Microtia Surgery in Children

Microtia is the most common major congenital deformity of the external ear, but it is rare enough that parents usually have never encountered it. It is rarely noticed on antenatal ultrasonography (US).

Because of the rarity of microtia, most parents and some healthcare providers may not fully understand how to care for children with this condition. However, technical advances in the reconstruction of the microtic ear have led to dramatically improved results in the hands of experienced ear reconstructive surgeons. Given the fine details that must be addressed in microtia reconstruction, it is essential for the surgeon to have a complete understanding of the three-dimensional (3D) form of the auricle and an awareness of sound surgical principles of soft-tissue management and transfer. The future of microtia surgery holds much promise.

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 state 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 is 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.

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.

Consultation regarding a patient born with microtia and atresia ideally should occur soon after birth. This allows the ear surgeon to discuss the options with the parents and to calm their fears and anxieties.

The initial examination consists of a detailed head-and-neck examination. The most important things to be determined in this examination are as follows:

• Type of microtia
• Presence or absence of atresia
• Size and location of the normal ear (in unilateral cases)
• Level of the hairline on each side

Although severe conductive hearing loss usually results from lack of an ear canal, the inner-ear function is almost always normal, resulting in some ability to hear on the affected side.

Because approximately 90% of children with microtia are affected only on one side, the contralateral ear is almost always normal, resulting in relatively normal speech development. During the initial consultation, the ear reconstructive surgeon should reassure the parents and outline the future management of their child's condition.

If microtia is the only developmental anomaly, the initial workup consists of evaluation of the child's hearing status. As previously stated, the inner-ear function is usually normal in patients with microtia and atresia. Also, the middle-ear status of the nonaffected ear is usually normal, resulting in overall normal hearing in the nonaffected ear.

Microtia is classified into four grades along a spectrum that extends from less severe (grade I) to total absence of the external ear (anotia).

Grade I

In grade I, the pinna is malformed and smaller than normal. Most of the characteristics of the pinna, such as the helix, triangular fossa, and scaphae, are present with relatively good definition (see the image below).

Grade II

In grade II, the pinna is smaller and less developed than it is in grade I. The helix may not be fully developed. The triangular fossa, scaphae, and antihelix (anthelix) have much less definition (see the image below).

Grade III

Grade III is considered the "classic" microtia. The pinna is essentially absent, except for a vertical sausage-shaped skin remnant. The superior aspect of this sausage-shaped skin remnant consists of underlying unorganized cartilage, and the inferior aspect of this remnant consists of a relatively well-formed lobule (see the image below).

Anotia

In anotia, total absence of the pinna is observed (see the image below).

It is not uncommon to refer the patients to a geneticist for evaluation of a syndrome associated with microtia and atresia. These specialists may also offer the parents an opinion about having another child with microtia.

Microtia is rarely noticed on antenatal ultrasonography (US), primarily because of the complexity of the fetal ear and the inherent nature of conventional two-dimensional (2D) US. Some authors suggest the use of three-dimensional (3D) US to provide a better examination of the fetal ear for purposes of antenatal diagnosis and genetic counseling. The image below is a 3D sonogram, with the arrow indicating the microtia.

Computed tomography (CT) of the ears is not recommended in children younger than 4 years. Obtaining a CT scan at an earlier age does not allow any earlier surgical intervention and therefore serves only to irradiate the child's head unnecessarily. Obtaining the scan just before the pinna reconstruction is recommended so as to facilitate counseling of the patient about candidacy for ear-canal and middle-ear surgery. The image below shows the lack of an ear canal on the left side.

An auditory brainstem response (ABR) test is recommended soon after birth to evaluate inner-ear (cochlear) function on both sides.

Frequent otologic evaluations are essential to rule out other possible problems, such as otitis media in the good ear. In the case of ear-canal narrowing or stenosis, it is important be aware of foul-smelling drainage. This could be a sign of a cholesteatoma growing medial to the stenosis.

