Microtia 

Updated: Dec 03, 2019
Author: Samuel J Lin, MD; Chief Editor: Deepak Narayan, MD, FRCS 

Overview

Problem

Microtia is a congenital malformation of variable severity of the external and middle ear. The microtic auricle consists of a disorganized remnant of cartilage attached to a variable amount of soft tissue lobule, which often is displaced from a position symmetrical with the opposite normal ear. The direction of displacement depends on the degree of associated facial hypoplasia. Depending on the severity of the anomaly, there may be evidence of external meatus formation. Microtia commonly involves the external canal and middle ear; hence, hearing can be affected. Microtia may present within a spectrum of branchial arch defects (hemifacial microsomia, craniofacial microsomia) or may manifest as an independent malformation.[1]

This article concentrates on the reconstruction of the external ear only, referencing middle ear reconstruction as it pertains to planning and reconstruction of the auricle. A review of the pertinent history, embryology, and anatomy is included.

Reconstruction of the ear, whether it be for microtia or major acquired deformities, has long been recognized as a demanding undertaking with well-recognized shortcomings, even in the hands of some very accomplished surgeons. Some of the shortcomings are inherent in the underlying tissue shortages, some are in the limitations of the donor tissues, and some are specifically operator-dependent. Even more demanding is the reoperation for a previously unsatisfactory result, as the recipient bed is now scarred, the donor tissues more limited, and the expertise of the operating surgeon even more critical.

Epidemiology

Frequency

Melnick and Myranthopoulos reviewed auricular deformities and associated anomalies in a series of 56,000 pregnancies in an ethnically diverse population (Caucasian 46%, African American 46%, Latino 8%), commenting on the incidence of anomalies and the embryogenesis and etiopathology of the varying deformities.[2] Ear deformities occurred in approximately 1.1% (11 in 1000) of births. Severe anomalies, such as microtia, occurred in approximately 3 in 10,000 live births. Occurrence has been reported to be 1 in 4000 in the Japanese population and as high as 1 in 900 to 1 in 1200 in the Navajo population.

Almost one half of the microtia patients in the Melnick and Myranthopoulos study (9/16) presented with craniofacial microsomia, also known as facial-auricular-vertebral syndrome. In the same study, the right side was affected almost twice as often as the left, and bilateral deformity occurred in 10% of patients, with the reported ratio of right-to-left-to-bilateral of approximately 5:3:1. Many sources report that vertebral, urogenital, and renal anomalies occur within the craniofacial microsomia syndrome, although this was not confirmed in this cohort.

Etiology

Both hereditary factors and vascular accidents in utero have been suggested as factors in the etiology of microtia. Several groups have studied their microtia patients as probands, finding evidence for familial craniofacial microsomia and patterns suggestive of multifactorial inheritance.

Specific causative factors also can include maternal rubella during the first trimester of pregnancy; Brent has reported thalidomide exposure during pregnancy as a cause.[3] Poswillo points to the varied timing of teratogenic insults in patients with ear deformities associated with mandibulofacial dysostosis (Treacher Collins-Franceschetti syndrome) and more common forms of branchial arch anomalies in hemifacial microsomia.[4]

A report by Ryan et al using the National Birth Defects Prevention Study indicated that risk factors for anotia/microtia also include male gender, multifetal pregnancy, parents of Hispanic ethnicity or of non-US birth, maternal obesity, and prepregnancy diabetes. The likelihood of the condition was lower in children of black mothers or mothers who reported taking daily supplements containing folic acid.[5]

Pathophysiology

Embryology

A review of embryology allows a better understanding of the pathophysiology of microtia. The anatomy of the microtic ear is similar to the anlage seen in the 6-week embryo. Microtia often is associated with atresia or absence of the external auditory meatus, suggesting an arrest of development.

The external and middle ear develop from the first (mandibular) and second (hyoid) branchial arches. The auricle begins development at 5 weeks from 6 hillocks, 3 on either side of the first branchial cleft between these 2 arches, which becomes the external canal. Ultimately, the hillocks of the first arch contribute to the tragus and the root of the helix, and the remainder of the auricle develops from the hillocks of the second arch. The middle ear ossicles develop from the first and second arch with the mastoid air cells, eustachian tube, and remaining middle ear developing from the first pharyngeal pouch. The tympanic membrane develops where the first pouch meets the first cleft.

Initially, the ear has a ventromedial position, which becomes more dorsolateral as the midface and mandibular processes grow and push it outward and upward. Interruption in the proliferation or fusion of the hillocks at varying stages of development can produce the variable rudimentary structures that present as microtia.

Pathophysiology

Microtia has been divided into two descriptive categories. More frequently, the lobular type presents as a soft tissue mass without any concha or auditory meatus formation within the cartilage remnant. See the image below.

Lobular type microtia. Lobular type microtia.

Less often, the conchal remnant type presents with more recognizable portions of a conchal bowl, tragus, and external meatus. See the image below.

Conchal remnant type microtia. Conchal remnant type microtia.

In most patients with isolated microtia, the ear remnant is positioned with relative symmetry or somewhat superiorly to the contralateral ear.

The descriptive term auricular dystopia has been applied in cases associated with significant craniofacial microsomia. See the image below.

Auricular dystopia definition. Auricular dystopia definition.

