The Value of Endoscopic Exposure of Round Window in Cochlear Implant via Facial Recess

Abstract

Abstract Background Cochlear implantation (CI) has been considered as the best treatment in patients with severe to profound hearing loss unaidable with hearing aids. The main value of endoscope-assisted cochlear implantation is improved visibility of the RW and reduced risk of complications, especially in patients with congenital malformations. Aim of the Work The aim of the present study was to assess the value of endoscopic assisted CI surgery via facial recess approach without elevating tympanic anulus. Methods This Prospective case series study non-randomized sample was performed on a total of 50 patients with severe to profound hearing loss unaidable with hearing aids undergoing unilateral endoscopic assisted cochlear implant surgery with round window electrode insertion at Ain Shams University hospitals from April 2020 till March 2022 and approved 94/2020MD by an ethical committee before the start of the recruitment. Results 50 CI operations with endoscopic assistance were prospectively evaluated. There were 23 male (46%) and 27 female (54%) patients. The majority of the cases were children (41 cases, 82%). Of those 50 patients, 39 (78%) were prelingually hearing impaired. Four cases (8%) had various inner ear abnormalities. The standard mastoidectomy and Posterior Tympanotomy (PT) approach were used for all cases. Med-El (FLEX28TM; FLEX24TM Med-El, Innsbruck, Australia), Advanced Bionics (AB)Mid-Scala Electrode and CochlearTM (NUCLEUS® CI422 WITH SLIM STRAIGHT, NUCLEUS® CI24RE CONTOUR ADVANCETM, Sydney, Australia) implants were used. Endoscope-assisted visualization of the RW region through the PT was performed in all cases Rigid endoscopes with 0o and 30o (1.9, 2.7 and 4 mm in width, 11 and 6 cm in length) and an HD (high-definition) camera system (Karl Storz, Tuttlingen, Germany) were used for the endoscopic evaluation. The RW region was visualized and identified by inserting the endoscope through the PT without elevating the tympanic annulus. Then we switched to the microscope and drilled the RW niche (tegmen) using both hands until a circumferential view of the RW membrane is obtained. After proper exposure, the electrode was inserted through an opening in the RW membrane mostly under microscopical vision. Endoscopic identification of the RW through the PT enabled us to perform regular surgery in all cases. The current study concludes the difference between microscopic exposure and endoscopic exposure represented by Saint Tomas classification regarding round window exposure found that endoscopic exposure of round window classification is better represented by downgrading in the classification of round window exposure as type I 29(58%), type IIa 18(36%) type IIb 3 (6%) Non were type III by endoscopic exposure compared to microscopic exposure of round window is a type I 7(14%), type II 14(28%), type IIb 22(44%) and type III 7 (14%). Conclusion As evident from the current study, Endoscopy proved a great value in exposure and identification of RW in CI surgery through posterior tympanotomy approach, especially in difficult cases. Endoscopic-assisted CI through facial recess could be easily done using 1.9mm 0-degree endoscopy even in cases e narrow PT or rotated cochlea