Temporal artery biopsy: Indications, complications and implications

Giant cell arteritis (GCA, temporal arteritis) is a vasculitis affecting medium and large sized vessels, with predisposition towards extracranial branches of the carotid artery. The main risks associated with GCA are blindness and stroke. GCA commonly presents with new onset headache, jaw claudication or visual disturbance. Associated features include abnormal temporal artery pulsation, abnormal fundoscopy, raised erythrocyte sedimentation rate (ESR) and raised platelet count. Clinical criteria such as the American College of Rheumatology (ACR) criteria for GCA and imaging by duplex ultrasonography can be used to diagnose GCA. However, the gold standard for diagnosis is temporal artery biopsy. This is performed by excising a segment of the superficial temporal artery, usually on the symptomatic side, with recommended specimen lengths of at least 1.5cm. Bilateral biopsies are not usually required. However due to the presence of "skip lesions" contralateral biopsy may be performed in instances where the initial biopsy is negative, although additional diagnostic yield is low. Due to the discontinuous nature of the disease, extensive cross-sections of the whole specimen should be examined. Multiple Haematoxylin and Eosin stained slides should be examined and immunohistochemical and elastic stains may also be required. Temporal artery biopsy has a low complication rate. The most commonly encountered complications are scarring, haematoma, wound infection and skin necrosis. Rarer, more serious complications include facial nerve injury and cerebral infarction, due to dependent collateral blood flow to the brain via the superficial temporal artery. Treatment of GCA requires prolonged courses of systemic corticosteroids. Steroid treatment is usually instigated as soon as GCA is suspected, often prior to temporal artery biopsy. Therefore temporal artery biopsy result has significant management implications. A positive temporal artery biopsy justifies the protracted course of steroids required; usually a minimum of one year's treatment is necessary. Conversely, where there is low clinical suspicion of GCA, a negative biopsy ensures that potentially harmful steroid treatment can be discontinued safely. However 15-40% of temporal artery biopsies from patients with GCA are negative. This can be due to inadequate specimen length, skip lesions of the temporal artery and duration of steroid treatment prior to biopsy.