The mandible, maxilla, facial musculature, and facial nerve, which also are derived from the same branchial arches, are affected in patients with craniofacial microsomia and microtia. Some consider isolated microtia to be a mild expression of the continuum of craniofacial microsomia. In auricular dystopia, the microtic ear is placed inferiorly and anteriorly compared to the unaffected side. The underlying bony hypoplasia of the temporal bone and mandible exacerbate this situation, presenting a further challenge to the reconstructive surgeon.

Because the inner (neural) portion of the ear develops on a different time scale and from different ectodermal tissue, most patients have some hearing in the affected ear. In the case of bilateral microsomia, acceptable hearing can be achieved with bone conduction hearing aids and eventual canal, ossicular chain, and tympanic reconstruction. Typically, auditory surgery is performed after auricle reconstruction. Many patients with unilateral defects and normal hearing on the unaffected side do not pursue middle ear and canal reconstruction. Insufficient improvement on the affected side with the surgical technology currently available still leaves the patient effectively monaural.

Presentation

Most patients present as infants or children. The head and neck examination should be complete; search for other evidence of craniofacial microsomia including facial asymmetry, epibulbar dermoids, malocclusion, facial nerve weakness, and macrostomia.

Vestige with meatus and canal. Vestige with meatus and canal.
Integrating auricular reconstruction with distract Integrating auricular reconstruction with distraction osteogenesis.

Consultation with a geneticist is often helpful to identify special subsets of microtia patients, such as those with Goldenhar syndrome. Genetic consultation is also helpful to the family to identify risk to future progeny of the parents and of the proband.

Using three-dimensional (3-D) chest computed tomography (CT) scanning, a study by Wu et al found a high incidence of congenital thoracic deformities in patients with microtia. The study included 239 patients with microtia, 68 of whom (28.5%) were found to have thoracic deformities, including rib and/or spinal deformities. The incidence was highest in cases involving a more serious grade of microtia.[6]

Indications

Both functional and psychological considerations enter into the decision to correct microtia. Functionally, without the presence of an auricle and its postauricular sulcus, the patient's ability to wear glasses and hearing aids is impaired. Psychologically, the absence of an ear is significant for both males and females. Even after adjusting hairstyles, the absence of an ear is noticeable to peers and others. Like other patients with blatant anomalies, many children with microtia have lower self-esteem and develop either behavioral problems or become excessively introverted.

Timing of reconstruction presents some relative contraindications. In the United States, most of the presenting patients are children although many untreated adults are seeking reconstruction. For symmetric reconstruction, a good estimate of the size and position of the contralateral ear must be made. See the image below.

Reconstruction of microtia. Reconstruction of microtia.

The ear reaches approximately 85% of adult size at age 3 years. Growth continues into adulthood but little change in the width or distance from the scalp occurs in individuals older than 10 years. For practical purposes, the normal ear is developed fully by age 6-7 years. To perform an autologous reconstruction, sufficient cartilage must be available. Generally, the costal cartilages are adequate by the time the patient is aged 10 years. The surgeon must balance concerns regarding the psychological impact of the deformity with having sufficient cartilage to carry out the optimal reconstruction in the fewest number of surgeries.

Optimal reconstruction requires costal cartilage of sufficient size and shape to carve the key framework details and maintain the strength to display these details through the overlying skin envelope. While some surgeons begin the reconstruction when patients are aged as young as 5-6 years, clearly better results can be obtained if the reconstruction is performed when patients are aged 9-10 years or older.

Clearly, the potential psychological issues of the child dealing with his or her deformity need to be balanced with the benefits of delaying the surgery for a few more years. As surgeons who have gradually made the transition of performing reconstruction at the lower end of that spectrum to feeling strongly that the surgery is better delayed, the authors think most children deal with the delay of the reconstruction without ill effects. Parents must be told that the best chance for an ideal reconstruction is the first attempt, even if this means delaying the surgery for a few years. They should be reminded that once the reconstruction is complete, children benefit from the improved outcome for the rest of their lives.

Opinions vary between surgeons as to the optimal sequence of procedures for reconstruction of the microtic ear. While the approach championed by Dr. Brent is well illustrated in the literature,[3] with excellent long term results, newer approaches by Drs. Nagata[7] and Firmin[8] have been followed by others, with possibly better results. The basic steps required are similar, but the staging and manner in which those steps are accomplished vary. While the senior author has adopted an approach closer to the latter, we will comment about the former as well.

The reconstruction of microtia, regardless of the type and associated deformities, requires 2 main elements. The first is sculpture of a framework from autogenous rib cartilage to reproduce the contours of the ear, and the second is coverage of the framework with the cutaneous remnant and adjacent skin. The greater part, if not the complete reconstruction, can be accomplished in 2 stages, with only minor revisions generally required beyond these 2 surgeries. Key to all reconstruction is the proper planning, and, ultimately, positioning of the reconstructed ear. This is even more critical in cases in which more significant facial hypoplasia is associated with the ear deformity.

Relevant Anatomy

The external ear consists of an elegant, 3-dimensional cartilage framework with a soft tissue lobule. An intricate terminology has developed to describe the convolutions of the auricle and is best reviewed visually.

Auricular structure. Auricular structure.

The skin on the anterior surface is densely adherent and sebaceous. The skin on the posterior or cranial aspect is applied more loosely and is generally glabrous. Dividing the structure into 3 levels or complexes helps to analyze the components necessary for recreating it; the most cranial level is the conchal bowl complex, followed by the antihelical-antitragal complex and finally, the helical rim-lobule complex.

