[A case of atypical Cogan's syndrome with a steroid-responsive headache and multiple cranial neuropathy as the initial symptoms].

Cogan's syndrome (CS) is an autoimmune disorder characterized by non-syphilitic interstitial keratitis and progressive audiovestibular impairment. Haynes et al. modified diagnostic criteria for patients with other ocular or vestibular symptoms and suggested this to be atypical CS. We report the case of a 71-year-old man with atypical CS. He was referred to our hospital with a headache, bilateral facial nerve palsy, left episcleritis and bilateral sensorineural hearing loss. Serological test results for syphilis and antineutrophil cytoplasmic autoantibodies were negative. Cerebral MRI revealed sinusitis and pituitary swelling. Contrast-enhanced computed tomography (CT) of the aorta demonstrated thickening of the wall and stenosis of the aorta with pathological uptake on fluorodeoxyglucose positron emission tomography. Biopsy of the sinus mucosa exhibited angiitis of the arterioles, capillaries, and venules. Atypical CS was diagnosed on the basis of episcleritis, progressive sensorineural hearing loss and exclusion of other inflammatory diseases. Intravenous injection of 500mg/day methylprednisolone for 3 days was effective for alleviating the patient's symptoms, except for hearing loss, but the disease recurred during the tapering of prednisolone (PSL). Combined therapy with PSL (10 mg/day) and methotrexate (6 mg/week) helped achieve remission of the disease. CS is causative of cranial polyneuropathy, but diagnosis of the former is not always straightforward as in the cases of cranial polyneuropathy. It has been considered that CS is a subtype of polyarteritis nodosa (PN); however, the clinical signs and size of the affected vessels in the present patient are different from those in PN. It is postulated that CS is a vasculitic syndrome that should be distinguishable from PN.