Development of morphological and physiological changes in the cochlea induced by cytomegalovirus

The effect of viral infection in the cochlea was investigated by inoculation of live cytomegalovirus or inactivated virus. Auditory thresholds were measured on the day of inoculation and on the terminal day. Two to 8 days following inoculation, the animals were killed and the cochleas were evaluated histologically. The compound nerve potential showed an increase in threshold prior to the cochlear microphonic, indicating the nerve was affected prior to the outer hair cells. All experimental cochleas contained inflammatory and cytomegalic inclusion cells and showed degenerative changes. The number of infected cells was small relative to the histopathology. Control cochleas had normal structure and function. The degeneration, therefore, might be mediated by inflammation as well as by the cytopathic effect of the virus. Viral infections, therefore, might be better managed with anti-inflammatory therapy in addition to antiviral agents.