The proportions and relative position of the ear to the face, jaw, and scalp are important in planning its reconstruction. They have been recited in multiple texts and are summarized best by Tolleth.[9]

Dimensions and proportions of the external ear. Dimensions and proportions of the external ear.

The height of the ear is approximately equal to its distance from the lateral brow at the level of the helical root. Its width is approximately 55% of its height. Its top aligns with the brow, and the lobular tip aligns with the columella. The mature ear typically is 5-6 cm long. The helical rim protrudes approximately 2 cm from the skull at an angle of 21-25°. The long axis of the ear does not parallel the nasal dorsum but is approximately 15-20° posteriorly rotated from the perpendicular axis of the body.

The blood supply to the external ear is from the postauricular artery, with minor contributions from branches of the superficial temporal artery. Venous egress is via the postauricular veins into the external jugular system. Lymphatic drainage follows the embryology with the derivatives of the first arch draining through the parotid nodes and the second arch derivatives through the cervical nodes.

The external ear is innervated by the great auricular nerve (C2-C3), the auriculotemporal nerve (V3), the lesser occipital nerve, and the auricular branch of the vagus nerve (Arnold nerve).

A study by Otto et al of patients with lobular-type microtia indicated that the affected ear has less than half of the available skin surface area that a healthy ear has. Imaging plaster ear models with a microcomputed tomography scanner or a cone-beam computed tomography (CT) scanner, and then converting the images into mesh models, the investigators determined that healthy, adult-sized ears in the study had a mean total skin area of 47.3 cm2, compared with an average of 14.5 cm2 for ears with microtia.[10]

Contraindications

The only absolute contraindication to ear reconstruction is a health condition preventing the patient from undergoing a series of 2-3 surgeries under general anesthesia. The remaining contraindications to ear reconstruction are relative.

As in all plastic surgery, the outcome of surgery depends on patient selection. Relative contraindications to surgery include lack of family support, inability to follow through with surgical care, and unwillingness of the child.

 

Workup

Imaging Studies

See the list below:

  • Thorough workup includes an evaluation of the kidneys and collecting system via ultrasound.

  • Evaluation of the cervical, thoracic, and lumbar spine by plain radiographs rules out occult malformations.

  • In patients with craniofacial microsomia, 3D CT scans aid in surgical planning.

Diagnostic Procedures

See the list below:

  • Infants should have baseline audiology evaluation of the affected and unaffected ears. Address hearing deficits promptly to prevent speech problems.

 

Treatment

Surgical Therapy

Reconstruction of the external ear can be performed in 1 of 3 fashions: prosthetic replacement, reconstruction with a prosthetic framework, or local tissue and/or flap coverage or reconstruction with an autologous framework. The latter of these methods is the criterion standard by which the former methods are judged. This article concentrates on autologous reconstruction after a brief discussion of prosthetic replacement and prosthetic frameworks.

Prosthetic ear replacements

Prosthetic ear replacements, when made well, can appear quite natural. The newer osseointegrated anchoring systems are more reliable than older adhesive-based systems. The procedure requires placement of a titanium anchor within the drilled temporal bone. After integration of several titanium posts, the surface magnet system and prosthesis can be attached. A prosthesis to replace an auricle alone without an integrated hearing aid (ie, without sensory input to the child) is likely to be ignored and not used by a child.

Children prefer not to wear them, and they frequently lose the prostheses, which are rather expensive to replace, to the consternation of parents and physician alike. However, in a patient otherwise dependent on hearing aids, a bone-conduction hearing aid can be built into an auricular prosthesis. Generally, this reconstructive option actually is better suited to adult patients with defects after radical extirpation or traumatic anotia.

Prosthetic frameworks

Cronin and Brauer reported prosthetic frameworks for auricular reconstruction in the mid-1960s; they then abandoned them because of the likelihood of erosion and exposure necessitating explantation in virtually all patients if observed long enough. Newer alloplasts also have been marketed with the promise of better tissue integration and spontaneous healing because of vascular ingrowth. The junior author's experience with Porex, reported to heal spontaneously at small sites of exposure, has been disappointing. The ability to have an anatomically designed, prefabricated framework is indeed appealing but the thin skin covering this foreign body and the exposed nature of the ear make the longevity of this reconstruction dubious.

Yang et al described the use of combined fascial flap and expanded skin flap for enveloping Medpor framework in microtia reconstruction.[11] No exposure or extrusion of the framework was observed during the postoperative follow-up for 3-12 months, but longer follow-up is required to establish the long-term success of the results.[11]

Romo et al described a 2-stage plastic-otologic approach to microtia-atresia with excellent cosmetic results and hearing outcomes. No major Medpor complications were reported. The first stage involved placement of a Medpor framework beneath a temporoparietal fascia flap, followed by a second-stage procedure for lobule transposition and bone-anchored hearing aid (BAHA) implantation.[12]

Autologous reconstruction

The criterion standard for external ear reconstruction is autologous reconstruction with cartilage. First reported by Pierce in the 1930s[13] and expanded upon by Converse[14, 15] and Tanzer in the 1940s,[16] autologous cartilage reconstruction came to the forefront with Brent in the 1980s.[3] Refinements in framework carving and techniques by the senior author, Nagata, and Firmin have increased the artistry and reliability of autologous ear reconstruction. See the image below.

Cartilage framework construction, Bauer technique Cartilage framework construction, Bauer technique (left) and Nagata technique (right).

