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Hemifacial Microsomia ‒ Introduction

Overview

Children born with hemifacial microsomia require a team of highly experienced physicians, surgeons, and health care providers to properly manage the issues associated with this condition. Facial reconstructive procedures should be performed by experienced craniofacial surgeons in order to achieve the best possible outcomes. The surgeons at our center have an extensive knowledge of hemifacial microsomia and are an integral part of the New Jersey Institute for Craniofacial Surgery functioning as Craniofacial Surgeons, Plastic & Reconstructive Surgeons, and Oral & Maxillofacial Surgeons for the Institute. Members of our team have led the center for more than 30 years.

 

Hemifacial microsomia is the second most common facial birth defect behind cleft lip and palate, affecting approximately 1 in every 3,500 to 5,600 to births.

 

Five major areas are affected by hemifacial microsomia:

  1. External ear

  2. Mandible (lower jaw)

  3. Orbit (eye bones)

  4. Facial nerve (the nerve controlling the muscles of facial expression)

  5. Facial soft tissues (muscle, subcutaneous tissues, fat, and skin)

 

Traditionally hemifacial microsomia occurs on only one side of the face (hemifacial); however, in 10 to 15 percent of cases, it may occur on both sides of the face. When it occurs on both sides of the face, it is referred to as craniofacial microsomia.

  • Hemifacial microsomia may be referred to by many names, including:

  • First and second branchial arch syndrome

  • Otomandibular dysostosis

  • Facio-auriculo-vertebral syndrome

  • Oculo-auriculo-vertebral spectrum

  • Lateral facial dysplasia

 

Hemifacial microsomia is commonly confused with Goldenhar syndrome. However, Goldenhar syndrome is a separate entity of which hemifacial microsomia is just one of the characteristics. Goldenhar syndrome is a rare congenital condition that also includes vertebral anomalies and epibulbar dermoids appearing as “skin patches” that extend onto the conjunctiva and cornea of the eye.

 

Etiology (Cause)

It is unclear exactly what causes hemifacial microsomia. It is believed that the process begins in the first trimester of pregnancy. The facial anomalies are not caused by something the mother did or something she ate; it usually just happens by chance. In a small number of cases, a child inherits the condition from his or her parents. An adult with hemifacial microsomia has about a 3% chance of having a child with the same condition.

Initially it was believed that this disorder was caused by an interruption of the blood supply (stapedial artery) to the affected side of the face. In the early 1970s, Dr. David Poswillo developed this theory by administering various medications to mice and monkeys and noting a disruption of the blood supply in a focal area of the face that led to the development of characteristics consistent with hemifacial microsomia in 100% of the animals.

However, now it is believed that hemifacial microsomia most likely occurs as a result of a disruption in the migration of neural crest cells. Dr. Malcolm Johnston and Dr. Peter Barsky developed this theory and proposed that the failure of migration of the various neural crest cells leads to both the diversity and variability seen in hemifacial microsomia.

In a recent study by Tuin, it was determined that although there is variability in the degree of deficiency in each of the affected facial structures, those developed from the first branchial arch (orbit, mandible, and soft tissue) are similar in degree of deficiency, as are the structures derived from the second branchial arch (facial nerve and ear).

 

Characteristics

Characteristics of hemifacial microsomia range from very mild to severe. A child with a mild form of hemifacial microsomia may have an unnoticeably smaller jaw and a skin tag in front of a normal appearing ear. In more severe forms, a child may present with a significantly deficient and asymmetrical jaw on the affected side in addition to a small orbit (eye socket), missing ear, lack of soft tissue, and decreased function of the facial muscles on the affected side. 


 

 

Figure 1 Variable Malformations Associated with Craniofacial Microsomia

 

Several classification systems exist to describe which structures are affected and to what degree. The most common systems are the OMENS and the Pruzansky/Kaban classification systems. For more information regarding these classification systems, refer to Hemifacial Microsomia Classification Systems.

