Presbycusis, presbystasis and presbyosmia as consequences of the analogous biological process.

Abstract

We found in the basal coil of the spiral tractus and in the depth of the internal auditory meatus a reduction in the number of the openings through which the nerve fibres of the acoustic nerve pass. This reduction was due to the apposition of bony substance. On the sections through the acoustic nerve of the same subject, the number of fibres was also reduced in the corresponding area. Analogous changes were found in the region of vestibular areas and also in the posterior part of the cribriform plate of the ethmoidal bone. These three places are similar in shape, i.e. consisting of a system of small openings through which pass the nerve fibres. In all these three places the apposition of bony substances increases with age and in all these three organs the function diminishes with age. We believe, therefore, that apposition of bone causes compression and degeneration of nerve fibres and hence the senile changes in hearing, vestibular function, and smell.