All autologous reconstructions have 3 main elements in common: (1) construction and placement of a cartilage framework; (2) lobule rotation, conchal excavation, and tragus formation; and (3) elevation of the pinna. The following discussion of surgical planning and technique centers on the senior author's experience and current strategies. Explanations are given when significant differences exist between other current popular techniques.

Numerous classification schemes have been used in the description of the microtic vestige. As the technique, planning, staging, framework construction, and incisions depend on the deformity treated, the authors will briefly review the common classifications.

Brent has classified the remnants into classical and atypical microtia.[3] The classical remnant is a sausage-shaped vestige, usually with absence of the external auditory canal. The larger portion of the vestige is lobule and the cartilage remnant is amorphous. The atypical vestige presents with more recognizable portions of the concha, antihelix, tragus, and antitragus, with the upper portion of the recognizable ear absent. The canal may or may not be present.

Nagata and many other surgeons have separated microtic ears into lobular and conchal remnant type deformities, categories which correspond to the classic and atypical deformities, respectively. The conchal remnant type is further divided into small and large type, depending on the degree of conchal development.

Firmin has developed a perhaps more useful classification based on the type of incision required for placement of the cartilage framework. She has divided all vestiges into Types 1-3, with Type 1 roughly corresponding to the incision for lobular type vestige, Type 2 incision for the large conchal remnant deformity, and Type 3 incision for the small conchal remnant deformity and varied atypical vestiges. A full appreciation for this type of classification comes with considerable experience with the spectrum of reconstruction techniques.

To the above, the senior author has long emphasized that the staging, as well as the type of reconstruction, needs to be modified in the face of significant degrees of associated facial hypoplasia. The displacement of the vestige, regardless of its overall form, requires special attention if the final reconstruction is to be in a position symmetrical with the uninvolved side. The term auricular dystopia has been chosen to describe both normal well-formed auricles and microtic vestiges, in which medial, inferior, and anterior displacement is secondary to the underlying deficiency of the facial skeleton (particularly the temporal bone). These remnants may or may not have an associated meatus and canal, and the presence of a dystopic canal must be addressed in the planning of the reconstruction.

In order to plan the first stage of reconstruction, take a radiograph (or other transparent celluloid material) template to fashion a pattern that demonstrates the proper symmetrical position for the reconstructed ear. The template demonstrates the key elements of the shape of the ear and the ear's relationship to the other facial structures (lateral brow, lateral canthus, alar base, nasal dorsum). This template of the normal side can then be transferred to the affected side, and the position for the reconstruction can be marked and the incisions planned. A second template is fashioned for the cartilage framework itself.

In most cases where microtia is present with only mild associated hemifacial microsomia, the remnant is positioned a bit anterior and superior to the proposed reconstruction. In cases where the hemifacial microsomia is moderate to severe, the dystopic remnant is usually anterior, inferior, and also medial (in the sagittal plane). This can be clearly demonstrated preoperatively with fabrication of the template.

The main elements of the staged reconstruction will be reviewed, explaining differences in the approach with each of the different deformities. The main emphasis is on treatment of the more typical forms of microtia, but some additional comment will be made regarding the treatment of the dystopic remnant.

Preoperative Details

Planning of the placement of the new ear is essential to optimal esthetic outcome. If the ear is misplaced with regard to the opposite ear or orbital and facial landmarks, the most exquisitely detailed auricle reconstruction appears abnormal.

  • Design one template for the placement of the ear and another for the cartilage framework. Unexposed developed radiograph film, which can be "flash-sterilized," is convenient for use in the operating room.

  • Fashion the templates from the normal side and transpose them to the affected side. The first template includes marks for the lateral orbit, brow, and the root of the helix. See the image below.

    Reconstruction of microtia. Reconstruction of microtia.
  • After transposing this information, mark the area for the pocket. Usually the pocket is under hair-bearing scalp in its posterosuperior aspect. Do not allow the hairline to guide the placement of the pocket, as that places the new ear inferior and anterior to the opposite side.

A retrospective study by Moon et al suggested that 3-D CT scanning of the rib cage is an effective means of preoperatively evaluating the size of the eighth costal cartilage prior to its use in microtia-related ear reconstruction. The study, which involved 97 patients, found that costal cartilage lengths assessed with 3-D CT scanning correlated well with those determined intraoperatively.[17]

Intraoperative Details

Cartilage framework construction

The costal cartilage framework is constructed from 3-4 costal cartilage segments (6th-9th), with the amount dependent on the size and shape of the patient's cartilage and the type of defect being reconstructed. Surgeons' preferences vary for ipsilateral (Nagata, Firmin) or contralateral (Brent, Bauer) cartilage for primary reconstructions. In older and larger patients, the visceral perichondrium can be retained when the cartilage graft is harvested, though opinions vary regarding how much this minimizes the donor site deformity. As is later addressed in the reoperative case, developing facility with framework construction from either side of the chest is important.

The cartilage framework is constructed from a base block (6th and 7th costal cartilages) onto which additional segments for the helical rim (8th cartilage), antitragus with superior and inferior crus, and tragus are spliced. Depending on the technique chosen, additional cartilage can be added beneath the base plate to increase the framework projection (although this is also routinely added in the second stage). The 3-dimensional framework is then further refined to accentuate the fine details of the normal ear, recognizing that the framework is made substantially thicker than normal ear cartilage in order to hold its shape, projection, and detail beneath the overlying skin.

