Temporal ArteritisDz

Synonyms: Giant cell arteritis (GCA), cranial arteritis.

ICD9 Code:   GCA 446.5
ICD10 Code:  GCA M31.6;  GCA with PMR M31.5

Definition: Temporal arteritis is a large vessel vasculitis preferentially affecting the superficial temporal artery and other branches of the external carotid artery system.

Etiology: The cause of temporal arteritis is unknown. There is an association with HLA-DR4 and particular HLA-DRB1 alleles. These alleles are similar to those associated with RA but involve polymorphisms in the second rather than the third hypervariable region. Research has focused on the unexplained increased prevalence in white people of northern European origin and possible seasonal variation, suggesting as-yet undetermined environmental agents as precipitating factors.

Pathology: Biopsy of an involved large vessel shows a mononuclear cell infiltrate with intimal hyperplasia and occasional giant cells focused along the internal elastic lamina. Disruption of the internal elastic lamina is characteristic. Vasculitis often occurs in a “skip” pattern, which underscores the need for a suitably large biopsy specimen (>3 cm in length) with careful cross-sectional and longitudinal histopathologic examination to minimize the number of false-negative results. The disease has a particular predilection for blood vessels that contain large quantities of elastic lamina. This may explain a low incidence of intracranial complications because arteries lose their internal elastic lamina after passing through the dura matter.

Demographics: The prevalence of temporal arteritis is highest in elderly Caucasians from northern Europe and in the north central United States. Temporal arteritis is very uncommon in nonwhites. Incidence increases with advancing age and varies from 15 to 94 cases per 100,000 in people older than age 50. Women are afflicted twice as commonly as men.

Cardinal Findings: Onset may be abrupt or insidiously develop over weeks to months. Characteristically, patients have profound constitutional symptoms with fever, weight loss, and occasional night sweats. Moderate to severe headache, particularly in the temporal or occipital area, is reported by >90% of patients. Scalp tenderness is common, particularly in the temporal area. Headache may sometimes be reproduced by pressure over an affected artery. Visual symptoms of diplopia, blurred vision, or amaurosis fugax may antedate development of sudden unilateral blindness. Many patients describe a fullness or pressure sensation behind their eyes. Unfortunately, visual loss may be the presenting ophthalmologic symptom in some cases. Overall, 20% to 40% of patients experience vision loss. The most common cause of visual loss is ischemic optic neuropathy. Jaw claudication with prolonged chewing results from vascular insufficiency to the muscles of mastication. Half of temporal arteritis cases are accompanied by polymyalgia rheumatic. Indeed, polymyalgia rheumatic and temporal arteritis may be varying manifestations of the same disorder, along a disease continuum. Seronegative synovitis may accompany temporal arteritis, with or without polymyalgia rheumatic. Tongue numbness or ulceration, cough, sore throat, dysphagia, hoarseness, and rare respiratory difficulties have all been described.

Uncommon Findings: Although the extracranial branches of the aorta supplying the eye and temporal area are preferentially affected, the aortic arch and subclavian vessels can be involved (10%) and lead to pulselessness, aortic dissection, or aortic valve insufficiency.

Complications: Neurologic complications appear uncommonly but may result from ischemia in the carotid or vertebral circulations. Transient ischemic attack or stroke has been reported in ~7% of cases. Peripheral neuropathies also have been reported.

Diagnostic Testing: Although biopsy-proven temporal arteritis with normal ESR is well documented, a markedly elevated ESR is seen in >95% of cases. CRP levels may be more sensitive to changes in disease activity and improvement with appropriate therapy. Anemia of chronic disease, decreased serum albumin, polyclonal gammopathy, and reactive thrombocytosis are also seen. Elevation in liver tests, particularly alkaline phosphatase, is common. Preliminary studies suggest a possible association of APL antibodies with temporal arteritis.

Biopsy/Imaging: A unilateral temporal artery biopsy is positive in ~80% of temporal arteritis cases, and the sensitivity for diagnosis increases to 90% with biopsy of both sides. Provided the disease remains active, the positive predictive value of the biopsy is only modestly influenced by previous short-term corticosteroid treatment. However, biopsy is best done as soon as possible when temporal arteritis is strongly suspected. If pulselessness, extremity claudication, angina, or symptoms of cerebrovascular ischemia are present, selective angiograms may be indicated.

Keys to Diagnosis: Look for markedly elevated ESR accompanied by headaches, significant constitutional symptoms, and polymyalgia rheumatica.

Diagnostic Criteria: The 1990 ACR classification criteria include (a) age at on-set >50 years; (b) new headache; (c) temporal artery tender to palpation, enlarged, or with decreased pulsation; (d) elevated erythrocyte sedimentation rate; and (e) abnormal temporal artery biopsy. The presence of any three carries a sensitivity of 93.5% and a specificity of 91.2%.

Differential Diagnosis: Other causes of headaches and visual disturbances include classic migraines and intracranial mass lesions. A markedly elevated ESR and fever may suggest occult malignancies (such as lymphoma, myeloma), chronic infections (including bacteria endocarditis), polymyalgia rheumatica or other inflammatory disorders (other vasculitides). Takayasu’s arteritis affects similarly sized vessels such as the subclavian arteries; however, it develops almost exclusively in young women.

Therapy: Because of the risk of visual loss, high-dose corticosteroid (prednisone 60 mg/day) should be initiated immediately if clinical suspicion is high. With appropriate treatment, the chance of subsequent blindness is <20%. Once the symptoms and signs have stabilized (usually within 1 month) and levels of acute-phase reactants have declined, the prednisone dose is tapered rapidly at first (5–10 mg every 2–4 weeks) and subsequently more slowly (1 mg every 1–2 weeks when <10 mg/day). When weaning from corticosteroids, the patient’s symptoms and ESR should be monitored closely. Limited data support the use of steroid-sparing agents, including weekly MTX or TNF inhibitors. NSAIDs may be added when the prednisone dose is <10 mg, particularly for symptoms of polymyalgia rheumatica. Angioplasty or vascular bypass may be required if large vessel involvement is producing claudication or other potentially treatable complications.

Prognosis: Although most patients successfully taper and discontinue corticosteroids within 2 years of disease onset, the relapse rate in the first year exceeds 60%. As a result, the mean requirement for corticosteroids exceeds 5 years. Consequently, the most devastating long-term complications from temporal arteritis commonly stem from corticosteroid-associated complications, particularly bone loss. As many as 60% of patients with temporal arteritis develop steroid toxicities, and steroid-associated fatalities may be as high as 21%.

BIBLIOGRAPHY

Hunder GH, Bloch DA, Michel BA, et al. The American College of Rheumatology 1990 criteria for the classification of giant cell arteritis. Arthritis Rheum 1990;33:1122–1128. PMID:2202311

Huston KA, Hunder GH, Lie JT, et al. Temporal arteritis, a 25-year epidemiologic, clinical, and pathologic study. Ann Intern Med 1978;88:162–167.PMID:626444

Salvarani C, Cantini F, Boiardi L, et al. Polymyalgia rheumatica and giant-cell arteritis. N Engl J Med 2002;347:261–271.PMID:12140303