Giant Cell Arteritis

Content of This Page

1- Definition and Classification

2-Epidemiology and Risk Factors

3-Pathogenesis and Histology

4- Cranial Symptoms

5– Ocular Involvement

6- Systemic and Constitutional Symptoms

7- Polymyalgia Rheumatica Association

8- Investigations and Diagnosis

9- Treatment Principles

10- Red Flags and Complications

11- GCA vs PMR – Quick Comparison

Definition and Classification

Giant Cell Arteritis is a granulomatous vasculitis of large- and medium-sized arteries, especially cranial branches of the carotid artery (temporal, ophthalmic).
It’s classified under large-vessel vasculitis, alongside Takayasu arteritis.

-Subtypes:

  • Cranial GCA: classic form—headache, jaw claudication, vision loss

  • Large-vessel GCA: aortic or subclavian involvement, often without cranial symptoms

  • Overlap with PMR (polymyalgia rheumatica)

© image from Wikimedia Commons

Epidemiology and Risk Factors

  • Age >50 (virtually never seen under 50)

  • Peak incidence in 70s

  • Female predominance (~3:1)

  • Most common in Northern European ancestry

  • Associated with HLA-DRB1*04

– PMR (Polymyalgia Rheumatica) is present in 40–60% of GCA cases.

Pathogenesis and Histology

  • T-cell–driven inflammation causes:

    • Granuloma formation with multinucleated giant cells

    • Disruption of internal elastic lamina

    • Intimal hyperplasia → lumen narrowing and ischaemia

-Histology from temporal artery biopsy remains the diagnostic gold standard.

© image from Wikimedia Commons

Cranial Symptoms

These are the classic presenting features:

  • New-onset temporal headache

  • Scalp tenderness

  • Jaw claudication (pain on chewing)

  • Visual disturbance:

    • Amaurosis fugax (transient loss)

    • Sudden permanent blindness from anterior ischaemic optic neuropathy

-Jaw claudication has high specificity (up to 90%) for GCA.

Ocular Involvement

  • Anterior ischaemic optic neuropathy is the most feared complication

  • Presents with:

    • Painless sudden monocular vision loss

    • Pale, swollen optic disc on fundoscopy

  • Other signs: diplopia, afferent pupillary defect

-This is an ophthalmologic emergency.

Systemic and Constitutional Symptoms

  • Fever, fatigue, weight loss

  • Night sweats

  • Raised inflammatory markers (CRP, ESR)

  • Anaemia of chronic disease

-In some cases, systemic symptoms are the only clue (so-called “occult” GCA).

Polymyalgia Rheumatica Association

  • PMR symptoms often precede, coincide with, or follow GCA:

    • Bilateral shoulder/hip girdle stiffness

    • Worse in the morning, improves with activity

    • No joint inflammation on exam

  • Responds to low-dose steroids (15–20 mg/day), unlike GCA which needs higher doses.

Investigations and Diagnosis

  • ESR > 50 mm/hr (often >100)

  • CRP markedly raised

  • FBC: normocytic anaemia, thrombocytosis

  • LFTs: raised ALP

  • Temporal artery biopsy:

    • Skip lesions → false negative possible

    • Shows: intimal thickening, giant cells, disrupted elastic lamina

  • Ultrasound of temporal artery:

    • “Halo sign” = hypoechoic wall thickening (non-compressible)

-Biopsy should be done within 1–2 weeks of starting steroids, but steroids should never be delayed if visual symptoms are present.

Treatment Principles

Acute Management:

  • If visual symptoms:

    • Start IV methylprednisolone 500–1000 mg/day for 3 days

  • Without visual symptoms:

    • Oral prednisolone 40–60 mg/day

    • Expect rapid resolution of systemic symptoms in 24–72 hours

-Tapering:

  • Gradual over 12–24 months

  • Aim to reduce to 10–15 mg by 8 weeks, then reduce slowly

-Steroid-Sparing Agents:

  • Tocilizumab (IL-6 inhibitor): reduces relapse, lowers steroid burden

  • Methotrexate: alternative in steroid-resistant or relapsing disease

-Bone Protection:

  • Calcium, vitamin D

  • Bisphosphonates if long-term steroids

Red Flags and Complications

  • Irreversible visual loss

  • Aortic aneurysm or dissection (especially thoracic)

  • Stroke or TIA (vertebrobasilar territory)

  • Steroid-related adverse effects: osteoporosis, hyperglycaemia, mood changes

-Monitor for relapse, especially during steroid taper.

GCA vs PMR – Quick Comparison

FeatureGCAPMR
Age>50>50
SymptomsHeadache, vision loss, jaw claudicationShoulder/hip stiffness
ESR/CRPVery highRaised
Steroid doseHigh (40–60 mg)Low (15–20 mg)
BiopsyYes (temporal artery)Not needed
RiskBlindness, strokeNone (but may evolve into GCA)
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