Microtia Surgery in Children

The reconstructive surgeon must have an intimate knowledge of the anatomy of the external, middle, and inner ear. Important landmarks include the following:

• Helix
• Helical crus
• Antihelix (anthelix)
• Crura of the antihelix
• Tragus
• Antitragus
• Scapha
• Triangular fossa
• Cymba conchae
• Cavum conchae
• Lobule

The primary blood supply to the external ear is via the superficial temporal artery and branches of the posterior auricular artery. The sensory innervation of the external ear is via the anterior and posterior branches of the greater auricular nerve.

The location and reference point of the ear must be well understood. The angle of the long axis of the ear approximates the angle of the nasal dorsum. The superior point of the ear is usually at the eyebrow level. In a child aged 5-7 years, the helical crus is usually approximately 6.5-7.0 cm from the lateral canthus. The most inferior aspect of the lobule on the microtic ear is usually 0.5 cm higher than the normal side.

During week 7 of gestation, the first and second arches give rise to six hillocks called the hillocks of His. The first three hillocks are derived from the first arch, and the final three are derived from the second arch. These hillocks then fuse, forming the future ear. The structures of the adult ear corresponding to the hillocks are the tragus (first hillock), helical crus (second hillock), the helix (third hillock), the antihelix (fourth and fifth hillocks), and the antitragus (sixth hillock).

The actual cause of microtia is relatively unknown. McKenzie and Craig stated that it may occur as a result of in-utero tissue ischemia secondary to obliteration of the stapedial artery or actual hemorrhage into the local tissues. ^[1]

Genetic studies have revealed several possible etiologic factors, such as chromosomal aberrations, multifactorial inheritance, and autosomal and recessive traits. The most common syndromes associated with microtia are Goldenhar syndrome and Treacher Collins syndrome.

In addition, several medications, such as thalidomide and isotretinoin, have been implicated as causing severe congenital malformations such as microtia; however, these drugs are no longer used or recommended during pregnancy.

Microtia has been reported to occur in 1 per 6000-12,000 births. Although the reason is unknown, microtia is seen more commonly in males than in females. In addition, the right side is affected more commonly than the left. Some studies have reported that the prevalence of auricular anomalies at birth increases with maternal age.

The affected ear usually has severe conductive hearing loss (~40-60 dB) secondary to lack of an external auditory canal (atresia) and ossicular fixation. As long as the microtia is unilateral, these children are likely to have normal speech.

Although some children do not want surgery, parents must discuss the benefits of the reconstructions with them. With good results, all children can have very positive physical and psychological outcomes.

Total auricular reconstruction is one of the most challenging procedures performed by the ear reconstruction surgeon. Understanding the psychological issues faced by patients with microtia and providing education to the parents of these patients are fundamental to a successful microtia practice.

Complete knowledge of the 3D anatomy of the ear and of sound surgical principles of soft-tissue management and tissue transfer is necessary. ^[2]

In children younger than 3-4 years, a microtic ear usually has little psychological impact, and surgery generally is not recommended by surgeons worldwide. After this time, children usually begin to notice that their ears are different. Parents must treat their child with microtia in the same way as they do their other children. Although parents may not realize, children feel the anxiety of their parents. Parents who attempt to cover the ear tend to hinder the confidence of the child. The children with the lowest self-esteem tend to be the ones whose parents transmitted anxiety about the ear throughout their childhood.

Patients whose ears have not been reconstructed as children may have difficulty dealing with the peer pressure of adolescence. During this time, fitting in with their peers is of considerable importance. Teenagers are particularly conscious of their looks and are very aware of their microtic ear. Although they tend to be more eager to undergo surgical reconstruction than younger children, their expectations tend to be more unrealistic.

Accordingly, it is imperative to counsel patients and parents as early as possible. With early counseling, expectations become much more realistic, and the patients are able to deal with certain social issues much more easily.

Microtia is rarely noticed antenatally; when discovered, it is very traumatic for parents. Another major stressor is the feeling of guilt that parents may experience. It is very important to reassure parents that they were not the cause of their child's condition. Such reassurance can be provided only through excellent communication between the parents, the child and the microtia surgeon.

For more information, patients and their parents may visit the Microtia-Congenital Ear Deformity Institute Web site.