Analyzing The Age Related Changes In The Human Cochlear Nerve: A Qualitative Microscopic Study

ABSTRACT

Background: Cochlear nerve serves as one of the nodal point for enabling the passage of sound in both directions.The knowledge of age related morphological changes in human cochlear nerve is important to understand itsrole in the manifestation of sensori-neural presbycusis.Materials and Methods: The study was conducted in 21 human cochlear nerve samples, collected in 3 differentage groups (0-30 years, 31-50 years, 51 years and above). Resin embedding of cochlear nerves was done. Semithin (1 µm) cross sections of the nerves were cut by glass knife on Reichert Ultra-microtome. Under light microscope,toluidine blue stained nerve sections were studied for shape, organization of connective tissue and number offascicles.Results: Cochlear nerve was comma-shaped across all the age groups studied. Majority of the nerve sections hada blunt round head and sharp tail. Few sections had blunt tail also. Nerve fascicles were well defined in all the21 samples studied. The approximate number of fascicles across the various age groups varied from 60 to 85 pernerve. Numerous Schwann cells and numerous small sized blood vessels were found in the endoneurium of olderage group compared to younger and middle aged groups.Conclusion: However, we didn’t observe major qualitative changes across different age groups, but the presentstudy provides novel baseline morphological data on the human cochlear nerve.