High Risk/Low Prevalence: GCA

Giant cell arteritis is an immune-mediated medium-vessel vasculitis where delayed recognition can cost a patient their vision or reveal itself later as aortic disease. Think temporal arteritis in adults over 50 with a new headache, temporal artery changes, jaw claudication, or visual symptoms.

Recognizing Giant Cell Arteritis

• Classic at-risk patient: GCA should move up the differential in adults over 50, especially women and patients with polymyalgia rheumatica, when a new headache appears with temporal artery tenderness or visual complaints.
• Vision-threatening presentation: Visual symptoms occur in roughly 20% of cases and can range from blurry vision or diplopia to complete monocular vision loss, the complication that makes early treatment urgent.
• Jaw claudication clue: Jaw claudication is a high-yield bedside clue, and the chewing gum test can reproduce ischemic pain with repetitive chewing. We walk through how to use that pearl in the episode.
• Classification criteria signal: The American College of Rheumatology criteria reach about 93% sensitivity and 91% specificity when 3 of 5 features are present, including age over 50, new headache, temporal artery abnormality, ESR elevation, and biopsy findings.
• High-stakes complications: Untreated disease is not just about headache and vision loss; first-order aortic branch involvement is common, and stroke or TIA clusters early after diagnosis.

Diagnosis and Emergency Management

• Inflammatory markers together: ESR and CRP are more useful together than alone, but normal markers do not exclude early GCA and platelet elevation may add diagnostic weight.
• Biopsy versus ultrasound: Temporal artery biopsy remains the reference standard, yet its sensitivity is imperfect and vascular ultrasound is increasingly used as a noninvasive confirmatory test.
• Steroids before confirmation: When suspicion is meaningful, start glucocorticoids before confirmatory testing; prednisone 60 mg daily is the headline outpatient regimen for less severe presentations.
• Severe symptom escalation: Vision loss or other major ischemic features call for methylprednisolone 1000 mg IV and admission, with additional disposition nuances we get into in the chapter.
• Follow-up determines disposition: Patients without severe features may go home only if close follow-up is reliable, ideally coordinated with primary care and rheumatology while confirmatory testing is arranged.

References: 

1. Lacy A, Nelson R, Koyfman A, Long B. High risk and low prevalence diseases: Giant cell arteritis. Am J Emerg Med. 2022 Aug;58:135-140. doi: 10.1016/j.ajem.2022.05.042. Epub 2022 May 31. PMID: 35688119.
2. Prior JA, Ranjbar H, Belcher J, et al. Diagnostic delay for giant cell arteritis—a systematic review and meta-analysis. BMC Med. 2017;15(1):120 
3. Kuo CH, McCluskey P, Fraser CL. Chewing Gum Test for Jaw Claudication in Giant-Cell Arteritis. N Engl J Med. 2016 May 5;374(18):1794-5. PMID: 27144869 
4. Kermani TA, Schmidt J, Crowson CS, et al. Utility of erythrocyte sedimentation rate and C-reactive protein for the diagnosis of giant cell arteritis. Semin Arthritis Rheum. 2012 Jun;41(6):866-71. PMID: 22119103 
5. Parikh M, et al. Prevalence of a normal C-reactive protein with an elevated erythrocyte sedimentation rate in biopsy-proven giant cell arteritis. Ophthalmology. 2006 Oct. 113(10):1842-5. PMID: 16884778
6. Costello F, et al. Role of thrombocytosis in diagnosis of giant cell arteritis and differentiation of arteritic from non-arteritic anterior ischemic optic neuropathy. Eur J Ophthalmol. 2004 May-Jun. 14(3):245-57. PMID: 15206651 
7. Rinagel M, et al. Diagnostic performance of temporal artery ultrasound for the diagnosis of giant cell arteritis: a systematic review and meta-analysis of the literature. Autoimmun Rev. 2019;18:56–61.
8. Luqmani R, Lee E, Singh S, et al. The role of ultrasound compared to biopsy of Temporal Arteries in the Diagnosis and Treatment of Giant Cell Arteritis (TABUL): a diagnostic accuracy and cost-effectiveness study. Health Technol Assess 2016;20:1–238.