Temporal Arteritis (Giant Cell Arteritis) — Diagnosis, Clinical Features, Treatment and Prognosis

Giant cell arteritis is a granulomatous large- and medium-vessel vasculitis affecting the aorta and its extracranial branches, with a predilection for the superficial temporal, ophthalmic, posterior ciliary and vertebral arteries.

It is the commonest primary systemic vasculitis of older people. It virtually never occurs before the age of 50 — age ≥50 is an entry criterion for classification — and incidence peaks between 70 and 80 years. Female to male ratio is about 2–3:1. It is far commoner in Northern Europeans than in Indians.

GCA overlaps closely with polymyalgia rheumatica: about 40–50% of GCA patients have PMR features and 15–20% of PMR patients develop GCA.

Dendritic cell activation in the arterial adventitia recruits CD4+ T cells; Th1 (interferon-γ) and Th17 (IL-17) pathways drive granuloma formation with multinucleated giant cells and fragmentation of the internal elastic lamina.

IL-6 drives the systemic inflammatory response, explaining the very high ESR and CRP — and the effectiveness of IL-6 receptor blockade.

Intimal hyperplasia narrows the lumen and produces ischaemia. Involvement is segmental with skip lesions, which is why an adequate biopsy length is essential.

Cranial symptoms: new-onset temporal or occipital headache (the commonest presenting feature), scalp tenderness (pain on combing the hair or resting on a pillow), and a thickened, tender, nodular, pulseless temporal artery.

Jaw claudication — masseter pain on chewing — is the single most specific symptom. Tongue claudication and, rarely, tongue or scalp necrosis may occur.

Visual features — the emergency: amaurosis fugax, diplopia, and sudden painless permanent monocular visual loss, usually from anterior ischaemic optic neuropathy with a pale, swollen “chalky white” disc; also central retinal artery occlusion. Untreated, the second eye is at risk within days to weeks.

Constitutional features: fever (GCA is a classic cause of pyrexia of unknown origin in the elderly), weight loss, anorexia, malaise and depression. GCA is an important reversible cause of frailty and functional decline in older people, and is often misdiagnosed.

PMR features: aching and morning stiffness of the neck, shoulder and pelvic girdle lasting more than 45 minutes, with difficulty rising and combing hair.

Large-vessel GCA: limb claudication, asymmetric pulses or blood pressure, bruits, and late thoracic aortic aneurysm or dissection. Rarely, vertebrobasilar territory stroke — giant cell arteritis should be considered in any elderly patient with posterior circulation ischaemia.

GCA is a medical emergency and a clinical diagnosis. Treatment must never be delayed for investigations or biopsy.

Acute-phase response: ESR is characteristically very high — an ESR above 75 mm/h in a patient with headache, jaw claudication or visual change should prompt urgent action. CRP is more sensitive and rises earlier. Also expect normocytic normochromic anaemia, thrombocytosis, raised alkaline phosphatase and low albumin. About 4% have both a normal ESR and CRP.

Temporal artery biopsy remains the diagnostic gold standard. Take a segment at least 1–2 cm long because of skip lesions, and perform it within 1–2 weeks of starting steroids — the yield falls with prolonged treatment, though positivity persists for some weeks. A negative biopsy does not exclude GCA.

Histology: transmural mononuclear infiltrate, granulomas with multinucleated giant cells, disruption of the internal elastic lamina, and intimal hyperplasia with luminal narrowing.

Colour Doppler ultrasound of temporal and axillary arteries shows the non-compressible “halo sign” (hypoechoic circumferential wall oedema) — now the first-line investigation in fast-track clinics, with the advantage of immediate availability.

Large-vessel imaging: CT or MR angiography and FDG-PET/CT identify aortitis and subclavian/axillary involvement; PET is especially valuable when GCA presents as a PUO. Baseline and periodic aortic imaging is advised for aneurysm surveillance.

2022 ACR/EULAR classification criteria (for classification, not diagnosis) require age ≥50 as an entry criterion, then score: morning stiffness of shoulder/neck, sudden visual loss, jaw or tongue claudication, new temporal headache, scalp tenderness, abnormal temporal artery examination, raised ESR/CRP, positive biopsy or halo sign, bilateral axillary involvement, and FDG-PET uptake in the aorta.

Start high-dose glucocorticoids immediately on clinical suspicion. For uncomplicated GCA, prednisolone 40–60 mg/day (about 1 mg/kg). For visual symptoms or established visual loss, IV methylprednisolone 500–1000 mg daily for 3 days, followed by oral prednisolone.

Symptoms usually improve dramatically within 24–72 hours; a poor response should prompt reconsideration of the diagnosis.

Taper slowly, guided by symptoms and inflammatory markers: maintain the initial dose for 2–4 weeks, reduce to about 15–20 mg by 3 months and 5 mg by 12 months. Most patients need 1–2 years of treatment, some longer.

Steroid-sparing therapy: tocilizumab (IL-6 receptor blocker) 162 mg subcutaneously weekly or every other week, or 6 mg/kg IV every 4 weeks — the GiACTA trial showed sustained steroid-free remission with a markedly lower cumulative glucocorticoid dose. Methotrexate is a cheaper alternative with modest benefit, relevant in Indian practice. Infliximab is not beneficial and is not recommended.

Adjunctive care in every patient: low-dose aspirin (reduces ischaemic events; weigh bleeding risk), a proton pump inhibitor, calcium, vitamin D and a bisphosphonate for glucocorticoid-induced osteoporosis, blood glucose and blood pressure monitoring, Pneumocystis prophylaxis if on high-dose steroid with additional immunosuppression, and vaccination.

Comprehensive geriatric assessment matters. Glucocorticoid toxicity in older people causes hyperglycaemia, hypertension, cataract, proximal myopathy, skin fragility, insomnia, delirium, infection and fracture — steroid harm often exceeds vasculitis harm after the acute phase.

Overall life expectancy is close to normal. Most morbidity comes from glucocorticoid toxicity and from aortic aneurysm and dissection (a roughly 17-fold increase in thoracic aortic aneurysm), rather than from the vasculitis itself.

Established visual loss is usually permanent — recovery is rare even with intravenous steroids. The entire aim of emergency treatment is to protect the second eye. The risk of blindness falls from about 30% untreated to under 5% with prompt therapy.

Relapse occurs in 40–60%, mostly during tapering in the first 18 months, and usually presents as headache or PMR symptoms rather than visual loss. Relapses require dose escalation and consideration of a steroid-sparing agent.