Aggressively treat middle-ear effusions of the normal ear to optimize the hearing status of the child and avoid speech delay. An ABR test is usually recommended approximately 3-6 months later. If the child is cooperative, audiologic testing can then be performed by sound-field testing and eventual bilateral pure-tone audiometry. Routine scheduled audiologic follow-up testing should be continued.

Indications for surgery

Unilateral microtia

Auricular reconstruction for unilateral microtia usually begins in children aged 6-7 years, depending on the child's size. Because the pinna reaches about 85-90% of its adult size at this age, surgery earlier than 6-7 years of age is generally not recommended or accepted worldwide. By this age, the child is usually large enough that rib size is sufficient to allow harvesting of an adequate rib graft. If the child is still small, the surgical procedure is postponed until an adequate rib for the framework can be harvested.

For example, if a very small 6-year-old child presents with microtia, postponing auricular reconstruction until 7-8 years of age, when rib growth is sufficient, is reasonable. On the other hand, if a very large 5-year-old child presents with microtia, the surgeon may consider reconstruction sooner because of adequate rib size; however, this is not the norm.

The ideal time to begin the reconstruction is the summer before the first grade. By the time the child starts the first grade, at least two of the three surgical procedures can be completed, allowing the child to have the semblance of an ear. Children tend to be teased during these early school years when the ear is not yet reconstructed.

Bilateral microtia

Surgical reconstruction in children with bilateral microtia is also started around 6-7 years of age, depending on their size. Before the pinna reconstructions, computed tomography (CT) of the temporal bones is performed to evaluate for ear-canal and middle-ear reconstructive surgery.

The ear reconstructions using the natural cartilage technique are started before the ear-canal surgery (atresiaplasty). If an attempt is made to open the canal before the external ear reconstruction, the elasticity of the "virgin" skin and the circulation are compromised. In addition, the scar tissue resulting from the ear-canal surgery makes it more difficult to attain the ideal result.

Because these children are dependent on bone-conduction hearing aids, the goal of starting earlier is to finish at least one ear. The canal may be opened soon after the ear is reconstructed. Obtaining adequate hearing without hearing aids is the eventual goal. If the child is not a candidate for atresia surgery, the bone-anchored hearing aid (BAHA) is also an option.

Contraindications for surgery

Contraindications for rib surgery for microtia reconstruction include high-risk surgical status and chest-wall deformities. In addition, patients with pulmonary hypoplasia are not candidates for rib-cartilage surgery, because of the potential risk of a pneumothorax (though in the hands of an experienced microtia surgeon, this event is extremely rare).

There are several options for hearing correction in patients with unilateral microtia and atresia, as follows:

• No intervention - Because the child has a normal-hearing ear, the use of the softband with auditory processor is optional
• Nonsurgical bone-conduction system that does not require a band or a surgical procedure
• BAHA Softband - This is basically a headband with a vibratory auditory processor
• Ear-canal surgery (ie, atresiaplasty or canalplasty) - A CT scan of the temporal bones must be obtained to evaluate the anatomy of the middle ear and inner ear and identify the location of the facial nerve; whether the child is a candidate for ear-canal surgery depends on the favorability of the anatomy
• Bone-anchored auditory processor - This is an option if the child is not a candidate for ear-canal surgery or if the family prefers this option regardless of candidacy for the ear-canal procedure; the earliest age at which a child with microtia and atresia can undergo this option is 5 years because of the thinness of the skull at this age
• Middle-ear implant system - This system is not yet approved by the US Food and Drug Administration (FDA) and is generally not a primary option

Similar options are available for hearing correction in patients with bilateral microtia and atresia, except for the no-intervention option, as follows:

• BAHA Softband
• Ear-canal surgery
• Bone-anchored auditory processor
• Middle-ear implant system

The most common options are the bone-anchored auditory processor and the ear-canal surgery.

