Actually, temporal arteritis is a subdivision of giant cell arteritis. The disorder involves medium-sized and large arteries, including the aorta. There is a granulomatous inflammation with varying numbers of multinucleated giant cells that involves the vessel wall in a discontinuous, or “skip,” fashion and disrupts the artery internal elastic membrane. In temporal arteritis, most (but not all) patients are Europeans over age 50 and about 70% are female. More than one half of the patients experience headache and have physical abnormality in one or both temporal arteries (tender or nodular to palpation). Important symptoms occurring in less than one half of the patients include visual disturbances and often systemic symptoms such as fever, weight loss, jaw claudication, and myalgias or arthralgias. However, the number of symptoms varies greatly. Occasionally patients have fever of unknown origin.

Laboratory abnormalities include anemia in more than 50% of patients with the characteristics of the anemia of chronic disease, and sometimes a leukocytosis. Liver function tests are mildly abnormal in about 30% of patients, with the alkaline phosphatase level being most frequently elevated. Liver biopsy findings are most often normal. The most characteristic laboratory abnormality is ESR elevation, most often more than 50 mm/hour (Westergren method). This test has been used both for screening, as a part of diagnostic criteria, and to follow therapy effects. However, sometimes the ESR is within reference range when the patient first presents and becomes elevated later; and a small number of patients (exact number unknown but estimated at 2%-9%) never develop an elevated ESR. Definitive diagnosis requires temporal artery biopsy. The detection rate of biopsy is said to be about 90% (range, 65%-97%). About one third of patients have temporal arteries that are not painful and feel normal. It has been emphasized that a 3- to 5-cm temporal artery segment should be obtained, since the lesions are scattered. If this biopsy result is normal on serial section, biopsy of the other artery increases detection rate about 5%-10%.