What are brainstem auditory evoked potential (BAEP) tests?

Updated: Oct 25, 2019
  • Author: Andrew B Evans, MD; Chief Editor: Selim R Benbadis, MD  more...
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The brainstem auditory evoked potential (BAEP), or brainstem auditory evoked response (BAER), measures the functioning of the auditory nerve and auditory pathways in the brainstem (see the image below).

Normal brainstem auditory evoked potentials. Normal brainstem auditory evoked potentials.

The short-latency BAEP generally is used for clinical purposes. The test can be performed with the patient under either sedation or general anesthesia. Standard broadband monaural click stimulation is used on the ear tested while a masking noise 30-40 dB lower in intensity is used on the contralateral ear. The intensity of the click should be 65-70 dB above the click perception threshold, and clicks should be repeated at a rate of about 10 Hz.

BAEPs are useful in estimating or aiding in the assessment of hearing loss. The most commonly used method for this is evoked response audiometry. The frequency of stimulation is 50-70 Hz, and at least 3 different intensities should be used. Wave V latency shifts are used to estimate the amount of hearing loss.

In children, especially those younger than 2 years, the BAEP can be used to screen for those in whom auditory amplification might facilitate achievement of more normal speech and language development. However, some children with a normal BAEP have abnormal hearing; Kileny showed middle latency abnormalities in some of these cases. [24] Nevertheless, the role of BAEP is to identify patients who could benefit from a hearing aid. Obviously, with a normal BAEP, a hearing aid would not be useful for correcting the hearing loss.

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