Giant cell arteritis (also called temporal arteritis) is an inflammation of medium – and large-sized arteries. The disorder most frequently involves one or more branches of the carotid artery, particularly the temporal artery. The disorder is a systemic disease which can involve arteries in multiple locations.
Incidence And Prevalence
Giant cell arteritis has a high incidence in Scandanavia and in regions of the United States with large Scandanavian populations, compared to a lower incidence in southern Europe. The annual incidence rates in individuals 50 years of age and older range from 0.49 to 23.3 per 100,000 population. It occurs almost exclusively in individuals older than 55 years; however, well-documented cases have occurred in patients 40 years old or younger. It is more common in women than in men and is rare in blacks. Familial aggregation has been reported, as has an association with HLA-DR4. In addition, genetic linkage studies have demonstrated an association of giant cell arteritis with alleles at the HLA-DRB1 locus, particularly HLA-DRB1*04 variants. The disease is closely associated with polymyalgia rheumatica, which is more common than giant cell arteritis. In Olmsted County, Minnesota, the annual incidence of polymyalgia rheumatica in individuals 50 years of age and older is 52.5 per 100,000 population.
Pathophysiology And Pathogenesis
Although the temporal artery is most frequently involved in this disease, patients often have a systemic vasculitis of multiple medium- and large-sized arteries, which may go undetected. Histopathologically, the disease is a panarteritis with inflammatory mononuclear cell infiltrates within the vessel wall with frequent giant cell formation. There is proliferation of the intima and fragmentation of the internal elastic lamina. Pathophysiologic findings in organs result from the ischemia related to the involved vessels. Distinct cytokine patterns as well as T lymphocytes expressing specific antigen receptors have been described suggesting the involvement of immunopathogenic mechanisms in giant cell arteritis. IL-6 and IL-1-beta expression has been detected in a majority of circulating monocytes of patients with giant cell arteritis and polymyalgia rheumatica. T cells recruited to vasculitic lesions in patients with giant cell arteritis produce predominantly IL-2 and IFN-gamma, and the latter has been suggested to be involved in the progression to overt arteritis. Sequence analysis of the T cell receptor of tissue-infiltrating T cells in lesions of giant cell arteritis indicates restricted clonal expansion, suggesting that an antigen residing in the arterial wall is recognized by a small fraction of T cells. Online Canadian Pharmacy
Clinical And Laboratory Manifestations
The disease is characterized clinically by the classic complex of fever, anemia, high ESR, and headaches in an elderly patient. Other manifestations include malaise, fatigue, anorexia, weight loss, sweats, and arthralgias. The polymyalgia rheumatica syndrome is characterized by stiffness, aching, and pain in the muscles of the neck, shoulders, lower back, hips, and thighs.
In patients with involvement of the temporal artery, headache is the predominant symptom and may be associated with a tender, thickened, or nodular artery, which may pulsate early in the disease but become occluded later. Scalp pain and claudication of the jaw and tongue may occur. A well-recognized and dreaded complication of giant cell arteritis, particularly in untreated patients, is ocular involvement due primarily to ischemic optic neuritis, which may lead to serious visual symptoms, even sudden blindness in some patients. However, most patients have complaints relating to the head or eyes for months before objective eye involvement. Attention to such symptoms with institution of appropriate therapy (see below) will usually avoid this complication. Claudication of the extremities, strokes, myocardial infarctions, aortic aneurysms and dissections, and infarctions of visceral organs have been reported. Visit Canadian Pharmacy Blog
Characteristic laboratory findings in addition to the elevated ESR include a normochromic or slightly hypochromic anemia. Liver function abnormalities are common, particularly increased alkaline phosphatase levels. Increased levels of IgG and complement have been reported. Levels of enzymes indicative of muscle damage such as serum creatine kinase are not elevated. Buy Generic Cialis
The diagnosis of giant cell arteritis can be made clinically by the demonstration of the classic picture of fever, anemia, and high ESR with or without symptoms of polymyalgia rheumatica in an elderly patient. The diagnosis is confirmed by biopsy of the temporal artery. Since involvement of the vessel may be segmental, the diagnosis may be missed on routine biopsy; serial sectioning of biopsy specimens is recommended. When the temporal arteries appear clinically normal, but giant cell arteritis is strongly suspected, a biopsy segment of a few centimeters may be required to establish the diagnosis. A temporal artery biopsy should be obtained as quickly as possible in the setting of ocular signs and symptoms, and under these circumstances therapy should not be delayed pending a biopsy. In this regard, it has been reported that temporal artery biopsies may show vasculitis even after more than 14 days of glucocorticoid therapy. A dramatic clinical response to a trial of glucocorticoid therapy can confirm the diagnosis.
Giant cell arteritis and its associated symptoms are exquisitely sensitive to glucocorticoid therapy. Treatment should begin with prednisone, 40 to 60 mg per day for 1 month, followed by a gradual tapering to a maintenance dose of 7.5 to 10 mg per day. In order to lessen side effects in elderly individuals, conversion to alternate-day therapy may be attempted, but only after the disease has been put into remission with daily therapy. When ocular signs and symptoms occur, it is important that therapy be initiated or adjusted to control them. Because of the possibility of relapse, therapy should be continued for at least 1 to 2 years. The ESR can serve as a useful indicator of inflammatory disease activity in monitoring and tapering therapy and can be used to judge the pace of the tapering schedule. However, minor increases in the ESR can occur as glucocorticoids are being tapered and do not necessarily reflect an exacerbation of arteritis, particularly if the patient remains symptom free. Under these circumstances, the tapering should continue with caution. The prognosis is generally good, and most patients achieve complete remission that is often maintained after withdrawal of therapy.