Pathophysiological changes of the cochlea during ageing--a review.

Research of the pathophysiology of the age-related human presbycusis was largely initiated by those investigations in which the cochlea's damages were experimentally induced by various acoustic exposures. It became apparent that the outer hair cells are more vulnerable to different noise influences than the inner hair cells. On the other hand, the role of the altered ultrastructural elements of various types, cannot be ruled out. The evolving of the age-related presbycusis was to a great extent established using large-scale model experiments, including mainly rodents. It seems that the age-bound presbycusis (cf. intrinsic degeneration of the cochlea) begins at the apical regions which will be later more worsening by various extrinsic traumas. It is suggested that the damages gradually taking part in the inner ear structures are bound to the age-dependent processes in which the ever-increasing formation of cross-linkages plays an important role as ageing progresses.