Auditory and cytocochlear correlates of inner ear disorders.

Pure-tone threshold audiograms showing sensorineural hearing loss, when plotted on a data-based anatomic frequency scale, show a close spatial correlation with their respective cytocochleograms. Whereas most of the cochleae show pathology of several different cell types, a sufficient number show losses that involve predominantly a single cell type, which permits the following deductions: (1) focal lesions of the organ of Corti are strongly tonotopic and are responsible for those instances of abrupt pure-tone threshold losses; (2) lesions of the stria vascularis show no tonotopic organization but lead to flat pure-tone threshold losses; and (3) the principal effect of neuronal losses is a diminished capability for word recognition. There is an indeterminate group where no pathologic correlate can be identified by light microscopy.