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. In New Zealand, Microtia/ Atresia occurs 3-4 times more commonly in children with Maori or Pacific Island Heritage.

• We have assessed more than 350 children with Microtia/ Atresia at the Microtia/ Atresia clinic, held at Starship Children's Hospital.

• 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 in 50% of those affected, other anomalies may occur as well. Most , but not all 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 child's 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 function 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 usually sufficient hearing for normal or nearly normal speech and language development to occur.

• ​

• Children with unilateral involvement usually cope quite well listening at home, when it is quiet. We do know that children with one sided hearing loss find it a lot harder to hear at school. Many studies have shown that these children find it harder to reach their full potential, however, it is quite possible also for a few children with single sided hearing loss to do well at school without any additional assistance.

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

​

My approach to treatment is:

1:  Hearing – this is the number one priority

The majority of children with microtia/atresia have inner ears that function normally. The problem that they face is getting sound from the outside world into their inner ears. Hearing tests chosen to assess this depend on the ages and stage of development of the child, and of their co operation.

 

Hearing testing:

ABR (Auditory Brainstem Response) measures tiny brainwaves which are the response to a sound provided by headphones. This test is usually performed with babies while they sleep. For most babies these days, this test is done as part of the neonatal hearing screening process. Children who have abnormally shaped ears are usually referred by the neonatal hearing screening programme directly to an audiologist or audiology department. An ABR test is then performed by a senior audiologist.

 

"Behavioural testing" is performed on children over the age of 6 months. This involves the child playing in a sound proof room , where their responses to calibrated sound is assessed.

 

Bilateral Deafness: 

Any bilateral hearing deficit should be treated with hearing aids. A head band type aid is recommended for all young children from the age of 6+ weeks.

 

Headband aids are available which may have an aid fitted for both the left and right ears for children 6 months of age and older. An excellent alternative is the Med El "AdHear" hearing aid, which is a "stick on" hearing aid, fitted with adhesive, to the skin behind the ear.

​

Unilateral deafness:

We now recommend a BAHA headband style hearing aid ( or an equivalent bone conducting hearing aid on a headband) be fitted for children (from 6 months of age) who have a  unilateral hearing loss. There is good evidence that this might help the hearing nerves and hearing centres in the brain develop more normally, and that this might also help with speech and language development too. It is likely to help with the development of more normal direction sense abilities and with the ability to hear better in background noise (especially classrooms). Currently, the preferred aid is the Oticon "Ponto Power" aid, but there are various options available, including the "Cochlear Sound Arc" for older children.

 

An remote microphone ("RM" or "FM" ) system can also be extremely helpful for children with hearing loss . This can be used both at pre school and at school. An RM system allows the teacher's voice to be carried from a small lapel  microphone  directly to the child's hearing aid or aids. Your audiologist will advise you about this. In New Zealand, these are typically fitted in conjunction with the support of the "advisors on deaf and hearing impaired children", who work for "Learing Support" at the Ministry of Education.

 

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  "pinna" reconstruction would be required prior to external ear canal reconstruction. If ear canal surgery is an option, we recommend it be done after the first stage of the external ear reconstruction and before the second stage.

 

Implanted hearing devices:

The MedEl "Bonebridge" is now available for children over 4 years who have suitably favourable anatomy on CT scanning. The Med El "Soundbridge" is also a treatmnent option for some children as young as two years of age. These are two part devices, with an implant under the skin inserted behind the ear during a short operative procedure, and a small,  round button shaped external aid which sits in the hair over the top of the internal device. They are held closely together by magnets. Unlike the BAHA device (mentioned below), there is no implant passing through the skin, and therefore there is no long term maintenance required. People who use these devices are able to swim and shower normally, but must remember to take the external aid off before doing so  (just like you should take your glasses off before showering!)- however waterproof covers are available. These devices are capable of an excellent level of hearing restoration.

 

Further information:

www.medel.com/bonebridge

www.medel.com/vibrant-soundbridge

 

Cochlear Osia

This is a newly available device with an implant inserted under the skin behine the ear, and with a "processor" ( which looks a little like a coat button) worn on the outside, in a manner almost identical to the Bone Bridge. This device is manufactured by the " Cochlear" company, which is based in Sydney. There are three main benefits to this device- it may be able to be fitted in children and adults who have a smaller mastoid bone ( this is the bone behind the ear ), and it has blue tooth and wireless remote capability.

 

Further information:

www.cochlear.com/us/en/professionals/products-and-candidacy/osia

 

BAHA or BAHD

The bone anchored hearing devices are capable of restoring excellent hearing quality. We now prefer these as an option in older children and above- 15 years and above.  A tiny titanium stud is inserted through the skin behind the ear, into the bone of the skull, during a short operative procedure under general anaesthetic. We have used many of these devices in young children, with positive reports from parents, but our research has also shown, that for reasons which are not entirely clear, that in New Zealand North Island children ( and in a range of different centres overseas) , there is a high risk of infections in the skin around the implants. This has necessitated frequent use of antibiotic creams and small surgical procedures to settle the infections. Older children and adults seem to be at far less risk of  skin infections. There are two main manufacturers of these devices-  "Cochlear" and "Oticon".

​