Introduction

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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 :








  • 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. A number of previous white papers and powerpoint presentations provide additional information to this topic (i.e. Hatzopoulos et al, 2002 ; Vink et al, 2006)

    • 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.