emDOCs Podcast – Episode 76: Giant Cell Arteritis
- Apr 25th, 2023
- Brit Long
Today on the emDOCs cast with Brit Long, MD (@long_brit), we look at giant cell arteritis (GCA), also known as temporal arteritis.
Episode 76: Giant Cell Arteritis
- Giant cell arteritis (or temporal arteritis) is an immune-mediated vasculitis that affects medium-sized vessels.
- It is the most common vasculitis.
- The pathophysiology behind GCA includes vascular endothelial injury with inflammation leads to the formation of giant cells, which causes disruption of vessel walls, narrows vessel lumen, and results in limited blood flow to critical organs. The most common vessels involved are the carotids and the aorta.
- Common characteristics of patients with GCA:
- Older age (>50 years); average age at diagnosis is 79.
- Highest incidences in people of Scandinavian origin.
- Females affected more commonly than males.
- Associated with polymyalgia rheumatica.
Diagnosis & Clinical Presentation:
- Risks of delayed diagnosis: irreversible vision loss, aortitis, limb ischemia, and TIA/stroke.
- Diagnostic challenges with GCA: unclear diagnostic criteria, delay in diagnosis from symptom onset, and fluctuating or transient symptoms.
- American College of Rheumatology Classification Criteria (need 3 of 5):
- >50 yo
- New headache
- Temporal artery abnormality (thickening, loss of pulse, tenderness)
- ESR >50
- Abnormal temporal artery biopsy
- 93% sensitive, 91% specific
- Other classification systems use constitutional symptoms, jaw claudication, vision changes, elevated CRP, and elevated PLT.
- A way to examine for jaw claudication is the chewing gum test. The patient chews gum at 1 chew per second. Pain at 2 minutes is positive.
- Vision changes are common.
- Classic change is complete monocular vision loss.
- 20-23% of patients will have some vision change (binocular, monocular, diplopia, blurry vision, decrease in vision, complete field loss).
- Complete vision loss is a rare first-time presentation with poor outcomes.
- Pain with vision changes is common.
- Inflammatory markers (IMs)
- CRP >10 mg/L
- Sensitivities vary based on the cutoff used.
- Up to 4% of patients will have normal IMs early in the disease.
- One study showed that an elevated platelet count (>400,000) may be better at making the diagnosis, and a normal platelet count at excluding it compared to IMs.
- Used to rule out other conditions. CTA of head and neck may show vascular changes.
- Reference standard for diagnosis is temporal artery biopsy. However, it is not very sensitive, and non-invasive imaging (e.g., US) is being proposed as a replacement.
- Guidelines recommend an outpatient imaging test to confirm the diagnosis.
- If suspect GCA, start steroids while waiting for confirmatory studies.
- Prednisone 60 mg/day for less severe
- Methylprednisolone 1000 mg IV for severe symptoms (vision loss).
- Other treatments if patients cannot take steroids or are refractory to treatment:
- Tocilizumab, methotrexate.
- Disposition is made in consultation with the PCP and rheumatology.
- Admit patients with severe symptoms (vision changes, large vessel complication) or those who cannot follow up.
- If less severe symptoms and good follow-up, discharge with close follow-up.
- Discharge with a prescription for prednisone 60 mg per day.
- The aorta & first-order branches are affected in 80% of patients and ⅔ have aortitis. Patients have a 3x increased risk of aortic aneurysm and dissection if the GCA is left untreated.
- Other signs of first-order branch involvement include cardiac valve regurgitation, limb ischemia, vascular bruit, neurovascular symptoms.
- Increased risk of TIA and stroke
- 7.5% experience a stroke or TIA within the first 4 weeks of diagnosis.
- ENT & dental issues: facial swelling/pain, dental pain, throat pain, macroglossia, tongue and scalp infarction.
- 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.
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- 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
- 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
- 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
- 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
- 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.
- 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.