<p>Disabling
hearing loss is a problem around the world, with the World Health Organization
estimating that 466 million people worldwide have disabling loss, and that this
number is expected to increase to over 900 million people by 2050. There are
different types of hearing loss, but sensorineural hearing loss (SNHL) is the
most common and results from damage to the inner ear. The audiogram is the most
common test used to diagnose hearing loss, but it is limited in that it can only
identify a shift in hearing sensitivity (thresholds), i.e., it cannot identify
the cochlear location causing SNHL. The electrocochleogram (ECochG) is an
evoked response consisting of several summed responses of electrical
potentials from within the inner ear. Several components represent activity
from different places in the inner ear: the compound action potential (CAP) is the
summed onset response of auditory nerve fibers, the cochlear microphonic (CM) is
the AC response of the hair cells (primarily outer hair cells), and the summating
potential (SP) is the DC hair cell response (primarily inner hair cells). Most
ECochG responses in humans are collected non-invasively (e.g., from the ear canal
or ear drum), whereas most ECochG responses in animal models are collected
invasively (e.g., from the cochlear round window). <br></p><p></p><p>In this project, we aimed to bridge
this gap by recording non-invasive ECochG responses from awake chinchillas. We
first started by calculating standard ECochG metrics from existing data across
different forms of SNHL. Next, we tested the feasibility of recording
non-invasive ECochG responses from the ear canals of awake chinchillas.
Finally, we defined and calculated additional metrics from ECochG responses to
further help in identifying location(s) of SNHL. The ability demonstrated here
to record non-invasive ECochG responses from awake animals increases the
translational applicability of pre-clinical SNHL animal models by permitting
detailed cochlear assessments at multiple time points post exposure. Detailed
ECochG measures can advance hearing science and audiology by helping to
identify the location of damage causing the hearing loss, which can ultimately
allow for more individualized treatment. </p><br>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/14186585 |
| Date | 16 March 2021 |
| Creators | Caitlin R Heffner (10276490) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/Electrocochleography_Measures_from_the_Ear_Canal_of_Awake_Chinchillas/14186585 |
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