Cogan's syndrome--clinical guidelines and novel therapeutic approaches

Abstract

Cogan's syndrome (CS) is a rare chronic inflammatory disorder, classically characterized by interstitial keratitis and sensorineural hearing loss. Recurrent episodes of inner ear disease might result in deafness. In some patients, it may also be accompanied by systemic vasculitis. Diagnosis of CS is often missed or delayed due to its rarity, the nonspecific clinical signs at onset, and the lack of a confirmatory diagnostic test. The mechanisms responsible for CS are unknown; however, in the last decade, the pathogenesis has been somewhat elucidated, suggesting that the disease is a result of inner ear autoimmunity. The autoimmune hypothesis postulates the triggering of the disease by a viral infection via a number of mechanisms, which are mainly as follows: antigenic mimicry, self-perpetuating inflammation by cytokine release, and unveiling hidden epitopes. Aside from its clinical resemblance to other autoimmune disorders, some autoantigen has apparently been identified, namely, CD148 and connexine 26. Treatment should begin as early as possible. While treatment is based primarily on glucocorticoids, there is no standard alternative for patients who respond poorly. Failure of conventional treatment could lead to profound sensorineural hearing loss. From the limited data we have, infliximab seems to be the most promising biological remedy, enabling steroid tapering and leading to improvement in auditory/ocular disease, with better results when administered in early stages. Proposed guidelines for the use of infliximab in CS are found in the last table of the review, in an attempt to define the proper timing for initiating infliximab treatment in order to avoid permanent disability.