Bilateral congenital ossicular chain disruption mimicking otosclerosis.

A rare case of bilateral congenital ossicular chain disruption whose history and findings mimicked those of otosclerosis is reported. A 54-year-old male consulted us for slowly progressing hearing loss. Audiogram showed bilateral intermediate mixed hearing loss. The stapedial reflex was negative and the tympanogram was normal A-type. Based on the diagnosis of otosclerosis, stapes surgery was planned for the left side. Surgical findings revealed normal mobility of the stapes and a small disruption at the incudostapedial joint with connection of intact mucosa. The disruption was repaired with auto-bone columella. The patient's hearing improved after surgery. The surgery for the other side was performed successively, and similar ossicular disruption was observed. The mechanisms of findings that misled the preoperative diagnosis are discussed.