الفهرس 
ACKNOWLEDGEMENTOnly 14 pages are availabe for public view
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Abstract
Stapedectomy consists of removing a portion of the sclerotic stapes footplate and replacing it with an implant that is secured to the incus. This procedure restores continuity of ossicular movement and allows transmission of sound; it depends greatly on the skill and familiarity with the procedure of the surgeon. Stapedectomies are done in most world centers under microscope with excellent results and low risks. Since the introduction of stapes surgery by Shea in 1956, numerous modifications of the classical stapes operation have been described in medical literature. Small hole fenestra technique was defined, different prosthesis models were described and different instruments were developed to make fenestration. Microscopic surgery of otosclerosis was performed with a great success and minimal complication rates by many authors. Endoscopes are being used increasingly in middle ear surgery in the last several years.
The aim of this study to compare the outcome of endoscopic with that of microscopic stapedectomy.
This comparative study involved a prospective analysis of patients with conductive hearing loss who underwent stapedectomy at the department of Otorhinolayngology , Assiut University hospital between July 2015 and October 2017. The patients were divided into two groups: Patients in group I were operated with endoscope and patients in group II were operated with microscope. Pure tone audiometry was carried out in all patients preoperatively and postoperatively. Air and bone conduction thresholds were measured at frequencies of 500, 1000, 2000 and 4000 HZ and the median and interquartile range (IQ) of the pre and postoperative air-bone gap were noted. Extent of bone work at the posterosuperior part of the external auditory canal, accessibility to the oval window and manipulation of the chorda tympani nerve, postoperative complications and hearing results were also noted and compared between the two groups.
The median preoperative air-bone gap was 35.8 dB(30.4-45.03) in group I (endoscopic) and 35.85 dB(32.1-43.38) in group II (microscopic) whereas the median postoperative air-bone gap was 16.7 dB(5-39.58) in group I and 15.85 dB(10 -19.58) in group II. There was no statistical difference for hearing results between both groups. The need for bone work and manipulation of the chorda tympani nerve for better visualization was more in microscopic group than the endoscopic group and the difference between both groups was statistically significant. The incidence of complications in both groups was nearly the same in both groups and the difference between them was statistically insignificant.
Endoscopic stapedectomy has many advantages over microscopic stapedectomy as better visualization, and easy accessibility to the stapes, oval window niche, and facial nerve. Drilling of the posterosuperior part of the external auditory canal or removal of the scutum and manipulation of the chorda tympani nerve are less frequent with the endoscopic technique.Endoscopic stapedectomy has many benefits over microscopic stapectomy as better visualization, and easy accessibility to the stapes, oval window niche, and facial nerve. Removal of the scutum and manipulation of the chorda tympani nerve are less frequent with the endoscopic technique. The postoperative hearing results are nearly the same in both techniques. Postoperative complications such as chorda tympani injury and resultant taste problems and facial nerve paralysis were less in endoscopic than microscopic stapedectomy. Education of surgical assistants is better with endoscopic stapedectomy due to better visualization.
On the other hand, endoscopic stapes surgery has some limitations such as one-handed surgery, experience is required, and it lacks the stereoscopic vision.• The use of the 2.7 mm diameter angled endoscope for good visualization of the oval window.
• The use of LED light during endoscopic stapes surgery to avoid the damaging thermal effect of Xenon light on the middle and inner ear.
• The surgical experience is the most important factor for successful surgical outcomes so, it is important that only well trained and experienced surgeons should perform stapedectomy either endoscopic or microscopic.
• It is necessary to extend work to include more patients in order to get more crucial results.