Congenital Ear Deformity, Microtia, and Anotia
Infants can be born with congenital ear malformations. Two of the more common are microtia and anotia infant ear deformities. Microtia means an incompletely formed external ear, called the pinna or auricle. It is a term used for a group of congenital external ear disorders. It may or may not be associated with atresia, or closure of the external auditory or ear canal. Anotia is the complete absence of the external ear. The majority of children with microtia do not have nerve deafness because their middle and inner ears are normal. They may need assistance with the transmission of sound to the inner ear but can lead very normal lives.
Anatomy of the outer ear:
The outer part of the ear collects sound. Sound travels through the auricle (cartilage covered by skin) and the auditory canal (ear canal), a short tube that ends at the eardrum (tympanic membrane).
Infant Normal Ear Anatomy
- Antihelix (antihelix) forms a ‘Y’ shape where the upper parts are located
- Antitragus is below the tragus
- Aperture is the entrance to the ear canal
- Auricular sulcus is the depression behind the ear next to the head
- Concha is the hollow next to the ear canal
- Conchal angle is the angle that the back of the concha makes with the side of the head
- Crus of the helix is just above the tragus
- Cymba conchae is the narrowest end of the concha
- External auditory meatus is the opening of the ear canal
- Fossa triangularis is the depression in the fork of the antihelix
- Helix is the folded over outside edge of the ear
- Intertragal notch is the space between the tragus and antitragus
- Lobe (lobule) may be attached or free, based on genetics
- Scapha is the depression or groove between the helix and the antihelix
- Tragus is the small pointed eminence of the external ear that is in front of the concha and projects back over the meatus
Why does microtia happen?
No one knows for certain the exact cause. One theory suggests a disruption in blood flow from the stapedial artery early in the development of the fetus. Others suggest genetic causes, environmental causes, or a combination of both.
Four Grades of Microtia:
- Grade I Microtia: Small external ear and a small but present external ear canal
- Grade II Microtia: A partially developed ear (usually the top portion is underdeveloped) with a closed external ear canal (atresia) producing a conductive hearing loss
- Grade III Microtia: Most common form of microtia with an absent external ear and small peanut-like vestige structure and canal atresia
- Grade IV Microtia or Anotia (Absent): Complete absence of the external ear with canal atresia
Does my child have hearing in that ear?
The inner and outer parts of the ear develop at different times. The inner ear houses the structures and nerve cells responsible for sensorineural hearing, and is not necessarily affected when microtia occurs. All the right parts of the inner ear may be there and working. If there is hearing loss in that ear, it is usually a conductive hearing loss because sound cannot reach the inner ear when there is a closed external ear canal (atresia). A child may need an assistance device for the transmission of sound to the inner ear. The health of both ears needs to be monitored closely throughout childhood.
How common is this?
Microtia is a birth defect that occurs in 1 in every 6,000-12,000 children. It is more common in boys than girls. It happens more frequently in people of Japanese or Navajo ancestry. It is rare to have both sides affected and usually affects the right side more often than the left.
Does this mean something else is wrong with my child?
No. Microtia can occur in isolation and may not be associated with other congenital abnormalities. It may, however, occur when one side of the face is less developed than the other side, called craniofacial or hemifacial microsomia. Microtia can also be a part of a syndrome like Treacher Collins syndrome, Goldenhar syndrome, and Nager syndrome.
What are my options?
There are several different options. The first would be to do nothing. Depending on the degree of deformity, some people choose to live with the current appearance of the ear. Surgical options include ear reconstruction with your own body’s skin and cartilage or reconstruction using a MEDPOR® implant that is covered by your own skin. The use of a prosthetic ear is also possible.
How many surgeries would my child need?
Reconstruction using a MEDPOR®framework usually requires 2 surgeries. The first surgery involves placing the framework under the skin in the correct position of the ear. A skin graft is used in this process. The ear will look flat against the side of the head after this surgery. This is normal and expected at this point. The second surgery raises the ear away from the head. The ear will be reshaped as well. The second surgery is planned about 3 months after the first, in order to allow your body time to heal.
Will we have to spend the night at the hospital?
You will need to stay a night or two in the hospital for the first stage of reconstruction using a MEDPOR implant. You would go home with a dressing in place that we would later remove in the office. The second stage of reconstruction usually does not require an overnight stay in the hospital.
How painful is the surgery?
As with any surgery, there is some degree of pain involved. Part of our job is to make you feel as comfortable as possible. We will make sure you go home with your pain well controlled on medicine that you can take by mouth.
MEDPOR® Implants are not harmful to living tissue (biocompatible). They are porous polyethylene implants used to reconstruct body parts like ear and skull defects. The implant’s interconnecting pore structure allows for tissue and blood vessels (fibrovascular) in-growth and integration of the patient’s tissue. More than 400,000 procedures have been performed with MEDPOR Biomaterial, and there are over 350 published clinical reports in cranial, reconstructive, oculoplastic, and cosmetic applications.