Anotia / Microtia

 

Condition Description

Anotia (an-NO-she-uh) means absence (also called atresia) of the external ear. This is to be distinguished from "aural atresia" which is absence of the ear canal, including the tympanic membrane. The more commonly used term is microtia (my-KRO-she-uh), which means incompletely formed external ear, and is the term for a group of congenital external ear disorders.

Early in fetal life (about the 5th week) the complex process of development causes cells to move to the correct position for ear formation. This process is interrupted for an unknown reason, and the cause of microtia is unknown. It may be due to a lack of blood supply to the ear of the developing fetus. It can also possibly be traced to mother's use of medications such as thalidomide and accutane. Fetal exposure to environmental toxins is also suspected as a cause in some instances.

There are 3 types of microtia. Grade I microtia is the term for a smaller-than-normal ear that has most of the components of a non-affected ear (called the helix or pinna or auricle, tragus, lobule and anti-helix). The ear canal may or may not be present and functional. Grade II microtia describes an ear that has some of the features of the helix and lobule but other features are missing. Grade III is the term for microtia involving a vertical skin appendage at the location of the ear, with a vestige of a lobule at the lower end and some amount of cartilage tissue at the upper end. No ear canal is present.

In most instances the children with microtia disorders will have normal middle and inner ears, making this a cosmetic condition rather than a typical cause of nerve deafness.

Prevalence

This is a relatively common group of disorders, occurring in 1 of every 6,000-12,000 live births. It is more common in Japanese and Navaho American Indians, and also more common in males. It is unusual in Hispanic populations. If unilateral, it is more typically the right ear that is affected. About 10% of the time, it is bilateral (both ears are involved). The chances of this condition recurring in a future pregnancy is less than 6%.

Common Associated Conditions

Most children with Grade III microtia will have atresia of the ear canal (absence of the ear canal, called aural atresia) as well as the external ear disorder. Some children with microtia will have other conditions such as Goldenhar syndrome, Treacher-Collins syndrome, and hemifacial microsomia (under-development of the structures on one side of the face). Children can have middle ear abnormalities as well. Dental and jaw abnormalities can also be associated with microtia.

Short-Term Treatment and Outcomes

Babies must be carefully examined for other disorders (syndromes, kidney disorders, facial defects), but in the absence of these, parents should be reassured that this condition is not going to cause great difficulties for the child, beyond the discomfort and concerns of the surgical reconstructions.

The first priority will be to test the child's hearing, especially in the unaffected ear since this will determine the need for hearing aids. In all cases the priority is to give the child maximum sound input to maximize brain development and speech development. A BAER (brain auditory evoked response) test will be recommended, perhaps adding a behavioral hearing test when the baby is a bit older. A CT (computerized tomography) scan will also be done to determine the anatomy of the bony structures and middle and inner ears.

Treatment plans will be unique to each child because of the variation in this condition. An interdisciplinary team will need to work together to give the child the best-coordinated care. This team will consist of an otolaryngologist (ear, nose and throat specialist), a plastic surgeon, an audiologist (hearing specialist), a dentist, a speech therapist, and a pediatrician or pediatric nurse practitioner. In some cases a social worker or psychologist can help support the family in coping with this condition and making decisions. A genetics counselor will also be very helpful to families.

If this disorder involves both ears, the treatment (reconstructive surgery) will occur sooner than if it involves only one ear because of the importance of maximizing the child's hearing as much as possible. Children with both ears affected will be fitted with bone-conduction hearing aids until the surgery is completed. If only one ear is affected, no hearing aids are usually needed because hearing will be adequate with one ear.

Reconstructive surgery is often delayed until the child has grown a bit because the surgery is difficult and doing it multiple times as the child grows is not an option due to scar tissue formation. Typically the child will be about 4-10 years of age when the ear reconstruction surgery is done. If both ears are affected the plan will begin with reconstruction of one ear in order to give the child improved hearing. The external ear will typically be reconstructed, sometimes using a piece of rib bone to form the structure of the ear. This external ear is allowed to heal for several months before the second-stage surgery to create the ear canals. This second-stage procedure involves drilling through the bone of the skull and creating a mucosa-lined passageway (ear canal) for sound to travel to the middle and inner ear structures.

Ear prosthesis can also be an option for some individuals with microtia/anotia. There can be difficulties in matching the appearance of the other ear, and of course, no hearing will be restored with prosthesis.

Long-Term Treatment and Outcomes

If children also have defects of the middle ear (such as Treacher-Collins Syndrome) the reconstructive surgery of the ear canal may not improve hearing. An option may be a bone-anchored hearing aid that is ideal for a child who has middle-ear problems but an intact inner ear and nerve structure to the brain.

Common Complications

The main complication is poor wound healing and infection that prevents successful ear reconstruction and causes scarring. Any sign of infection (cellulitis) should be quickly treated. Pneumonia post-operatively is a rare complication. Pain control is important post-operatively as well as careful protection of the healing ear so that the best possible surgical result is obtained.

Ear infections that are so common in all children can be especially problematic for children with anotia/microtia. Ear infections should be quickly treated, both to fight the infection and also to maximize the child's hearing. Middle-ear fluid, a common after-effect of middle ear infections in all children, will decrease hearing for several weeks, a condition especially to be avoided in a child with other hearing loss.

Sometimes, in an attempt to help the child's cosmetic appearance, minor surgeries will be done to remove part of the ear tissue. This should be avoided because those minor surgeries will cause scar formation that can affect the final repair. Also, the small tissue pieces might be very useful for the final ear construction.

Implications for Children's Development

If families can be supported to raise the child with microtia normally this condition should not have a particularly notable affect on the child's development (as long as the child does not have other significant congenital or acquired problems). Because the surgery will typically be delayed for several years to allow the structures to grow, the parents need to help the child accept this condition and not be unduly self-conscious about it. Self-esteem can be affected in children who are very concerned about visible differences between themselves and other children. However, parents can be very helpful in focusing on the child's strengths and minimizing the differences to encourage the child to be active in physical and social pursuits.

Hearing aids are very effective, and if the microtia is unilateral, hearing aids may not be needed. It will be important for the child and family to receive counseling and support to have a good cosmetic and developmental outcome since this condition is very treatable with typically excellent outcomes.

For more information, including resources for parents and general information about congenital ear conditions, visit the following websites: