Microtia

Microtia is a rare congenital condition in which the external ear is small and not properly formed. Microtia usually develops during the first few weeks of pregnancy and can affect one or both ears. Microtia is a common feature of hemifacial microsomia, a condition where multiple facial structures are underdeveloped.

Many children with microtia experience partial hearing loss due to malformation or absence of the middle and external ear. However, the inner ear — which is responsible for hearing — is typically unaffected and can be supported by hearing aids.

At Boston Children’s Hospital, our specialized Microtia Program operates under the Departments of Otolaryngology and Communication Enhancement for hearing enhancement and atresia repair and the Department of Plastic and Oral Surgery for external ear construction.

The Microtia Program is made up of various specialists uniquely trained to provide seamless care for young patients and their families. Our team is here to answer your questions and support your family throughout treatment.

Microtia includes a spectrum of ear anomalies, ranging from smaller yet normal-appearing ears with ear canals, severely malformed ears lacking ear canals, and a completely absent ear (anotia).

The symptoms of microtia can vary depending on the severity of the condition but may include:

• Abnormal ear size and shape
• Missing ear canal
• Hearing loss

The causes of microtia are largely unknown. It may sometimes result from genetic changes or abnormalities in a single gene. In addition, factors during pregnancy, such as exposure to certain medications, may be associated with an increased risk of microtia and other congenital anomalies.

Your child’s doctor can recognize and diagnose microtia immediately upon delivery through a physical exam. Your child’s doctor may recommend an Auditory Brainstem Response Evaluation soon after delivery to evaluate your baby’s inner ear function on both sides.

What is an Auditory Brainstem Response Evaluation (ABR)?

An ABR test evaluates how well sounds travel along the hearing nerve from the ear to the brainstem. ABR assesses electrical activity from the auditory nerve and the auditory pathway in the lower part of the brain and determines the presence, type, and degree of hearing loss. There are two main types of hearing loss:

• Conductive hearing loss: Problems transmitting sound from the outer ear (where sound is collected) to the inner ear (the hearing organ/“cochlea” and hearing nerve). It is the most common type of hearing loss associated with microtia.
• Sensorineural hearing loss: Problems with or damage to the inner ear structures such as the cochlea, where thousands of sensory hair cells transmit sound signals to the brain, or with the hearing nerve that connects the cochlea to the brain. Sensorineural hearing loss is present in only 10 to 15 percent of children with microtia.

How is ABR performed? 

We place three or four small stickers on your child’s head that connect to leads going to a computer. Sounds will be presented through earphones while a computer analyzes the changes in the brain wave pattern in response to sounds.

Your child should be sleeping for the duration of the test. The test is performed while your baby is sleeping naturally, typically following a feeding. Children older than 6 months require sedation, but children under 6 months are not usually sedated.

The test is not painful or uncomfortable, but it is necessary for your child to be asleep during it to obtain clear recordings.

You will be in the room with your child during the test, and the results will be explained immediately afterward.

How long does an ABR take?

ABR evaluations, either with or without sedation, take two to three hours to complete.

What pre-test directions are there for before an ABR test?

Important: Please follow these feeding instructions before your child’s ABR test:

Your child should arrive at their ABR appointment tired and ready to sleep, but not yet asleep. If they typically fall asleep after feeding, please bring them ready to eat. You will have time to feed them during the appointment.

If your child has a hearing loss related to microtia, they will be followed by an audiologist (hearing specialist) and an otolaryngologist (ear, nose, and throat expert). Together, the team will:

• Monitor the hearing loss with regularly scheduled hearing tests (audiograms).
• Recommend hearing aids and any other ways to maximize auditory input.
• Suggest a hearing aid (either worn as a headband or implanted into the bone) in the event of hearing loss that may affect communication.
• Offer surgery to recreate a missing ear canal (atresia repair) and improve hearing. Alternatively, your provider may offer a bone-anchored hearing system (BAHS).
• Recommend additional language or developmental assessments for your child, as needed.
• Direct you to community resources for educational or financial assistance.

Timeline of care

• Infancy: Possible headband hearing aid
• 3 years of age or older: Possible external ear reconstruction. Possible bone-anchored hearing system (BAHS).
• 6 years or older: Possible first-stage autologous (rib cartilage) reconstruction
  • Six months later: Second-stage autologous reconstruction
  • Six months later: Third-stage autologous reconstruction
  • Six months later: Possible atresia repair

Treating microtia involves creating or fixing the malformed or missing ear(s) to improve appearance, make it easier to wear eyeglasses and eyewear, boost self-esteem, and enhance the quality of life. Treatment requires a team of specialists, including plastic surgeons, audiologists, and otolaryngologists, to coordinate hearing aids and ear reconstruction.