 

Treatment

As is the case for any patient with a complex craniofacial deformity, individual treatment varies depending upon the degree of involvement of the various structures. Possible treatments include the following.

 

Breathing-related treatments in infancy
  • Positioning

  • Tongue lip adhesion

  • Distraction of the mandible

  • Tracheostomy

 

Correction of fronto-orbital deficiencies
  • Correction of the forehead and orbit (eye bones) on the affected side

 

Correction of a deficient or absent ear
  • Reconstruction of an absent or malformed external ear

 

Functional orthodontics
  • May be required to correct and prevent further maxillary (upper jaw) asymmetry

 

Corrective jaw surgery/distraction
  • Corrective jaw surgery is typically required in moderate to severe cases. In certain circumstances, a rib graft or a process referred to as distraction osteogenesis may be recommended in order to achieve optimal results.

 

Custom facial implants
  • May be required in addition to the above procedures in order to achieve the best aesthetic results

 

Because multiple structures may be involved in hemifacial microsomia, continued monitoring is important. Facial growth should be monitored throughout childhood and adolescence, adjusting the treatment plan as necessary.

 

References

Horgan JE, Padwa BL, LaBrie RA, et al. OMENS-Plus: analysis of craniofacial and extracraniofacial anomalies in hemifacial microsomia. Cleft Palate Craniofac J. 1995;32:405-412.

Grabb W: The first and second branchial arch syndrome. Plast Reconstr Surg. 1965;36:485-508.

Johnston M, Bronsky P. Prenatal craniofacial development: new insights on normal and abnormal mechanisms. Crit Rev Oral Biol Med. 1995;6:368.

Poswillo D. Hemorrhage in development of face. In Bergsma D, ed. New York: Alan R. Liss, 1975:61-81.

Poswillo D: The pathogenesis of the first and second branchial arch syndrome. Oral Surg Oral Med Oral Pathol. 1973;35:302-328.

Tuin AJ, Tahiri Y. Clarifying the relationships among the different features of the OMENS+ classification in craniofacial microsomia. Plast Reconstr Surg. 2015 Jan;135(1):149e-156e.

 

Image Reference

Figure 1: GeneReviews®. Pagon RA, Adam MP, Ardinger HH, et al., eds. Craniofacial Microsomia Overview., GeneReviews® [Internet]. Seattle, WA: University of Washington, Seattle, 1993-2015. Copyright © 1993-2015, University of Washington, Seattle. All rights reserved.

 

 
 
 

Hemifacial Microsomia ‒ Classification

Many classification systems have been developed to help categorize and treat the severity of the hemifacial microsomia patients. The two most popular classifications, and the most clinically useful ones, are Dr. Samuel Pruzansky’s classification of the mandibular (lower jaw) anatomy, with a modification by Dr. Leonard Kaban, and the OMENS classification developed by Dr. John Mulliken, which helps to determine which facial features are involved and to what degree.

 

Pruzansky/Kaban Classification of Mandibular Deficiencies

Type I – Mandibles are essentially normal in shape and morphology; however, they are small when compared to the opposite “normal” side.

 

Type IIa – Mandibles have an abnormal shape and morphology, but the TMJ is functional and appropriately positioned to allow for “symmetrical opening of the mandible.”

 

Type IIb – Mandibles have an abnormal shape and morphology with the TMJ malpositioned inferiorly, medially, and anteriorly, rendering it nonfunctional.

 

Type III – Mandibles are missing the TMJ (ramus and glenoid fossa), with essentially no mandibular development behind the teeth.

 

 
OMENS Classification

 

Orbit

Evaluated using radiographs and clinical evaluation.

O0: Normal orbital size and position

O1: Abnormal orbital size

O2: Abnormal orbital position

O3: Abnormal orbital size and position

 
Mandible

Evaluated using radiographs, with mandibles categorized using the Pruzansky/Kaban classification described above.

Mo:  The mandible is normal.

