What Is Microtia/Anotia?

A baby's ears begin to take shape in the womb in the second trimester and are usually complete by 28 weeks. Sometimes, one or both ears don't form completely. When the outside part of the ear is small or missing, it’s called microtia. The word itself means "little ear." When the entire outer ear is missing, it’s a type of the condition called anotia.

Microtia is rare. It affects only 1 to 5 of every 10,000 babies.

It usually affects only one ear -- most often, it’s the right ear. This is called unilateral microtia. When it affects both ears, it's bilateral.

Children with this condition often have some hearing loss in the affected ear. This can make it harder for them to learn to speak. Surgery can help with that and with the look of the ear.

Different Grades

Microtia has four grades:

  • Grade 1: The ear looks normal, but it’s smaller than usual.
  • Grade 2: The outer ear is only partly formed and 50 to 66 percent smaller than the contralateral external ear. The ear canal, which runs from the outer ear to the middle ear, is narrow or closed off.
  • Grade 3: The outside part of the ear is a tiny piece of cartilage (strong, flexible tissue) shaped like a peanut. There’s no ear canal or eardrum to send sound to the middle ear.
  • Grade 4: Anotia -- the outer ear is missing.

 

Cause

Most of the time, doctors can't find a cause. It usually occures in boys. Sometimes the condition runs in families and happens because of a change (mutation) to a gene. It also can be part of a syndrome, such as:

  • Hemifacial microsomia -- the lower half of the face doesn't grow correctly on one side
  • Goldenhar syndrome -- the ear, nose, lip, and jaw don't form completely
  • Treacher Collins syndrome -- a condition that affects the cheek, jaw, and chin bones

Some things might increase the risk, for instance if the mother:

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Hearing Loss

If a child has hearing loss because of microtia, it’s usually a type called conductive hearing loss. Sound can't travel from the outer ear to the inner ear.

A smaller number of children with the condition have sensorineural hearing loss. This can happen when the tiny hairs that carry sound from the inner ear to the brain are damaged. This type of hearing loss is usually permanent.

The doctor will want to see how well your child can hear. One of the more common tests is an auditory brainstem response test (ABR). Small stickers (called electrodes) are put on your child’s head and around his ears. Then a computer measures how his hearing nerve responds to sounds.

The test isn't painful, but your child will need to lie still. If he’s younger than 6 months old, it can be done while he naps. If he’s between 6 months and 7 years old, he may need medication to help him sleep through it.

Treatment

If your child has mild microtia and no hearing loss, she may not need any treatment. Kids with more severe problems may have surgery to fix the affected ear and help with self-esteem. Surgery can help with hearing if your child has conductive hearing loss.

Doctors usually wait to do the surgery until the child is 5 to 8 years old, when the other ear has grown almost to its adult size.

The surgeon creates a new ear with a piece of cartilage taken from the child's ribcage. It's usually done in three or four different stages:

  • The surgeon removes cartilage from the child's ribcage and uses it to shape a new ear.
  • The new ear is positioned on the side of the child's head.
  • The ear is lifted to line up with the other ear.
  • The doctor might need to open the ear canal to help the child hear better.

The new ear won't look exactly like the unaffected one, but they should closer to the same, and if the child needs glasses, the new ear will help your child be able to wear them.

Your child should have regular hearing tests. The doctor also might suggest hearing aids, speech therapy, or extra help in school.

WebMD Medical Reference Reviewed by Lisa Bernstein, MD on August 01, 2018

Sources

SOURCES:

American Speech-Language-Hearing Association: "Conductive Hearing Loss," "Sensorineural Hearing Loss."

Boston Children's Hospital: "Microtia Symptoms & Causes."

CDC: "Facts about Anotia/Microtia."

Children’s Hospital of Pittsburgh: "Auditory Brainstem Response (ABR) Test."

Children's National Health System: "Pediatric Microtia."

Ear Community: "FAQ's About Microtia."

Idaho Government: "Fetal Development."

Medscape: "Microtia."

Orphanet: "Anotia."

UNC School of Medicine: "Microtia and Anotia."

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