Giant Cell Arteritis (GCA)

A 55 year old female presents to the neurology clinic with a 7-day history of right-sided temporal headache. On the morning of presentation, she experienced a sudden episode of painless transient visual loss in the right eye that resolved within 15 to 20 minutes. She also reports scalp tenderness, jaw claudication, and bilateral shoulder stiffness. Over the past 6 months, she has had fatigue, unintentional weight loss, and low-grade fever. On examination, temperature is 99.9°F. Palpation reveals a tender, thickened temporal artery with reduced pulsation. Neurological examination is otherwise normal. Laboratory studies show ESR 100 mm/hr, elevated CRP, and anemia of chronic disease. Temporal artery biopsy demonstrates granulomatous inflammation with multinucleated giant cells. CT angiography shows arterial wall thickening with luminal narrowing of the carotid artery. Diagnosis? 

Diagnosis is Giant Cell Arteritis (Temporal Arteritis).

1. Definition

Giant cell arteritis is a chronic granulomatous vasculitis of large and medium-sized arteries, predominantly involving branches of the carotid artery, especially the external carotid artery such as the temporal artery, but it may also involve the aorta and its major branches. It occurs in patients older than 50 years and is strongly associated with polymyalgia rheumatica.

2. Pathogenesis

1. Immune-mediated inflammation involving T lymphocytes and macrophages
2. Activation of vascular dendritic cells
3. Release of cytokines such as IL-6 and IFN-γ
4. Leads to:
• Granuloma formation with multinucleated giant cells
• Intimal hyperplasia
• Luminal narrowing and ischemia

3. Clinical Features

3.1 Cranial Features

1. New-onset temporal headache
2. Scalp tenderness
3. Jaw claudication, highly specific
4. Visual symptoms such as amaurosis fugax, diplopia, or vision loss

3.2 Systemic Features

1. Low-grade fever
2. Fatigue
3. Weight loss

3.3 Associated Condition

1. Polymyalgia rheumatica with shoulder and hip girdle stiffness

4. Diagnostic Evaluation

4.1 Laboratory Findings

1. Elevated ESR and CRP, often markedly increased
2. Normocytic anemia
3. Thrombocytosis may be present

4.2 Imaging

1. Ultrasound showing halo sign
2. CTA or MRA showing:
• Arterial wall thickening
• Luminal narrowing
• Large vessel involvement

4.3 Temporal Artery Biopsy

1. Gold standard for diagnosis
2. Shows granulomatous inflammation with multinucleated giant cells
3. Segmental involvement (skip lesions) may cause false negatives

5. Management

5.1 Immediate Principle

1. Start glucocorticoids immediately when GCA is suspected
2. Do not delay treatment for biopsy

5.2 Glucocorticoid Therapy

1. Without visual symptoms:
• Oral prednisone 40 to 60 mg daily
2. With visual symptoms or impending vision loss:
• IV methylprednisolone 500 to 1000 mg daily for 3 days
• Followed by high-dose oral prednisone
3. Gradual taper over 12 to 18 months based on clinical response and inflammatory markers

6. Adjunctive Therapy

1. Tocilizumab for relapsing or steroid-dependent disease
2. Methotrexate as an alternative

7. Antiplatelet Therapy

1. Low-dose aspirin is often recommended to reduce risk of ischemic complications

8. Supportive Therapy

1. Calcium and vitamin D
2. Bisphosphonates

9. Complications

1. Irreversible vision loss due to anterior ischemic optic neuropathy
2. Aortic aneurysm and dissection
3. Stroke

10. Important Clinical Rule

1. Do not delay steroids for biopsy
2. Biopsy should ideally be performed within 1 week, but may remain positive up to 2 weeks after starting steroids

11. Key Clinical Insight

Age > 50 + new headache + jaw claudication = Giant cell arteritis until proven otherwise

Transient visual loss is a warning sign of impending permanent blindness

12. Exam Level Pearls

1. Jaw claudication is the most specific symptom
2. ESR is often > 100 mm/hr
3. Temporal artery biopsy is the gold standard
4. Skip lesions can cause false-negative biopsy
5. Immediate steroids prevent vision loss