MI:    The mandible and glenoid fossa are small with a short ramus.

M2:   The mandibular ramus is short and abnormally shaped.

2a:     Glenoid fossa is in anatomically acceptable position with reference to opposite TMJ.

2b:     TMJ is inferiorly, medially, and anteriorly displaced, with severely underdeveloped condyle.

M3:    The ramus, glenoid fossa, and TMJ are completely absent.

 

Ear

Categorized based on clinical examination and standardized photographs.

Eo:  Normal ear

E1:   Mild hypoplasia and cupping with all structures present

E2:  Absence of external auditory canal with variable hypoplasia of the concha

E3:  Malpositioned lobule with absent auricle; lobular remnant usually inferiorly and anteriorly displaced

 

Facial Nerve

Categorized on the basis of clinical examination.

N0:   No facial nerve involvement

N1:    Upper facial nerve involvement (temporal and zygomatic branches)

N2:    Lower facial nerve involvement (buccal, mandibular, and cervical branches)

N3:    All branches of the facial nerve affected, with other involved nerves also analyzed, such as the trigeminal N5 (sensory) and hypoglossal N12, and the remaining cranial nerves signified by the appropriate number in superscript

 

Soft Tissue

Modified from the system proposed by Murray et al. (1984), which included nerve weakness. This assessment is based only on subcutaneous and muscular deficiency using clinical examination.

S0:   No obvious soft tissue or muscle deficiency

S1:     Minimal subcutaneous/muscle deficiency

S2:    Moderate, between the two extremes, Stand S3

S3:    Severe soft tissue deficiency due to subcutaneous and muscular hypoplasia

 
References

Horgan J. OMENS-plus: analysis of craniofacial and extracraniofacial anomalies in hemifacial microsomia. Cleft Palate Craniofac J. 1995;32:405-412.

Kaban L, Moses M, Mulliken J. Surgical correction of hemifacial microsomia in the growing child. Plast Reconstr Surg. 1988;82: 9-19.

Pruzansky S. Not all dwarfed mandibles are alike. Birth Defects. 1969;4:120.

Vento A, LaBrie R, Mulliken J. The OMENS classification of hemifacial microsomia. Cleft Palate-Craniofacial J. 1991;28:68-77.

 

Hemifacial Microsomia ‒ Functional Orthodontics 

 

Orthodontics in children with facial clefts and facial asymmetry is a unique specialty of orthodontics involving functional orthodontics. Functional orthodontics is a specialized form of orthodontics that can help to correct not only the position of the teeth, but also the position and function of the jaws. This type of orthodontics is particularly important in children with facial clefting and facial asymmetry because it can help to prevent or lessen some of the more common irregular jaw relationships that may develop.

 

Functional orthodontics is a way of tricking the teeth and jaws to grow and develop in a planned manner. Functional orthodontics can create space for teeth and jaws to grow by using various types of appliances, retainers, and dental adjustments. In children with hemifacial microsomia, the deficient lower jaw is canted and occupying the space where the teeth of the upper jaw would normally be positioned. This prevents the teeth and bones from developing into this area, resulting in a canting of the upper jaw and an asymmetrical appearance. Sometimes by placing an appliance between the upper and lower teeth on the opposite side, a space can be created on the affected side, allowing the upper teeth and bone to grow into a more normal position. Once the teeth move into the space, they will maintain it and prevent further distortion.

 

Typically, functional orthodontics cannot be performed until the permanent molars have erupted (around 6 years of age). It is important to be evaluated by an orthodontist with experience in treating children with hemifacial microsomia so that intervention can be made at the appropriate time. If intervention is delayed, certain opportunities may be missed.

Rib Graft Harvest Procedure

 

It may be necessary to utilize rib grafts in children for ear reconstruction, nasal reconstruction, or reconstruction of the lower jaw.

 

Rib graft harvest is a commonly performed procedure in craniofacial surgery. It provides the best source of firm cartilage necessary for ear, nasal, and lower jaw reconstruction.

