Giant Cell Arteritis and Polymyalgia Rheumatica

• Giant cell arteritis (GCA) is the most common primary form of vasculitis in adults. GCA has a predilection for involving large- and medium-sized arteries. (It does not involve veins.) • Arteries of the head and neck are often affected by GCA, as are the aorta and its primary branches. • Polymyalgia rheumatica (PMR) can occur simultaneously with or independently of GCA. • The occurrence of GCA or PMR in an individual younger than 50 years of age is exceptionally rare. (Some experts believe, in fact, that such events do not occur at all.) • The GCA/PMR disease spectrum is approximately three times more common in women than in men. • The most dreaded complication of GCA is the acute and permanent loss of vision, which usually occurs through the mechanism of anterior ischemic optic neuropathy (AION). Other feared long-term complications are those related to large-vessel events such as aortic aneurysms. • Temporal artery biopsy has been the traditional gold standard for the diagnosis of GCA. The sensitivity of this test is not known for certain, but it is probably poor—on the order of 60–70%. Large-vessel imaging studies are playing an increasing role in the diagnosis of GCA. The most important diagnostic test, however, remains the clinical history taken by an astute clinician. • The diagnosis of PMR is a clinical one, based essentially entirely upon the history and physical examination. • When considering the diagnosis of PMR, it is crucial to exclude the concomitant occurrence of GCA and the alternative diagnosis of rheumatoid arthritis. • Acute phase reactants are usually elevated in patients with GCA and PMR, but cases of these diagnoses occurring with completely normal values of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are well documented. • Glucocorticoids remain a cornerstone of treating GCA and PMR, but clinicians should move quickly to steroid-sparing agents in the interest of reducing glucocorticoid toxicity. Interleukin-6 receptor (IL6-R) blockade is an excellent treatment for GCA.