While the senior author has, in the past, carved the cartilage details with a series of X-Acto hobby shop routers, the senior author now carves the fine detail with a set of gouges (2, 4, 6 mm Buxton). The cartilage segments are joined with fine stainless steel wire and clear nylon sutures. The cartilage framework is modified in the reconstruction of conchal remnant microtia to make maximum use of the definable portions of the concha, lower antihelix, and antitragus. While great variations exist between individual surgeon's skills and experience, with time, the framework construction becomes the most routine step in the reconstruction. Oyama et al described an intraoperative simulation device that may be beneficial as a training tool, using negative pressure for construction of framework in microtia reconstruction to give immediate feedback on the postoperative appearance.[18]

At the completion of the framework construction, a segment of unused cartilage is retained and banked in the subcutaneous tissue at the donor site for harvest in the second stage to add additional projection to the framework.

Dissection of the remnant and placement of the framework

The cartilage framework is constructed and placed in the first stage to make maximal use of the unscarred skin envelope. The incision(s) for placement of the framework vary, depending on whose technique is followed, but can roughly be divided between the techniques that allow for rotation of the lobule and tragal construction in the first stage (Nagata, Firmin, Bauer) and those that delay the lobule transposition and tragal construction until the second stage (Brent).

Nagata was the first to popularize the lobule rotation in the first stage and has emphasized the importance of maintaining a subcutaneous pedicle into the superior skin flap while allowing considerable movement of the lobule on a relatively small, but always hearty, pedicle. The incision is additionally planned such that the skin from the greater part of the posterior surface of the lobule is included in the superior flap, thereby increasing the skin available to line the concha and posterior surface of the tragus. Firmin does not feel the pedicle is as vital to the integrity of the upper flap but risks possible partial loss of the skin flap that we have not seen following Nagata's approach. The varied approach to the incision and placement of the framework into the lobule seen in Firmin's varied flap designs, however, still provides reasonable protection of the flaps from possible vascular compromise.

In the lobular type reconstruction, the entire amorphous cartilage remnant is excised, freeing maximal skin to drape over the framework and providing maximal depth for the conchal depression. The skin flap is elevated at least 1 cm beyond the borders of the planned reconstruction to additionally recruit skin for tension-free closure over the 3-dimensional construct. Hemostasis is accomplished with bipolar cautery and is checked meticulously before the framework is placed.

The framework is rotated into place, wrapping around the subcutaneous pedicle, and is seated in its appropriate symmetrical position using the prefabricated template. It is fixed in place with clear nylon sutures. Two drains (19-gauge butterfly IV lines) are placed deep to the concha and sulcus and connected to wall suction initially, then subsequently to vacuum tubes (postoperatively). Additional through-and-through fine quilting or bolster sutures can be placed to further enhance the skin/cartilage coaptation if the suction is felt to be insufficient for optimal draping of the skin envelope.

Postoperative dressings vary, but the authors prefer bacitracin ointment and Xeroform gauze, covered with a Glasscock dressing (with all lining gauze removed and holes sealed with Tegaderm). This provides a pressure-free dressing, which avoids any risk of pressure necrosis during the critical first days after the reconstruction. The drains are maintained until the 4th-6th postoperative day; they are changed every 2 hours in the first 48 hours, then every 4 hours after that (except at night).

In the reconstruction of conchal remnant type microtia, the incisions are modified to make maximal use of the additional skin available. The framework is also modified and spliced into the useable portions of the cartilage remnant (though the concha, even if well-formed, usually needs expansion or partial resection). Firmin's modified incisions and flap designs for Type 2 and Type 3 deformities (small and large conchal remnant microtia, respectively) seem to make better use of the available skin than those used by Nagata. In these cases, efforts to maintain the subcutaneous pedicle to the upper flap may limit optimal redraping of the skin over the framework and sacrifice skin that is better maintained for coverage of the postauricular surface of the framework.

Second stage reconstruction

The second stage reconstruction varies based on whether the surgeon follows the model of Drs. Nagata and Firmin or the techniques described by Brent. As the senior author's preference is the former, we discuss this first, but then review the latter approach as well. The second stage reconstruction is generally carried out 3-4 months after the first stage. Unlike the first stage, the second stage is generally performed as an outpatient procedure. For some patients, this stage completes the reconstruction.

As the tragal construction and lobule rotation were included in the first stage, the second stage involves the elevation of the reconstructed ear and creation of the postauricular sulcus. The innovation introduced by Nagata was to add a banked cartilage graft to the underside of the elevated framework to help project the ear outward from the head, minimizing or eliminating the need to carry out a setback of the contralateral ear for symmetry. The graft essentially mimics the posterior conchal wall.

With the ear elevated and the graft positioned beneath the framework, the bare cartilage needs the vascular coverage of either a temporoparietal fascial flap or postauricular fascial flap, and of the skin graft. The skin graft is typically split-thickness (or ultra-thin, as described by Nagata) and harvested from the adjacent scalp. The graft is sutured in place with 5-0 chromic catgut suture, and multiple quilting sutures of 4-0 chromic are placed meticulously to prevent any possibility of tenting of the graft from the multiple contours of the posterior surface of the ear and mastoid region. Following this approach, a well-packed Xeroform gauze dressing covered with fluffy gauze and head wrap is all that is required. A tie-over dressing is not needed. The dressing is typically left in place for one week.

For patients whose reconstructions have followed the Brent model, the second stage involves the rotation of the lobule, conchal excavation, and construction of the tragus with a composite graft from the contralateral concha. The lobule is released and can be dissected with a pocket between the layers that allows the lobule to be fitted over the inferior pole of the cartilage framework. The tragus is created by backing an anteriorly-based skin flap with the composite graft, creating a shadow behind this construct to suggest the presence of an external auditory meatus and canal. A full-thickness skin graft may also be attached to the composite graft to gain additional lining in the area of the pseudomeatus.

