Morphological changes to the cochlea in an animal model of profound deafness.

We have used systemic application of the ototoxic drug amikacin, to induce total cochlear haircell loss in the chinchilla, in order to create an animal model of profound deafness. We have produced models of both neonatal deafness (by treatment of new-born pups), as well as of acquired total hearing loss (by treatment of mature animals). We present a description of our techniques for producing cochlear lesions and for evoked potential monitoring of the resulting threshold elevations. We also give a qualitative description of cochlear haircell damage as viewed by scanning electron microscopy, and a quantitative assessment of the spiral ganglion cell survival after total haircell loss.