 
 

Hemifacial Microsomia ‒ Jaw Surgery

 Corrective jaw surgery for patients with hemifacial microsomia is a unique subspecialty of corrective jaw surgery. A thorough understanding of the causes, treatment options, variations, and surgical procedures is necessary to provide comprehensive treatment. Surgical execution of the required procedures should be performed by a facial reconstructive surgeon experienced in complex jaw reconstructive procedures in order to achieve the best outcome. All of the surgeons at our center have an extensive knowledge of hemifacial microsomia and are an integral part of the New Jersey Institute for Craniofacial Surgeryfunctioning as Craniofacial Surgeons, Plastic & Reconstructive Surgeons, and Oral & Maxillofacial Surgeons for the Institute. Members of our team have led the center for more than 35 years.

 
Key Points

Some key points to understand that are unique to jaw surgery for hemifacial microsomia are:

 

  1. Although the primary disturbance is in the mandible (lower jaw), secondary disturbances in the maxilla (upper jaw) typically require correction as well.

  2. An understanding of the comprehensive treatment plan is necessary. Proper planning of incisions is critical to avoid damaging blood supply necessary for future ear and soft tissue reconstructions. Improper placement of incisions can compromise future reconstructions.

  3. The mandible (lower jaw) is typically deficient in size, shape, and position. Therefore, simply repositioning the jaw may not be enough and further augmentation may be required.

 

Jaw Surgery

There is much variation in the treatment of jaw abnormalities related to hemifacial microsomia ranging from treatment using only a custom facial implant to treatment requiring reconstruction of the maxilla (upper jaw), mandible (lower jaw), TMJ, chin, and placement of custom facial implants.

 

Early vs. Late

In more severe cases, some surgeons recommend surgery at a young age while the lower jaw is still growing to avoid secondary disturbances in the maxilla (upper jaw). These procedures are followed by a second definitive jaw surgery procedure when facial growth is completed.

 

Other surgeons recommend functional orthodontics during facial growth followed by jaw surgery only after facial growth is completed.

 

At our center, we follow a more conservative approach of avoiding surgery until facial growth is completed if at all possible. We have had great success using functional orthodontics to minimize secondary disturbances to the maxilla.

 

Jaw Surgery after Facial Growth Is Completed

Once facial growth is completed, an appropriate treatment plan can be determined. Treatment is based on the following factors:

  1. The size, shape, and volume of the mandible on the affected side

  2. The amount of secondary disturbance of the maxilla (upper jaw)

  3. The anatomy of the condyle and TMJ (Pruzansky/Kaban classification)

Most cases will require correction of the maxilla (upper jaw), mandible (lower jaw), and chin.

 

Cases in which the anatomy of the condyle and TMJ produce improper function (Pruzansky/Kaban type IIb and III) may require additional procedures to reconstruct the condyle and TMJ. Correction in these situations may be achieved using either one or more of the following techniques:

 

  • Rib graft reconstruction to create a new condyle on the affected side

  • Distraction osteogenesis to create a new condyle and to “grow” bone in the affected area. (For more information please visit our distraction osteogenesis portal.)

  • Custom-fabricated prosthetic titanium TMJ and condyle

  • Custom facial implants

 

References

McCarthy JG, Schreiber JS, Karp NS, et al. Lengthening of the human mandible by gradual distraction. Plastic Reconstr Surg. 1992;89:1.

Meurmann Y. Congenital microtia and meatal atresia. Arch Otolaryngol. 1957;66:443.

Molina F, Ortiz-Monasterio F. Mandibular elongation and remodeling by distraction: a farewell to major osteotomies. Plast Reconstr Surg. 1995;96:825.

Mulliken JB, Kaban LB. Analysis and treatment of hemifacial microsomia in childhood. Clin Plast Surg. 1987;14:91.

Munro IR, Lauritzen CG. Classification and treatment of hemifacial microsomia.