Third stage reconstruction

Following the Brent model, the third stage reconstruction involves elevation of the reconstructed ear, initially described without additional cartilage block for framework projection, but now, on occasion, with a similar approach to the Nagata technique for the second stage surgery. Additional third stage procedures may include further refinement of the framework details, additional release of the elevated ear in cases where split-thickness skin graft contracture has overcome part of the initial elevation (despite the added framework support), and enhancement of the tragal projection, where the prominence or underlying shadow is inadequate. This latter condition is more likely to exist in cases of reconstruction performed before the patient was aged 10 years and in which cartilage or cartilage strength was inadequate to maintain the tragal projection.

As an alternative to the technique of tragal construction described by Brent, we have found that the degree of tragal projection, delicate anatomy, and ability to create and maintain the hollow or shadow behind it is made significantly easier using a turnover tragal-shaped skin flap based toward the concha, covered on its anterior raw surface with a composite conchal graft. The donor defect from elevation of the flap is closed by advancing the cheek skin to the base of the tragus. The anterior or lateral surface of the tragus is then formed by applying the composite graft. The angle or plane of projection of the tragus is adjusted by fixating the cartilaginous part of the composite graft to adjacent costo-cartilage framework.

Given the donor site of the graft, the color match is excellent and the skin of the concha or posterior surface of the tragus does not tend to contract, as it is lined by a flap rather than a graft. This approach creates a comparable shadow to the area of the pseudo-meatus and can be gained either by initial placement of the cartilage as part of the framework or by the Brent technique. Any additional adjustments of the lobule, helical rim, and so on, may often be carried out at this procedure or may be left for a final touch-up under local anesthesia following a period long enough to allow all the scars to mature and tissues to settle into the cartilaginous hollows and contours.

Reconstruction of the dystopic auricle

One of the most difficult problems encountered in the reconstruction of the microtic ear is a microtic vestige that is markedly displaced from a symmetrical position with the other side. This displacement is due to the marked degree of both skeletal and soft tissue deficiency associated with the more significant degrees of hemifacial microsomia. In these cases, the procedures required to place the final reconstruction in a symmetrical position and the issues of timing of the auricular and mandibular reconstruction remain to be solved. The approach described here takes these factors into account and allows coordinated treatment of both auricular and mandibular deformities.

While an in-depth discussion of the lobular transposition, framework modifications, and sequencing of the auricular reconstruction with mandibular distraction, skeletal augmentation, and other craniofacial-related techniques is beyond the scope of this chapter, issues of positioning the reconstructed ear and the use of fascial flaps for coverage of the cartilage framework are directly pertinent to reoperation for a previously unsuccessful result. In the former case, a skin graft over the fascial flap coverage of the framework is often necessary because the symmetrically-positioned ear is often over hair-bearing skin. In the latter case, scarring from previous surgery may make the adjacent skin unusable.

Fascial flaps in ear reconstruction

While the use of fascial flaps in reconstruction of microtia is typically reserved for treatment of cases with atypical anatomy, as is seen in auricular dystopia, flaps may also be required in the salvage of complications of microtia reconstruction and treatment of acquired deformities. One must remember that the anatomy of the superficial temporal artery, postauricular, and occipital vessels is altered to varying degrees, depending on the extent of hemifacial microsomia. As part of the preoperative planning, these structures should be mapped with a Doppler probe.

The temporoparietal fascial flap (TPFF) is the most commonly used fascial flap in complex ear reconstruction. It is equally versatile in secondary reconstruction. The flap is supplied by both the superficial temporal artery (STA) and postauricular artery (PAA). While the flap is typically elevated on the STA alone, both vessels should be included, whenever possible, to minimize the risk of partial flap necrosis. While the TPFF has also been used as a random flap by Brent and Byrd, this is generally not recommended in reconstruction of the congenital ear deformity. TPFF may be endoscopically harvested with the advantages of minimizing scarring, alopecia, and surgical time.[19]

The postauricular fascial flap, supplied by the PAA and occipital arteries, is a continuation of the TPFF (superficial temporal fascia). The deep temporal fascial flap is supplied by the middle temporal artery, which arises from the STA. It may also include a branch of the PAA. Both of these flaps may play a role in secondary or reoperative ear surgery, particularly as salvage after failure of the TPFF. While the former is quite effective in coverage of small areas of skin or flap loss in the mid and lower thirds of the ear (even, on occasion, in preference to the TPFF), these other flaps are used relatively rarely.

First stage transposition of the microtic vestige

Given the tri-planar malposition of the dystopic remnant, the remnant must often be moved as close as possible to its ultimate position prior to the stage when the cartilage framework will be placed. This will help to preserve the blood supply to the remnant and allow further positioning of the remnant at the time of the formal first stage reconstruction, when the framework is placed either beneath the adjacent skin (if adequate non–hair-bearing skin is available) or beneath a temporoparietal fascial flap. The movement of the remnant depends on whether a patent auditory meatus and canal are associated with it.

