الفهرس 
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Abstract
Cochlear implants (CI) are electronic devices that enable the auditory rehabilitation and the management of individuals with severe to profound bilateral hearing loss in children as well as adults. These devices work due to electric stimulation of the auditory nerve fibres, in such a way as to replace cochlear function. Around the world different types of devices and techniques are being applied to improve surgical results, and several large studies have published low rates of intraoperative and postoperative complications in experienced hands.
Cochlear implants remain a popular and effective therapy for patients with sensorineural hearing loss in whom traditional hearing aids do not provide satisfactory results. Although CI is very successful, cochlear implants remain expensive and require an extensive program of accompanying therapy to be most effective.
The objectives of this study were to evaluate the surgical and audiological outcomes obtained in patients who underwent cochlear implantation in Sohag university hospital.
A cross-sectional retrospective study was done for 200 patients who were admitted to ENT Department at Sohag University Hospital during the period between October 2014 and February 2017 who included in the Cochlear Implant Program (CIP).
Analysis of the medical charts of the patients that underwent CI surgery was done to investigate variables such as gender, age at the time of surgery, classification of deafness according to its etiology, onset and type of hearing loss, otological examination, preoperative radiological examinations and their findings, implanted ear side, intraoperative findings of each patient including intraoperative difficulties, type of CI device, degree of electrode insertion, and complications.
Full audiological evaluation was done by aided behavioral, speech tests and OAE examination. Phoniatric and psychological evaluation was done by I.Q. test, full speech and language assessment. Radiological evaluation was done by HRCT temporal bone, MRI inner ear and audiovestibular bundle. Correlation between radiological and intraoprative findings were recorded.
Postoperative surgical follow up for three months was recorded and statistically analyzed.
Audiological fitting of the external device was done after one month of the surgery and with follow up for the next 6 months.
Results of the study showed that incidence of hearing loss was slightly equal in both male and female and mainly prelingual as the commonest age group of onset of deafness was in pediatrics below two years (160 patients below two years of age 80%) and main cause of hearing loss was congenital heredofamilial (69%). Commonest age at surgery in our study was 3.94±1.18 and this strongly correlated with many other researches.
The left ear was implanted more than the right in our study and the selection of the side of implantation is governed by the most patent cochlea, the ear with the shortest duration of deafness, the better surgical ear and the surgeon preference.
As sensitivity of preoperative radiology is 77.5%, surgeons faced surgical difficulties in 27% patients and the commonest were difficulty in electrode insertion, posterior rotated cochlea and middle ear abnormality.
Anatomical variations of the round window niche, such as the presence of a prominent posterior superior bony overhang, may render RW approach challenging. According to STH classification of RWM visibility, 73% of patients were Type I where the RWM were visible entirely.
Rate of overall complications were 23.5% and rate of minor complication 11% mainly wound infection and major complications rate were 12.5% mainly device failure which was the main cause of revision in our study and these results was correlated with many other researches. Mean average aided threshold was 27.62±11.10 indicating of good postoperative audiological performance in our study.
Conclusion
Cochlear implantation marked an era in the rehabilitation of profound and severe hearing loss. Along with the advancement in implant technology and surgical experience, as patients benefited from implantation, CI has gradually gained widespread acceptance all around the world
Cochlear implantation is an effective hearing rehabilitation surgical technique associated with a low complication rate.