Children's Hospital Colorado

Microtia in Children

What is microtia?

A child with microtia has an ear(s) that isn't fully developed; microtia affects how the outer ear looks. This condition develops before babies are born, during the first four months of a mother's pregnancy.

Ears affected with microtia can be:

  • Slightly smaller than normal
  • Significantly smaller than normal with differences in parts of the ear 
  • Absent (anotia)

What is atresia of the ear canal?

A child with atresia is born without an external ear canal. Atresia can be complete where there is no ear opening or there can be a very thin opening of the external ear canal. The level of hearing loss that atresia creates varies depending on the opening.

What is microtia-atresia?

Children with microtia-atresia have both a small or absent outer ear and they are missing an ear canal.

A child with microtia-atresia may have additional health challenges, including syndromes that affect the face like hemifacial microsomia or Oculo-Auriculo-Vertebral (Goldenhar) syndrome.

When an individual has microtia or microtia-atresia and no other developmental conditions, it's called isolated microtia.

Where did the name microtia-atresia come from?

The name can be broken down into "micro," which means small; "otia," which means ear; and "atresia," which means without an opening.

What causes microtia and atresia?

Microtia happens because of a mix of genetic and environmental factors. The exact cause for most patients is not clear. Sometimes, the condition is passed to a child from a parent. 

Microtia and atresia has not been linked to anything the mother did or didn't do during pregnancy, except in very rare cases of taking certain prescription drugs. The prescription drugs Isotretinoin (Accutane) and Thalidomide, for example, can cause microtia (and other conditions) when used during early pregnancy. Both drugs are not allowed to be used in women who are pregnant.

Who gets microtia and atresia?

Babies of any ethnicity can get microtia-atresia. However, it's more common in Hispanic and Native American ethnic groups.

Rate of occurrence by ethnicity:

Navajo, Inuit, Andean: 1 in 1,200 live births
Native Americans: 1 in 1,800 live births
Hispanic: 1 in 10,000 live births
Asian: 1 in 10,000 live births
Caucasian: 1 in 20,000 live births
African: 1 in 40,000 live births

Get to know our pediatric experts.

Kenny Chan, MD

Kenny Chan, MD

Otolaryngology

Erin Teravest, PA

Erin Teravest, PA

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Melissa Raines, NP

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Norman Friedman, MD

Norman Friedman, MD

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