The reconstruction should begin with the initial assessment of the patient and determination of the position of the auricular remnant in relation to the ideal, symmetrical position for the reconstructed ear. A radiograph film or celluloid sheet is ideal for this evaluation. Unlike the more typical microtia cases discussed above, in which the remnant tends to be positioned antero-superiorly, these cases are typified by the antero-inferior position of the remnant. The initial postero-superior movement of the vestige may be carried out in early childhood, years before the main reconstruction. Doing this part of the procedure early has the considerable benefit of getting the remnant to a location closer to normal and making the overall deformity less conspicuous. This may have significant psychological benefits for the affected child during the years of waiting for the formal reconstruction.

The remnant is most commonly transposed with a Z-plasty–type maneuver but can also be advanced posteriorly on the leading edge of a cheek flap or as an island flap. As the remnant and adjacent flap interchange position, a relative gain occurs in skin, anteriorly widening the distance between the ear and the lateral canthus and other central facial landmarks.

In some patients, the dystopic remnant includes the meatus and displaced canal (this is common in more severe cases of hemifacial microsomia). The extent of movement depends on the length of the canal and the complexity of the adjacent anatomy (particularly the facial nerve). CT scanning or MRI may give some preoperative insight into the course of the canal and nerve. The cartilaginous canal is not separated from its connection with the bony canal but can still pivot and move on it. In addition to identifying and protecting the facial nerve, determine the course of the superficial temporal and postauricular arteries and protect them as vascular pedicles for the future temporoparietal fascial flap.

Second stage placement of the augmented auricular framework and coverage with the temporoparietal fascial flap

See the list below:

  • Framework construction

    • The framework construction must be modified, in these cases, to make up for the fact that the framework sits on a hypoplastic base. The costal cartilage framework is carved in the same manner as described above, but it is then modified by adding an infrastructure of cartilage, which is designed to compensate for the hypoplastic temporal bone and project the framework out into a symmetrical plane with the normal opposite ear. This is most easily accomplished by completing the initial reconstruction and then positioning the framework in the appropriate location and measuring the amount of added projection necessary to place the framework symmetrically in all planes.

    • The additional block of cartilage is then added beneath the framework, often using a T-shaped wedge to prevent it from folding under. The placement of the framework is checked repeatedly by using the initial template, as well as by looking directly at the normal side (for comparison of positioning in the sagittal plane), to assure a symmetrical final position for the reconstruction.

  • Temporoparietal fascial flap in auricular dystopia reconstruction

    • Every effort should be made to include both the STA and PAA in the flap. This requires dissection of a wider-than-normal flap because the correctly-positioned dystopic reconstruction is posterior and superior to the original position of the remnant. The need for this is best understood by remembering that the STA, like the associated remnant, has developed in a more anterior position in these hypoplastic cases. A larger-than-normal flap is also required to provide enough tissue to cover the augmented framework.

    • With the above in mind, recognize that, during the elevation of the TPFF, the temporal branch of the facial nerve may cross directly beneath the fascia as the anterior border of the flap is cut. The nerve is easily identified and protected. The TPFF is covered with a split-thickness skin graft, which can be harvested from the adjacent scalp.

Correction of skeletal hypoplasia in treatment of auricular dystopia

The final element in treatment of this complex auricular deformity lies in correction of the hypoplastic temporal bone in cases of auricular dystopia unassociated with microtia (an otherwise normal or prominent ear appearing to be sheared off the side of the head) and in cases where the microtic ear has been successfully reconstructed but the auricle is still in a dystopic position. In both of these cases, the auricle can be freed sufficiently from the underlying skeletal and soft tissues to allow placement of a cranial bone strut beneath it as a cantilevered graft off the temporal bone.

The auricle or reconstructed ear is elevated at the subperiosteal plane with the incision around the ear planned to assure that a good vascular pedicle remains. Part of the access for dissection can be obtained through a hemi-coronal incision used to harvest the cranial graft. When necessary, the dissection is carried along the cartilaginous canal and the cranial graft is shaped as a supporting hook around the canal. This bony augmentation is distinct from that accomplished with either zygomatic arch/temporomandibular joint reconstruction or correction of the mandibular asymmetry. The bone graft is secured with either lag screw or microplate and screws.

Integration of auricular reconstruction and distraction osteogenesis

While beyond the scope of this article, note that current staging of procedures for reconstruction of the ear and mandible does allow for some integration of procedures, which, at times, minimizes the overall number of surgeries from beginning to completion of reconstruction. In more severe cases of hemifacial microsomia, lengthening of the mandible may be accomplished fairly early using distraction osteogenesis. Initial transposition of the dystopic vestige may be carried out at the time of one of these early procedures or at the time the hardware is removed, if this is required. Even if the skeletal reconstruction is incomplete, the ear can still be reconstructed in a symmetrical final position following the above principles.

Postoperative Details

See the list below:

  • Perform the first two stages under general anesthesia.

  • To monitor flap viability after placement of the cartilage frame, maintain the patient in-house overnight and discharge him or her when pain management at the cartilage donor site is adequate.

  • Remove suction catheters on the fourth or fifth day after the edema starts to settle.

  • The second stage operation often is performed in a day surgery setting.

  • Remove dressings 5-7 days after grafting and elevation.

  • Begin scar massage 2-3 weeks postoperatively.

Follow-up

Long-term results of ear reconstruction have been gratifying for both patients and surgeons. See the image below.

Reconstruction of microtia. Reconstruction of microtia.

Autogenous reconstruction of the ear can look quite lifelike but does not have the flexibility to touch. If indicated, auditory surgery can be performed after the second stage elevation, and touch-up work can be delayed. Interestingly, growth has been reported in reconstructed ears in children.

