The spectrum of polymyalgia rheumatica.

Polymyalgia rheumatica and temporal arteritis are common syndromes of unknown cause that afflict older patients, the great majority of whom are white. Polymyalgia, which is seen more frequently, is a benign synovitis and can be differentiated from rheumatoid arthritis by the distribution of inflamed joints and by its rapid and complete response to small doses of prednisone. Temporal or giant cell arteritis occurs in approximately 20 per cent of patients with polymyalgia rheumatica and may present with either localized or systemic symptoms. Once the diagnosis is confirmed by temporal artery biopsy, patients should be treated with a large dose of prednisone for at least 1 month. The erythrocyte sedimentation rate is a useful test in suspecting the diagnosis initially, but is a poor gauge to tapering the steroid dose.