Key Facts

GCA is an ophthalmological and rheumatological emergency. The principle of management is to treat immediately on clinical suspicion to prevent irreversible blindness.

Epidemiology

• Most common vasculitis in adults >50
• UK incidence: ~20 per 100,000 in >50s
• Peak age 70-80; almost never occurs <50
• F:M 2-3:1
• More common in Northern European/Scandinavian populations

Pathophysiology

• Granulomatous vasculitis of medium/large arteries
• CD4+ T-cell and macrophage-driven inflammation in arterial adventitia
• Multinucleated giant cells in vessel wall (not always present)
• Intimal hyperplasia → luminal narrowing → ischaemia
• Temporal artery: headache; ophthalmic artery: visual loss; vertebral/aortic: aortitis
• IL-6 is a key cytokine → rationale for tocilizumab

Classic Features

• New-onset headache (temporal, often unilateral; sometimes diffuse)
• Scalp tenderness (pain on brushing hair, wearing hat)
• Temporal artery abnormality: thickened, beaded, tender; reduced/absent pulse
• Jaw claudication: pain in jaw muscles on chewing (highly specific, ~50%)
• Visual symptoms (15-20%): amaurosis fugax, diplopia, sudden visual loss (AION)

Constitutional

• Fatigue, malaise, weight loss, fever, night sweats
• PMR symptoms (50%): bilateral shoulder/hip girdle pain and stiffness

Large-Vessel GCA

• Aortitis: aortic aneurysm (thoracic), aortic dissection
• Limb claudication: subclavian, axillary artery involvement
• Aortic regurgitation

Red Flags

• ANY visual symptom in suspected GCA → immediate high-dose steroids and urgent ophthalmology
• Jaw claudication → high positive predictive value for GCA
• Permanent visual loss can occur within hours of first visual symptom
• Second eye at risk within days-weeks if untreated

Bloods

• ESR: often >50 (frequently >100 mm/hr); 15-20% may be normal
• CRP: elevated (more sensitive than ESR)
• FBC: normocytic anaemia, thrombocytosis
• LFTs: raised ALP (25-30%)

Imaging

• Temporal artery USS (with expertise): halo sign (circumferential hypoechoic wall thickening); sensitivity 77%, specificity 96% (TABUL trial)
• MRI temporal arteries: mural enhancement and oedema
• CT/PET angiography: for large-vessel GCA (aortitis)

Biopsy

• Temporal artery biopsy: gold standard; ≥1cm specimen; perform within 14 days of starting steroids
• Histology: transmural granulomatous inflammation, giant cells, intimal hyperplasia, fragmentation of internal elastic lamina
• False-negative rate 15-20% due to skip lesions; contralateral biopsy if high suspicion and first negative

Ophthalmological

• Visual acuity, fundoscopy, visual fields: at presentation
• AION: pale, swollen optic disc; splinter haemorrhages

Emergency Treatment (Start BEFORE Investigations)

Without visual symptoms:

• Prednisolone 40-60mg OD (do not delay for biopsy)

With visual symptoms or jaw claudication:

• IV methylprednisolone 500mg-1g daily × 3 days, then oral prednisolone 60mg
• Urgent ophthalmology review

Steroid Tapering (BSR Guidelines)

• Taper prednisolone over 12-18 months minimum:
  • 40-60mg for 4 weeks → reduce by 10mg every 2 weeks to 20mg
  • 20mg → reduce by 2.5mg every 2-4 weeks to 10mg
  • 10mg → reduce by 1mg every 4-8 weeks
• Guide taper by symptoms and CRP/ESR (not ESR alone)
• ~50% relapse during taper

Steroid-Sparing

• Tocilizumab (IL-6 inhibitor): 162mg SC weekly or fortnightly (NICE TA518)
  • GiACTA trial: 56% sustained remission with tocilizumab vs 14% with steroids alone at 1 year
  • Allows faster steroid taper; reduces cumulative steroid dose
  • Caution: masks CRP (cannot use CRP to monitor disease activity)
• Methotrexate 10-15mg weekly: modest steroid-sparing effect; used if tocilizumab unavailable

Supportive

• Bone protection: calcium/vitamin D + bisphosphonate (prolonged steroid use)
• PPI: gastric protection during high-dose steroids
• Low-dose aspirin 75mg: consider for vascular risk reduction (limited evidence)
• Aortic screening: CT/MR angiography at diagnosis and periodically (aortic aneurysm risk)

Referral Criteria

• All suspected GCA → immediate treatment + urgent rheumatology referral
• Visual symptoms → emergency ophthalmology
• Large-vessel GCA → vascular MDT

• Visual loss prevention: if treated before permanent damage, vision can be preserved in >95%
• Permanent visual loss: occurs in 15-20% if untreated; once established, usually irreversible
• Relapse rate: ~50% during steroid taper; tocilizumab significantly reduces this
• Steroid complications: major morbidity (osteoporosis, diabetes, infections, weight gain)
• Aortic aneurysm: develops in 10-20% (particularly thoracic); lifelong surveillance recommended
• Mortality: near-normal life expectancy with treatment; increased CV risk
• Most patients can discontinue steroids by 2-3 years

BSR Steroid Taper for GCA

GCA vs PMR