A rare case of atypical Cogan's syndrome presenting as encephalitis.

Cogan's syndrome (CS) is a rare autoimmune vasculitis of unknown aetiology characterised by non-syphilitic interstitial keratitis, audiovestibular symptoms, sometimes systemic symptoms, and multi-organ involvement. Atypical CS has other ocular features, such as scleritis, episcelritis, retinitis, and optic neuritis. Diagnosis of CS is purely clinical without a confirmatory test. Hereby, we report a case of atypical CS presenting with features of encephalitis who was treated successfully with intravenous pulse methylprednisolone with cyclophosphamide. It is important to consider CS in the differential diagnosis of encephalitis with ocular and vestibular symptoms in young patients, as high morbidity and mortality rates are effectively lowered by early immunosuppressive treatment.