Vasculitides A. giant cell arteritis, polymyalgia rheumatica, and Takayasu's arteritis

Giant cell arteritis (GCA) and Takayasu's arteritis (TA) are prototypes of large vessel vasculitis, tending to involve the aorta and its branches. Giant cell arteritis predominantly affects the secondto fifth-order aortic branches, often in the extracranial arteries of the head. Giant cell arteritis occurs exclusively among individuals who are 50 years of age or older. The mean age at diagnosis onset is approximately 72. In TA, the aorta and its major branches are the prime disease targets. Both GCA and TA are associated with granulomatous inflammation within the blood vessel wall. In both GCA and TA, clinical symptoms of vascular inflammation and vascular insufficiency are usually accompanied or preceded by a systemic inflammatory process. Visual loss is the most feared complication of GCA. Visual loss may occur through the syndrome of anterior ischemic optic neuropathy, caused by narrowing of the posterior ciliary artery and other vessels to the eye. The diagnosis of GCA is made usually by biopsy of the temporal artery. Polymyalgia rheumatica (PMR), a syndrome of muscle pain and stiffness in the neck, shoulders, and hips, often occurs with GCA but can occur independently. Glucocorticoids are the cornerstone of treatment for GCA, TA, and PMR. Isolated PMR requires a lower dose of prednisone for disease control.