Cardiology >  Giant Cell Arteritis 

Background

Giant Cell Arteritis (GCA), also known as temporal arteritis, is a chronic granulomatous vasculitis of large- and medium-sized arteries, predominantly affecting branches of the external carotid artery, especially the temporal artery. It can lead to irreversible vision loss and other ischemic complications if not treated promptly. GCA is closely associated with polymyalgia rheumatica. 

II) Classification/Types 

By Vessel Involvement: 

• • Cranial GCA: Affects branches of the carotid artery (e.g., temporal, ophthalmic). 

• • Large-vessel GCA: Involves aorta and major branches (e.g., subclavian, axillary, iliac). 

• • Overlap with Polymyalgia Rheumatica (PMR): 40–60% of patients with GCA may have concurrent PMR. 

By Histology: 

• • Granulomatous GCA: Multinucleated giant cells, medial destruction, and elastic lamina fragmentation. 

• • Non-granulomatous GCA: Less common, with lymphocytic infiltration. 

III) Pathophysiology 

GCA is an autoimmune-mediated vasculitis triggered by environmental and genetic factors (notably HLA-DRB1*04 alleles). Activated dendritic cells in vessel walls recruit CD4+ T-cells and macrophages, which form granulomas and secrete pro-inflammatory cytokines (IL-6, IFN-γ, TNF-α), leading to intimal hyperplasia and luminal narrowing. 

IV) Epidemiology 

• • Sex: Female > Male (3:1) 

• • Age: Almost exclusively >50 years 

• • Ethnicity: More common in people of Northern European descent 

• • Comorbidities: Polymyalgia rheumatica (~50% of cases), atherosclerosis 

Etiology

I) Causes 

Autoimmune vasculitis with no single identified cause; likely multifactorial: 

• • Genetic predisposition (HLA-DR4 association) 

• • Aging-related immune dysregulation 

• • Environmental triggers (possible infections) 

II) Risk Factors 

• • Age >50 years (mean onset ~70) 

• • Female sex 

• • Northern European ancestry 

• • History of PMR 

• • Family history of autoimmune disease 

Clinical Presentation

I) History (Symptoms) 

• • New-onset temporal headache (most common) 

• • Scalp tenderness, especially when combing hair 

• • Jaw claudication (highly specific symptom) 

• • Vision changes: transient monocular vision loss (amaurosis fugax), diplopia, or permanent vision loss 

• • Constitutional symptoms: fever, fatigue, weight loss 

• • Polymyalgia rheumatica symptoms: proximal muscle stiffness, especially in shoulders and hips 

• • Large-vessel GCA: limb claudication, asymmetric pulses, aortic aneurysm or dissection 

II) Physical Exam (Signs) 

Vitals: 

• • Fever of unknown origin 

• • Elevated systolic BP (may be asymmetric) 

Head and Neck: 

• • Tender, thickened, non-pulsatile temporal artery 

• • Decreased or absent temporal artery pulse 

Ocular: 

• • Fundoscopic signs of anterior ischemic optic neuropathy (AION) 

• • Pale, swollen optic disc 

Extremities: 

• • Bruits over subclavian or carotid arteries 

• • Decreased upper extremity pulses 

Differential Diagnosis (DDx)

• • Tension or migraine headache 

• • Trigeminal neuralgia 

• • Polymyalgia rheumatica (without vasculitis) 

• • Takayasu arteritis (especially in younger patients) 

• • Infectious causes of vision loss (e.g., herpes zoster ophthalmicus) 

• • Atherosclerotic vascular disease 

• • Amaurosis fugax from carotid stenosis 

Diagnostic Tests

Initial Tests: 

• • Erythrocyte Sedimentation Rate (ESR): Often >50 mm/hr (very sensitive) 

• • C-Reactive Protein (CRP): Elevated; may rise earlier than ESR 

• • CBC: Normocytic anemia, thrombocytosis 

• • Liver enzymes: Mild elevation in ALP 

Specific Tests: 

• • Temporal Artery Biopsy (TAB): 

• • • Gold standard for diagnosis 

• • • Shows granulomatous inflammation with giant cells, intimal thickening, fragmented elastic lamina 

• • • Negative biopsy does not rule out GCA (skip lesions possible) 

• Imaging: 

• • Ultrasound of temporal artery (halo sign): hypoechoic wall thickening 

• • MRI or CT angiography: for large-vessel involvement 

• • PET-CT: for systemic vascular inflammation 

Treatment

I) Medical Management 

• • Immediate glucocorticoids: 

• • Prednisone 40–60 mg daily for uncomplicated GCA 

• • IV methylprednisolone 500–1000 mg/day x 3 days if visual symptoms are present 

• • Taper steroids gradually over months guided by symptoms and inflammatory markers 

• • Aspirin (81 mg daily): reduces risk of ischemic complications (e.g., stroke, vision loss) 

• • Bone protection: calcium, vitamin D, bisphosphonates due to long-term steroid use 

• • Steroid-sparing agents: 

• • Tocilizumab (IL-6 inhibitor): for relapsing or refractory disease or to minimize steroid exposure 

• • Methotrexate as an alternative or adjunct 

II) Interventional/Surgical 

• • Ophthalmologic emergency: urgent steroid therapy may prevent further vision loss but cannot reverse existing damage 

• • Vascular surgery consult for aneurysm repair (rare) 

Patient Education, Screening, Vaccines

• • Educate on urgency of treatment to prevent blindness 

• • Stress medication adherence and slow tapering schedule 

• • Monitor for steroid side effects: mood changes, glucose elevation, osteoporosis 

• • Avoid abrupt cessation of steroids 

• • Vaccinations: 

• • Influenza annually 

• • Pneumococcal vaccine (PPSV23 and PCV20/PCV15) 

• • COVID-19 vaccination 

• • Herpes zoster (Shingrix) if age ≥50 

Consults

• • Rheumatology: for diagnosis confirmation and long-term immunosuppressive therapy 

• • Ophthalmology: if any visual symptoms 

• • Vascular Surgery: for large-vessel involvement or aneurysmal disease 

• • Endocrinology: if steroid-induced diabetes or adrenal suppression develops 

• • Primary Care/Internal Medicine: for vaccine updates, bone health, and comorbidity management 

Follow-Up

• • Weekly to monthly ESR/CRP monitoring during taper 

• • Regular follow-up visits to assess for recurrence or steroid toxicity 

• • Bone mineral density testing at baseline and periodically 

• • Monitor vision status closely 

• • Repeat imaging if large-vessel GCA suspected or symptoms evolve 

• • Relapse signs: recurrent headache, jaw claudication, visual changes, elevated markers