Introduction
Temporal Arteritis, also known as Giant Cell Arteritis (GCA), is a systemic vasculitis affecting medium and large-sized arteries, with a predilection for branches of the external carotid artery. GCA is a critical cause of Pyrexia of Unknown Origin in patients over the age of 50. It is closely linked with Polymyalgia Rheumatica (PMR), and prompt treatment is necessary to prevent irreversible ischemic visual loss.
Clinical Manifestations
Headache: New-onset, localized temporal or occipital headache.
Temporal Artery Abnormalities: Nodular, tender, thickened, or pulseless temporal arteries.
Jaw Claudication: Pain or fatigue in jaw muscles during chewing (highly specific).
Visual Disturbances: Amaurosis fugax (transient monocular vision loss) or diplopia, leading to permanent blindness if untreated.
Polymyalgia Rheumatica (PMR) Association: Bilateral pain and morning stiffness in pelvic and shoulder girdles.
Diagnostic Criteria (ACR 1990 Criteria)
Diagnosis requires $\ge 3$ of the following 5 criteria:
Age of onset $\ge 50$ years.
New-onset localized headache.
Temporal artery tenderness or decreased pulsation.
Erythrocyte Sedimentation Rate (ESR) $\ge 50\text{ mm/hr}$ (Westergren).
Abnormal temporal artery biopsy showing necrotizing vasculitis with multinucleated giant cells.
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| ACR DIAGNOSTIC CRITERIA FOR GCA |
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| [X] Age >= 50 years |
| [X] New Localized Headache |
| [X] Temporal Artery Tenderness / Reduced Pulse |
| [X] ESR >= 50 mm/1st hour |
| [X] Biopsy showing Granulomatous Vasculitis |
| --> Presence of >= 3 Criteria confirms diagnosis |
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Management Protocol
Immediate Corticosteroid Therapy: Do NOT wait for biopsy results if clinical suspicion is high.
Uncomplicated GCA (No visual loss): Prednisone 40–60 mg/day orally.
Complicated GCA (Threatened or active visual loss): Intravenous Methylprednisolone (500–1,000 mg daily for 3 days), followed by oral prednisone.
Biopsy: Unilateral temporal artery biopsy ($>2\text{ cm}$ length) performed within 1–2 weeks of initiating steroids.
Steroid-Sparing Agents: Tocilizumab (anti-IL-6 receptor antibody) or Methotrexate for relapsing disease.