Congenital cholesteatoma. Preservation of cochlear function after extensive labyrinthine destruction

A patient with a large congenital cholesteatoma of the left temporal bone is presented. The case is unique in that, although the cholestetoma invaded all three semicircular as well as the basal coil of the cochlea, the patient retained normal hearing. She had an almost complete left-sided facial paralysis, yet she retained sensori-neural hearing postoperatively, in spite of removal of the superior part of the labyrinth (semicircular canals and utricle). The possible mechanisms behind such an unusual event are discussed together with the possible function of the utriculo-endolymphatic valve.