Surgical options

Surgical options for treatment of microtia and atresia are as follows::

• Natural cartilage technique (rib technique) - For the past 50 years, this technique has been the "gold standard," and it continues to be the most widely accepted microtia repair technique worldwide; approximately 98-99% of microtia surgeons utilize the natural cartilage technique as their preferred choice
• Alloplastic implant (porous polyethylene implant) ^{[2, 3]} - This technique is used by a few surgeons, though it is not widely accepted, because of the plastic foreign body material and the hardness of the implant; there is a risk of infection, rejection, or fracture over the lifespan of the implant
• Prosthetic - This technique is usually reserved for failed reconstructions; a few surgeons use it as the initial option, but this is very rare
• No surgical intervention - Because microtia surgery is elective, the option of watchful waiting by the patient should always be offered

Unilateral microtia and atresia

Tanzer and Brent advocated multistage reconstructions, which are currently favored by most ear reconstruction surgeons worldwide. Some surgeons favor a two-stage procedure. Microtia reconstruction using the natural cartilage technique involves three surgical stages. To optimize the healing process, there is a 2-month interval between stages 1 and 2 and between stages 2 and 3. The three stages in the author's preferred approach are as follows:

• Stage 1 - Rib-cartilage harvesting with carving and sculpting of the main ear framework, including the tragus, and insertion under a skin pocket on the side affected by microtia
• Stage 2 - Formation of the lobule (ie, earlobe) and deepening of the conchal base
• Stage 3 - Separation and elevation of the ear with insertion of an implant wedge and a postauricular full-thickness skin graft

In cases of bilateral microtia, the surgical procedures are combined in order to minimize anesthesia time. 

Stage 1: rib-cartilage harvesting and framework insertion

The first stage consists of two separate components, as follows:

• Harvesting the costal cartilage
• Inserting the carved sculpted cartilage into a skin pocket on the microtia side

A small, slightly oblique incision is made over the sixth, seventh, and eighth ribs (see the image below). When the child is thin, the incision is usually very small (~1.0-1.5 in. [~2.5-3.5 cm]). The incision is made on the side opposite the microtia because this provides the convexity required for the normal ear. In other words, if the patient has microtia on the right side, the costal cartilage is removed from the left chest area.

The synchondrosis of the sixth and seventh ribs and the cartilaginous portion of the eighth rib are harvested according to a previously measured template (see the image below).

A small piece of synchondrosis is used to form the tragus. The cartilaginous part of the eighth rib is used to form the rim or helix. The three pieces of rib are carved, sculpted, and sutured together to yield a cartilaginous framework in the shape of an ear (see the image below).

The first stage concludes with placement of the newly formed ear under the skin pocket (see the video and the image below).

Because an epidural injection is placed while the child is under general anesthesia, it is very common to for the child to wake up without any pain or discomfort. Patients are sent home with pain medication as needed and antibiotics. An ear dressing without pressure is applied during surgery and left intact for about 3 days. At that time, the wound is checked and the ear is rebandaged.

The drain stays in place for about 5-7 days to provide negative suction so that the skin can coapt to the newly inserted framework. The child is seen 1 week after surgery to remove the drain in the office. The sutures are removed on postoperative day 7. In the image below, obtained at the 1-week postoperative visit, it is apparent that the ear has a very natural shape and that the skin color is normal.

The child usually resumes normal activity within 1 week, though heavy contact sports are restricted for approximately 4-6 weeks. The hair may be washed 1 week after surgery. The second stage of the reconstruction may be carried out approximately 2 months later.

Stage 2: formation of lobule and deepening of conchal bowl

The second stage consists of formation of the earlobe (transposition of the lobule). An incision is made both in front of and behind the skin vestige (see the image below). The skin vestige is rotated into place via a Z-plasty and spliced to the cartilaginous framework that was sculpted during the first stage. The conchal bowl is deepened as well, and the tragus is refined.

The image below shows the new ear 2 weeks after the second stage. It may be seen that the earlobe is in its natural location, the tragus is well formed, and the conchal bowl is naturally deepened.

Patients are sent home the same day, and pain medication is rarely needed. An ear dressing is placed for 3 days. Sutures are removed on postoperative day 7. Patients may resume normal activities after 1 week if the ear is protected with a protective cup. The hair may be washed soon after surgery. The third and final stage of the reconstruction may be carried out approximately 2 months later.

Stage 3: separation and elevation of ear

The final stage of the repair consists of elevating the newly formed ear from the side of the head. A full-thickness skin graft is harvested from the groin area so that the incision site can be hidden (see the image below).

