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Giant Cell Arteritis

Discover the shocking truth about Giant Cell Arteritis and learn why this mysterious condition is often misdiagnosed, affecting more people than you might think.
2023-07-07

USMLE Guide: Giant Cell Arteritis

Introduction

Giant Cell Arteritis (GCA), also known as temporal arteritis, is a systemic vasculitis that primarily affects medium and large arteries. It most commonly involves the branches of the carotid artery, especially the temporal artery. GCA predominantly affects individuals over the age of 50 and is more prevalent among women. This USMLE guide aims to provide a comprehensive overview of the key features, diagnosis, treatment, and complications of GCA.

Clinical Presentation

  • Headache: New-onset, severe, and unilateral headache is the hallmark symptom of GCA, often described as a temporal headache.
  • Vision changes: GCA can lead to anterior ischemic optic neuropathy (AION), causing sudden vision loss or blurred vision. Diplopia may also occur.
  • Scalp tenderness: The temporal artery may be tender to palpation and sometimes appear enlarged, nodular, or pulseless.
  • Systemic symptoms: Fever, fatigue, weight loss, anorexia, and malaise are common non-specific symptoms associated with GCA.
  • Polymyalgia Rheumatica (PMR): Approximately 50% of patients with GCA also have PMR, characterized by proximal muscle pain and stiffness.

Diagnostic Evaluation

  • Erythrocyte Sedimentation Rate (ESR): An elevated ESR greater than 50 mm/h is highly sensitive for GCA, but not specific.
  • C-Reactive Protein (CRP): Elevated CRP levels are also indicative of inflammation and can support the diagnosis.
  • Temporal Artery Biopsy: The gold standard for diagnosis involves obtaining a biopsy of the temporal artery, showing transmural inflammation with giant cells.
  • Imaging: Doppler ultrasound may show temporal artery halo sign or stenosis, aiding in diagnosis when biopsy is inconclusive.

Treatment

  • High-Dose Corticosteroids: Immediate initiation of high-dose oral prednisone (40-60 mg/day) is essential to prevent vision loss and other complications.
  • Adjunctive Therapy: Methotrexate or tocilizumab may be added as steroid-sparing agents for long-term management.
  • Monitoring: Regular follow-up is crucial to monitor symptoms, ESR, CRP, and taper corticosteroids based on clinical response.

Complications

  • Blindness: Permanent vision loss is the most feared complication of GCA, occurring in up to 20% of untreated patients.
  • Aortic Aneurysm: Aortic involvement can lead to aneurysm formation, dissection, or rupture, necessitating careful monitoring.
  • Systemic Inflammation: GCA can affect other large arteries, potentially leading to ischemic complications in various organs.
  • Corticosteroid Side Effects: Prolonged corticosteroid use increases the risk of osteoporosis, infection, diabetes, and cardiovascular disease.

Conclusion

Giant Cell Arteritis is an important diagnosis to consider in elderly patients presenting with new-onset headache, vision changes, and systemic symptoms. Prompt recognition and treatment with high-dose corticosteroids are crucial to prevent irreversible complications such as blindness. Understanding the clinical features, diagnostic evaluation, treatment options, and potential complications of GCA is essential for medical students preparing for the USMLE examination.

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