Reversible damage to the nerve fibres in the organ of Corti after surgical opening of the cochlea in the rat.

After minimal opening of the cochlear bony wall, the efferent and the outer spiral fibres showed no changes; inner radial fibres (afferents to inner hair cells) were highly sensitive to this mild trauma, appearing swollen and empty of cytoplasmic content. Available data suggest that this may be due to alterations in the cochlear micromechanical environment, related to the surgical manipulation. The swellings were reversible, although the normal structure had not completely recovered until one month after the manipulation.