الفهرس 
Chapter I: Anatomy and physiology of hearingOnly 14 pages are availabe for public view
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Abstract
Cochlear implant is an auditory prosthesis that electrically stimulates the
primary auditory nerve fibers to elicit sound perception in individuals with severe to
profound sensorineural hearing impairment. A substantial number of studies have
demonstrated that the use of CI can facilitate the development of speech and language
skills of children who are prelingually deaf (born deaf or become deaf before 3 years of
age) (3).
In clinical field, persons involved with CI always (patients, caregivers,
professionals) face a challenge in choosing which ear to be implanted (better or poor
hearing ear). As the implantation of the poorer ear allows the possibility of bimodal
stimulation by utilizing a contralateral hearing aid. However, implantation of the poorer
ear has raised concerns that the implant could be less beneficial in an auditory system
that has been long deprived of stimulation And implantation in the better ear gives
better speech discrimination and better language outcome as it contains residual neural
tissues (5).
So, the aim our study is to know the effect of the preimplant degree and duration
of hearing loss on side selection to be implanted, by evaluating language outcome, in
order to reach the better decision of the site to be implanted for better language and
speech outcome. This retrospective study was conducted on (30) patients with bilateral
a symmetrical sever to profound SNHL who had been implanted. The study was carried
out by evaluating 30 patients who had complete recorded files. These patients fitted
with their first HA before the age of 3 years with for least 6 months with extensive
auditory training but without any benefits.
The patients were divided into three groups according to the degree and the
duration of hearing loss of the implanted ear before implantation. The first group has
been implanted in the worse and short duration of deafness. The second group has been
implanted in the worse and long duration of deafness. The third group has been
implanted in the better ear regardless the duration of deafness.
Every case was subjected to the protocol of phoniatric assessment for hearing
impairment. This protocol was applied to detect which group shows the better language
outcome by applying PLS-4 Arabic form (116).
This study declared that children in each group suffering from delayed language.
While the third group is the best comparing with the other because, it is the better
functional ear contain some residual hearing and it is important for better speech
discrimination and so on better language outcome. The first group is better than the
second group due the short duration of deafness in the first group. The short duration of
deafness provides more residual neural tissue for electrical stimulation that leads to
better speech recognition. The long duration of deafness leads to degradation of
peripheral neural structures, spiral ganglion cells and the cochlear nucleus.
This study revealed positive correlation between functionality of the ear and
language outcome (implantation in the better function ear gives better language
outcome) and negative correlation between the duration of deafness and language
outcome ( as the duration of deafness increases the language outcome will be poor)