Giant Cell Arteritis

Abstract

Giantcell arteritis (GCA) involves the major branches of the aorta with predilection for the extracranial branches of the carotid artery. It occurs in individuals older than 50 years, and the incidence increases with age. The signs and symptoms of GCA can be classified into four subsets: manifestations of cranial arteritis (mainly headache, jaw claudication and visual manifestations), extracranial arteritis, systemic symptoms and polymyalgia rheumatica. Patients may develop any combination of these manifestations, which are associated with laboratory evidence of an acute-phase reaction. The only test that confirms the diagnosis is a temporal artery biopsy showing vasculitis with mononuclear cell or granulomatous inflammation usually with giant cells. However, areas of vasculitis may be missed by the biopsy and the histological examination is normal in about 15% of the cases. Some imaging modalities may aid in the diagnosis of GCA. Among these, color duplex ultrasonography of the temporal arteries is more commonly used. There are no independent validating criteria to determine whether GCA is present when a temporal artery biopsy is negative. The American College of Rheumatology (ACR) criteria for the classification of GCA may assist in the diagnosis. However, meeting classification criteria is not equivalent to making the diagnosis in individual patients, and the final diagnosis should be based on all clinical, laboratory, imaging and histological findings. Glucocorticoids are the treatment of choice for GCA. The initial dose is 40–60 mg/day for most uncomplicated cases. Addition of low-dose aspirin (100 mg/day) has been shown to significantly decrease the rate of vision loss and stroke during the course of the disease.