What Is Microtia?
Microtia is a birth defect of a baby’s ear. A little one’s ears begin to take shape in the womb in the second trimester. They’re usually complete by 28 weeks. Sometimes, one or both ears don't form all the way. 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.
Grades of Microtia
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% smaller than the outer ear on the other side. 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.
Microtia Causes and Risk Factors
Most of the time, doctors can't find a cause. It usually affects boys. Sometimes the condition runs in families and results from a change (mutation) to a gene, but this only happens in around 5% of cases and can skip generations.
Microtia 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 development of the cheek, jaw, and chin bones
Some things might increase the risk, for instance, if the mother:
- Has diabetes
- Eats a diet low in folic acid and carbohydrates during pregnancy
- Takes the acne drug isotretinoin in pregnancy
- Has rubella during the first trimester of pregnancy
- Drinks alcohol during pregnancy.
Microtia and 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.
Microtia Diagnosis
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). The doctor puts small stickers (called electrodes) on your child’s head and around their ears. Then a computer measures how their hearing nerve responds to sounds.
The test isn't painful, but your child will need to lie still. If they’re younger than 6 months, your doctor can do the test while they nap. If they’re between 6 months and 7 years old, they may need medication to help them sleep through it.
Other tests for microtia include:
- Ultrasound of the kidneys. This test checks how the organs are growing.
- CT scan. This test uses a series of X-rays to make a picture of your child’s insides. The doctor will likely wait until your child is older to give it. This avoids exposure to radiation and gives their bones more time to fully form. CT scans require the patient to be still, which also is more difficult for children.
Microtia Treatment
If your child has mild microtia and no hearing loss, they may not need any treatment. Kids with more severe problems might need 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.
Treatment options include:
Rib cartilage graft surgery. The surgeon creates a new ear with a piece of cartilage taken from the child's rib cage. This is usually done in three or four different stages:
- The surgeon removes cartilage from the child's rib cage and uses it to shape a new ear.
- They position the new ear 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.
Medpor graft surgery. This surgery uses a synthetic material instead of rib cartilage. The surgeon will cover the implant with tissue from your child’s scalp. They’ll need one surgery and can have it done as early as age 3. The downside is that few surgeons perform this challenging operation.
Prosthetics. A specialist can make a natural-looking prosthetic ear that your child will wear with an adhesive or attached to an anchor system, which requires minor surgery.
Hearing aid. Whether it’s worn or implanted, this device can improve your child’s hearing and help them with their speech.
If your child gets a new ear, it won't look exactly like the other one, but they should be close to the same. If they need glasses, the new ear will help.
Your child should have regular hearing tests. The doctor also might suggest hearing aids, speech therapy, or extra help in school.
