subject: Microtia Tests [print this page] Microtia. Children born with microtia usually have one of two types of hearing loss birth defect(s). The first hearing loss caused by the birth defect microtia is known as aural atresia. Aural atresia microtia means that the child has hearing loss because the child has no ear canal or some type of ear deformity blocking the ear canal. Hearing loss because of no ear canal means that the sound usually conducted from the external ear through the ear canal to the inner ear cannot travel from the external ear to the internal ear because of the blockage or no existing ear canal. No ear canal formation during child/fetus development is caused by the congenital birth defect, microtia.
Aural atrasia microtia causing hearing loss can be corrected by a surgery which opens up the ear canal or replaces the ear canal or removes microtia blockage tissue to open up the ear canal or actually surgically makes an ear canal where there was no ear canal before. Creating an ear canal passage where sound can be conducted from the external ear to the inner ear usually repairs the hearing loss completely on a child with aural atrasia microtia. However, if there is still hearing loss the child can have hearing aids to amplify the sound and completely correct hearing loss.
Another type of microtia hearing loss caused by microtia is known as sensorineural hearing loss. With the birth defect caused by microtia in this case, there is damage to the cochlear or an ear deformity within the cochlear part of the ear. Usually hearing aids can help a microtia child correct hearing loss in this case. If hearing aids do not correct the hearing loss, there is a possibility of a corrective surgery in replacing the child's cochlear all together. A cochlear implant would be performed during a surgery which would correct hearing loss to the microtia child.
Other types of microtia hearing loss occur in a child with microtia due to other ear deformity situations where the inner ear doesn't have all it's parts. For instance, a child may be born without an eardrum or other small ear bones. Or a microtia child may be born completely without an inner ear. In this case there may not be a corrective surgery option.
These last types of microtia ear deformity and hearing loss are not common birth defect cases, rather these microtia cases are very rare. Microtia usually occurs in one child out of 10,000 children born. So, microtia is not a very common birth defect. Of all the microtia birth defect patients the majority of children tend to have aural atresia microtia cases. Aural atresia is a more common birth defect among microtia children whereas sensorineural hearing loss and hearing loss due to a non-existent inner ear or severely underdeveloped inner ear are the minorities in microtia cases.
To determine the severity of microtia and the underlying ear deformity that causes hearing loss, a doctor will perform a series of tests on a child with microtia. CAT-Scans are among the most common tests to see pictures of the inner ear deformity and ear canal development or underdevelopment. The other type of microtia test is called the BAER hearing loss test which checks the Brain-Stem and Auditory Response of a child with microtia or a child with any type of hearing loss. Microtia
