You are in: eMedicine Specialties > Pediatrics: Surgery > Otolaryngology MicrotiaArticle Last Updated: Jan 17, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Arturo Bonilla, MD, Founder and Director of Microtia-Congenital Ear Deformity Institute Arturo Bonilla is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery and American Medical Association Editors: Orval Brown, MD, Director of Otolaryngology Clinic, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Texas Southwestern Medical Center at Dallas; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc; Alan D Murray, MD, Pediatric Otolaryngologist, ENT for Children; Consulting Staff, Department of Otolaryngology, Medical Center of Lewisville, Children's Medical Center at Dallas, Cook Children's Medical Center; Full-Time Staff, Texas Pediatric Surgery Center, The Pediatric Surgery Center; Paul D Petry, DO, FACOP, FAAP, Clinical Assistant Professor of Pediatrics, University of North Dakota, School of Medicine and Health Sciences; Consulting Staff, Altru Health System; Maureen Strafford, MD, Arnold P Gold Foundation Associate Professor, Departments of Anesthesiology and Pediatrics, Tufts University and Tufts-New England Medical Center Author and Editor Disclosure Synonyms and related keywords: microtia, congenital anomaly of the external ear, ear deformity, microtia reconstruction, absence of the external ear, malformed ear, auricular anomalies, congenital malformations, hearing loss, reduced hearing, unilateral microtia, bilateral microtia, microtic ear, anotia, auricle, pinna INTRODUCTIONSection 2 of 12
  Microtia is the most common major congenital anomaly of the external ear but is rare enough that parents usually have never encountered it. Because of the prominent location of the ears, any deformity is visible. Health care providers may also be unfamiliar with this condition. Because of technical advances in the reconstruction of the microtic ear, results have dramatically improved in the hands of experienced ear reconstructive surgeons. Because of the fine details of microtia reconstruction, the surgeon must have a complete understanding of the 3-dimensional form of the auricle and sound surgical principles of soft tissue management and transfer. The future of microtia surgery holds much promise. History of the ProcedureThis condition is rarely noticed prenatally and is very traumatic for parents. Another major stressor is the feeling of guilt that parents may experience. Reassure parents that they were likely not the cause of their child's condition. The affected ear usually has severe conductive hearing loss (approximately 40-60 dB) secondary to lack of an external auditory canal and ossicular fixation. These children are likely to have normal speech. ProblemMicrotia is classified as follows based on a gradient from less severe (grade I) to total absence of the external ear (anotia):
FrequencyMicrotia has been reported to occur in 1 per 1000-20,000 births. Although the reason is unknown, microtia is seen more commonly in males than in females. In addition, the right side is affected more commonly than the left. Some studies have reported that the prevalence of auricular anomalies at birth increases with maternal age. EtiologyThe actual cause is relatively unknown. McKenzie and Craig state that microtia may occur as a result of in utero tissue ischemia secondary to obliteration of the stapedial artery or actual hemorrhage into the local tissues.6 Genetic studies have revealed several possible etiologic factors, such as chromosomal aberrations, multifactorial inheritance, and autosomal and recessive traits. The most common syndromes associated with microtia are Goldenhar syndrome and Treacher Collins syndrome. In addition, several medications, such as thalidomide and isotretinoin (Accutane), have been implicated as causing severe congenital malformations such as microtia. PathophysiologyDuring the seventh week of gestation, the first and second arches give rise to 6 hillocks called the hillocks of His. The first 3 hillocks are derived from the first arch, and the final 3 hillocks are derived from the second arch. These hillocks then fuse, forming the future ear. The structures of the adult ear corresponding to the hillocks are the tragus (first hillock), helical crus (second hillock), the helix (third hillock), the antihelix (fourth and fifth hillocks), and the antitragus (sixth hillock). ClinicalConsultation regarding a patient born with microtia ideally should occur soon after birth. In addition to evaluation of the major organ systems, the initial hearing status of the child is of utmost importance. Although severe conductive hearing loss results secondary to a malformed ear and absence or stenosis of the external