The Effects of Combined Gentamicin and White Noise on the Spiral Organ of Young Guinea Pigs. A Structural Study

The present work describes the effects on the spiral organ of very young guinea pigs, of continuous white noise (76 dB SPL, 7 days) combined with gentamicin, using surface preparations and both transmission and scanning electron microscopy to analyse structural changes. Gentamicin only, at 80 mg/kg/day for 5 days did not cause any perceptible loss of hair cells, and only minimal structural changes. When combined with 7 days of white noise, there was a widespread effect on outer hair cells throughout the cochlea, some changes being similar to those induced by sound alone, others being seen only in the combined experiments. Outer hair cell losses with sound and gentamicin treatment were highly variable, but in addition to apical damage, also seen in sound-treated animals, a more basal area of cell loss appeared in the spiral organ.