The clinical applications of otoacoustic emissions are mainly focused on the identification of sensorineural losses in the auditory periphery. Despite the fact that the otoacoustic emissions signals are affected by alterations in the sound transmission chain (outer ear to middle ear and middle ear to outer ear) there are no current applications based on the transmission loss concept.
If you need additional information on an application you do not find extensive references or related material, please contact us.
The clinical applications can be divided into the
following categories :

- Children's hearing screening (Pre-school
and school age) Readers interested in this argument
should consult the following white papers :
- Ototoxicity monitoring
(see adults section)
- Tinnitus monitoring
(see the adults section)
- Detection of central auditory disorders
(OAE suppression studies.
The
reader might find interesting the following white
papers:
- Auditory
Neuropathy: 20 Questions and answers.
By Linda Hood Ph.D.
Kresge Hearing Research Laboratory of the South
LSUHSC, New Orleans, LA.(1998).This article is
mirrored (with slight modifications in terms of
esthetics) from the Louisiana State University
Health Sciences Center site. It is an excellent
source of information on the Auditory Neuropathy
and the audiometric tests (OAEs
included) used for it's detection.The
article is presented in three
web pages covering questions 1-7,
8-15,
and 16-20
respectively.
- The
Medial Efferent Olivocochlear System in Neonates
and Infants : By Thierry
Morlet, Ph.D. Kresge Hearing Research
Laboratory of the South LSUHSC, New Orleans, LA
(2001). This introductory paper highlights some
important clinical aspects of contralateral OAE
suppression in neonates.
- Differential diagnosis: (OAEs
present but ABR altered), these cases belong to clinical
profiles involving acoustic neuroma tumors and other
central auditory system disorders. Interestingly,
a number of research papers have indicated that OAEs
(TEOAES or DPOAEs) can be both
affected or unaffected by the presence of acoustic
neuromas. An explanation for such data can be derived
from information of how the growth of the tumor affects
the vascular supply of the cochlea or how the growth
of the tumors induces mechanical pressure alterations
on the vascular supply and the cochlea itself. OAE-based
measures can provide information on the sensory
component of any hearing disorder, thus they can provide
precise indexes of evaluating sensori-neural
hearing impairment cases.
- Noise Induced Hearing Loss
Monitoring in Industrial or Military environments.
Recordings of OAEs can be used to assess initial signs
of cochlear injury (developing noise induced hearing
loss - NIHL). Research has indicated that NIHL induces
a threshold elevation in the mid to high frequencies
and OAE protocols can be used very efficiently
to monitor the threshold elevation progress. With
the development of more accurate sensor and transducer
technology it is now possible to test even higher
frequencies (cubic distortion DPOAEs, up to 12- 16
kHz -referenced to F2 -) in order to define
any on-set NIHL effects.
The
reader might find interesting the following resources:
- Ototoxicity monitoring:
Monitoring of the course of a potentially ototoxic
drug (this area overlaps with the topics of "biophysics
and OAEs") such as cisplatin, oxalyplatin,
salicylate (aspirin) loop diuretics and aminoglycoside
antibiotics. In 2003 several editorials
will provide information on antineoplastic treatment
and OAEs (Dr. Nabil S. Al-Muhtaseb, Dr. Stavros
Hatzopoulos)
- Cisplatin and Derivatives:
Data from patients undergoing several (or more)
cisplatin treatment cycles, have shown significantly
reduced OAEs specially in the high frequencies.
The clinical data verify reports from various
animal models and cisplatin, that is elevated
doses of the drug affect first the basal regions
of the cochlea and progressively affect more apical
regions.In the animal models tested the ototoxic
effects of cisplatin are Irreversible.
Nevertheless other reports in the literature
also report a significant VARIABILITY
of the recorded OAEs under the same cisplatin-treatment
conditions. The latter complicates the use of
OAE-protocols in the monitoring of the ototoxic
effects.
- Carboplatin:
It should be noted that carboplatin-based or carboplatin
derivatives are also used in a number of antineoplastic
treatment protocols, but work on animal models
has clearly shown that the induced ototoxicity
has an effect mainly
on the Inner and not on the Outer hair cells of
the organ of Corti. At higher levels of accumulated
carboplatin the basal-OHCs are also effected,
therefore in these scenarios it is possible to
employ successfully OAE protocols for ototoxicity
monitoring.
- Salicylates:
Data in the literature report that the administration
of acetalsalicytic acid results in a temporary
elevation of threshold accompanied in many cases
by a sensation of ringing. In terms of OAEs oral
administration of acetalsalicytic acid results
in reduced TEOAEs and SOAEs. Cubic Distortion
otoacoustic Emissions seem to be unaffected
by salicylates, even at low stimulus
intensities. On the contrary laboratory animals
(rats, guinea pigs) are more sensitive to salicylates
and they present significantly reduce DPOAEs.
- Loop Diuretics:
Clinically loop diuretics (drugs containing ethacrynic
acid or furosemide)
are used in clinical cases of kidney failure and
elevated doses can produce a temporary threshold
shift. Reports in the literature have shown that
in animal models treated with furosemide the amplitude
of DPOAEs follows very closely the decline of
the Action Potential and it recovers faster.
- Aminoglycoside Antibiotics:
The chronic administration of first generation
antibiotics (i.e. gentamicin) can cause a permanent
threshold shift in the higher frequencies. For
example, subjects with cystic fibrosis, treated
with gentamicin, have shown significant amplitude
reductions in their DPOAE responses. The treatment
combination of aminoglycoside antibiotics and
loop diuretics is very synergistic for induced
ototoxic effects and animal models have indicated
that the combination of drugs is more ototoxic
than the single drugs.
- Tinnitus monitoring:
This category requires undoubtedly additional research
in order to validate a number of assumptions presented
in the literature, relating OAEs with the tinnitus
phenomenon. Since Tinnitus Retraining Therapy
has become a clinical option, the possibility of evaluating
objectively the cochlear function of tinnitus patients
with OAEs presents considerable advantages. Readers
who are interested in this argument might consult
the Tinnitus
page.
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