الفهرس 
Introduction & aim of the work
Dead regions in the cochleaOnly 14 pages are availabe for public view
 |  | from | 91 |  |  |
| | | from | 91 | | |
Abstract
Sensoryneural hearing loss often associated with damage to the hair cells within the cochlea, this damage results in elevated thresholds in two main ways damage to outer hair cells impairs ability to hear soft sounds and damage to inner hair cells reduces the efficiency of transduction.
The cochlear region where inner hair cells are injured, inactive, or absent, and the neurons that innervate this region are in active or even degenerated, has been named the dead region of the cochlea (Moore., 2001).
The dead regions in the cochlea cannot be reliably detected by pure tone audiometry but they can be detected by doing a pure tone audiometry in the presence of a special background noise called threshold equalizing noise (TEN test, Moore et al 2000).
This study was designed to use the TEN test to detect the presence of dead regions in the cochlea and their relation to occurrence of tinnitus in normal hearing persons and in patients with sensoryneural hearing loss with different audiometric configurations.
This study consisted of 40 adults 20-60 years (80 ears), 20 ears with mild to moderate Sensorineural hearing loss without tinnitus, 20 ears with moderate to severe Sensorineural hearing loss without tinnitus, 20 ears with mild to moderate Sensorineural hearing loss with tinnitus and 20 ears with moderate to severe Sensorineural hearing loss with tinnitus. And 20 ears have normal hearing sensitivity with tinnitus, and 20 ears have normal hearing sensitivity without tinnitus as a control group.
Equipments used in this study were two channel audiometer, sound treated booth, immittancemeter, compact CD containing TEN (HL) test (Moore et al,. 2002).
All subjects in this study were submitted to full history taking, Otological examination, basic audiological evaluation, TEN (HL) test for each ear.
34 patients with sensoryneural hearing loss gave negative results in TEN test and 6 patients gave positive results for TEN test.
Dead regions in the cochlea were more common in moderate to severe sloping sensorineural hearing loss patients in mid frequencies.
Dead regions in the cochlea could present in cases of tinnitus even with normal hearing.