In: Caronni EP, ed. Craniofacial Surgery. Boston: Little, Brown, 1985:391-400.

Obwegeser HL. Correction of the skeletal anomalies of otomandibular dysostosis. J Maxillofac Surg. 1974;2:73.

Vento AR, La Brie RA, Mulliken JB. The O.M.E.N.S. classification of hemifacial microsomia. Cleft Palate Craniofac J. 1991;28:68.

Hemifacial Microsomia ‒ Custom Facial Implants

 

Hemifacial microsomia produces a complex three-dimensional deficiency of the face. Corrective jaw surgery to reconstruct and reposition the jaws will correct the occlusion (bite) and correctly position the jaws in space. However, it will not address the decreased volume of the cheeks and jaws.

 

A comprehensive presurgical evaluation of the facial skeleton combined with computerized 3D virtual surgical planning will help to identify whether additional procedures are required to compensate for the decreased volume of these structures in order to achieve the best possible aesthetic results.

 

Options to correct deficient volume include facial implants, bone grafts, and soft tissue grafts. We prefer to utilize custom facial implants whenever possible because bone and soft tissue grafts are not precise, not predictable, and tend to resorb with time. We have not used “standard” or “off-the-shelf” implants in more than 10 years, as we believe the only implant option is a custom-designed and fabricated implant.

 

Custom facial implants are superior to standard implants for many reasons:

  • They fit with precision to the underlying bone anatomy.

  • The size and amount of projection is custom created to fit each patient’s individual needs.

  • They require less surgical time and there is no need for trimming or carving at the time of surgery.

  • The results are more predictable.

 

Our surgeons use a 3D printed precise replica of the patient’s skull. The surgery is performed on the replica and the facial bones are repositioned. If we believe that custom facial implants are indicated, each implant is sculpted in a special material on the skull until the desired result is accomplished. Implants are then fabricated as exact replicas of the sculpted material.

Hemifacial Microsomia ‒ Microtia Repair

 

Microtia is the technical term for a small or malformed ear. The degree of microtia can range from almost no deformity at all to a complete absence of the external ear. Because of the specific anatomy and location of the ear, reconstruction is a complex process requiring an experienced facial reconstructive surgeon as well as an otologist.

 

Hearing

There are two components to hearing:

 

  • Conduction (external and middle ear) – conducting sounds to the inner ear

  • Reception (inner ear) – interpreting sounds that have been conducted to the inner ear

 

The conductive portions of the ear (external and middle) are derived from the first and second branchial arches, which are different embryonic tissues than those that develop the receptive portions of the inner ear. Since hemifacial microsomia is typically isolated to disturbances of the first and second branchial arches, hearing problems are related to conduction disturbances and not reception issues.

 

For this reason, the inner ear is rarely involved in microtic ears and children typically have at least some hearing in the affected ear. Even children with bilateral microtia (microtia on both sides) usually have serviceable hearing and can use bone-conductive hearing aids to overcome the transmission block.

 

As many patients do well without middle-ear surgery, most surgeons believe the potential gains from middle-ear surgery in unilateral microtia (microtia on one side only) are outweighed by the potential risks and complications of the surgery and that this surgery should be reserved for bilateral (microtia on both sides) cases. Syndromes such as Treacher Collins may involve the inner ear as well as the external ear. Decisions should be made with a team that includes a reconstructive surgeon, an otoloigst, and an audiologist.

 

When performing middle-ear surgery, the external ear construction should be performed prior to the middle-ear surgery, as the middle-ear surgery will create scars in the area of the external ear reconstruction, thus compromising the final aesthetic result.

