Reconstruction of Congenital Auricular Malformations

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Chapter 23

Reconstruction of Congenital Auricular Malformations

E. Fred Aguilar, III

Introduction

Reconstruction of auricular malformations requires a comprehensive knowledge of microtia for selection of the proper surgical approach. Inadequate knowledge and experience of reconstruction of the ear has led to disastrous results. For this reason, the plastic surgeon should be well aware of the many surgical options that exist to treat microtia. This chapter covers ear deformities ranging from simple protruding ears to major congenital deformities. The single most important ingredient for a successful result is the surgical experience of the surgeon. Adequate study and meticulous attention to detail will lead to the best possible outcome. In addition, the plastic surgeon should realize that the care of the patient with an ear deformity might necessitate a team approach that includes an otologist, psychiatrist, audiologist, and radiologist. The family of the patient afflicted with an auricular malformation deserves a coordinated approach and should be aware of the complete plan at the outset of treatment.

Topographic landmarks of a normal ear are shown in Figure 23-1. Development of the auricle is first observed in the 5-week-old embryo. The auricle begins as six mesenchymal proliferations at the dorsal ends of the first and second pharyngeal arches surrounding the first pharyngeal cleft. Initially, the external ear is located in the lower neck of the embryo. As the mandible develops, the ear ascends to the side of the head at the level of the eyes. The commonly accepted embryologic theory (Fig. 23-2) is that the six hillocks correlate directly with the tragus, helix, cymba, scapha, antihelix, and antitragus.¹

FIGURE 23-1 Topographic anatomy of auricle.

FIGURE 23-2 Auricle in 5-week human embryo develops from six hillocks. OV, otic vesicle; AF, auricular fold.

The auricle receives its blood supply from the superficial temporal, posterior auricular, and occipital arteries. The venous drainage of the auricle is by the posterior auricular, external jugular, superficial temporal, and retromandibular veins. The lymphatics of the ear drain anteriorly to the parotid lymph nodes and posteriorly to the cervical lymph nodes. The auricular muscles are innervated by branches of the seventh cranial nerve. The temporal branch of the facial nerve supplies the anterior and superior auricular muscles, and a posterior auricular branch of the same nerve supplies the posterior auricular muscle. Sensory innervation of the auricle is from the lesser occipital, great auricular (C2, C3), and auricular temporal nerves. Arnold’s nerve, a branch of the tenth cranial nerve, supplies the concha.

A normal auricle is shown in Figure 23-3. The vertical axis of the normal auricle is tilted posteriorly approximately 20°. The vertical height of the normal ear is approximately equal to the distance between the lateral bony orbital rim and the root of the helix at the level of the eyebrow (about 6-cm). The width of the ear is approximately 55% of its height. Typically, the helical rim protrudes 1- to 2-cm from the skull, and the angle of protrusion should be between 25° and 30°. The superior aspect of the ear is usually level with the eyebrow.²

FIGURE 23-3 Normal-appearing auricle.

Preoperative Considerations

A number of congenital auricular deformities exist that may require surgical intervention. To achieve the most natural appearing ear possible through surgery, the surgeon must assess the deformed ear for the presence of several important auricular landmarks. Recognizing and grading the deformity will allow the surgeon to craft the proper surgical options. Involving family members of the patient with an ear deformity is important. Eavey ³ observed that children with microtia and significant auricular malformations require comprehensive attention directed to early family counseling and evaluation of the patient for expected and unexpected hearing loss, impaired language development, and associated medical conditions. Both auricular and otologic reconstructive procedures may be necessary and must be coordinated. In 1999, Wang⁴ identified that the early use of an auricular prosthesis is psychologically beneficial to children who have an ear defect resulting from congenital malformation. Wang also described techniques to establish the proper location and orientation of auricular implants used to secure auricular prostheses by using information from computed tomography (CT) scans. The techniques were applied to children and adults to ensure accurate implant placement, leading to improved positioning and orientation of auricular prostheses.

Congenital Malformations

External ear deformities exist in 1% of births. Correcting major congenital malformations of the auricle tests the plastic surgeon’s surgical skills. Microtia has been the subject of numerous publications as clinicians have attempted to establish a method of classification of the severity of a given deformity. Tanzer 5,6 in 1959 published the first scientific article on auricular reconstruction with autogenous rib cartilage. In 1966, Cronin⁷ popularized the use of silicone as an implant material to reconstruct auricles. Brent,⁸ who first reported his work in 1974, is considered the world’s foremost authority on auricular reconstruction.

Classification

In 1988, Aguilar and Jahrsdoerfer ⁹ amended the 1926 grading system used to classify the severity of microtia described by Marx. In 1996, Aguilar¹⁰ reaffirmed this concise classification of congenital ear malformations: grade I is a normal ear; grade II has some of the auricular framework present, but there are obvious deformities; and grade III is the standard “peanut ear” deformity (Fig. 23-4), which encompasses anotia (Marx’s grade IV).

FIGURE 23-4 A, B, Grade III microtia.