auditory canal, inner ear function is almost always good, resulting in some ability to hear on the affected side. The contralateral ear almost always is normal, resulting in relatively normal speech development. During the initial consultation, the ear reconstructive surgeon should reassure the parents and outline the future management of their child's condition. If microtia is the only developmental anomaly, the initial workup consists of the evaluation of the child's hearing status. As previously stated, the inner ear function is usually normal in patients with microtia. Also, the middle ear status of the nonaffected ear is usually normal, resulting in overall normal hearing in the nonaffected ear. The contralateral ear is normal in most patients. INDICATIONSSection 3 of 12
Unilateral microtia Auricular reconstruction for unilateral microtia usually begins in children aged 6-8 years because the pinna reaches about 85-90% of its adult size at this age. By this time, the child is usually large enough that rib size is sufficient to harvest an adequate rib graft. If the child is still small, postpone surgery until an adequate rib for the framework can be harvested. For example, if a very small 6-year-old child presents with microtia, postponing auricular reconstruction until age 7-8 years, when rib growth is sufficient, is reasonable. On the other hand, if a very large 5-year-old child presents with microtia, the surgeon may begin reconstruction sooner because of adequate rib size. The ideal time to begin the reconstruction is the summer before the first grade. By the time the child starts the first grade, at least 2 of the surgeries can be performed, allowing the child to have the resemblance of an ear. Children tend to be teased during these early school years when the ear is not yet reconstructed. Bilateral microtia When a child is affected on both sides, the auricular reconstructions may begin at about age 4 years. Before the pinna reconstructions, a CT scan of the temporal bones is obtained to evaluate for ear canal and middle ear reconstructive surgery. Because both ears are abnormal, sizing of the reconstructed ears is of less importance. Two relatively smaller ears are not as noticeable as one asymmetric ear. Starting the external ear reconstructions before the middle ear surgery is very important. If an attempt is made to open the canal before the external ear reconstruction, the elasticity of the "virgin" skin and the circulation are compromised. Because these children are dependent on bone-conduction hearing aids, the goal of starting earlier is to finish at least one ear. The canal may be drilled soon after the ear is reconstructed. Obtaining adequate hearing without hearing aids is the eventual goal. RLEVANT ANATOMYSection 4 of 12
The reconstructive surgeon must intimately know the anatomy of the external, middle, and inner ear. Important landmarks include the helix, helical crus, antihelix, crura of the antihelix, tragus, antitragus, scapha, triangular fossa, concha cymba, concha cavum, and lobule. The primary blood supply to the external ear is via the superficial temporal artery and branches of the posterior auricular artery. The sensory innervation of the external ear is via the anterior and posterior branches of the greater auricular nerve. The location and reference point of the ear must be well understood. The angle of the long axis of the ear approximates the angle of the nasal dorsum. The superior point of the ear is usually at the eyebrow level. In a child aged 5-7 years, the helical crus is usually approximately 6.5-7 cm from the lateral canthus. The most inferior aspect of the lobule on the microtic ear is usually 0.5 cm higher than the normal side. CONTRAINDICATIONSSection 5 of 12
Contraindications to rib surgery for microtia reconstruction include high-risk surgical status and chest wall deformities. In addition, patients with pulmonary hypoplasia are at risk of a pneumothorax occurring during the rib harvest. WORKUPSection 6 of 12
Imaging Studies
Diagnostic Procedures
TREATMENTSection 7 of 12
Medical therapyIf hearing in the unaffected ear is found to be normal, a hearing aid is not usually recommended. If the child is found to have severe hearing loss in the normal-appearing ear, or if the child is born with bilateral microtia and atresia, hearing aids should be fitted immediately after birth. Surgical therapyUnilateral microtia/atresiaTotal external ear reconstruction requires 3-4 surgical stages. On the average, intervals of 2-3 months elapse between surgical stages to optimize the healing process. Some surgeons favor a 1- or 2-stage procedure. Tanzer and Brent advocated multistage reconstructions, which are currently favored by most ear reconstruction surgeons.
