Auditory Brainstem Response Test (ABR)
The auditory brainstem response (ABR) test gives information about the inner ear (cochlea) and brain pathways for hearing (auditory nerve).
This test is also sometimes referred to as auditory evoked potential (AEP). The test can be used with all populations.
How is the test performed?
The ABR is performed by placing sticky electrodes on the head, forehead and earlobes. Earphones are placed in the ear to deliver the click stimulus. The person being tested rests quietly or sleeps while the test is performed. No response is necessary, however the person is instructed to remain relaxed and quiet with their eyes closed for the duration of the test. This is to prevent muscle artifact.
What does ABR measure?
As the clicks are delivered through the earphones, the electrodes measure the electrical activity from the auditory pathway. These electrical responses are analyzed by the computer and produce a waveform. The different peaks on the resulting waveform provide information on the time it takes various structures of the auditory pathway to respond following the stimulus.
Delayed times of these peaks help in identifying acoustic neuromas (larger than 1 cm) along the auditory pathway. Hearing sensitivity can also be estimated using the ABR for patients who cannot be tested reliably using behavioral testing techniques (i.e. infants or adults who are mentally challenged).