Auditory Brainstem Response Testing
Auditory brainstem response (ABR) testing may be ordered following a basic hearing test to further evaluate the status of the hearing nerve and brainstem pathways that conduct sound from the inner ear to the brain. In rare cases, the neural pathways may not conduct sound normally. Changes in the function of the neural pathways may occur for many reasons including growths along the nerve, demyelinating disease, stroke, viral infections and many others.
ABR testing involves the placement of four electrodes on the head. An electrode is placed on each earlobe. One electrode is placed on the forehead and one electrode is placed on the top of the head. Prior to electrode placement the skin is prepped with rubbing alcohol and a mild abrasive agent.
Conducting paste is then placed in small cup electrodes and the electrodes are taped on the skin.
Sound is introduced into the ears using foam insert earphones that are placed in the ear canals. Electrical activity that is generated by the hearing nerve and brainstem pathways in response to a clicking noise is recorded with the electrodes and fed into a computer where it is recorded. The audiologist analyzes the data obtained and a report is written.
ABR testing is not uncomfortable. During the test, the patient is placed in a comfortable reclining chair and is asked to close their eyes and relax. It is important to relax the muscles in order to obtain accurate recordings. It is preferable to avoid caffeine the day of the test and arrive for testing somewhat tired, if possible. No response is required from the patient. In fact, the patient can sleep during the test session.