USMLE Guide: Temporal Arteritis

Introduction

Temporal arteritis, also known as giant cell arteritis (GCA), is a systemic vasculitis primarily affecting medium to large-sized arteries. This USMLE guide aims to provide a concise overview of temporal arteritis, including its epidemiology, clinical presentation, diagnostic approach, treatment, and potential complications.

Epidemiology

• Temporal arteritis primarily affects individuals over the age of 50, with a peak incidence in their 70s.
• It is more prevalent in women, with a female-to-male ratio of 2:1.
• The condition is more commonly observed in individuals of Scandinavian or Northern European descent.

Clinical Presentation

• Temporal arteritis commonly presents with headache, which is often severe and localized to the temporal region.
• Patients may also complain of scalp tenderness and pain while combing their hair.
• Jaw claudication, an indicator of ischemia, may be present during mastication and can lead to weight loss.
• Visual symptoms, such as diplopia and transient vision loss, may occur due to involvement of the ophthalmic artery.
• Constitutional symptoms, including fatigue, weight loss, and fever, can also be observed.

Diagnostic Approach

• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are frequently elevated in temporal arteritis. ESR > 50 mm/h and CRP >1 mg/dL are suggestive but not diagnostic.
• Temporal artery biopsy is the gold standard for diagnosis. It reveals mononuclear cell infiltration and fragmentation of the internal elastic lamina.
• Ultrasound of the temporal artery may show a "halo sign" characterized by a hypoechoic outer wall thickening.
• Magnetic resonance angiography (MRA) or computed tomography angiography (CTA) can help evaluate for large vessel involvement.

Treatment

• Immediate initiation of high-dose glucocorticoids is crucial to prevent irreversible vision loss and systemic complications.
• Prednisone 40-60 mg/day is the initial treatment regimen.
• Once symptoms improve and ESR/CRP normalize, the dose can be tapered gradually over several months.
• Methotrexate or tocilizumab can be considered as steroid-sparing agents in refractory cases or to minimize side effects of prolonged corticosteroid use.

Complications

• The most feared complication of temporal arteritis is permanent vision loss due to anterior ischemic optic neuropathy (AION).
• Aortic aneurysm or dissection may occur in large vessel involvement.
• Other potential complications include stroke, myocardial infarction, and mesenteric ischemia.

Remember to stay vigilant for signs and symptoms of temporal arteritis, especially in elderly patients presenting with headache, scalp tenderness, jaw claudication, and visual symptoms. Early diagnosis and prompt treatment can prevent severe complications and improve patient outcomes.