In 1977, Tanzer ¹¹ proposed a clinical classification of auricular deformities. This has been used by others and consists of the following:

Anotia

Complete hypoplasia (microtia)

With atresia of the external auditory canal

Without atresia of the external auditory canal

Hypoplasia of the middle third of the auricle

Hypoplasia of the superior third of the auricle

Constricted (cup and lop) ear

Cryptotia

Hypoplasia of entire superior third

Prominent ear

In 1974, Rogers ¹² published a similar classification that divided deformities into four groups: macrotia, lop ear, cup ear, and prominent ear. Weerda¹³ combined all of the classifications proposed by Marx and Tanzer and modified by Rogers.¹⁴ This classification is included for completeness, and demonstrates the awkwardness of classification schemes that are too comprehensive or detailed. Weerda’s system included surgical guidance for each classification:

First-degree dysplasia. Average definition: most structures of a normal auricle are recognizable (minor deformities). Surgical definition: reconstruction normally does not require the use of additional skin or cartilage.

Macrotia

Protruding ears; synonyms: prominent ears, bat ears

Cryptotia; synonyms: pocket ear, group IV B (Tanzer)

Absence of upper helix

Small deformities: absence of the tragus, satyr ear, darwinian tubercle, additional folds (Stahl ear)

Colobomas; synonyms: clefts, transverse coloboma

Lobule deformities; synonyms: pixed lobule, macrolobule, absence of lobule, lobule colobomas (bifid lobule)

Cup ear deformities

Type I: Cupped upper portion of the helix, hypertrophic concha, reduced height; synonyms: lidding helix, constricted helix, group IV A (Tanzer), lop ear, minor (mild or moderate) cupping

Type II: More severe lopping of the upper pole of the ear; rib cartilage is used as support when a short ear must be expanded or the auricular cartilage is limp

Second-degree dysplasia. Average definition: some structures of a normal auricle are recognizable. Surgical definition: partial reconstruction requires the use of some additional skin and cartilage. Synonym: second-degree microtia (Marx).

Cup ear deformity, type III: the severe cup ear deformity is malformed in all dimensions; synonyms: cockleshell ear, constricted helix, group IV (Tanzer), snail-shell ear

Mini-ear

Third-degree dysplasia. Average definition: none of the structures of a normal auricle are recognizable. Surgical definition: total reconstruction requires the use of skin and large amounts of cartilage. Synonyms: complete hypoplasia group II, peanut ear, third-degree microtia (Marx); normally there is a concomitant congenital atresia.

Unilateral: one ear is normal; no middle ear reconstruction is performed on any child; auricular reconstruction is begun at age 5 or 6 years

Bilateral: bone conduction hearing aid before the first birthday; middle ear surgery at age 4 years without transposition of the vestige; bilateral reconstruction of the auricle at age 5 or 6 years

Anotia

The treatment recommendations by Rogers are debatable because of certain alternative options. For bilateral microtia, a bone conduction hearing aid is usually implemented at birth. In addition, even in bilateral cases, middle ear surgery can follow the first two stages of auricular reconstruction rather than being the first procedure.¹⁵

Surgical Reconstruction of Auricular Deformities

In cases of congenital microtia and concomitant atresia, there should be complete coordination between the otologist and the plastic surgeon. Aguilar ¹⁰ in 1996 presented the concept of the integrated auricular reconstruction protocol. As shown in Table 23-1, he recommended that microtia repair be accomplished in five stages. The work of the plastic surgeon should be performed first, and the operations should be staged to facilitate total reconstruction of the microtia-atresia complex.

TABLE 23-1

Treatment of Congenital Malformation of the Auricle

Stage	Treatment
I	Creation of a cartilaginous framework with autogenous rib cartilage
II	Lobule transposition
III	Atresia repair (by otologist)
IV	Tragal construction
V	Elevation

Despite advances made in surgical techniques and middle and inner ear radiographic imaging in recent decades, experienced otologists do not agree on several key issues concerning surgery to restore hearing. These controversial issues include the ideal age for performing middle ear surgery, if and when to operate on cases of unilateral atresia, and the likelihood of success when operating on patients with severe craniofacial malformations. Most agree that the youngest age at which to proceed with otologic surgery is 4 to 5 years. By this age, there is usually adequate mastoid and middle ear pneumatization and the likelihood of adequate patient compliance with postoperative wound care.

The majority of clinicians believe that otologic surgery should be initiated at a younger age in cases of unilateral atresia with evidence of cholesteatoma, infection, or very thin atretic plates. However, opinions differ in regard to treating other cases of unilateral atresia. Jahrsdoerfer believes that the benefit of binaural hearing exceeds the risk of facial nerve injury and other complications that may be a result of otologic surgery to restore hearing. De la Cruz also favors early operations on unilateral atresias if CT findings point to a favorable outcome. Correction of microtia typically begins at the age of 6 years for unilateral cases. The preferred structural material for construction of the ear is autogenous costal cartilage. By the age of 6 years, there is sufficient costal cartilage to permit surgical reconstruction, and the patient is old enough to manage the necessary postoperative care. Patients with bilateral microtia and atresia can be operated on at an earlier age, but only if sufficient costal cartilage exists to serve as grafts for auricular frameworks.