While treatment for microtia depends on the severity of the condition, surgery is the most common and effective treatment.

What are the surgical options for microtia?

At Boston Children’s, the most common surgeries are hearing amplification with a hearing aid attached to bone and external ear construction. There are two common types of external ear construction performed — autologous ear construction (also called rib cartilage reconstruction) and alloplastic ear construction).

In autologous ear construction, pediatric plastic surgeons use cartilage from your child’s ribcage to create a new ear on the affected side of the head. This process uses your child’s own tissue, which helps enable the new ear to heal own its own if injured. Autologous ear construction is typically performed when a child is 6 to 10 years old, as they need to have grown enough rib cartilage for the reconstruction. The process usually involves three procedures, depending on the type and severity of your child’s microtia. Procedures are typically scheduled three to six months apart to allow time for proper healing.

• First procedure: Surgeons remove cartilage from the ribcage to build a new ear.
• Second procedure: Surgeons refine and reposition the new earlobe.
• Third procedure: Surgeons deepen the space behind the ear to enable wearing glasses and tucking hair behind the ear, and they perform “touch-ups” as needed.

In alloplastic ear construction, a specially trained pediatric plastic surgeon wraps a combination of scalp tissue and skin from other areas around an implant, known as porous polyethylene. This allows tissue to grow into the implant, making it a permanent part of your child’s body. The surgery can be done as early as 3 but typically occurs around 5 to 7 years old. While often a single operation, touch-up procedures may be necessary.

In addition to external ear reconstruction, your child might also benefit from an operation to improve their hearing. The most common surgical option for microtia and atresia is a bone-anchored hearing aid. Placing a bone-anchored hearing aid can be done at the same time as alloplastic ear construction, before alloplastic or autologous ear construction, or as a = separate procedure. Other procedures to enhance hearing include atresia repair to reconstruct a missing ear canal, or a cochlear implant. The type of surgery recommended for your child will depend on their anatomy and the severity of their hearing loss.

Surgery can help treat aural atresia, which is when a person is born without an ear canal. There are two main surgical options: bone-anchored hearing systems (BAHS) and atresiaplasty.

BAHS implants are often recommended because they usually lead to better results with less invasive surgery. These implants have two parts: an internal piece placed in the skull behind the ear, and an external piece that looks like a hearing aid and attaches to the internal component. Surgery to place a BAHS implant takes about 30-90 minutes and is done through a small cut behind the ear. Children typically recover in about a week and may start using the device within a few weeks to months.

Though uncommon, the risks of BAHS implant surgery include infection, bleeding, and spinal fluid leak. Percutaneous (through the skin) devices with abutments need daily cleaning but generally provide better hearing outcomes than transcutaneous (over the skin) devices with magnets.

Atresiaplasty is a treatment option for families that want to avoid using external hearing devices. To determine if a child is a suitable candidate for atresiaplasty, the surgeon evaluates how much normal ear anatomy is present behind the closed or underdeveloped ear canal. This evaluation typically involves using a CT scan of the temporal bone, which houses the external, middle, and inner parts of the ear.

During atresiaplasty, surgeons make an incision behind the ear and use a drill to create a new ear canal. They then use skin grafts harvested from other parts of the child’s body (often from the thigh) to create a new eardrum and line the newly created ear canal. The hearing bones in the middle ear (ossicles) are then either sculpted and repositioned or replaced with a titanium prosthesis. The surgery takes a few hours and patients often stay in the hospital overnight afterward.

After surgery, follow-up visits are necessary to replace packing in the canal to prevent it from closing. Successful atresiaplasty can sometimes mean a child no longer needs a hearing aid, but some may still need one if hearing loss persists. Risks of atresiaplasty include infection, bleeding, changes in taste, facial weakness, dizziness, ringing in the ears, worsened hearing loss, and the need for additional surgeries.

How will my child look after ear reconstruction?

While your child’s reconstructed ear won’t look exactly like their other ear, it will greatly enhance their appearance and allow practical things like wearing glasses and sunglasses.

What are non-surgical options for microtia?

Ear construction offers children a permanent solution that can make it easier to wear glasses, boosts self-esteem, and improves their quality of life. At the same time, every child and family are different and pursuing surgery and the deciding the type of surgery is your choice. Your doctors will work with you to decide on the right option for you and your child.

Alternatives to ear construction include:

• Ear prosthesis: An artificial ear made from a synthetic material that can be attached to the side of your child’s head with adhesive or a minimally invasive procedure. Disadvantages include the need for daily care.
• Observation/no treatment: You may opt to not have any treatment. Speak with your child’s care team for guidance and advice.