Written by
Hlolo Ramatsoma
Hlolo Ramatsoma

Hlolo is a clinical, research & support Audiologist at eMoyo. He is involved in many parts of the business, from consulting to R&D to supporting and training customers. He earned his BSc in Audiology from the University of Cape Town and is an experienced clinical audiologist specialized in ototoxicity monitoring, product specialist and training audiologist.

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Acoustic Stapedial Reflex Measurements with the KUDUwave TMP

On account of the exciting launch of the KUDUwave TMP, our previous blog post covered the importance of tympanometry in every hearing healthcare setting. The KUDUwave TMP is a Type 1 Clinical aural immittance instrument (IEC 60645-5). For those of us who are not clued up regarding the standards that audiometric measurements tools have to comply to, a Type 1 immittance instrument is the highest functional tympanometer as per IEC 60645-5. With the KUDUwave TMP, a clinician can conduct automatic and manual (pressure change) tympanometry assessments, and ipsilateral and contralateral acoustic reflex measurements (with pure tones and broad-band noise).


New or old, every KUDUwave device can be upgraded to include the TMP, allowing it to have Tympanometry and Acoustic Stapedial Reflex Measurements. A truly all-in-one device!

In today’s blog I would like to address the next big question; What is the value of the Acoustic Stapedial Reflex Measurement in your practice? Why should you upgrade?

 

The Clinical Value of Acoustic Reflex Measurements

 

Acoustic reflex threshold (ART) testing has been an essential part of the audiological test battery since the 1970s. Clinical measurement of acoustic stapedius reflex threshold (ASRT) has been found to be significantly valuable for differential diagnosis of pathologies such as vestibular schwannoma, auditory neuropathy spectrum disorder, and superior canal dehiscence. The acoustic reflex, also known as stapedial reflex is the involuntary contraction of the stapedius muscle as a response to loud sounds. This is NOT a test for hearing, it is the assessment of reflected energy as a result of the loud sounds introduced to the ear canal.

 

Traditionally, when the reflex-eliciting stimulus (also known as the activator) is presented to the same ear as the probe stimulus (reflex measurement ear), the measurement is ipsilateral. With contralateral measurement, the activator stimulus is presented to the ear opposite the probe stimulus. The activator-stimuli are usually 500, 1000, 2000 and 4000 Hz pure tones, or broad-band noise. Whereas the probe stimulus used to measure the reflex is generally 226 Hz for adults. Acquiring and analysing reflex thresholds in these two ART measurements is clinically crucial for the differential diagnosis of various auditory disorders.

 

Although the clinical value and importance of measuring both ipsilateral and contralateral acoustic reflex has been scientifically proven, recent surveys amongst American and Canadian audiologists shows a decline in the measurement of contralateral acoustic reflex. This data is not surprising as many immittance instruments with acoustic reflex (AR) measurement capabilities do not come standard with contralateral AR measurement. The lower cost of having an ipsilateral measurement only instrument and the ease of use of instruments without contralateral measurement are also some of the factors associated with the declined use. This is a clinical concern, because the use of both measurements offers a powerful differential diagnosis tool. Because it is such a powerful differential diagnosis tool, one can make strict and direct referrals at their practice.

 

Due to the complexity of reflex pathways (also known as the reflex arc) it can be impacted by pathologies of the outer, middle and inner ear, as well as those of the eighth nerve and lower brainstem. There are methods described by the earlier work of Jerger [1,2] characterizing various acoustic reflex measurement patterns associated with various sites of lesions. From these reflex patterns, which most clinicians have learnt in their respective tertiary institutes, one can note that acoustic reflexes are significantly sensitive in the diagnosis of retrocochlear dysfunction, neural dysfunction, and lesions of the low brainstem - to name a few.

 

Acoustic reflex measurement has been proven to provide diagnostic relevant information related to the peripheral and central auditory system when measuring ipsilateral and contralateral. Clinicians should always strive to ensure that their assessment test battery is as comprehensive as possible, to ensure that they provide accurate and quality management, treatment and timely referrals. Provided the ease of use, every clinician should be integrating these in their practices.

 

What makes the KUDUwave TMP Acoustic Reflex different?

 

With the KUDUwave TMP you can measure acoustic reflexes at 500, 1000, 2000 and 4000 Hz frequencies, and use broand-band noise activator-stimuli.

 

We recognize the value of both ipsilateral and contralateral measurement, therefore the KUDUwave TMP comes standard with ipsilateral and contralateral measurement! The device is equipped with the activator-stimulus and probe-stimulus in each ear side, this allows for the measurement of ipsilateral and contralateral acoustic stapedial reflex without alternating the probe tip and the stimulus/ activator earphone. This is the only reflex measuring device with this ability.

 

Special tests such Reflex Decay also come standard.

Set-up of Acoustic Reflex Measurement with the KUDUwave TMP

Set-up of Acoustic Reflex Measurement with the KUDUwave TMP

Acoustic reflex measurements are crucial, and the KUDUwave just integrated them seamlessly into your pure tone, speech audiometry and tympanometry test battery. This is an easy, fast and powerful diagnostic tool.

 

References

  1. Jerger S, Jerger J. Diagnostic value of crossed versus uncrossed acoustic reflexes: Eighth nerve and brainstem disorders. Arch Otolaryngol 1977;103:445–53.
  2. Jerger J, Jerger S, Hall JW III. A new acoustic reflex pattern. Arch Otolaryngol 1979;105:24–28.

Topics: tympanometry, reflexes

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