Noise Induced Hearing Loss (NIHL) Flashcards
What is NIHL?
Temporary or permanent hearing loss due to long term exposure to high levels of noise
NIHL can be secondary to …
Temporary Threshold Shift
Leads to a hearing loss that usually recovers within 24 to 48 hours
Happens when you go to a club or a concert
NIHL hearing loss can also be secondary to …
Permanent threshold shift (PTS)
Occurs after many exposures that results in TTS
THIS IS COMPLETELY PREVENTABLE
Why do temporary threshold shifts occur?
Uncoupling of OHC stereocilia from tectorial membrane
Metabolic exhaustion: cells bloat from rapid influx of endolymph
Synaptopathy: damage/swelling of ribbon synapse
NIHL begins with the loss of OHCs or IHCs and eventually progress to …
OHCs go first, followed by IHCs
Neural degeneration eventually occurs as well
What is acoustic trauma?
Hearing loss as a result of exposure to a single episode of intense noise (greater than 130 dB SPL)
Acoustic trauma typically leads to ….
Mechanical deconstruction of the auditory structures like
- TM perforation (CHL)
- Ossicular discontinuity (CHL)
How can NIHL be treated?
Completely preventable
Isolate in silence for a time period
Rest periods in continuous noise
NIHL can be ____ and ______
Occupational (job related) and non-occupational (hunting, concerts)
NIHL subjective findings (think of symptoms)
Tinnitus, hearing loss, otalgia
NIHL effect on otoscopy
WNL if not due to acoustic trauma which can damage the TM
NIHL effect on tympanometry
NIHL, no trauma: WNL
Acoustic trauma:
-TM perforation: Type B large volume
- Ossicular discontinuity: broken bones in ossicular chain, type Ad
NIHL effect on acoustic reflexes
NIHL, no trauma: elevated or absent
Acoustic trauma: absent, leads to CHL
NIHL effect on OAEs
Consistent with degree and configuration of hearing loss
Useful to detecting NIHL at preclinical stage
NIHL effect on audiometry
Noise notch at around 4000 Hz, drop in both AC and BC
Degree of hearing loss consistent with duration of noise exposure
