The diagnosis of giant cell arteritis.

Giant cell arteritis (GCA) is the most common primary vasculitis in adults older than 50 years. The potential of GCA to cause bilateral, sequential vision loss makes it often a true neuro-ophthalmic emergency. Approximately one fifth of patients with GCA will present with ophthalmic complaints alone. The diagnosis of GCA requires a high index of suspicion and a systematic approach to diagnostic testing. The combination of abnormal laboratory markers of systemic inflammation and unilateral temporal artery biopsy is usually diagnostic. Additional testing with other diagnostic modalities may be required in cases in which clinical suspicion remains high despite a negative initial workup. We systematically review the diagnostic modalities used in suspected GCA patients who present with neuro-ophthalmic symptoms and signs.