Ultra-Structural Changes in Vestibular Sensory End Organs After Viomycin Sulfate Intoxication

Abstract

Vestibular end organ pathology was studied electron microscopically in the squirrel monkey and cat, after systemic and local administration of viomycin sulfate. The ampullar crista was more vulnerable than the utricular macula in both species when viomycin sulfate was injected systemically. On the other hand, less differences in pathology were noticed when the drug was used topically. Vacuolization, vesicle formation, degenerated mitochondria, nuclear chromatin aggregation, etc. were more commonly observed in Type I hair cells which were consistently more damaged than Type II hair cells. The free cellular surface was usually not involved after systemic injection. The nerve chalice was swollen and the cytoplasmic contents were decreased. This indicates that primary involvement of this area after viomycin sulfate injection also occurs, as irregular cytoplasmic boundary was found where the hair cells were least involved. This investigation was supported in part by the National Institutes of Health Grants 5-K03-NB38619, NB 07237, the Deafness Research Foundation, and the McFadden Charitable Trust Fund.