[Effect of steroid hormone on experimental viral labyrinthitis in guinea pigs]

Clinical and experimental reports confirm that steroid treatment enhances viral pathogenicity in acute infections in vivo. Despite this, steroids are commonly used for the treatment of sudden deafness even though viral infection is thought to be one of the etiological factors involved in the disease. In order to investigate the effect of steroid hormones on viral labyrinthitis, hydrocortisone was administered intramuscularly to 45 guinea pigs before or after Sendai virus (HVJ) was inoculated into their cochleas. Tissue samples were later examined electron-microscopically. Virus-induced cytopathic lesions in the stria vascularis and Reissner's membrane in the steroid-treated animals were more severe than those observed in the control group. Furthermore, steroid treatment allowed virus infection to spread to the organ of Corti, interdental cells and spiral prominence epithelium, and caused degeneration of the tectorial membrane in the infected animals. Pathological findings demonstrated in this study such as degeneration of the organ of Corti, vacuolation and atrophy of the stria vascularis and detachment and degeneration of the tectorial membrane were similar to those demonstrated in studies of pathological changes caused by virus infection in human temporal bones. These results strongly suggest restraint in using steroid treatment in the early stages of sudden deafness, especially when a viral etiology is suspected.