Makindo Medical Notes

Related Subjects: | Temporal (Giant Cell GCA) Arteritis | Tocilizumab

🩺 Giant Cell Arteritis (GCA) is a large-vessel vasculitis and ophthalmological emergency. ⚠️ Can cause irreversible blindness (20% of cases) but preventable if diagnosed and treated promptly. Commonly seen in rheumatology, ophthalmology, and stroke/TIA clinics.

💡 Tocilizumab: Humanised monoclonal antibody targeting the IL-6 receptor. Used in GCA for relapse prevention and steroid-sparing, given as weekly SC injections.

ℹ️ About GCA

• 🎯 Vasculitis of large/medium arteries, especially branches of the external carotid (temporal, ophthalmic, ciliary, retinal).
• 👁️ Blindness risk due to anterior ischaemic optic neuropathy from posterior ciliary artery occlusion.
• 🧑‍🦳 ~50% overlap with Polymyalgia Rheumatica (PMR).

📊 Epidemiology

• Mean age of onset ~70 yrs; rare <50.
• ♀:♂ ratio ≈ 3:1.
• Most common in Caucasians, Northern Europeans.

🔎 Phenotypes

• 🧠 Cranial GCA (cGCA): Headache, scalp tenderness, jaw claudication, visual loss.
• 🫀 Extracranial GCA (ecGCA): Limb claudication, systemic features, aortic involvement.
• ⚖️ Mixed: Combination of both.

🩸 Vessels Involved

• Posterior ciliary arteries → AION → blindness.
• Central retinal artery → sudden visual loss.
• Extraocular muscle ischaemia → diplopia.
• Aorta may be affected → aneurysm/dissection later.

🧬 Aetiology & Pathogenesis

• Cause unclear – immune response to unidentified antigen.
• Chronic granulomatous inflammation with multinucleated giant cells.
• Driven by Th1-mediated response, ↑ IL-6 levels central.
• Genetic: HLA-DRB1 association increases susceptibility.

📋 ACR Diagnostic Criteria (≥3/5 = GCA)

🩺 Clinical Presentation

• 🌡️ Systemic: Fever, weight loss, malaise, fatigue.
• 👁️ Visual: Transient/monocular visual loss, AION, diplopia.
• 🧠 Headache: Abrupt, often unilateral, temporal or occipital.
• 🖐️ Temporal artery: Tender, thickened, pulseless.
• 🦷 Jaw claudication (masseter ischaemia) = highly specific.
• 🚫 Stroke rare (internal carotid usually spared).
• 📉 Complications: Blindness, aortitis, aortic aneurysm/dissection (late).

🔬 Investigations

• 🩸 FBC: Normocytic anaemia, thrombocytosis.
• 🔥 ESR >50, ↑ CRP (more sensitive). ALP ↑ in 30%.
• 🖥️ Duplex US: “Halo sign” = hypoechoic wall thickening. Resolves after steroids.
• 🔬 Gold standard: Temporal artery biopsy (long segment; skip lesions common). Ideally <2 weeks after steroids.
• 👁️ Fluorescein angiography: Choroidal hypoperfusion.

💊 Management

• 👁️ Visual symptoms: Start high-dose steroids (Prednisolone 60 mg/day or 1 mg/kg). Urgent ophthalmology input. Add PPI & bone protection.
• Non-visual symptoms: Start steroids, rheumatology follow-up.
• ⏳ Taper steroids slowly over 18–24 months. Monitor relapses.
• 🧬 Tocilizumab (IL-6 inhibitor): Steroid-sparing option; SC 162 mg weekly.
• 🦴 Long-term: Bone protection, fracture prevention, cardiovascular risk management.

📚 References

• Hassan N et al. Giant Cell Arteritis. BMJ 2011;342:d3019.

Case 1 – Classic cranial GCA with visual risk

A 71-year-old woman presents with a new, severe unilateral temporal headache, scalp tenderness when brushing hair, and jaw claudication; she reports transient amaurosis fugax in the right eye. Exam shows a tender, thickened temporal artery; vision is 6/9 with a relative afferent pupillary defect. Bloods: CRP 78 mg/L, ESR 92 mm/h; platelets high-normal. Treat immediately (don’t delay for tests) with high-dose glucocorticoids—if visual symptoms, give IV methylprednisolone 500–1000 mg daily × 3 then switch to oral prednisolone 40–60 mg daily with PPI and bone protection; add low-dose aspirin if no contra-indication. Arrange urgent temporal artery ultrasound (halo sign) and/or biopsy within 7 days, plus ophthalmology review; baseline glucose/BP/DEXA and plan a slow taper with rheumatology follow-up. Watch for complications: arteritic AION, stroke, aortic aneurysm.

Case 2 – Polymyalgia phenotype with dull headache systemic features

A 68-year-old man with 4 weeks of proximal shoulder/hip girdle pain and morning stiffness develops low-grade fever, weight loss, and new dull headache without jaw pain. Exam: reduced active abduction, no overt temporal artery tenderness. Bloods: CRP 56, ESR 70; mild normocytic anaemia. Given red flags for GCA in a PMR-like presentation, start prednisolone 40 mg daily the same day; symptoms improve within 48 hours, supporting the diagnosis. Arrange temporal artery ultrasound (± biopsy) and consider large-vessel imaging (CTA/MRA) to assess aorta. Add calcium/vitamin D, bisphosphonate if at risk; screen for steroid toxicity and consider steroid-sparing therapy (e.g., methotrexate or tocilizumab in refractory/relapsing disease) under rheumatology. Educate on urgent return if visual change, jaw claudication, or limb ischaemia develops.

Case 3 – Pure Polymyalgia Rheumatica (no GCA features)

A 73-year-old woman reports 3 weeks of bilateral shoulder and hip girdle pain with morning stiffness >60 minutes, difficulty rising from a chair, and sleep disturbance, but no headache, jaw claudication, visual symptoms, or limb ischaemia. Exam: painful but full passive ROM; no synovitis or temporal artery tenderness. Labs: CRP 48 mg/L, ESR 62 mm/h, mild normocytic anaemia; CK, TSH, Ca, RF/anti-CCP and urine dip are unremarkable. Diagnosis: PMR (after excluding mimics—rotator cuff disease, OA, hypothyroidism, myeloma, infection, malignancy). Start prednisolone 12.5–15 mg daily with a structured taper over months, review in 1–2 weeks for >70% symptom and CRP/ESR response; add bone protection (vitamin D ± bisphosphonate as per FRAX), GI and diabetes risk mitigation, and vaccinations. Safety-net: urgent assessment if any GCA red flags develop; consider methotrexate if relapsing/steroid-intolerant; involve rheumatology if atypical course.