Health Encyclopedia

BAER - brainstem auditory evoked response

Definition

Brainstem auditory evoked response (BAER) is a test to measure the brain wave activity that occurs in response to clicks or certain tones.

Alternative Names

Evoked auditory potentials; BAEP - brainstem auditory evoked potentials; Evoked response audiometry

How the test is performed

You lie on a reclining chair or bed and remain still. Electrodes are placed on your scalp and on each earlobe. The earphones give off a brief click or tone. The electrodes pick up the brain's responses to these sounds and record them. You do not need to be awake for this test.

How to prepare for the test

You may be asked to wash your hair the night before the test.

How the test will feel

There is little discomfort.

Why the test is performed

The test is done to help diagnose nervous system problems and hearing losses (especially in low birth weight newborns), and to assess neurological functions.

Normal Values

The normal range for auditory brain stem values will vary among patients and with the instruments used.

What abnormal results mean

Abnormal test results may indicate a hearing loss, multiple sclerosis, or stroke.

Additional conditions under which the test may be performed:

Acoustic neuroma
Brain injury
Brain malformation
Brain tumor
Central pontine myelinolysis
Speech disorders

This test may also be performed during surgery to decrease the risk of injury to the auditory nerve and the brain.

What the risks are

There are no risks.

Review Date:10/20/2008
Reviewed By:Luc Jasmin, MD, PhD, Departments of Anatomy and Neurological Surgery, University of California, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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