 

Classification
Tanzer’s Clinical Classification of Auricular Defects (Tanzer, 1975)
  1.  Anotia (no ear)

  2.  Microtia—complete hypoplasia (lack of growth)

  3.  With atresia (absence) of external auditory canal

  4.  Without atresia (absence) of external auditory canal

  5.  Hypoplasia (lack of growth) of middle third of auricle

  6.  Hypoplasia (lack of growth) of superior third of auricle

  7.  Constricted (cup and lop) ear

  8.  Cryptotia

  9.  Hypoplasia (lack of growth) of entire superior third

  10. Prominent ear

 
Reconstruction

Currently, three possible reconstructive options are available:

  1. Reconstruction using a custom-sculpted rib graft

  2. Reconstruction using a synthetic ear framework

  3. Reconstruction with a prosthetic ear that locks onto the ear site

 
Reconstruction with Rib Graft

The methods described by Dr. Burt Brent represent the gold standard for external ear reconstruction with a rib graft. This procedure is traditionally performed in four stages. Some doctors have promoted a two-stage approach; however, this is not the standard. Ear reconstruction is started around 6 years of age. At this age the ear has achieved approximately 90% of its final size and there is ample rib cartilage to create the ear framework.

 

Stage I

With the use of preoperatively determined measurements and a custom-created template, the ear position is determined and marked.

 

Rib cartilages are obtained from the side opposite to the ear being constructed. A horizontal incision is made in the area of the ribs that the cartilage will be removed from and the ribs are exposed. The custom template is placed on the exposed cartilages to determine the design of the graft, and the appropriate portions of the ribs are removed.

Figure 1: Framework Fabrication and Implantation

 

The framework is sculpted using scalpel blades and rounded chisels into the planned design. A small incision is made in the scalp and a thin-skinned pocket is developed, preserving the blood supply of the tissues. The cartilage framework is then inserted into the pocket and secured in position. A suction drain is placed under the skin to create a vacuum to bring the overlying tissue and the framework together.

 

Stage II

The earlobe is transposed into a more normal position.

 

Stage III

The ear is raised from the head and a skin graft is placed on the backside of the ear, creating a sulcus behind the ear.

 

Stage IV

The ear is fine-tuned (tragus and conchal bowl), which is combined with an otoplasty (ear pinning) of the unaffected ear if desired.

 

Reconstruction with a Synthetic Ear Framework

Dr. John Reinisch pioneered this technique using Medpor® implants. The benefits of using an implant are that it avoids the need for a rib graft procedure and it can usually be performed in two stages. However, the implant is a foreign body and thus presents a unique set of issues. It can become infected and/or can extrude through the overlying tissues requiring removal. Even a well-healed implant can be disrupted many years later if it is injured.

 

Stage I

The Medpore® implant is contoured to match the unaffected ear. A fascia flap is carefully elevated and folded over the implant. A skin graft from the back of the opposite ear is placed on top of the fascia-wrapped implant and an additional skin graft is placed behind the ear. Because the fascia flap has its own blood supply, the implant is wrapped in tissue that can support a skin graft. If a skin graft is placed directly over an implant, it will have no blood supply and will not survive.

 

Stage II

A second surgery is performed to reposition the earlobe and tissues around the ear.

 

Reconstruction with a Prosthetic Ear

If a decision is made to not proceed with a rib graft or implant reconstruction or the child is not a candidate, an experienced maxillofacial prosthodontist can fabricate a prosthetic ear using a mold of the unaffected ear or can make a “best fit” if both ears are affected. The prosthetic ear is made with accuracy and precision to best match the shape, skin color, and size of the unaffected ear. This usually requires a surgical procedure to remove the existing ear remnants and to place titanium implants into the bone. The implants will serve as anchors to which the prosthetic ear will attach.

 

Although prosthetic ears are highly realistic and offer an excellent “nonsurgical” option for the treatment of microtia, they have some disadvantages.

