Evidence for hair cell degeneration as the primary lesion in hearing loss of the elderly.

All patients in a geriatric unit showed a hearing loss with a mean value of approximately 60 dB HL. Auditory brain stem evoked responses had normal amplitudes but, in most cases, waves I and II were absent. Extratympanic electrocochleograms produced well-marked action potentials with evidence of a type of recruitment. These results suggest a primary disturbance of cochlear function peripheral to the cochlear nerve. Examination of stained surface preparations of the organ of Corti showed complete atrophy of all hair cells at the end of the basal coil and severe outer hair cell loss in all three coils. This was accompanied by a severe alteration - giant stereociliary degeneration - in some surviving cells in all cases, but no other consistent alterations in the cochlea. These findings point towards degenerative change in the hair cells as the basis for hearing loss in the elderly.