OJAI, CA—Headache specialists may play an important role in diagnosing giant-cell arteritis, a vasculitis of large and medium vessels, because new headache is the initial symptom in about a third of cases, according to a lecture provided at the Ninth Annual Headache Cooperative of the Pacific Winter Conference. Early treatment with corticosteroids can help prevent permanent visual loss in this disorder. “If you strongly suspect the diagnosis, start prednisone and then proceed, in terms of trying to confirm the diagnosis,” said Jerry W. Swanson, MD, Professor of Neurology at the Mayo Clinic College of Medicine in Rochester, Minnesota. “If there have been any ischemic complications, which most commonly would affect the eye, therapy should be started immediately.”
Jerry W. Swanson, MD
Diagnosing giant-cell arteritis without sufficient evidence, however, can subject patients to the risks of long-term steroid use unnecessarily, he noted.
A Feared Complication
In the United States, an estimated 1% of women and 0.5% of men develop giant-cell arteritis. Prevalence is estimated to be one in 500 individuals over age 50, and peak incidence is in the 70s. “You virtually never see this before the age of 50,” said Dr. Swanson. The disorder has a genetic component and is most common in individuals of Scandinavian descent.
Research indicates that giant-cell arteritis “is an immunologic, not an infectious, problem,” said Dr. Swanson. The pathophysiology of the disease appears to involve dendritic cells in the vessel wall, which initiate a cascade of events that involves two major immune-response networks and leads to lumen-obstructive intimal hyperplasia and remodeling of the arterial wall.
Permanent visual loss is the most frequent and feared complication. It occurs in about 20% of patients. Transient monocular, and rarely binocular, vision loss can be an early manifestation of the disorder. This transient visual loss may soon be followed by permanent visual loss. The usual mechanism of visual loss is anterior ischemic optic neuropathy.
Headache Features Have Limited Use
The diagnosis of giant-cell arteritis should be considered in a patient age 50 or older with new headaches, abrupt onset of visual disturbances, symptoms of polymyalgia rheumatica, or jaw claudication. Systemic symptoms such as low-grade fever and anemia may arise, as well as high erythrocyte sedimentation rate or high serum C-reactive protein.
Headache is the most common symptom, occurring in almost three-quarters of patients. The headaches typically are acute or subacute and are associated with scalp tenderness near the temporal or occipital arteries. The headache features otherwise are not particularly helpful. “The headaches have been described as persistent or remittent, and they can resemble primary headache disorders just as cardiac cephalalgia can,” said Dr. Swanson. Features similar to migraine, cluster headache, or idiopathic stabbing headache have been described.
Jaw claudication is highly specific for giant-cell arteritis. Persistent dry cough and manifestations such as sore throat, tongue pain, trismus, and choking also have been described. Audiovestibular manifestations are fairly common, and polymyalgia rheumatica is present in 40% to 50% of patients with giant-cell arteritis.
Ophthalmologic exam can be normal, although some patients have cotton wool spots in the retina, suggesting retinal ischemia. Physicians should carefully examine the superficial temporal arteries for tenderness, absent pulsations, or marked prominence of the arteries.
Screening Test of Choice
Elevated erythrocyte sedimentation rate is one of the major hallmarks of giant-cell arteritis and “the screening test of choice,” said Dr. Swanson. In a series of more than 940 biopsy-proven cases, only 4% of patients had a normal sedimentation rate. “If the [sedimentation] rate is normal, still consider the diagnosis if clinical features are present, but it’s much less likely,” he said.
Although imperfect, temporal artery biopsy is the gold standard for diagnosing giant-cell arteritis. “Unfortunately, attempts to develop an algorithm that would say, ‘If they have a certain score, for instance, then do a biopsy or not,’ have failed,” he said. “You have to take the entire picture and then develop some sort of index of suspicion.”
Of all patients suspected of giant-cell arteritis, about a third of biopsies are positive. Positive yield increases if biopsies are 2 cm or longer. There is no clear consensus on whether to biopsy the temporal artery on one or both sides. At the Mayo Clinic, surgical pathologists often biopsy the side that is more symptomatic. Surgeons have the patient remain and may biopsy the other side if the first biopsy is negative and there is a high index of suspicion. “I realize that may not be possible at most institutions, but it seems to be a prudent approach,” Dr. Swanson said.