Cytomegalovirus labyrinthitis in an infant: morphological, virological, and immunofluorescent studies.

The inner ears obtained from an infant who died of severe congenital cytomegalovirus infection were examined using virological and morphological methods. The techniques of microdissection and surface preparations, immunofluorescent microscopy, and transmission and scanning electron microscopy were employed. Cytomegalovirus was isolated from the perilymph. Injury to the cochlea was minor and was confined to the first half of the basal turn. There were signs of a severe labyrinthitis of the vestibular endolymphatic system. Vestibular organs, especially the saccule and utricle, showed severe damage, with collapse of the saccular membranous wall. Inclusion-bearing cells containing cytomegalovirus antigen, as shown by immunofluorescent staining, and cytomegalovirus virions, as observed by electron microscopy, were found on the endolymphatic surface of the membranous walls, mainly in the saccule and utricle. In the utricle, the infected cells appeared to be concentrated in the regions where the so-called dark cells were located. These dark cells are similar to the proximal tubule cells in the kidney, another common target for cytomegalovirus infection.