Sensorineural Hearing Loss in Old Age People

Objectives: this study was undertaken in order to show the effect of age on the auditory system. Design: case –control study. Setting: Al-Jamhory teaching Hospital-Advisory clinic department-hearing and speech unit in Mosul during the period from first of January till the end of June 2011 A


Introduction
Sensorineural hearing loss includes all cases of deafness due to impairment of function of the organ of corti or its central connection.The term "sensory deafness "is sometimes used when the lesion is in the cochlea, and "neural" or "retrocochlear deafness" may be used when the lesion is in the auditory nerve (1) .Sensorineural hearing loss is divided into congenital and acquired; there are two types of acquired sensorineural deafness: sudden and chronic.The age related changes in the auditory system that have the most significant effects on the hearing of the person occur in the cochlea with several interacting processes involved (2,3) .Different principle lesions have been described in table 1. Age-related hearing loss, also called presbycusis, is the gradual loss of the ability to hear sounds (often high-pitched sounds).This loss of ability occurs so slowly that many people are not aware that they have hearing loss.

Causes of Age-Related Hearing Loss
The most common cause of hearing loss in aging adults is a loss of tiny hair cells in the ear.These cells act as receptorsthey vibrate when sounds are present.The loss of hair cells is largely thought to be due to aging itself, though the following factors may also be important in some cases:

Results
There was a significant difference in the auditory thresholds at all frequencies from 250 Hz to 8000 Hz between group2 subjects and group1 subjects and most of the subjects of group 2 showed sensorineural hearing loss changes on audiogram.The group1 subjects, all had normal hearing thresholds, whereas the old age persons showed a gradual increase in hearing loss starting at 250 Hz and becoming pronounced as the frequency increased.This difference is highly statistically significant at 1% confidence interval.

Discussion
This study demonstrates a significant hearing loss in old age subjects in all the frequencies tested.This could be explained by the fact that when the person ages, their cochlear hair cells may become damaged.This results in a high-frequency hearing loss that can start as early as middle age.The adult male of the species appears to be at greater risk, particularly if he is over 40 years old (5) .Statistics show a large percentage of older folks develop presbycusis.As many as half over 75years may have hearing loss.According to the a Profile of Older Americans from the federal Department of Health and Human Services Administration on Aging, hearing loss was one of the most common condition experienced by mature people in a survey (5) .The result of this study agrees with the study of Taylor and Irwin (6) whose found a correlation between hearing levels and age of the subjects in their study.Similar conclusions were drawn by Axelson (7) .Mark Stibich (4 ) reported that about 30 to 35 percent of people between the ages of 65 and 75years have some form of hearing loss.This can include partial hearing loss, the inability to hear certain frequencies, or hearing loss in one ear.Almost 50 percent of people over the age of 75 years have some form of hearing loss with 30 percent of those over the age 85years having deafness in at least one ear.

Conclusion
The present study shows that there is a significant decrease in the hearing threshold of old age people especially at high frequency.