Giant cell arteritis

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Key Recommendations

Diagnosis is made on the basis of history, blood tests, and a diagnostic temporal artery biopsy. However, treatment should not be delayed in suspected disease while awaiting biopsy result.

History

Diagnosis should be considered in a patient 50 years or older who presents with new onset of temporal headache, visual disturbances, or jaw or tongue claudication.[1] Approximately one third of patients will have symptoms of polymyalgia rheumatica, characterized by pain and stiffness in the head and neck and proximal upper and lower extremities. Constitutional symptoms including fatigue, weight loss, malaise, and fever also are common presenting symptoms.

When present, symptoms of jaw claudication and diplopia are powerful predictors of a positive temporal artery biopsy result.[33] Neurologic manifestations may include stroke, transient ischemic attack, or neuropathy.[2][3][9] Respiratory tract symptoms are uncommon but may include cough or sore throat. Rarely, dental pain, tongue pain, or infarction of the tongue may be present.[2][5] Also, some patients who predominantly have polymyalgia rheumatica can have subtle evidence of GCA that could be missed.[6]

Patients with large-vessel stenoses (clinically apparent in approximately 10% to 15% of patients) may present with claudication of (usually) the upper extremities,[7] though, rarely, involvement of lower extremity vessels results in leg claudication.[8]

GCA can rarely present as an unexplained systemic illness or fever of unknown origin with elevated levels of inflammatory markers without headache, jaw claudication, shoulder or hip girdle stiffness, or visual disturbances.

Examination

On physical examination there may be scalp tenderness and abnormalities of the temporal artery including thickening, tenderness, and nodularity. Other scalp arteries, including the facial and occipital arteries, may be affected. Fundoscopic abnormalities may include pallor and edema of the optic disk, possibly with cotton-wool patches and hemorrhages. Auscultation over the carotid or subclavian arteries may reveal bruits in patients with large-vessel involvement. Pulses in the neck or the arms may be decreased or absent in this subset of GCA. Patients with large-vessel stenoses (approximately 10% to 15% of patients) may have asymmetric blood pressures or decreased pulses.[7]

Laboratory tests

First tests to order are inflammatory markers and simple blood tests (complete blood count, liver function tests, erythrocyte sedimentation rate [ESR], and C-reactive protein [CRP]). The ESR is often markedly elevated, with an ESR ≥50 mm/hour being one of the indicators used for diagnosis of GCA.[1] However, a minority of patients may have a normal ESR. CRP is typically markedly elevated and may be a more sensitive indicator of inflammation. A CRP level ≥10 mg/L is one of the criteria that support the diagnosis of GCA.[1] Most patients have a normochromic, normocytic anemia related to the chronic inflammation and elevated platelet count. About one third of patients may have mildly abnormal results on liver function tests, particularly elevation of alkaline phosphatase. Tests for autoantibodies, such as rheumatoid factor and antinuclear antibody, are usually negative and are not typically ordered in the initial investigation.

Temporal artery biopsy

Temporal artery biopsy is considered the definitive test for the diagnosis of GCA.[1][34]

For patients with suspected GCA, initially, a unilateral biopsy is recommended.[34] The biopsy is performed on the side with abnormal clinical findings (if present). However, bilateral temporal artery biopsies may be appropriate if the symptoms are not clearly localized to one temporal artery.[34] If the biopsy on one side is normal, a second biopsy on the contralateral side may be considered.[34] An adequate length of temporal artery (>1 cm) should be obtained because inflammatory lesions may be present in a segmental fashion.[34]

Treatment should not be delayed while waiting for the biopsy to be performed. The American College of Rheumatology recommends obtaining a temporal artery specimen within 2 weeks of starting treatment with oral glucocorticoids.[34] However, after several weeks of glucocorticoid therapy, temporal artery biopsy may still yield a diagnosis of arteritis.[35][36] Indeed, the majority of temporal artery biopsies (9 of 12) performed in a small cohort of patients with treated GCA had persistent histopathologic evidence of vasculitis even after 6 months of glucocorticoid therapy.[37] Ongoing vasculitis was apparent in 4 of 9 biopsies after 12 months of treatment.

Temporal artery biopsy is less helpful in patients with large-vessel GCA and may be negative in up to 50% of these patients.[38]

Temporal artery ultrasound

Imaging is being increasingly used for diagnosis and ultrasound is the preferred early imaging test in guidelines for patients with suspected GCA.[1][39] Ultrasound has the advantage of being noninvasive and is more cost-effective than biopsy. A temporal artery halo sign (wall thickening) on ultrasound is a supporting diagnostic feature of GCA.[1]

In patients with GCA, ultrasound may also show stenosis, or occlusion. It has been suggested that the diagnosis of GCA can be made on the basis of the clinical syndrome and ultrasonography findings without resorting to temporal artery biopsy.[40] However, it is operator-dependent and is best performed in experienced centers, where it may be a useful and complementary tool for diagnosing GCA.[34] Results are influenced by treatment (i.e., signs of inflammation quickly disappear with glucocorticoid treatment).[34]

Systematic reviews of temporal artery ultrasonography have reported a pooled sensitivity of 87% and a specificity of 96% compared with the clinical diagnosis, and a sensitivity of 75% and specificity of 83% compared with temporal artery biopsy.[40][41] In a meta-analysis of 20 studies, the sensitivity and specificity of a hypoechoic halo (halo sign) compared with positive temporal artery biopsy were 68% and 81%, respectively.[42]

EULAR guidelines recommend ultrasound as the preferred early imaging test in patients with suspected GCA.[39]

Noninvasive vascular imaging

If large-vessel involvement is suspected, this may be diagnosed by ultrasound, computed tomography angiography (CTA) or magnetic resonance angiography (MRA).[34][43] Imaging the large vessels of the neck/chest/abdomen/pelvis may provide additional evidence of extracranial disease when the diagnosis is uncertain following negative temporal artery biopsy results.[34][43]

Noninvasive vascular imaging with CTA or MRA of the neck/chest/abdomen/pelvis is also recommended for patients with newly diagnosed GCA to evaluate large vessel involvement.[34][43] Where large vessel involvement is confirmed, routine noninvasive vascular imaging can identify early and long-term complications, such as aneurysms and stenoses, and assess stability of existing lesions.[34]

Emerging investigations

Positron emission tomography (PET) may be useful in the assessment of active disease, where it may demonstrate 18F-fluorodeoxyglucose (FDG) uptake in the large vessels (aorta and major branches).[1][43][44][45][46] In patients with elevated markers of inflammation and uncertain diagnosis, FDG-PET may be helpful in detecting an occult malignancy or infection in patients who present with constitutional symptoms similar to vasculitis.[43] However, in routine clinical practice FDG-PET is not currently able to assess inflammation in the superficial temporal arteries. FDG-PET may have some utility for the assessment of persistent or recurrent GCA in the appropriate clinical context.[47] The main concern with FDG-PET/CT is that its sensitivity is affected by immunosuppression.[43][48][49][50] Within three days of high-dose glucocorticoid treatment, FDG PET/CT can diagnose large-vessel GCA with high sensitivity. After 10 days of treatment, FDG PET/CT sensitivity decreases significantly.[51]

Venepuncture and phlebotomy: animated demonstration

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