[Immuno-injury to the inner ear auditory system following secondary endolymphatic sac immune response]

This study investigated immuno-injury to the inner ear auditory system following inner ear immune response in the guinea pig. The endolymphatic sac (ES) was directly challenged with keyhole limpet hemocyanin (KLH). Auditory brainstem response with click sound stimulation was assessed pre and post KLH challenge of the ES. In systematically presensitized animals, secondary KLH challenge to the ES produced significant elevation of the mean threshold level on day 3 and 17 as compared to that of pre challenge levels. However, no significant prolongation of the latency (N1-N3) was observed. On the other hand, neither phosphate buffered saline injection into the ES nor primary KLH challenges of the ES were capable of elevating the threshold level and changing the latency. These results indicate that elevation of threshold was apparently induced by a secondary immune response of the ES, not by nonspecific mechanical damage to the ES, the central auditory system or KLH toxicity to the inner ear, suggesting that local immune response of the ES is a possible pathogenesis of sensorineural hearing loss.