Changes in cochlear microphonic response after Y-ray irradiation of the inner ear of the guinea-pig

The effects of ionizing irradiation on the cochlear microphonic response of guinea-pigs were studied. The cochlear microphonics (CM) of both ears were recorded in a total of 36 animals. Recording was carried out by the differential electrode technique on the basal turn of the cochlea. One week prior to recording, the left ear of each animal had been exposed to 35-70 Gy radiation in increments of 5 Gy. Doses of 40 Gy and above led to a reduction in CM response. After doses of 60 Gy or more, no CM response could be detected. Damage most probably occurred in the outer and inner hair cells.