Auditory Neuropathy Workup

Updated: May 15, 2018
  • Author: Wayne T Shaia, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Workup

Laboratory Studies

No hematologic workup is necessary to diagnose auditory neuropathy/auditory dyssynchrony (AN/AD). History and audiologic testing establish the diagnosis (see History and Other Tests).

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Imaging Studies

See the list below:

  • Imaging studies are not necessary in the newborn period.

  • Once the diagnosis is made correctly, conservative treatment can be initiated. If the parents choose surgical intervention, high-resolution computed tomography scanning of the temporal bones should be performed. This test helps the otologist or neurootologist determine the possibilities of inner ear malformations that might contribute to the disorder. In addition, the inner ear can be visualized and preparations for cochlear implantation can be made. [6]

  • Typically, magnetic resonance imaging (MRI) has no role in AN/AD.

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Other Tests

See the list below:

  • The most pertinent audiologic tests for auditory neuropathy/auditory dyssynchrony (AN/AD) are briefly summarized, as follows [7, 8] :

    • Pure tone audiogram testing: This is a graphic plot of a patient's thresholds of auditory sensitivity for pure tone (sine wave) stimuli. It does not test a patient's ability to process sound. This test shows only the patient's ability to hear sounds or tones.

    • Speech audiometry: These tests use spoken words and sentences rather than pure tones. Tests are designed to assess sensitivity (threshold) or understanding (intelligibility) of speech.

    • Acoustic reflex (AR) measures: This measures the contraction of the stapedius muscle in the middle ear. Deviation from the normal threshold on AR testing indicates potential abnormalities of the hearing nerve and auditory system.

    • Otoacoustic emissions (OAEs): These are measured by the presentation of a series of clicks to the ear through a probe inserted in the ear canal. This test measures the integrity of the outer hair cells of the cochlea and cochlear function. Cochlear microphonics (CMs) tests the function of the cochlea similarly.

    • Auditory brainstem responses (ABRs): This test uses scalp electrodes to measure electrical activity in response to sound clicks. Abnormal results of ABR testing indicate that the hearing nerve, as well as the brainstem nuclei, may not correctly process the sounds.

  • Criteria for the diagnosis of AN/AD are as follows:

    • With the advent of newborn hearing screens, children with auditory detriments are being identified and treated at increasingly earlier ages. All of the following must be present in newborns to diagnose AN/AD:

      • Absent or severely abnormal ABR test results at maximal stimulus (100 dBnHL)

      • Normal outer hair cell function as determined by OAEs or CMs

      • Absent or elevated stapedial reflex thresholds

    • Suspect AN/AD in older children or adults with the following audiologic findings:

      • Pure tone thresholds are abnormal. The entire range of abnormalities, from near-normal to profound, may be seen. A more severe loss is usually displayed in the lower frequency thresholds.

      • Poor speech discrimination scores are out of proportion with the level of loss suspected based on the pure tone average.

      • The audiogram findings may vary some, but the overall milieu usually remains unchanged.

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