Giant Cell Arteritis - Temporal Arteritis

Indications for Testing

Patient >50 years with visual changes or new onset headache

Criterial for Diagnosis

American College of Rheumatology (1990); 3 of 5 required
- Age >50 years
- New localized headache
- Temporal artery tenderness or decreased pulsation
- ESR >50 mm/hr
- Abnormal arterial artery biopsy

Laboratory Testing

CBC – may have platelet count >375,000 (L.R. 6.0); normochromic normocytic anemia
ESR/ CRP – elevated; if both are elevated, increases sensitivity of diagnosis to 99%
- ESR usually exceeds 50 mm/hr and may exceed 100 mm/h (L.R. 2.5)
ANCA – 75% have pANCA with MPO+ (rarely PR3 is positive)

Histology

Temporal artery biopsy – medium and large vessel vasculitis with giant cell infiltration
- May have skip lesions; therefore, 2 cm long biopsy is recommended
Biopsy should be performed before day 4 of steroid therapy
If initial biopsy is negative, perform biopsy on other side

Imaging Studies

Duplex ultrasonography – halo sign is often present
- Sensitivity <70%
- Defined as hypoechoic region around the lumen of the artery

Differential Diagnosis

Infectious
- Viral infections
- Endocarditis
- Hepatitis A, B, C
- HIV
Malignancy
Multiple myeloma
Connective tissue
- Systemic lupus erythematosus
- Rheumatoid arthritis
- Polymyositis
Fibromyalgia
Myalgias from statin therapy
Osteoarthritis
Other vasculitis

Giant cell arteritis (GA), also known as temporal arteritis, is a systemic vasculitis that can produce permanent blindness if not treated in a timely manner.

Epidemiology

Incidence – 18-22/1 million in the U.S.; most common primary vasculitis in older patients
Age – almost exclusively >50 years; peak age 70-80 years
Sex – F>M; 2-6:1
Ethnicity – more common in Caucasians than African Americans; rare in Hispanic population

Pathophysiology

Medium and large vessel vasculitis – tends to affect aorta and extracranial branches of the carotid artery
Causes ischemic disease (most common in the optic nerve) – can lead to vision loss, caused primarily by occlusive vasculopathy
Granulomas form in arterial media
Often associated with polymyalgia rheumatica

Clinical Presentation

Constitutional – fever, fatigue, malaise, weight loss
Otorhinologic – jaw claudication (L.R. 4.0)
Ophthalmologic – transient visual changes, diplopia (L.R. 3.4), visual field cuts, permanent vision loss
Cardiovascular – arm claudication, thoracic artery aneurysm
Neurologic – headache, temporal artery pain (L.R. 2.0), mononeuropathy
Polymyalgia rheumatica symptoms occur in up to 50% of patients
- Manifests with severe stiffness and pain in shoulders, thighs and buttocks