Microtia Infant Ear Deformity

Microtia is a congenital (present at birth) ear deformity characterized by an underdeveloped and malformed outer ear which occurs prenatally, typically during the first three months of pregnancy. Microtia, which means “little ear”, presents in approximately 1 in 6,000 births and is more common among people of Asian, Hispanic, and Native American descent. Microtia occurs in males twice as often as females and is twice as likely to appear on the right side of the head as the left. The ear deformity usually affects only one ear (unilateral microtia) but can present bilaterally in rarer cases (about 20% of microtia patients). In most cases of microtia, the earlobe is present however, other parts of the ear may be missing or malformed. While microtia is a description of the outer ear, it often occurs in conjunction with the absence of the ear canal (canal or aural atresia) or narrowing of the ear canal (canal stenosis).

Types of Microtia

Microtia is categorized into four types or grades of severity:

Grade 1: In this mildest form, the ear appears normally shaped in all or most aspects but is smaller than a typical ear. Minor malformation may be present, and ear canal atresia or stenosis can occur in some cases.

Grade 2 (also called conchal type microtia): The lower portion of the ear, including the earlobe, is present and can appear normal, but the upper ear, including the helix and antihelix, are missing or malformed. The ear canal is frequently very narrow and may be completely closed off or missing. Conductive hearing loss (impaired transmission of sound from the outer or middle ear to the inner ear) is a typical symptom.

Grade 3 (also called lobular type microtia): Grade 3 microtia is the most common type which presents as a disorganized piece of cartilage where the top of the ear should be and a small, peanut-shaped earlobe. The ear canal is usually missing.

Grade 4 (known as anotia): Grade 4 microtia is called anotia and is characterized by the complete absence of the outer ear. In this severe form, the ear canal is also missing.

What Causes Microtia?

Microtia is not considered to be a genetically inherited condition in most occurrences, as 95% of cases have no family history of the ear deformity. While the exact cause of microtia is often unknown, it does present more frequently in conjunction with certain syndromes such as:

Hemifacial microsomia
Goldenhar syndrome
Treacher Collins syndrome

Other possible contributing factors include:

Prenatal exposure to Accutane (isotretinoin) acne medicine, thalidomide, or mycophenolate
Maternal diabetes
Prenatal alcohol use

In many cases, researchers believe the ear deformity is a result of a combination of genes and environmental factors such as maternal diet (insufficient folic acid or carbohydrates) or exposure to specific medications or illness during pregnancy. Decreased oxygen levels or blood supply to the fetus during the first trimester has also been linked with microtia.

Treatment Options for Microtia

Microtia is usually diagnosed at birth since the external ear appears smaller and, in many cases, malformed. A CT scan of the affected ear can shed light on how extensive the deformity is and whether other ear structures are involved. An ENT specialist and/or pediatric audiologist may be enlisted to evaluate the inner ear and determine if hearing loss exists. Recommended treatment for microtia is often a collaborative effort by a team of pediatric experts (which can include an otolaryngologist, audiologist, geneticist and plastic surgeon) and will depend on the severity of the condition.

For patients with hearing loss, traditional hearing aids can be utilized, or a bone anchored hearing aid (BAHA) can be surgically implanted to transmit sound through existing bone. Cochlear implants are also an option to improve hearing impairment. These can be extremely beneficial for speech development. Surgery to improve hearing can be performed for patients with conductive hearing loss.

For Grade 1 microtia cases that involve no hearing loss, no treatment may be necessary. In most microtia cases, ear reconstruction surgery is the recommended treatment option for the external ear deformity. Surgical reconstruction is usually not performed until the child is between four and ten years old when the unaffected ear has reached maturity. Waiting until a child is older also allows for more available cartilage for grafting if that is the recommended treatment.

Several options for surgical ear reconstruction are available:

Rib cartilage graft: Rib cartilage from the patient’s chest is removed and implanted under the skin where the new ear will be created. Once the rib cartilage has integrated, additional skin grafts and procedures are performed to position and shape the ear, typically over a period of several months
Medpor graft: Ear-shaped synthetic material is implanted and covered by scalp tissue to create the new ear. While the procedure usually only requires one surgery, some additional complications can occur with infection or implant loss due to not being incorporated as thoroughly as a rib cartilage graft.
Prosthetic ear: Prosthetics can be secured with adhesives or an implanted anchor system. While prosthetics need to be replaced occasionally, they can be useful for children who have been unable to undergo surgery.

Keep in mind that any reconstructed ear will have less detail and delicacy than a natural ear. Creating a long-term plan with your plastic surgeon can reassure you and your child and help set realistic expectations for how reconstruction will be performed and its outcome. If your child has been diagnosed with microtia, we offer an extensive list of qualified pediatric plastic surgery experts who can work with you and your child’s doctors to provide the most successful outcome possible.