In 1997, Williams et al ¹⁶ reported on the use of polyethylene (Medpor) implants in auricular reconstruction. The implants can be used with skin grafts to reconstruct auricles with deficient auricular cartilage. Animal studies demonstrated that the implant material is well tolerated and could serve as replacement for native cartilage in auricular reconstruction. Williams et al¹⁶ reported that wounds in which polyethylene (Medpor) implants were exposed to the exterior as early as 4 days after implantation could heal by secondary intention and subsequently support a skin graft placed over the implant. The authors concluded that this was possible because of the extent of the fibrous tissue ingrowth from surrounding tissue into the pores of the implant. The porous nature of the implant material served as a scaffolding for ingrowth of native tissue. However, in the clinical situation, the use of this type of implant has been a problem. Exposure of the Medpor implant usually requires débridement and frequently removal of the implant. Historically, the use of other materials for auricular frameworks has generally been unsuccessful. Neither irradiated cartilage nor Silastic implants have stood the test of time. Irradiated cartilage tends to be absorbed over time, and Silastic implants are notorious for their inability to withstand trauma, resulting in a tendency to extrude with time.

Surgical Planning and Treatment

Preoperative planning for reconstruction of auricular malformations includes photographing the patient and preparation of the template used to design the cartilaginous framework. In unilateral cases, the template is based on the patient’s contralateral ear; in bilateral cases, the model is made from the mother’s ear. The site of implantation of the cartilaginous framework on the side of the head should be properly measured to avoid malpositioning of the reconstructed ear.

A high-resolution CT scan of the temporal bones is obtained before surgical reconstruction of the auricle is initiated. Although a CT scan is unnecessary for the repair of microtia, the study provides information to the surgical team caring for the patient. Using the information from the CT scan, the team can determine the course of planned repair and the surgical stages that will be necessary to restore hearing in cases of atresia of the middle ear.

The first surgical stage of auricular reconstruction begins with framework construction from rib grafts and implantation of the fabricated framework beneath the skin at the recipient site. The dissection of rib cartilage is extraperichondrial, and no stripping of the perichondrium of the graft is performed (Fig. 23-5). The technique to sculpt the costal cartilage framework has been described by Brent.¹⁷ The framework is constructed of segments of the sixth, seventh, and eighth ribs, which are joined together with 5-0 stainless steel wire (Fig. 23-6). The framework is placed beneath the skin of the lateral face with proper positioning and orientation as determined by the preoperative patient assessment (Fig. 23-7). When it is performed by trained surgeons, the technique produces reliable results. The most common complication that occurs from the first-stage procedure is atelectasis. Other complications include pleural tear (not a complication unless it is not recognized intraoperatively), pneumothorax, pneumomediastinum, chest wall deformity, hypertrophic scarring, and pneumonia.

FIGURE 23-5 A, B, Costal cartilage harvested from sixth, seventh, and eighth ribs and dissected extraperichondrially.

FIGURE 23-6 By use of template as guide, cartilage framework is sculpted from costal cartilage and assembled with 5-0 stainless steel wire. A-C, Sculpting of left auricular framework.

FIGURE 23-7 A, B, Cartilaginous framework beneath skin for reconstruction of right and left auricles.

The second surgical stage consists of transposing the lobule. To avoid protrusion of the lobule, the incision on the medial aspect of the lobe should be fairly high. The inferiorly based pedicle of the earlobe flap is quite thin; thus, great care is taken in its handling (Fig. 23-8).

FIGURE 23-8 A, Cartilaginous framework beneath skin and malpositioned lobule. B, Drawing showing incisions for transposition of lobule. C, Lobule transposed. Superior aspect of malpositioned lobule discarded.

On completion of the first two surgical stages for reconstruction of the auricle, attention is then turned to the surgery required to restore hearing in cases of associated atresia of the middle ear. This is considered the third stage of treatment and is performed by an otologist. The location of the temporal bone remnant dictates the location for the opening of the external canal in the overlying skin. It is easy to manipulate the fabricated framework and position it so that an otologist may properly reconstruct the external auditory canal. If the external canal is created before the first two stages of auricular reconstruction, the complication rate of microtia repair is much higher. This is because it is difficult to properly position and orient the auricular framework around an external auditory canal as a result of the adjacent scarring created by the canal surgery. The scarring also impairs the vascular supply to the region of reconstruction, and this may contribute to an increased risk of complications.

The third stage of auricular reconstruction (fourth stage of treatment) is performed after the creation of the external auditory canal. It is directed toward reconstruction of the tragus (Fig. 23-9). This is accomplished by obtaining a composite auricular graft from the opposite ear. The composite graft is fashioned into a triangle-shaped graft, which is transferred to the appropriate location at the reconstructive site. Auricular elevation with creation of a supra-auricular and postauricular sulcus is performed during stage V of treatment (Fig. 23-10). This is accomplished by dissecting the cartilaginous framework with the overlying skin as a large composite flap. The flap is elevated away from the head superiorly and posteriorly, creating a tissue void where the anticipated superior and posterior sulci will be. The area of the tissue void as well as the medial aspect of the dissected flap is covered by a full-thickness skin graft.