# Evaluation of noise-induced injury and restorative agents in the vestibular periphery

> **NIH VA IK2** · VETERANS HEALTH ADMINISTRATION · 2020 · —

## Abstract

Clinical reports suggest a link between noise-induced hearing loss and balance disorders in Veterans (Akin et
al., 2012), but the structural and physiological basis for this linkage is not well understood. Furthermore, animal
models which provide a mechanistic basis connecting noise-induced vestibular dysfunction and fall risk are
limited. The vestibular system plays a critical role in detection of head movements and orientation with respect
to gravity and is essential for normal postural control. Due to their anatomical proximity to the cochlea, the
otolith organs are exposed to sound pressure and are at risk for noise overstimulation, which may contribute to
vestibular dysfunction. Recent studies have linked noise overstimulation to decreased vestibular nerve activity
and loss of a specialized class of irregularly firing vestibular afferents which exhibit enhanced sensitivity to
acceleration (Stewart et al., 2018). It is likely that these afferents play an important role initiating postural
compensation for abrupt changes in head or body position due to their physiological characteristics and it has
been established that these afferents project to secondary vestibular neurons that project to the spinal cord
(e.g., Boyle et al., 1992). Although deficits in control of head and body posture may not be obvious during
sustained movements, deficits may become apparent when sudden perturbations require rapid resets of center
of gravity or head position in space. Such perturbations may naturally occur to avoid obstacles in one’s path or
regain postural stability after a slip, abrupt turn, or unexpected change in heading direction. The goal of this
proposal is to characterize fall risk in rodents with noise induced vestibular insults that preferentially impact
irregularly firing afferents, and to test the potential for restorative therapies that have been effective in cochlear
noise-induced injury models. Development of restorative therapies may hold significant clinical relevance for
Veterans, who often experience delayed effects of intense battlefield noise and may not seek treatment for an
extended period of time. Based on available evidence and our preliminary data, I propose that noise exposure
preferentially damages irregular vestibular afferents, resulting in reduced ability to react to abrupt perturbations
of the head in space.
The underlying hypothesis of the proposed studies is that noise will induce both immediate and long-term
vestibular dysfunction resulting in a balance disorder with components that can be “hidden” until challenged by
an abrupt motion which requires rapid compensation to maintain center of gravity. This will be tested in rats at
different times after exposure to noise. Changes in sensory cell synapses and vestibular nerve activity will be
correlated with fall risk in a balance beam task that measures postural stability and center of gravity. I then
predict that repairing the synapses by delivery of re-innervation inducing ...

## Key facts

- **NIH application ID:** 9950792
- **Project number:** 1IK2RX003271-01A1
- **Recipient organization:** VETERANS HEALTH ADMINISTRATION
- **Principal Investigator:** Courtney Elaine Stewart
- **Activity code:** IK2 (R01, R21, SBIR, etc.)
- **Funding institute:** VA
- **Fiscal year:** 2020
- **Award amount:** —
- **Award type:** 1
- **Project period:** 2020-02-01 → 2024-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9950792

## Citation

> US National Institutes of Health, RePORTER application 9950792, Evaluation of noise-induced injury and restorative agents in the vestibular periphery (1IK2RX003271-01A1). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9950792. Licensed CC0.

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