# Improving an animal model of human hearing loss: quantifying risks associated with common otolaryngology procedures

> **NIH NIH R21** · UNIVERSITY OF COLORADO DENVER · 2021 · $155,500

## Abstract

Project Summary/Abstract
Many surgical procedures, including otological procedures intended to restore hearing, involve substantial
manipulation of components of the middle and inner ear. In particular cochlear implants (CIs), which are
increasingly indicated for patients with some residual acoustic hearing, involves direct manipulation of the
contents of the inner ear. Unfortunately, up to ~50% of these patients lose their residual acoustic hearing, and
a substantial proportion of all CI patients experience balance dysfunction either immediately or some time after
surgery. Several studies aimed at determining the cause of the immediate hearing loss have suggested that
while the presence of a CI electrode does not substantially alter sound transmission in the cochlea, high-level
transients are generated in the cochlea during insertion. These intracochlear pressure (PIC) transients can
show peak pressures in excess of 170 dB SPL peak equivalent ear canal SPL (PEAC), thus could cause noise-
induced hearing or vestibular loss. These studies were the first to identify the presence of PIC transients, but
failed to identify the sources and the risks to hearing from these exposures. The goal of this proposal is to
overcome these previous shortcomings using two techniques. First (aim 1), we will further characterize PIC
transients during CI surgery in cadaveric human specimens. PIC measurements will be conducted during
insertion, manipulation, and removal of CI electrodes to quantify the number of PIC transients generated, and
correlate with features such as CI electrode manufacturer, geometry, and insertion style (i.e. with a sheath or
stylet or via forceps). The source of PIC transients will be investigated with live fluoroscopic imaging in a subset
of these experiments to correlate PIC events with electrode position in the cochlea. Second (aim 2), the risk of
hearing loss from these PIC transients will be determined in chinchillas. PIC transients recorded in aim 1 will be
translating into acoustic stimuli that produce identical intracochlear exposures in chinchilla using the recently
quantified relationship between sound transmission into the inner ear in chinchillas and humans. This
technique, which will generate acoustic stimuli that produce PIC in chinchillas that are identical to the PIC in
human cochlea observed during CI surgery, requires use of two recent innovations:1) characterization of this
relationship, and 2) development of a loudspeaker capable of generating the necessary high-level acoustic
stimuli. The experiments thereafter follow a standard noise-exposure protocol in which physiological measures
of animal hearing are assessed before, and at several time points after noise exposure to assess the resulting
permanent hearing loss. These measurements will thus provide a quantitative estimate of the hearing loss
expected from exposure to PIC transients generated during CI surgery that may lead to improved electrode
design and surgical tec...

## Key facts

- **NIH application ID:** 10240682
- **Project number:** 5R21DC017809-03
- **Recipient organization:** UNIVERSITY OF COLORADO DENVER
- **Principal Investigator:** Nathaniel Tussing Greene
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $155,500
- **Award type:** 5
- **Project period:** 2019-09-26 → 2023-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10240682

## Citation

> US National Institutes of Health, RePORTER application 10240682, Improving an animal model of human hearing loss: quantifying risks associated with common otolaryngology procedures (5R21DC017809-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10240682. Licensed CC0.

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