How is microtia diagnosed?
Because microtia is a congenital condition, your child's malformed ear will be obvious at birth, and therefore diagnosed by the doctor immediately upon physical examination.
Doctors also recommend an Auditory Brainstem Response Evaluation soon after every child’s birth to evaluate babies’ inner ear function on both sides.
What is an Auditory Brainstem Response Evaluation (ABR)?
An ABR is a type of test that evaluates how well sounds travel along the hearing nerve pathways from the ear to the brainstem.
There are two main types of hearing loss:
Conductive hearing loss—problems transmitting sound from the outer ear (where sound is collected) to the inner ear.
This is the predominant type of hearing loss that’s associated with microtia.
Sensorineural hearing loss—problems with the nerves connecting the inner ear to the brain. In the inner ear, tiny hairs on the cochlea act as a neural pathway, transmitting through the inner ear. Usually, problems with these hairs on the cochlea are responsible for sensorineural hearing loss.
Sensorineural hearing loss is present in 10 to 15 percent of children with microtia.
How does it work?
An ABR test is a sleep EEG hearing test, which shows the softest sounds your child's ears can detect at various pitches. The ABR compares changes in brain activity to the timing of repetitive sounds to determine whether the particular intensity of sound can be heard.
How is the test performed?
There will be three or four small stickers on your child's head, connected to leads going into a computer. Sounds will be presented through an earphone to each ear separately while a computer analyzes the changes in the brain wave pattern in response to sounds.
Your child should be sleeping for the duration of the test. Young children under the age of 6 months are not usually sedated, and the test is performed while your baby is naturally sleeping, following a feeding. Children older than 6 months are usually sedated.
The test is not painful or uncomfortable in any way, but it is necessary for your child to be asleep in order to obtain clear recordings during the test.
You will be in the room with your child during the test, and the results will be explained immediately afterward.
How long does an ABR test take?
ABR evaluations, both sedated and unsedated, take two to three hours to complete.
Please follow these feeding instructions before your child’s ABR test.
Under 6 months of age:
no solid food, milk or formula for four hours before the test
6 months or older:
no solid food, milk or formula for six hours before the test
For all children:
Clear liquids such as water, breast milk or apple juice should be given until two hours before the test.
Please bring your child awake but very sleepy.
|If your child has significant hearing loss because of his microtia, Children’s Diagnostic Audiology Program can help.|
Specially trained audiologists conduct diagnostic tests to:
- assess hearing disorders
- provide guidance to families of children with hearing loss
- recommend appropriate care for hearing loss