Clinical Features of Giant Cell Arteritis
Giant cell arteritis (GCA) should be suspected in any patient over 50 years old presenting with new-onset headache, jaw claudication, visual disturbances, or temporal artery abnormalities, as these represent the cardinal manifestations of this potentially blinding vasculitis. 1
Cranial Manifestations
Headache and Scalp Symptoms
- New-onset headache is the most common presenting symptom, occurring in two-thirds of patients and up to 90% of biopsy-confirmed cases 1
- Scalp tenderness is highly suggestive with a positive likelihood ratio of 3.14 1, 2
- Scalp necrosis represents a rare but severe ischemic complication 3
Temporal Artery Abnormalities
- Temporal artery thickening has the strongest diagnostic value with a positive likelihood ratio of 4.70 1, 2
- Loss of temporal artery pulse carries a positive likelihood ratio of 3.25 1, 2
- Tenderness on palpation of the temporal artery is a significant finding with positive likelihood ratio of 3.14 2
Jaw and Limb Claudication
- Jaw claudication is the most specific symptom with a positive likelihood ratio of 4.90, present in approximately 50% of patients 1, 2
- Limb claudication has the highest positive likelihood ratio of 6.01 among all clinical features 2
Visual Complications
- Visual disturbances (transient vision loss, diplopia, or blurred vision) occur in 20% of patients before permanent blindness develops 1
- Vision loss occurs in 14-18% of patients and represents the most feared complication, though this has decreased from historical rates of 50% in untreated patients 1, 3, 2
- Visual loss typically results from arteritis of the ophthalmic branches of the internal carotid artery 4
Other Cranial Ischemic Complications
- Stroke can occur from vasculitis of extradural vertebral or carotid arteries 3
- Cranial nerve palsies may develop as ischemic complications 3
Systemic Manifestations
Constitutional Symptoms
- Polymyalgia rheumatica symptoms (proximal muscle pain and stiffness) are frequent manifestations 5, 2
- Weight loss, fatigue, and fever are common systemic features 5
- Malaise, night sweats, and depression may occur 6
Large Vessel Involvement
- GCA affects both cranial and large extracranial vessels 5
- Large-vessel aneurysms and vascular stenoses can complicate the disease course 5, 3
- Aortitis may develop as a complication 7
Laboratory Findings
Inflammatory Markers
- Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are elevated in more than 95% of cases at diagnosis 5, 1, 2
- ESR >100 mm/h has a positive likelihood ratio of 3.11 1, 2
- The absence of ESR >40 mm/h has a negative likelihood ratio of 0.18, making it useful for ruling out disease 1
- The absence of CRP ≥2.5 mg/dL has a negative likelihood ratio of 0.38 1
- CRP in conjunction with ESR has 97% specificity for diagnosing GCA 8
Hematologic Findings
- Platelet count >400 × 10³/μL has a positive likelihood ratio of 3.75 and is common in active disease 1, 3, 2
Demographic Factors
- Age over 50 years is a defining characteristic, with the disease primarily affecting older adults 5, 1
- Age over 70 years has specific diagnostic implications 1
- Female predominance exists with a 3:2 ratio (women:men) 1
- Lifetime risk is 1.0% for women and 0.5% for men 1
- More frequent in populations of Northern European descent 1
Histopathological Features
- Arterial wall thickening with narrowed lumen is the hallmark finding 5, 3
- Presence of mononuclear inflammatory cells with invasion of the media layer 5, 3
- Multinucleated giant cells in the media (though rarely seen) 5, 3
- Intimal hyperplasia and progressive arterial lumen occlusion result from the inflammatory remodeling process 3
Clinical Pitfalls
The absence of highly sensitive individual features means GCA can present atypically, making diagnosis challenging when classical features are absent 7, 6. The disease manifestations can occur singly or in any combination and may fluctuate over time 6. Respiratory involvement with chronic cough occurs in less than 10% of cases and may be overlooked 3.