Fluctuating hearing loss following immune reaction in the endolymphatic sac of guinea pigs.

This study has investigated immune injuries to the inner ear auditory system of guinea pigs. Following secondary antigen challenge to the endolymphatic sac, the mean hearing threshold significantly increased in the early phase from day 1 to day 3 and thereafter recovered. In the early phase, hearing threshold significantly increased simultaneously to the elevation of perilymph antibody levels. The size of hydrops was not the only factor that causes an increase in hearing loss as well as in AP/SP ratio. Scale-out hearing loss was seen in 2 animals with severe degeneration of the stria vascularis as well as the organ of Corti associated with the inflammatory cellular infiltration especially in the perilymphatic space, even in the absence of keyhole limpet hemocyanin antigen in the cochlea. On the other hand, control animals did not suffer hearing loss. These results suggest that an immune reaction in the endolymphatic sac is a possible pathogenic etiology of Ménière's disease or sudden deafness.