Giant cell arteritis (GCA) is a segmental systemic granulomatous arteritis affecting medium and large arteries in individuals >50 yr. Inflammation primarily targets branches of the extracranial head and neck blood vessels (external carotids, temporal arteries, ciliary and ophthalmic arteries). The aorta and subclavian and brachial arteries can also be affected. Intracranial arteritis is rare.

GCA

Temporal arteritis

Cranial arteritis

Horton disease

GCA can present with the following clinical manifestations:

• Headache, often associated with marked scalp tenderness-noticed while brushing hair (hair comb allodynia)
• Constitutional symptoms (fever, weight loss, anorexia, fatigue)
• Polymyalgia rheumatica (aching and stiffness of the trunk and proximal muscle groups)
• Visual disturbances (transient or permanent monocular or binocular visual loss)
• Intermittent claudication of jaw and tongue on mastication that is especially prominent when solid food such as steak is chewed
• Table E1 describes atypical manifestations of GCA

Important physical findings in GCA:

• Vascular examination: The temporal artery demonstrates tenderness, decreased pulsation, and nodularity (ropy) (Fig. E1); diminished or absent pulses in upper extremities may be seen.

Vasculitis of unknown etiology. An association with HLA-DRB∗04 has been identified. Recent demonstration of varicella zoster virus virion, antigen, and DNA within the vessel walls of the temporal arteries on histopathologic specimens of GCA suggest an association. A proposed model for the pathogenesis of GCA is illustrated in Fig. E2.

• Polymyalgia rheumatica (Table E2)
• Other vasculitis syndromes
• Nonarteritic anterior ischemic optic neuropathy (NAION)
• Pituitary apoplexy
• Primary amyloidosis
• Transient ischemic attack, stroke
• Infections
• Occult neoplasm, multiple myeloma

• ESR elevated, although up to 22% of patients with GCA have normal ESR before treatment.
• C-reactive protein (CRP) is typically included in laboratory investigation; it may have greater sensitivity than ESR. CRP typically rises before the ESR.
• Mild to moderate normochromic normocytic anemia, elevated platelet count.
• Temporal artery biopsy: A unilateral biopsy specimen can be examined immediately by frozen section. If the frozen section is negative for GCA, the contralateral temporal biopsy can be biopsied to increase diagnostic yield.¹ Unilateral biopsy only misses the diagnosis in 5% of cases.^1a

Imaging studies do not play a major role in diagnosing GCA and are rarely indicated:

• Color duplex ultrasonography (CDUS) of temporal artery produces three characteristic features-periluminal “halo” over the temporal artery involved (Fig. E4), segmental arterial stenosis, and arterial luminal occlusion in severe cases. CDUS of the temporal artery has 40% to 75% sensitivity and 79% to 83% specificity for diagnosis of GCA. Clinical utility is not superior to clinical examination with biopsy.
• Contrasted MRI of temporal artery may be performed in patients with contraindications to surgical biopsy of the superficial temporal artery if treatment with steroids has not been initiated. MRI has a 78.4% sensitivity and 90.4% specificity in detecting temporal artery involvement in patients with a clinical diagnosis of GCA.
• Angiography of the arms is indicated in patients with peripheral vascular insufficiency.
• Fluorine-18-fluorodeoxyglucose (18F-FDG) PET/computed tomography (18F-FDG PET/CT) imaging may be used to detect large-vessel inflammation in GCA. Sensitivity is 64% in the maxillary or temporal arteries and increases to 82% if vertebral arteries and increases specificity is 100%.

• If there is clinical suspicion of GCA, treatment should be initiated without waiting for results of laboratory or imaging studies.
• Intravenous (IV) methylprednisolone (250 to 1000 mg for 1 to 3 days) is considered standard of care in patients with severe clinical manifestations such as visual loss from ischemic optic neuropathy.
• Oral prednisone (1 mg/kg/day): High-dose oral regimen should be continued at least until symptoms resolve and ESR returns to normal; usually 3 to 4 wk after treatment initiation. Steroid taper is very slow (10% to 20% per mo) with monitoring of clinical features as well as ESR and CRP. When dose <10 mg/day, taper by 1 mg/mo. Treatment may last up to 2 yr or more.
• Although corticosteroids have traditionally been the treatment of choice, tocilizumab, an interleukin (IL)-6 receptor blocker, is approved by the FDA for the treatment of GCA. Patients treated with tocilizumab and prednisone achieved remission faster, had a greater reduction in steroid dosage, and had prolonged maintenance of remission when compared with those treated with prednisone alone.
• There is no evidence for the role of other steroid-sparing agents.

• With steroid therapy there is a dramatic improvement of systemic symptoms, but not vision in patients with ischemic optic neuropathy. In one study only 4% of eyes improved in both visual acuity and central visual field.
• Management of flares: Repeat prednisone induction if patient experiences severe flare. If mild flare, increase prednisone by 10% to 20% and slow down prednisone taper.

Surgical or ophthalmologic referral for biopsy of temporal artery

• Rheumatology referral for long-term immunosuppressive treatment management

• The relation between polymyalgia rheumatica and GCA is unclear, but the two frequently coexist. They are considered to be different points along the gradient or spectrum of the same disease.
• Clinical picture rather than ESR should be the prime yardstick for continuing prednisone therapy. A rising ESR in a clinically asymptomatic patient with normal hematocrit should raise suspicion for alternative explanations (e.g., infections, neoplasms).
• GCA is associated with a markedly increased risk for the development of aortic aneurysm, which is often a late complication and may cause death. Annual chest x-ray examination in chronic GCA patients has been suggested, as well as emergent chest CT or MRI for clinical suspicion.
• GCA is also associated with increased risk of myocardial infarction, stroke, and peripheral vascular disease.
• Coadministration of low-dose aspirin (81 mg/day) has been reported by some as effective for further reduction of risk of blindness. Additional trials may be needed before it can be recommended as standard therapy.

Giant Cell Arteritis (Patient Information)

Vasculitis, Systemic (Related Key Topic)