Polymyalgia Rheumatica

Epidemiology

Polymyalgia rheumatica is a syndrome that affects primarily adults over the age of 50. The average age of onset is 70 years old, and tends to affect women twice as often as men. There are differences in the number of new cases each year (annual incidence rates) of polymyalgia rheumatica depending on the geographical region. For example, in the northern regions of Europe, annual incidence rates are 113 per 100,000 per year. In the southern regions of Europe, the annual incidence rates are 13 per 100,000 per year.

Pathology/Clinical Findings

Before the onset of polymyalgia rheumatica, patients tend to be healthy. When the symptoms begin, it can be a process that develops over weeks to months causing muscle and joint aches of the shoulder girdles, torso, neck, and pelvic girdles. The joint aches are believed to be caused by inflammation of bursa, which functions as cushions around a joint, or the synovium, which is the lining of a joint. Constitutional symptoms may also be present, which consist of feelings of discomfort, anorexia, weight loss, fatigue, and low-grade fever may also accompany the aches. The muscle and joint aches usually affect both sides of the body; however, occasionally they will present on only one side. The aches, if associated with the shoulders or hips, can cause patients to experience trouble with performing activities of daily living. These include tasks such as fixing one's hair, putting on clothes, cooking, and so forth.

[Page 1402]The exact cause of polymyalgia rheumatica in unclear at this time. It is believed that there is an immune response in the blood vessels throughout the body. The response then causes specialized cells to produce cytokines (proinflammatory products), which then cause inflammation. However, the production of cytokine cannot be directly linked to the vessel inflammation.

Diagnosis

The three most agreed-upon diagnostic criteria are as follows:

• Patient must be 50 years or older at the onset of disease.
• Both sides of the body are aching and have morning stiffness for at least one month in at least two of the following areas: neck or torso, shoulders or upper arms, and hips or thighs.
• Erythrocyte sedimentation rate of 40 mm/hour or more.

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