Giant cell arteritis is considered a rheumatologic emergency, but it is not always recognized as such before permanent damage occurs.
Dr. Stephen A. Paget
Primarily a disease of the elderly, giant cell arteritis (GCA) is a systemic vasculitis predominantly characterized by inflammation of the large- and medium-size vessels in the scalp and head, especially the arteries over the temples. Although genetic, infectious, and autoimmune factors have been implicated in the pathogenesis of the disease, its cause is still unknown. If not diagnosed and treated early, however, the self-limiting condition can lead to irreversible vision loss resulting from necrosis of the posterior ciliary branch of the ophthalmic artery.
Unfortunately, diagnostic delays are common, because many cases begin insidiously with multiple, subtle symptoms that are not unusual in elderly patients, including headache, jaw pain, scalp pain, visual loss, fevers, chills, and weight loss, according to Dr. Stephen A. Paget, program director of the Cornell Arthritis and Multipurpose Arthritis and Musculoskeletal Diseases Center (MAMDC) at the Hospital for Special Surgery in New York.
The key to early recognition of GCA lies in the treating clinician’s awareness of the characteristic ophthalmic and systemic signs and symptoms and their inclusion of the condition in the differential diagnosis when an elderly patient presents with multiple nonspecific complaints, said Dr. Paget. Because of the diversity of symptoms, however, “GCA patients may go to multiple physicians – including but not limited to internists, ophthalmologists, neurologists, otorhinolaryngologists, dentists, and rheumatologists – before a diagnosis is made,” he said, noting that the diagnosis is often missed.
In this month’s column, Dr. Paget discusses some of the important diagnostic and treatment considerations in the management of GCA.
Question: How common is GCA, and what are the telltale signs and symptoms?
Dr. Paget: GCA frequently occurs in concert with polymyalgia rheumatica (PMR). Half of patients with GCA also have the proximal, symmetrical achiness, stiffness, and soreness of PMR, and 5%-10% of those with pure PMR develop temporal arteritis within a year after the onset of the first disease. In the United States, the average annual incidence of PMR is 52.5 per 100,000 patients aged 50 years and older, and the prevalence is about 0.5%-0.7%. The incidence and prevalence of GCA are about one-third that of PMR.
These disorders occur primarily in patients over age 50 years, with risk increasing with age. GCA and PMR affect more women than men. Prominent presenting signs and symptoms of GCA include soreness, severe and persistent headache, jaw pain with eating, tongue pain, sudden visual loss, flashing lights, coming and going visual loss, fever, fatigue, and weight loss.
Question: What triggers the immune system to attack the temporal arteries in CGA?
Dr. Paget: As with other autoimmune diseases, the exact cause remains unknown. We suspect there may be an inciting antigen in the blood vessel elastica that acts as a cofactor along with an infection to trigger the illness in a genetically predisposed person.
Question: What are the diagnostic criteria for GCA?
Dr. Paget: The American College of Rheumatology 1990 criteria for the diagnosis of GCA require the presence of three of the following: age 50 years or older; new onset of localized headache; temporal artery tenderness on palpation or decreased pulsation; erythrocyte sedimentation rate of 50 mm/hr or higher; and/or abnormal temporal artery biopsy.
Question: Much has been reported recently about the use of various imaging modalities in the diagnosis of GCA, particularly the possibility that an ultrasound-detected bilateral halo sign indicating temporal artery edema may be sensitive and specific enough to prompt treatment without a temporal artery biopsy (BMC Musculoskelet. Disord. 2010;11:44). What is the role of imaging in GCA?
Dr. Paget: The temporal artery biopsy is still the gold standard for diagnosing GCA, but PET scanning and ultrasound can be helpful in supporting a clinical diagnosis before biopsy results return and in those GCA patients in whom the biopsy is negative.
Question: What is the current treatment standard for GCA? Is there a role for DMARDs?
Dr. Paget: Prednisone continues to be a superb drug for GCA and should be started once the clinical diagnosis is made, even before the biopsy results return. In fact, the characteristic dramatic improvement within 1-3 days of initiating steroid therapy helps confirm the diagnosis. The main concern with prednisone is the side effects, particularly in light of the many comorbidities of the elderly patients who get the disease. Methotrexate and azathioprine can be used for steroid sparing, but they should not be used for treatment initially. Studies of anti–tumor necrosis factor (anti-TNF) agents haven’t been successful. Finding a disease-modifying medication that works as well as steroids is a major research goal.