Endoscope assisted versus microscopic cochlear implantation-a double blinded randomized trial.

Abstract

Objective: Cochlear Implantation by classical Trans-mastoid Posterior tympanotomy approach for Round window insertion using microscope is often difficult due to limited visualization of Round window membrane niche. Our study aims to use Endoscope as an adjunct to classical microscopic technique to overcome this difficulty.

Methods: Our study is a Double blinded Randomised controlled trial with patients undergoing Cochlear implantation & having St Thomas Hospital classification IIb and III intraoperatively included in study. They were divided into two groups. Group A underwent Microscopic Cochlear Implantation while Group B underwent Endoscope assisted Cochlear Implantation. Based on visibility Round window niche structural visibility index (RSVI) score was recorded using both microscope and Endoscope.

Results: In Endoscope assisted group mean RSVI score was 8.44 ± 1.37 as compared to microscopic group was 5.47 ± 2.56 and it was Statistically significant with p < 0.05. Intraoperative mean electrically evoked compound action potentials(ECAP) for electrodes 1 to 8 was 187.9 ± 2.84 in microscopic group as compared to 179.44 ± 2.30 in Endoscopic group and the same for electrode 9 to 15 was 178.69 ± 3.16 & 175.3 ± 3.65 respectively but ECAP for electrode 16-22 was statistically insignificant between the groups considering p-value < 0.001. Endoscope assisted Cochlear Implantation was found to be associated with Statistically significant(p < 0.05) chances of Round window insertion with Chi square value of 15.45.

Conclusion: Microscope is the tool of choice for Cochlear Implantation but in cases with difficult visualization Endoscope can adjunct microscope in better visualization thus increasing chances of Round window insertion and promoting hearing preservation.