20-17: Polymyalgia Rheumatica & Giant Cell Arteritis

GENERAL CONSIDERATIONS

Polymyalgia rheumatica and giant cell arteritis probably represent a spectrum of one disease. Both affect the same population (patients over the age of 50), and the incidence of the disease increases with each decade of life. Both show preference for the same HLA haplotypes, and show similar patterns of cytokines in blood and arteries. Giant cell arteritis is a systemic panarteritis affecting medium-sized and large vessels. Giant cell arteritis was previously called temporal arteritis because the temporal artery is frequently involved, as are other extracranial branches of the carotid artery. However, the aorta and its major branches may be involved in giant cell arteritis as well. Polymyalgia rheumatica and giant cell arteritis also frequently coexist. The important differences between the two conditions are that polymyalgia rheumatica alone does not cause blindness and responds to low-dose (10–20 mg/day orally) prednisone therapy, whereas giant cell arteritis can cause blindness and large artery complications and requires high-dose (40–60 mg/day) prednisone.

CLINICAL FINDINGS

A. Polymyalgia Rheumatica

Polymyalgia rheumatica is a clinical diagnosis based on pain and stiffness of the shoulder and pelvic girdle areas, frequently in association with fever, malaise, and weight loss. In approximately two-thirds of cases, polymyalgia occurs in the absence of giant cell arteritis. Because of the stiffness and pain in the shoulders, hips, and lower back, patients have trouble combing their hair, putting on a coat, or rising from a chair. In contrast to polymyositis and polyarteritis nodosa, polymyalgia rheumatica does not cause muscular weakness either through primary muscle inflammation or secondary to nerve infarction.

B. Giant Cell Arteritis

The mean age at onset is approximately 79 years. About 50% of patients with giant cell arteritis also have polymyalgia rheumatica. The classic symptoms suggesting that a patient has arteritis are headache, scalp tenderness, visual symptoms (particularly amaurosis fugax or diplopia), jaw claudication, or throat pain. Of these symptoms, jaw claudication has the highest positive predictive value. The temporal artery can be normal on physical examination but may be nodular, enlarged, tender, or pulseless. Blindness usually results from anterior ischemic optic neuropathy, caused by occlusive arteritis of the posterior ciliary branch of the ophthalmic artery. The ischemic optic neuropathy of giant cell arteritis may produce no funduscopic findings for the first 24–48 hours after the onset of blindness.

Asymmetry of pulses in the arms, a murmur of aortic regurgitation, or bruits heard near the clavicle resulting from subclavian artery stenoses identify patients in whom giant cell arteritis has affected the aorta or its major branches. Clinically evident large vessel involvement—characterized chiefly by ...