Increased serum alkaline phosphatase, glutamicÐ oxaloacetic transaminase, glutamyl transferase may also be found in GCA [390, 407], as well as prolonged prothrombin time and decreased peripheral blood CD8+ (suppressor/cytotoxic) lymphocytes [408]. Increased levels of IgG, complement, and enzymes indicative of muscle damage (serum creatine kinase) have been reported.

should be done within 1 week of initiation of steroid therapy because the rate of positive biopsy falls from 82% in patients who had received no steroid to 60% in patients who had received up to 1 week of steroid therapy [411]. The false-nega- tive rate has been reported as 5 [412] and 9% [413]; these data may be explained, at least in part, by the inclination of some clinicians to biopsy with minimal evidence of the disease.

6.1.12.5 Diagnosis

The diagnosis of GCA should be considered in any patient over the age of 60 years who has a new onset of headache, transient or irreversible visual loss, PMR, unexplained prolonged fever or anemia, and elevated ESR. Temporal artery biopsy, or less commonly facial or occipital artery biopsy, is necessary to conÞrm the diagnosis [409]. Because the arterial involvement may be focal, a symptomatic or clinically suspicious arterial segment several centimeters long (1Ð5 cm) should be biopsed and carefully sectioned serially for histopathological examination at several points along its length. The pathological diagnosis is based on the presence of nongranulomatous inßammation with mononuclear cells or granulomatous inßammation with epithelioid cells with or without LanghansÕ (foreign body type) multinucleated giant cells in the arterial wall. Although characteristic of GCA, giant cells need not be present to make the diagnosis pathologically. Because skip areas have been described along the length of affected arteries [410], patients with GCA and elevated sedimentation rates may have a negative temporal artery biopsy. However, a patient with clinical features suggestive of GCA and an elevated sedimentation rate should have a temporal artery biopsy. The opposite temporal artery may be biopsed if the Þrst biopsy is negative and clinical suspicion of the diagnosis is high. Ultrasonography of the temporal artery has been reported to be helpful in diagnosis.

High-dose oral steroid therapy should be started immediately in a patient with ocular or systemic symptomatology suggestive of GCA and an elevated sedimentation rate, even before performing the biopsy. However, the biopsy

6.1.13 Cogan’s Syndrome

CoganÕs syndrome is a systemic disease of unknown etiology that is typically manifested as nonsyphilitic interstitial keratitis associated with vertigo, tinnitus, and profound deafness. Young adults are most likely to be affected. Atypical forms with ocular manifestations other than keratitis may occur. It is probable that most cases of this syndrome are caused by a small-sized vessel vasculitis of the inner ear and eye.

6.1.13.1 Clinical Manifestations

There are typical and atypical forms of CoganÕs syndrome. The typical form, as it was Þrst described by Cogan in 1945 [414], is characterized by an abrupt onset of pain and redness in the eyes, reduced vision, vertigo, nausea, vomiting, noises in the ears, and progressive hearing loss [414, 415]. The ocular signs consist of patchy midstromal corneal inÞltrates that tend to ßuctuate in intensity and distribution, are usually located in the periphery, and are associated with deep corneal vascularization in the later stages of the disease [414]. As the inßammation subsides, deep stromal inÞltrates remain; they are interrupted by clear intervals around the now empty old vessels. It has been suggested that nummular anterior stromal keratitis may be an early manifestation of interstitial keratitis; progression to interstitial keratitis may be halted by suppression of nummular anterior stromal keratitis with topical steroid treatment [416]. Either the ocular or the vestibuloauditory symptoms may be affected Þrst, but the time between both types of manifestations never exceeds a few months [417]. A small population of patients (10%) develops a systemic