, and functional abnormalities.  In one study, the ESR was strikingly elevated in 99% of patients, hemoglobin levels were decreased in 47%, a2-globulin levels were abnormal in 33%, aspartate aminotransferase levels were elevated in 23%, and alkaline phosphatase levels were increased in 10%.  An increased fibrinogen level and normal creatine kinase and aldolase levels are also common.  A dramatic response to corticosteroids (in 24 to 48 hours) helps confirm the diagnosis of PMR, although this finding is not specific.

Treatment and Prevention

Because PMR and GCA are often parts of the same disease spectrum, therapy must be directed at both symptomatic relief and prevention of catastrophic visual loss.

Complications

PMR causes the arteries on the upper front side of the head, called the temporal arteries, to narrow.  The arteries can become blocked and this can result in loss of vision or even blindness.