PRE AND POST- OPERATIVE ELECTROCOCHLEOGRAPHY IN COCHLEAR IMPLANT CASES - A STUDY TO PRESERVE RESIDUAL HEARING

Abstract

INTRODUCTION E l e c t r o c o c h l e o g r a p h y ( E C o c h G ) i s a n electrophysiological technique that records electrical potentials generated by different components of the inner ear and peripheral cochlear nerve in response to acoustic stimulation. Electrical evoked potential has been long used in cochlear implant to record the neural responses during intra or post-surgery. During cochlear implant electrically evoked compound action potential(E-CAP) or neural response telemetry (NRT) test used to measure the neural responses. Historically, ECochG found its main application in the diagnostic evaluation of Meniere's disease. However, in the last decade, the focus has shifted towards cochlear implantation (CI). MATERIAL AND METHOD The aim of the study is to measure residual hearing in pre and post operative cochlear implant patients using electrocochleography. With the help of ASSR and ECochG test it could be identified thatresidual hearing is preserved or not.Less traumatic CI electrode array design and the use of “soft surgery” techniques allow for the preservation of residual low-frequency acoustic hearing. In patients with residual hearing after CI, combined electric and acoustic stimulation has resulted in improved hearing and speech outcomes. CONCLUSION Preservation of acoustic hearing allows individuals with CIs to take advantage of periodicity, commonly referred to as voice pitch, and temporal fine structure, offering improved spectral resolution and supports in speech intelligibility better understanding in CI users. Pre implant and Post implant electrocochleography r e s u l t s w e r e c o m p a r e d a n d e v a l u a t e d . Comparison was made by comparing of pre and post implant peak and wave morphology, Summation Potential (SP) /Action Potential(AP) Area ratio and SP/AP Amplitude ratio. Keywords Meniere's disease, Soft surgery, Residual hearing.