Giant cell arteritis (GCA) is the commonest form of large-vessel vasculitis and affects branches of the external carotid artery but also the ciliary and retinal arteries. The symptoms are caused by local ischaemia due to endovascular damage and cytokine-mediated systemic illness. There is considerable overlap with polymyalgia rheumatica (PMR): 16–21% of patients with PMR have GCA on temporal artery biopsy, and symptoms of PMR are present in 40–60% of patients with GCA.1 GCA occurs in 2.2 per 10 000 patient-years in the UK.2 A full-time GP may expect to see one new case every 1–2 years. It is virtually unknown in people aged under 50 years. Early recognition is critical to prevent visual loss, that otherwise occurs in up to 20% of cases.3 Once high-dose corticosteroids are started, visual loss is extremely rare.
Guidelines for the diagnosis and management of GCA, have recently been published by the British Society of Rheumatologists and British Health Professionals in Rheumatology.4