 

  1. They are not made of human tissues and will not look as lifelike as a rib graft or implant reconstruction.

  2. It can be difficult to conceal the “seam” where the ear meets the skin.

  3. They must be removed at night and before playing sports.

  4. They must be replaced periodically (every 1 to 3 years) at an additional cost each time.

  5. They can be dislodged while playing.

  6. They need to be removed and cleaned daily.

 

There are two types of prosthetic ears. The first type, which has been around for many years, attaches to the skin using a special medical adhesive. The downsides of this type are that it is more difficult to conceal the seam, it can fall off more easily, it gets worn out faster, and the adhesive can begin to accumulate on it.

 

A newer, more sophisticated prosthetic is called an osteointegrated prosthesis. A facial surgeon places several titanium implant posts into the bone around the ear. A metal framework is attached to the implants. The prosthesis will then snap securely onto these implants or metal framework. Both types of prostheses are removable; however, the implant-retained prosthesis is much less likely to come off inadvertently.

 

Future

Two reconstructive options are in development:

  1. 3D fabrication of a custom implant

  2. Tissue engineering

 

3D Fabrication of Custom Implant

Custom 3D printing of an ear framework that can be fabricated to meet the individual needs of any patient may produce more natural-appearing results and may provide the opportunity for the implants to be made of various materials other than Medpore®.

 

Tissue Engineering

Tissue-engineering techniques using a patient’s own cells to “grow” a new ear in the laboratory may be an alternative in the future. This technology is currently finding success with mice; however, it may be some time before it becomes useful technology for humans.

 

References

Brent B. The acquired auricular deformity. A systemic approach to its analysis and reconstruction. Plast Reconstr Surg. 1977;59:475.

Brent B. Auricular repair with autogenous rib cartilage grafts: Two decades of experience with 600 cases. Plast Reconstr Surg. 1992;90:355.

Brent B. The correction of microtia with autogenous cartilage grafts: II. Atypical and complex deformities. Plast Reconst Surg. 1980;66:13.

Brent B. Discussion of Nagata, S: modification of the stages in total reconstruction of the auricle. Plast Reconstr Surg. 1994;93:267.

Brent B. Ear reconstruction with an expansile framework of autogenous rib cartilage. Plast Reconstr Surg. 1974;53:619.

Brent B. Technical advances in ear reconstruction with autogenous rib cartilage grafts: Personal experience with 1200 cases. Plast Reconstr Surg 1999;104:319.

Brent B. Total auricular construction with sculpted costal cartilage. In: Brent B, ed. The Artistry of Reconstructive Surgery. St. Louis. MO: C.V. Mosby, 1987:113-127.
Nagata, S. A new method of total reconstruction of the auricle for microtia. Plast Reconstr Surg. 1993;92:187–201.

Nagata, S. Modification of the stages in total reconstruction of the auricle: Part I. Grafting the three-dimensional costal cartilage framework for lobule-type microtia. Plast Reconstr Surg. 1994;93:221–230.

Nagata, S. Modification of the stages in total reconstruction of the auricle: Part II. Grafting the three-dimensional costal cartilage framework for concha-type microtia. Plast Reconstr Surg. 1994;93:231–242.

Nagata, S. Modification of the stages in total reconstruction of the auricle: Part III. Grafting the three-dimensional costal cartilage framework for small concha-type microtia. Plast Reconstr Surg. 1994;93:243–253.

Nagata, S. Modification of the stages in total reconstruction of the auricle: Part IV. Ear elevation for the auricle. Plast Reconstr Surg. 1994;93:254–266.

Peer LA. Reconstruction of the auricle with diced cartilage grafts in a vitallium ear mold. Plast Reconstr Surg. 1948;3:653.

Tanzer RC. Total reconstruction of the external ear. Plast Reconstr Surg. 1959;23:1.
Tanzer RC. Microtia—A long-term follow-up of 44 reconstructed auricles. Plast Reconstr Surg. 1978;61:161.

Tanzer RC. The constricted (cup and top) ear. Plast Reconstr Surg. 1975;55:406.

Reinisch RF, Lewin S. Ear reconstruction using a porous polyethylene framework and temporoparietal fascial flap. Facial Plast Surg. 2009;25:181.