16. Does the microtia patient always have a hearing problem?
Ninety percent of microtia patients have one normal ear and are born adjusted to monaural hearing. The main functional issue of these microtia patients is sound location. Noisy crowds can be an issue as well. It is wise to talk with teachers so that a microtia child can be seated favorably in the classroom.
Bilateral (both sides) microtia is another issue. These children need to be fitted with a bone-conductive hearing aid in the first few months of life so that they can develop speech.
A person with microtia and atresia hears by conduction of sound through bone to reach the inner ear (the cochlea, or nerve center), which is almost always normal in microtia since it develops from a tissue source separate from the middle and outer ear. Bone-conductive hearing aids are worn against the bone just behind the ear region, and thus bypass the abnormal middle ears by amplifying and directing sounds to the normal inner ears. This allows a child with both ears involved to hear and develop speech.
Within the first few days of life and certainly within a couple of weeks, a BAER test (Brain stem Auditory Evoked Response) can be performed on the child with microtia. This is particularly critical in bilateral microtia cases, but occasionally I have seen unilateral microtia cases with abnormal hearing in the opposite side even though the outer ear appears normal. The BAER test allows one to determine hearing in a child too young to cooperate for Behavioral Testing done in standard audiograms.
A child with normal hearing in one ear will not require a hearing aid, but children with bilateral microtia will need the amplification that an aid provides in order to develop speech. They should be fitted with a bone-conducting hearing aid within the first few months of life. When the hearing aid-dependant child begins to speak, he/she may need to work with a speech therapist.
Fortunately, 90 percent of microtia involves only one side. These children do not require hearing aids and usually develop normal speech as long as the one hearing ear remains healthy and normal. Many children (with or without microtia) develop frequent ear infections, so it is particularly important to be aggressive when treating such infections in the microtia child’s normal ear. Frequent monitoring of hearing and speech is important when recurrent ear infections occur in these children.
Because the kidneys and their drainage system develop at the same time as ears, urogenital deformities are a little more common in children with microtia (4 percent in my first 1,000 microtia patients). A renal ultrasound can determine the status of the kidneys. CT scans of the temporal bone give information about the degree of development of middle ear structures and help to determine whether or not the microtia-atresia patient is a candidate for functional restoration canal surgery. Simultaneously, this “CAT Scan” can rule out a cholesteatoma (a cyst-like formation in the middle ear which has been cited as frequent as 15 % in atresia patients).
The BAHA (Bone-Anchored Hearing Aid) is a box-shaped amplification device that couples to a metal fixture which is anchored into the skull via two surgical procedures. While this hearing device gives better hearing than a bone conductive aid, it does require surgery and then lifetime care of the scalp as long as the aid is used. The scarring caused by this aid mandates that it is either placed after the microtia is addressed and outer ear is constructed, or if installed beforehand it certainly has to be placed VERY FAR BACK on the skull.
I have seen a number of BAHA placements that prevented any possibility of ever doing an outer ear repair of the microtia. I personally think that if a BAHA is being considered for the child that it would be best to wait until after the outer ear is constructed. In a child with bilateral microtia, one can use a bone conductive hearing aid until the microtia is repaired, and then do the BAHA surgery and application afterward.
If the surgeon has the ability to carve a good ear framework from rib cartilage, the outcome of microtia repair is largely determined by virginal, unscarred skin in the ear region. Repairing microtia by constructing the outer ear first does not impede atresia repair and canal surgery, but the opposite is not true. If the canal is created first, the skin is usually no longer suitable for microtia repair; the surgeon is likely forced to use a fascial scalp tissue “membrane” flap (with all of its liabilities) instead of the original, invaluable virginal skin to cover an ear framework.
As mentioned previously, the child is neither concerned about the outer ear appearance nor cooperative for the required surgery at that early age. Regarding atresia, the superb healing powers of very young children may actually be a disadvantage in atresia repair, i.e., it has been shown that bony re-growth is frequent when operating on patients this young. For example, if a young child develops a cholesteatoma, it’s removal often requires drilling out bone to expose and remove the cyst-like mass, and re-operation some months later to reconstruct the middle ear. When this two-step procedure becomes necessary in very young children, otologists often find that the previously drilled-out mastoid area has filled in with new bone growth when they go back in 9-12 months later to do the reconstruction!  Therefore, if atresia surgery is performed in a very young child (such as in age 2-4), the above-described cholesteatoma experience suggests that there is a real risk that the child’s canals will be obliterated by bony re-growth and that this initial surgery was detrimental.
Even in children 7-8 years of age, it is estimated that re-operation is required because of bony re-growth or narrowing of the canal in as many as 15-20% of cases. The consensus by very experienced otologists is that the percentage will be much higher in younger children because of their remarkable regenerative healing powers.[1-3]
One other important issue arises when discussing the timing of atresia repair. There has been great concern that if the atretic ear is not opened early enough in the child’s life, the brain will not be able to interpret or understand the signal it receives from the “new hearing” provided to that ear by the surgery. While this is absolutely true for the ocular (eye) system, it is thankfully untrue for the auditory system.
In the ocular system, if the brain does not receive input from one eye, the brain “shuts off” its ability to process or understand the signal it receives from that eye. We call this amblyopia, or lazy eye. That eye, in essence, is blind.
Fortunately, this does not occur with the auditory system. The signal from one ear is transmitted to the same side of the brain and crosses over to the other side of the brain very early in the auditory pathway. In other words, both sides of the brain receive the signal from both ears from the day of birth (and even before). This means that whenever the ear with atresia is opened, both sides of the brain are able to process and understand the new signal it is receiving, regardless of the patient’s age at the time of surgery.
For all these reasons, it seems prudent to postpone microtia/atresia repair until the age of six or seven.
Opening the ear canal in cases of unilateral atresia will improve a child’s ability to hear in spite of background noise (a noisy classroom, playground, etc.) and to locate sound in space. Studies are currently underway at the University of Virginia to quantitate this phenomenon and further characterize and define its benefit to children. I suggest that you visit their web site, which will also provide excellent comprehensive information on atresia: http://www.healthsystem.virginia.edu/internet/atresia/.
Approximately 50 percent of microtia-atresia patients have middle ears whose development is sufficient to make them candidates for hearing-improvement surgery. Their candidacy for this procedure is determined by CT Scan.
cartilage vs. synthetic ear frameworks
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his web site provides information about surgical reconstruction of the missing outer ear, absent either from birth (microtia), or from traumatic injury. It is meant also to be a comprehensive information source for the family and patient with microtia and is derived from Dr. Burt Brent's personal experience in surgically repairing ears for more than 1,700 patients during a 28-year period. This information focuses on his total management of over 1,500 congenital microtia patients and the repair of their ears, but also includes relevant supplementary input from experience he has gained by managing more than 200 traumatic auricular deformities.
Dr. Brent strictly limits his practice to repair of the outer ear, and has dedicated his professional life to helping children and other patients with microtia, traumatic ear loss, and cosmetic ear problems.
When an infant is born with microtia, the family has many questions: "Can our infant hear?;" "Did we do anything wrong to make this occur?;" "Will future children have the same deformity?;" and "What can be done about the disfigurement of a missing auricle or gnarled ear remnant that marks our child as abnormal, and invites teasing and probing questions by outsiders?" The information herein will thoroughly address all these questions and more.