Stage 1 - Rib cartilage harvesting and framework insertion The first stage consists of 2 separate procedures: (1) harvesting the costal cartilage (see Media file 6) and (2) inserting the carved sculpted cartilage into a skin pocket under the microtic ear. A slightly oblique chest incision is made over the sixth, seventh, and eighth ribs close to the sternum (on the side opposite the microtic ear). The cartilaginous portion of the eighth rib and the synchondrosis of the sixth and seventh rib are harvested according to a previously measured template. A small piece of extra synchondrosis of rib 6 is harvested for use during the third stage in unilateral cases and third and fourth stages in bilateral cases. The sixth and seventh rib synchondroses form the base framework of the new ear. The eighth rib is used to form the rim or helix (see Media file 7). Once the 3 pieces of rib are carved, sculpted, and sutured together, the shape shown in Media file 8 ensues. In cases of unilateral microtia, an extra piece of rib is harvested and embedded in a separate incision posterior to the reconstructed ear. This piece of cartilage is used as an extra support to keep the reconstructed ear elevated during the third stage. In cases of bilateral microtia, extra pieces of rib are harvested for 2 reasons. Part of the saved rib is used for support to keep the ear elevated during the third stage. The other part of the saved rib is used for tragus construction bilaterally during the fourth stage. The new framework is inserted into a skin pocket under the microtic ear (see Media files 9-10). Patients are sent home with pain medication and antibiotics. An ear dressing is applied during surgery and left intact for about 3 days. At that time, the wound is checked and the ear is rebandaged. The drain stays in place for about 5-7 days to provide negative suction so that the skin can coapt to the newly inserted framework. The sutures are removed on the seventh postoperative day. Contact sports are restricted for approximately 4-6 weeks. The hair may be washed a few weeks after surgery. The next stage may proceed approximately 3 months later. Stage 2 - Transposition of the lobule The second stage consists of forming the earlobe, otherwise known as transposition of the lobule. An incision is made both in front and behind the skin vestige (see Media file 11). The skin vestige is then rotated into place via a Z-plasty and spliced to the cartilaginous framework that was sculpted during the first stage (see Media file 12). Sutures are placed, and antibiotic ointment is applied. Patients are sent home with pain medication. An ear dressing is placed for 3 days. Sutures are removed on the seventh day postoperation. Patients are restricted from contact sports for about 3-4 weeks. The hair may be washed a few weeks after surgery. The next stage may proceed approximately 3 months later. Stage 3 - Elevation of the ear and skin graft placement Approximately 3 months after the second stage is completed, the third stage is begun. The third stage consists of elevating the newly formed ear from the side of the head. A 0.017-inch skin graft is placed on the undersurface. The graft is taken from the upper buttock area on the same side as the microtic ear. The graft harvest site is hidden under the bathing suit or underwear region (see Media file 13). An incision is made behind the newly constructed ear, and the undersurface is undermined. The banked cartilage harvested from the first stage is then placed under the framework to provide support and elevation (see Media files 14-15). This raw tissue is then lined with a skin graft. Once the graft is secured, a bolster dressing is placed behind the ear. An ear dressing is applied. In addition, a special bandage is placed over the graft site. Surgery lasts approximately 2.5 hours, and the patient goes home the same day with pain medication and antibiotics. The ear dressing and the sutures are removed on about the seventh postoperative day. The upper buttock dressing is left intact until it falls off on its own. Contact sports are avoided for about 4 weeks. The hair may be washed a few weeks after surgery. The final stage may proceed approximately 3 months later. Stage 4 - Formation of the tragus and excavation of the conchae, achieving symmetry of the ears Approximately 3 months after the third stage is completed, the fourth and final stage is begun. The fourth stage consists of formation of the tragus, excavation of the concha (to mimic an actual opening into the ear), and achieving symmetry of the ears. First, the reconstructed ear is marked for the future placement of the tragus. An incision is made as shown in Media file 16. At this point, a J-shaped incision is made in the conchal area of the microtic ear. A skin/cartilage composite graft and a full-thickness skin graft are taken from the contralateral ear as shown in Media file 17. Once the grafts are taken and the skin is sutured, the projection of both ears is very similar. The skin/cartilage graft is secured in place where the initial incision was placed on the