Temporal Arteritis

Definition/diagnostic criteria Temporal arteritis, also known as giant cell arteritis (GCA), is a vasculitis of medium and large arteries, typically involving the temporal arteries. The 1990 American College of Rheumatology criteria, widely accepted in the UK, include age at disease onset ≥ 50 years, new headache, temporal artery abnormality, elevated erythrocyte sedimentation rate (ESR), and abnormal artery biopsy. A diagnosis requires three of these five criteria.

Epidemiology Temporal arteritis is the most common form of systemic vasculitis in adults over 50 years, with a higher prevalence in women and those of Northern European descent. In the UK, the incidence is about 2.2 per 10 000 patient-years in the UK– which means the average GP will see one new case every year or two.

Diagnosis

Clinical Features: Key symptoms include new-onset headache, scalp tenderness, jaw claudication, visual disturbances, and polymyalgia rheumatica (PMR) symptoms. Physical examination may reveal a tender, thickened, or pulseless temporal artery. However, these signs are not always present, making clinical diagnosis challenging.

Investigations: Initial investigations include ESR and C-reactive protein (CRP) tests, which are typically elevated in active GCA but are not definitive. Temporal artery ultrasound showing a “halo sign” is increasingly used as a diagnostic tool. Temporal artery biopsy remains the gold standard for diagnosis, although it can be negative in up to 40% of cases due to skip lesions.

Treatment Immediate high-dose corticosteroid therapy is the mainstay of treatment to prevent serious complications, particularly vision loss. Prednisolone is typically initiated at a dose of 40-60 mg daily. The duration of treatment is usually 2-3 years, with a gradual tapering of the dose based on symptoms and ESR/CRP levels. Methotrexate or tocilizumab may be used by specialists as steroid-sparing agents.

Prognosis With prompt treatment, the prognosis of temporal arteritis is generally good. The most serious complication is irreversible vision loss, which occurs in about 15-20% of untreated cases. Other complications include aortic aneurysm and stroke. Long-term corticosteroid use can lead to complications like osteoporosis, diabetes, and hypertension. Regular monitoring and management of these risks are essential.