Polymyalgia rheumatica and giant-cell arteritis are closely related conditions that affect persons of middle age and older and frequently occur together. Many authorities consider them to be different phases of the same disease. Polymyalgia rheumatica is an inflammatory condition of unknown cause characterized by aching and morning stiffness in the cervical region and shoulder and pelvic girdles. It usually responds rapidly to low doses of corticosteroids and has a favorable prognosis.
The first description of polymyalgia rheumatica was provided by Bruce in 1888, who called this condition "senile rheumatic gout," thus emphasizing its occurrence in the elderly.1 In 1957, Barber proposed the use of the term "polymyalgia rheumatica."2 In 1963, Bagratuni outlined the nonerosive articular nature of polymyalgia rheumatica,3 and in the 1990s, diffuse swelling of the hands and edema were reported in some patients.4
Giant-cell arteritis is a chronic vasculitis of large and medium-sized vessels. Although it may be widespread, symptomatic vessel inflammation usually involves the cranial branches of the arteries originating from the aortic arch. The first clinical description of giant-cell arteritis was presented by Hutchinson in 1890.5 However, it was not reported again until the 1930s, when Horton and colleagues6 described the histologic appearance of granulomatous arteritis of the temporal vessels. The relation between polymyalgia rheumatica and giant-cell arteritis was not widely accepted until more than 20 years later, and Paulley and Hughes were among the first to recognize the association.7
Epidemiology and Diagnostic Criteria
Polymyalgia rheumatica is a common illness in certain populations, with a prevalence of 1 case for every 133 people over the age of 50 years.8 Giant-cell arteritis is less frequent than polymyalgia rheumatica. In Olmsted County, Minnesota, the average annual incidence was 17.8 cases per 100,000 persons 50 years of age and older.9 However, autopsy studies suggest that giant-cell arteritis may be more common than is clinically apparent.10 Women are affected twice as often as men.
The incidence of polymyalgia rheumatica and giant-cell arteritis increases after the age of 50 years and peaks between 70 and 80 years of age. Population surveys show higher frequencies of polymyalgia rheumatica and giant-cell arteritis at higher latitudes.8,9,11,12,13,14,15 The incidence of polymyalgia rheumatica appears to have been relatively stable in recent years; in contrast, the incidence of giant-cell arteritis appears to have increased. In addition, there is evidence of periodic clustering of cases of giant-cell arteritis.9 The mortality rate in patients with polymyalgia rheumatica and giant-cell arteritis is similar to that expected in general populations of similar age and sex, although thoracic aortic aneurysms and dissection of the aorta are important late complications of giant-cell arteritis.16
The current diagnostic criteria for polymyalgia rheumatica were empirically formulated by Chuang et al.17 and Healey18 (Table 1). The two sets of criteria are similar, the only difference being the inclusion in the Healey criteria of responsiveness to corticosteroids. Criteria for the classification of giant-cell arteritis were formulated by the American College of Rheumatology in 1990 (Table 2).19 These criteria were designed for use in investigative studies to help distinguish giant-cell arteritis from other types of vasculitis; they are not useful for making the diagnosis in individual patients.20
Temporal-artery biopsy is recommended in all patients who are suspected of having giant-cell arteritis. The inflammatory involvement of affected arteries is often intermittent rather than continuous. If the temporal artery is clearly abnormal on physical examination, only a small specimen needs to be removed for histopathological review. When extracranial arteries are normal on palpation and giant-cell arteritis is suspected, it is important to obtain a biopsy of a longer segment of temporal artery (3 to 5 cm) and consider performing a contralateral biopsy if the results of the first biopsy are normal. We used this approach and found that only 10 percent of patients had negative findings on biopsy.21 When possible, temporal-artery biopsy should be performed before treatment is initiated; however, examination of temporal-artery朾iopsy specimens may reveal evidence of arteritis after more than two weeks of corticosteroid therapy.22
Population-based studies of polymyalgia rheumatica have demonstrated the presence of biopsy-proved giant-cell arteritis in 16 to 21 percent of patients.8,11 Conversely, symptoms of polymyalgia rheumatica have been observed in 40 to 60 percent of patients with giant-cell arteritis in clinical series.9 Polymyalgia rheumatica may thus begin before, at the same time as, or after giant-cell arteritis.
Patients with polymyalgia rheumatica who do not have symptoms of claudication or abnormalities of temporal arteries on examination have a very high probability of having normal findings on biopsy.23 Consequently, we perform temporal-artery biopsy only in patients with polymyalgia rheumatica who present with cranial symptoms or signs.
