Effects of Repeated Changes in Atmospheric Pressure on Inner Ear of Guinea Pigs

Abstract

To investigate the inner ear disorders caused by repeated changes in atmospheric pressure, 48 guinea pigs were exposed to compression and decompression between 1 absolute pressure (ATA) and 2 ATA in a pressure chamber once each week for 16 weeks. During the changes in atmospheric pressure, 8 animals developed spontaneous nystagmus, most of them during the early phase of repeated pressure loadings. In the animals with spontaneous nystagmus, the most marked morphological change was damage to the organ of Corti. There was little damage to the vestibule. Spontaneous nystagmus did not occur during the later phase of loadings, perhaps because the pressure change may not have been transmitted to the endolymph due to the degeneration of the organ of Corti. Except for the cases of acute barotrauma, repeated pressure loadings of the inner ear did not cause significant morphological impairment, but the auditory function of such animals was disturbed as compared to that of controls. Thus it is indicated that chronic barotrauma to the inner ear may result from repeated pressure loadings.