Complications

A retrospective study by Fu et al of patients who underwent autologous cartilage microtia reconstruction using either the Nagata or Brent technique found the complication rate to be higher in the former (12.2%) than in the latter (2.99%).[20]

However, major complications following ear reconstruction are few. When counseling patients and their parents preoperatively, the discussion should center on the possibilities of infection, secondary cartilage graft loss, tissue ischemia, and secondary soft tissue loss. Prior to costal cartilage harvest, mention can be made of the potential for pneumothorax, which is rare, from damage to the parietal pleura.

In the case of infection, management should be aggressive and early. Order intravenous antibiotics for cellulitis. Prompt incision and drainage of pus is indicated. If the infection affects the cartilage graft, the detail and bulk are lost. Attempt to preserve as much of the cartilage graft as possible. Once the initial purulence is controlled, local vascularized flaps such as a temporoparietal fascial flap (TPFF) may be indicated. As routine auricular reconstruction is a clean case, the most likely contaminants are skin flora; however, anaerobic organisms can be harbored in auricular dystopia and conchal remnants with stenotic canals.

To minimize stress to the auricular skin flap, dissection should be gentle, sharp, and meticulous. Hemostasis should be absolute. The authors prefer to use suction catheter drains to keep the skin flap applied to the cartilage framework rather than bolsters or retention sutures, which place pressure and, in theory, reduce capillary flow. Additionally, drains prevent accumulation of postoperative fluids that also can challenge the skin flap. To prevent any pressure from positioning, a Glasscock dressing (less the cotton padding) can be used. This hemispheric plastic bowl allows the surgeon to peek at his work easily and provides a cradle over the ear to protect it. If small areas of breakdown do occur, they should be kept clean with antibiotic ointment applied sparingly (the junior author recommends 10% Sulfamylon cream because it can penetrate cartilage). Usually, they heal on their own.

Pneumothorax should be a theoretical complication only. No occurrence has been reported in the senior author's series of over 500 reconstructions. Upon closing the donor site, the area can be examined under a water seal with a large positive pressure breath. If air leaks, the wound can be closed over a red rubber catheter and the air drained from the hemithorax. If a pneumothorax is found on the postoperative upright film, it can be managed conservatively with observation since the damage is most likely to the parietal pleura.

Most of the minor complications of this surgery center around pain control issues at the rib harvest site. Atelectasis and fever secondary to splinting can be reduced by placing intercostal blocks with long-acting agents in the operating room and instituting aggressive pulmonary toilet immediately postoperatively.

Outcome and Prognosis

Ear reconstruction with autogenous cartilage grafts is well received by patients with microtia. The success of outcome depends greatly on preoperative planning. Placing the auricle in a symmetrical position with respect to the facial landmarks and obtaining symmetrical projection from the skull are of paramount importance for optimum outcome. The skill and patience of the surgeon in planning and executing this operation determine its success, barring complications.

A retrospective study by Akter et al of patient-reported outcomes after autologous reconstruction for microtia found that out of 50 patients, 83% were satisfied with the result, and 80.9% felt that their newly constructed ear was similar to the other ear.[21]

Reoperation for symmetrical ear positioning

Though discussed above in the section on treatment of auricular dystopia, a final comment seems appropriate regarding the proper positioning of the reconstructed ear. One of the areas of greatest concern to patients seeking further microtia reconstruction is the malposition of the reconstructed ear.

Typically, the ear is positioned anterior and inferior to its normal counterpart (as well as rotated from a normal axis). Some patients may present with dystopia and an incomplete reconstruction and need both correction of dystopia and additional staging of surgeries. Each case needs to be assessed for the extent of surrounding scarring and the distance of movement that is necessary for optimal symmetry. The rich vascular supply in this area will allow a reasonable amount of elevation and movement of the reconstructed ear, but a wide enough pedicle needs to be maintained (with at least as much attachment as is seen at the second stage ear elevation in the routine microtia reconstruction) to avoid vascular compromise. The movement often requires interposition of a skin or fasciocutaneous flap from behind the dystopic auricle to fill the defect anterior and medial to the ear, as is needed in the early transposition of the vestige discussed above. 

Each case must be carefully assessed. Certainly, some patients must be counseled that the risk of distortion or loss of the reconstructed ear does not warrant the risk of this movement. They should also be aware of the additional scars that will result from the transposition of skin anterior or inferior to the repositioned auricle in cases where the anterior skin is not lax enough to allow advancement back to the newly-positioned ear. Some patients, while unhappy with the ear position, may not be willing to accept these additional scars, and the surgeon should then counsel acceptance of the current deformity.

Future and Controversies

Building on lessons from the past, today's surgeons have decreased what was a 4-stage operation in the 1950s to a 2-stage reconstruction today. As lessons learned today are applied, even more realistic reconstructions can be expected from future reconstructive surgeons. In the future, tissue engineering and newer alloplasts may replace autologous reconstruction; however, they must measure up to the criterion standard set by autologous reconstruction.

Final thoughts

Successful staged reconstruction of the ear, whether for microtia or major acquired ear deformities, requires meticulous attention to all aspects of the available auricular and donor tissue and the soft tissue environment surrounding the planned reconstruction. Whether one chooses to follow a Nagata, Firmin, or Brent model for the initial microtia reconstruction, careful attention to the vascular supply of the skin flaps minimizes the risk of flap ischemia and cartilage exposure. With considerable variation in auricular remnants, meticulous planning is perhaps the most important factor in reducing complications.