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Microtia Atresia

Microtia means "small ear".

Atresia means "not formed" - in this situation applying to the ear canal.

• Microtia  and or atresia occur in one in every several thousand births. Up to 20 children or so are born with this in New Zealand every year. It is relatively common in New Zealanders, and also in some other populations, such as the Japanese and the Navajo Indians.
• Microtia occurs more commonly in males and on the right side (unilateral).  Approximately 10% may occur on both sides (bilateral).
• Microtia may occur as an isolated deformity although it typically presents as part of a spectrum of other defects, either minor or major.  Most people with microtia also lack an external auditory canal. This is known as "atresia" of the ear canal.  Atresia may occur in some cases, without microtia.  Microtia is known to occur as part of a spectrum of syndromes, especially hemifacial microsomia, Goldenhar syndrome and Treacher-Collins syndrome. These syndromes typically involve some under development of part of the facial struture and/or jaw.

What are the causes of microtia Atresia?

Although causes of microtia are difficult to define, some theories include:

• Decreased blood supply to the developing ear while the baby is developing in the womb.
• Medication taken by the mother during pregnancy such as Accutane, Thalidomide and retinoic acid.
• Environmental factors
• Genetic factors: sometimes there is more than one family member with microtia or atresia.

At present, it is not often we are able to define for sure the cause of an individual childs ear anomaly.

Why couldn't we see this on antenatal ultrasound?

Although many anatomic abnormalities may be identified on the ultrasound, it is difficult to fully evaluate the external ear. In addition, most ultrasound technicians and physicians are concentrating on organs such as the heart and kidneys, rather than the ears.

Is my child deaf? Although the possibility of permanent "nerve" hearing loss is present, most children with microtia/atresia have a relatively normal inner ear. However,the middle ear  and hearing bones are usually underformed/deformed to some degree, or may be absent and this results in a "conductive" loss of hearing on the affected side. This means that while the inner ear on the affected side could still function, it is not able to perform properly because sound is not delivered to it though a normal ear canal, ear drum and hearing bones. Children with single sided (unilateral) atresia and microtia usually have  normal hearing ear on the other side. This is perfectly sufficient hearing for normal speech and language development to occur.

Children with unilateral involvement usually cope satisfactorily in the education environment, but many do have some difficulties hearing in background noise  (you may notice this at home when the TV  or radio is on) and most do have difficulties localising where sound is coming from.

When both ears are involved, there will not be sufficient hearing for speech and language to occur.

My approach to treatment

1:  Hearing

This is the number one priority.

Hearing testing: ABR (Auditory Brainstem Response) or behavioural testing (playing in a sound proof room and reponding to carefully calibrated sound)  with a qualified audiologist to ensure normal inner ear function is present in both ears

Bilateral Deafness: Any bilateral hearing deficits should be treated with hearing aids. A head band type aid is recommended for very young children and for older children a bone anchored hearing aid ("BAHA") may be recommended (see seperate section on "BAHA" -Bone anchored hearing aid)  

Headband hearing aid (commonly called a BAHA headband)

Unilateral deafness: I recommend an "FM" system be fitted for the class  (pre- school and school) for all children with single sided hearing loss . An FM system allows the teacher's voice to be carried from a small lapel or "Madonna" style microphone to speakers placed strategically in the room. Not only does this help a child with hearing loss, it appears to help all children hear better in the classroom.Some school age children with  single sided deafness may benefit from treatment with a hearing aid--- to help with background noise and direction sense.  

Ear canal reconstruction: this is an opearation which may be  offered for some children with bilateral atresia and who have suitable partial formation of the middle ear. In some children/adults with unilateral atresia and very favourable middle configurations-this may be possible too. An external ear would be required prior to external ear canal reconstruction.

Bone anchored hearing aids: an excellent way of establishing  near normal hearing--- can be fitted from age 2 in bilateral cases. May be fitted in school age children  in single sided atresia where school progress is not as expected (See section on the "BAHA" )

2: CT Scan:

3:External ear reconstruction: External ear reconstruction requires 2 but sometimes more surgical stages.  Several months at least are required between stages.

The essentials are that rib cartilage is used to create a framework for the new ear. The framework is inserted under the skin in its new site on the side of the head. The ribs are not big enough to do this until approximately age 10- depending on the build of the child.

The rib framework once inserted under the skin is later "elevated" at the second procedure  so that it projects out more normally.

Surgically created ears can look quite natural and seem to be well liked by the children who have them- although it is not possible to create an ear which is "perfect."

Although having a child born with microtia/atresia is a traumatic experience, it is important to also see things in a positive light. Unfortunately, there are many children born with life-threatening illnesses and anatomic abnormalities. Microtia/atresia in itself is a relatively benign condition and should be treated as so. This is a difficult concept to accept when one has a child with microtia/atresia. It takes time! As long as there are not other severe associated abnormalities, these children live a relatively normal life and are able to fulfil their potential.