Morphological changes of stria vascularis in congenital hearing impairment due to membranous labyrinth underdevelopment.

Congenital malformations of the inner ear may involve either the bone and membranous labyrinth or the membranous labyrinth alone. The same labyrinth structures can be affected with an acquired disease, toxaemia or viral labyrinthitis, for instance, with the same or very similar histologic findings. So far, there have been no studies examining the possible morphological changes of stria vascularis in different diseases with sensorineural anomalies. We examined the temporal bones of 16 patients, from whom audiograms and history data on hearing impairments present at birth or later were obtained previously. When malformation of the membranous labyrinth was caused by a congenital anomaly, three groups of typical changes of stria vascularis were observed: i) pseudocystic formation which replaced the strial tissue, with dark-stained deposits: ii) accumulation of endothelial cells or irregularly shaped cells in the basal coil of the cochlea: and iii) atrophy of the stria vascularis tissue in all coils. These findings may prove important for accurate diagnostic procedures.