An incision is made behind the newly constructed ear, and the undersurface is undermined. A small, custom-designed alloplastic wedge is placed behind the ear and covered with a conchal-based flap. The full-thickness skin graft is then placed and sutured with 6-0 polypropylene sutures. Once the graft is secured, a sterile sponge is placed to prevent a seroma or hematoma. An ear dressing without pressure is applied. (See the video and the image below.)

The surgical procedure lasts approximately 2 hours, and the patient goes home the same day with pain medication as needed and antibiotics. The sponge behind the ear is removed in 1 week, and the sutures are removed 1 week later. Contact sports are avoided for about 4 weeks. The hair may be washed a few weeks after surgery.

The images below are "before" and "after" pictures of a patient with grade III microtia and atresia treated by means of the natural cartilage technique.

Bilateral microtia or atresia

Children born with bilateral microtia or atresia are treated differently from those with unilateral microtia or atresia. CT of the temporal bones is performed before the onset of the first microtia surgery. The CT scan will reveal the anatomy of the outer, middle, and inner ear.

To minimize surgical intervention, combination stages are performed in patients with bilateral microtia. In other words, after the first stage of surgery on one side, the contralateral first stage and the ipsilateral second stage may begin within 4-6 weeks. After an interval of 2 months, the next combination stage, consisting of the contralateral second stage and the ipsilateral third stage, is performed. After another 2 months, the contralateral third stage is performed.

After 3-4 months, the ear canal may be drilled to improve hearing status (if the anatomy is favorable). Although beginning the middle-ear surgery early for hearing improvement is advantageous, the surgical risks must be considered. The most common risk associated with middle-ear surgery is restenosis of the external auditory canal. The most detrimental risk is actual damage to the facial nerve, though such damage is extremely rare. As a result, the CT scan must be examined carefully so that the location of the facial nerve can be tracked.

Ongoing technical developments

Technical options for microtia reconstruction are being developed and studied. One of the more exciting developments in the treatment of microtia is the research involved in three-dimensional (3D) printing of cartilage cells that are harvested from the actual patient (see the image below). If this becomes the norm, it is very likely that rib cartilage harvesting and the plastic porous polyethylene allplastic implants will become obsolete.

Cao et al described a tissue-engineered autologous cartilage to use in place of harvested rib cartilage.[4] In this approach, autologous chondrocytes are harvested and seeded into a mesh that is shaped in the form of the normal ear. This new framework is then inserted under the microtic vestige as a first-stage procedure. Other investigators have also reported promising results with similar approaches.[5, 6]

Natural cartilage technique

If done correctly, this option gives the best and longest-lasting results with minimal complications. Potential complications include an unpleasant aesthetic result, infection, and bleeding. A pneumothorax during rib excision is a very rare complication.

Alloplastic porous polyethylene implant

Because the polyethylene is a foreign material, the risk of infection, rejection, and fracture (see the video below) exists for life. Loss of hair, loss of sensation, or an unsightly scar on the scalp can also occur as a complication of the harvesting of the temporoparietal fascia flap. Another common complaint is that the plastic material used to reconstruct the ear is very hard and that it hurts to sleep on the side of the alloplastic implant.

There are several specialists that should be involved in the management of a child with microtia and atresia, including the following:

• Neonatologist - This specialist is in charge of alerting pediatrician and other specialists to the microtia
• Primary care physician (pediatrician or family physician) - This individual is usually the primary doctor who refers to all of the multiple specialties
• Geneticist - This individual performs a detailed family history, rules out other syndromes, and assesses the chances of having another child with microtia
• Microtia/ear reconstruction surgeon - This specialist must be involved early on so as to educate the parents about the treatment of microtia
• Otolaryngologist/neurotologist - This specialist monitors for ear infections and hearing loss and is also involved with ear canal surgery recommendations
• Audiologist - This professional performs hearing tests
• Speech/language therapist - This professional is involved if there is a concern about speech delay
• Psychologist (rarely necessary) - The participation of this specialist may be required if there are psychological issues with the child or the family