AOS005 - Risks of Noise-Induced Hearing Loss during Cochlear Implant Insertion Errors
Friday, April 29, 2022
2:27 PM – 2:34 PM CT
Location: Landmark A
Carolyn A. Chabuz, MD
Joseph Gonzalez, MD
Kenny Rodriguez, MD
John Peacock, PhD
Renee M. Banakis Hartl, MD
Stephen P. Cass, MD
Nathaniel T. Greene, PhD
Resident Physician University of Colorado School of Medicine Denver, Colorado
Hypothesis: We have previously shown that during cochlear implantation (CI), the electrode contacts cochlear structures and generates high pressure transients that may cause injury; we hypothesize that pressure transients may coincide with and be used to identify insertion errors.
Background: CIs have been an effective treatment for severe to profound hearing impairment, and are increasingly offered to patients with residual acoustic hearing; however, a large subset of patients lose this residual hearing after CI implantation. Several mechanisms have been investigated as sources of this hearing loss, and we have identified generation of high amplitude pressure transients in the cochlea during CI insertion that may be sufficiently loud to cause noise induced hearing loss. Insertion errors may represent an additional cause of residual hearing loss, but are often difficult to identify during surgery
Methods: To determine whether intracochlear pressures predict errors, cadaveric human heads were surgically prepared with a mastoidectomy and extended facial recess. Fiber-optic pressure sensors were inserted into the scala vestibuli and scala tympani near the oval and round windows to measure intracochlear pressures. CI electrodes were inserted via a round window approach under fluoroscopy.
Results: CI electrode mis-insertions produced pressure transients in the cochlea up to 160-170 dB SPL equivalent. The electrode position within the cochlea, design-related electrode dynamics, and poor surgical technique were associated with increased rates of insertion errors and pressure transients.
Conclusions: These results provide insertion pressure profiles for CI mis-insertions and suggest that appropriate ‘soft ’ surgical techniques can minimize acoustic exposure during CI surgery.
Professional Practice Gap & Educational Need: There are a variety of speeds/depths for electrode insertion along with different techniques and surgical skill levels that can affect residual hearing outcomes. We hope to create insertion pressure profiles for the major CIs on the market along with profiles for purposeful mis-insertions to better understand the generation of these intracochlear pressure transients and how to further preserve residual hearing.
Learning Objective: Understand the dynamics of CI insertion, including the extant and patterns of cochlear damage associated with surgical approaches, electrode types, and speed and depth of insertion. Determine whether similar pressure transients are generated with CI mis-insertions and if intracochlear pressure monitoring may be used to identify such deleterious outcomes.
Desired Result: Create insertion pressure profiles for specific CI electrodes along with profiles for mis-insertions.