Turn it up: Auditory Brainstem Response
It’s a summery afternoon and Rina decided to enjoy the moment and take a stroll at the park. She puts her headphones on and listens to her favorite playlist as she gets a glimpse of a child doing sign language.
“The kid must be deaf or something,” she says to herself as she observes the scenario where the mother of the child intently watches the child do the sign language and offer a few nods in response. This makes Rina wonder, how would one know if someone has difficulty hearing? Do they wait for it to show or is there something that would help determine whether someone has problems with his/her hearing? She contemplates quietly as she decides to research more about it later on when she arrives home.
ABR: An Overview
The auditory brainstem response (ABR) is a test that gives information about the inner ear or the cochlea and brain pathways for hearing. Also sometimes referred to as auditory evoked potential (AEP), this test can be used with children or others who have a difficult time with conventional behavioral methods of hearing screening. Furthermore, it is also indicated for a person with signs, symptoms, or complaints suggesting a type of hearing loss in the brain or a brain pathway.
In simpler words, ABR test measures the reaction of the parts of a child’s nervous system that affect hearing as it measures the hearing nerve’s response to sounds.
This test is often ordered if a newborn fails the hearing screening test given in the hospital shortly after birth, or for older children if there is a suspicion of hearing loss that was not confirmed through more conventional hearing tests. This test is safe and does not hurt. Also, it can be completed only if the child is sleeping or lying perfectly still, relaxed and with his or her eyes closed.
The test is performed by pasting 3-4 electrodes on the head (just like those electrodes placed around the heart when you do an electrocardiogram) and recording brain wave activity in response to sound. As sounds are made through the earphones, -the electrodes measure how the child’s hearing nerves respond to them.
The audiologist then looks for certain neurological “markers” as the child’s hearing nerves respond to sounds. Here, the softest intensity or loudness level at which these markers appear roughly corresponds to the child’s hearing level in that frequency range or pitch. By reading a computer printout of the child’s responses and interpreting these markers, the audiologist can tell if the child has a hearing problem.
The person being tested rests quietly or sleeps while the test is performed and no response is necessary. ABR can also be used as a screening test in newborn hearing screening programs. When used as a screening test, only one intensity or loudness level is checked, and the baby either passes or fails the screen.
- For those babies under 6 months, the mother may show up with a tired, hungry baby since most young babies will sleep through the entire test if they are brought to the appointment ready for a feeding and a nap.
- For those children older than 6 months but younger than 7 years, they may usually need anesthesia medication in order to sleep throughout the test. However, when anesthesia medication is needed, there are important rules for eating and drinking that must be followed in the hours before the test.
- For those children older than 7 years, they can be tested while they are awake if they relax and lie still during the test. But if the child is not able to cooperate, the test might need to be rescheduled so it can be done under anesthesia.