Mondini dysplasia; a clinical and pathological study.

Mondini dysplasia is characterized by bony and membranous anomalies of the inner ear exhibiting a wide range of morphological and functional abnormality. Typically the cochlea is flat, the cochlear duct is short, the auditory and vestibular sense organs and nerves are immature, the vestibule is large, the semicircular canals are wide, small or missing and the endolymphatic sac is bulbous. Incomplete expressions of the disorder may occur with little or no loss of auditory or vestibular dysfunction, while severe forms show no hearing or vestibular response. The disorder may occur in association with anomalies in other organs, such as in Klippel-Feil syndrome. Pendred's syndrome, trisomy syndrome, and DiGeorge's syndrome, or it may occur in isolation. It may occur in one or both ears and is readily diagnosed by polytomographic radiologic studies. In some cases the footplate of the stapes is partly or totally replaced by a thin membrane which may rupture and lead to spontaneous CSF otorrhea and meningitis. The quality of auditory and vestibular function will determine the method of surgical closure. Usually ears developing such fistulae have no auditory function and the leaks are permanently stopped by simply introducing an autogenous soft tissue graft through the oval window into the vestibule.