Cogan's syndrome: Clinical significance of antibodies against the inner ear and cornea

The aim of this study was to evaluate the pathological significance of anti bodies against cornea and inner ear tissue in the development of audiovesti bular and ocular symptoms in patients with Cogan's syndrome (CS). We analys ed the serum of 5 CS patients for binding of IgM and Ige to fresh cryosecti ons of rat labyrinth (semicircular canals, ampulla, utricle, saccule) and c ornea by indirect immunofluorescence (IF). The predominant pattern of anti- corneal IgM was staining of the superficial cell layer of the non-keratiniz ing squamous epithelium. IgM against cornen was found in 3 patients, all of whom had bilateral inflammatory eye signs at the start of the disease. How ever, IgM was also detected in the chronic stage of the disease when no cli nical signs of eye involvement were apparent. The study includes the first follow-up examination of anti-corneal IgM and IgG antibodies during a compl ete episode of active CS. During the first episode of CS in 1 patient, anti -corneal IgM became detectable 1 week after the onset of interstitial kerat itis and 3 weeks after the onset of audiovestibular symptoms. It increased over several weeks and then fell to very low levels. However, at no time wa s anti-corneal IgG found. In the course of follow-up examinations. the seru m of 4 patients intermittently contained;lined low titre IgG antibodies aga inst inner ear labyrinthine tissue, but without any clear correlation with the active stages of CS. In addition, high-resolution MRI (HR-MRI) of the i nner ear was performed in the acute and chronic stages of CS to evaluate th e activity of CS. In the acute stage, HR-MRI revealed abnormal MRI signals in the vestibule, semicircular canals, vestibular nerve. or cochlea. In the chronic stage, patients showed narrowing or occlusion of semicircular cana ls and the cochlea on the 3D-CISS images, bur no high signal lesions (T1) a nd no enhancement. Antibodies against cornea or labyrinthine tissue were no t consistently detected in CS and the el of organ-specific antibodies did n ot correlate with the activity of the disease.