Microtia and Atresia: A Primer

We are excited to promote National Microtia and Atresia Awareness Day on November 9! This annual day was established to inform the public about microtia (literal translation: “little ear”) and atresia (absence or closure of the ear canal), their impact on those who have one or both conditions, and potential treatments, including bone anchored hearing systems (BAHS) for associated hearing loss. This day also allows us to celebrate those who advocate on behalf of themselves and loved ones to be treated with understanding, kindness, and respect.

The following is provided as a primer. You can use it to better understand these conditions and to educate others.

What is microtia?

Microtia is a condition that occurs the first trimester of fetal development that causes one or both ears to only partially develop or not develop at all. In some cases, it is accompanied by atresia, which describes ear canals that are either underdeveloped or nonexistent. Many people with microtia also have craniofacial microsomia, which affects facial symmetry and involves differences related to the jaw and general appearance.

How many types of microtia are there?

Microtia is classified according to the following four types:

• Type 1: Smaller-than-average external ear (pinna) with functioning hearing organs
• Type 2: Only part of the pinna developed and is undersized
• Type 3: Very little of the ear exists or functions
• Type 4: Complete absence of an external ear

Is microtia inherited?

The condition may run in some families, but far more often there is no prior family history. Based on current scientific data about microtia, with and without atresia, it is usually a random occurrence affecting embryos during their early development.

However, in a handful of cases, microtia has been found to affect members in multiple generations of a family, although it sometimes skips generations. Having one child with microtia increases the risk of having another by 5 percent. The likelihood of someone with microtia having a child with the same condition also increases by 5 percent.

How common is microtia?

Microtia, with and without atresia, occurs in approximately 1-5 births out of every 10,000 in the United States. It affects children assigned male at birth more frequently than those assigned female. It most often affects the right ear. Studies have indicated that it occurs more frequently in people of Asian, South American, and Western European descent, but is rarer in those of  African descent.

How does microtia affect hearing ability?

For many people with microtia, it only affects appearance and not hearing ability, so long as they have a functioning ear canal and inner ear organs (i.e., a working cochlea). However, for those with atresia, partial or complete hearing loss may result in the affected ear(s).

What options are available for people with microtia?

Some parents may elect reconstructive surgery for a child missing most or all of their outer ear for cosmetic reasons. This may involve using the child’s own tissue and cartilage, synthetic materials, or a combination to create as realistic appearing an ear as possible.

If enough of a child’s ear canal exists, it may be possible to open it with surgery, thus enabling at least some hearing. If there is no ear canal or surgery to the ear is otherwise not an option, a BAHS (bone anchored hearing system) may be recommended to provide hearing ability.* This might be a bilateral (two-sided) system if both ears are affected or unilateral (single-sided) if only one ear is affected. A full BAHS consists of a small titanium implant screw placed in the skull bone, and a skin-penetrating abutment onto which a sound processor is affixed. Alternately, sound processors can be worn on a soft or hard band without surgery.

For more information about microtia and atresia, including National Microtia and Atresia Day,  please visit www.earcommunity.org.

For more about bone conduction hearing treatments like the Ponto BAHS, please visit www.oticonmedical.com/us.

* Implantation of bone anchored hearing system implants is contraindicated for children under 5 years of age. Not all hearing loss patients are candidates for a bone anchored solution.