microtic ear. The tragus is then formed. Once the concha on the microtic ear is excavated, the second skin graft is placed to line the raw conchal tissue. The ear now has the appearance of having an external auditory canal. A bolster is placed over the conchal area, and an ear dressing is placed over both ears. Patients go home with pain medication. Ear dressing and sutures are removed around the seventh postoperative day. Contact sports are avoided for approximately 4 weeks. The hair may be washed a few weeks after surgery. Media files 18-19 depict the transition from a typical preoperative grade III microtia to the final result. Bilateral microtia/atresiaChildren born with bilateral microtia/atresia are treated differently than those with unilateral microtia/atresia. A CT scan of the temporal bones is obtained before the onset of the first microtia surgery. This depicts the anatomy of the outer, middle, and inner ear. After the first stage of surgery, the contralateral first stage of surgery may begin within 4-6 weeks. Approximately 3 months are allowed to pass before proceeding to the next stage. To minimize surgeries, both second-stage operations may be performed at the same time. Three months later, both ears may be separated from the head at the same time. During the final stage, the tragus on each side may be constructed by retrieving the saved rib obtained from the first stages. After 3-4 months, the canal may be drilled to improve hearing status (if the anatomy is favorable). As previously stated, pinna reconstruction is begun at an earlier age for several reasons. Because no ears are present for comparison, the cartilaginous framework may be sculpted using a smaller rib. In addition, the middle ear surgery may begin at an earlier age in order to improve the patient's hearing sooner. Although beginning the middle ear surgery early for hearing improvement is advantageous, the surgical risks must be considered. The most common risk associated with middle ear surgery is restenosis of the external auditory canal. The most detrimental risk is actual damage to the facial nerve. As a result, the CT scan must be examined carefully in order to track the location of the facial nerve. Follow-upFor more information, patients and their parents may visit the Microtia-Congenital Ear Institute Web site. COMPLICATIONSSection 8 of 12
Because of the complex anatomy of the external ear, great attention to detail must occur during the reconstruction. The most common complication of microtia reconstruction is an unpleasant cosmetic result. Other less common complications are infection, bleeding, or pneumothorax during the rib harvest. Hematoma formation under the skin pocket of the new ear cartilaginous framework can also result in an infection. Excessive cartilage resorption is an uncommon complication. OUTCOME AND PROGNOSISSection 9 of 12
Although some children do not want surgery, parents must discuss the benefits of the reconstructions with them. With good results, all children can have very positive physical and psychological outcomes. Total auricular reconstruction is one of the most challenging procedures performed by the ear reconstruction surgeon. Understanding the psychological issues faced by patients with microtia and providing education to the parents of these patients is fundamental to a successful microtia practice. Complete knowledge of the 3-dimensional anatomy of the ear and sound surgical principles of soft tissue management and tissue transfer is necessary. Children younger than 3-4 years with a microtic ear usually have little psychological impact. After this time, children usually begin to notice that their ears are different. Parents must treat their child with microtia the same as other children. Although parents may not realize, children feel the anxiety of their parents. Parents who attempt to cover the ear tend to hinder the confidence of the child. The children with the lowest self-esteem tend to be the ones whose parents transmitted anxiety about the ear throughout their childhood. Patients whose ears have not been reconstructed as children may have difficulty dealing with the peer pressure of adolescence. During this time, fitting in with their peers is of much importance. Teenagers are particularly conscious of their looks and are very aware of their microtic ear. Although they tend to be more eager to undergo surgical reconstruction than younger children, their expectations tend to be more unrealistic. Therefore, counseling patients and parents as early as possible is imperative. With early counseling, expectations become much more realistic, and the patients are able to deal with certain social issues much easier. FUTURE AND CONTROVERSIESSection 10 of 12
Because of the rarity of microtia, most parents and some health care providers may not fully understand how to care for these children. Microtia is rarely noticed on prenatal ultrasonography, primarily because of the complexity of the fetal ear and the inherent nature of conventional 2-dimensional ultrasound. Some authors suggest the use of 3-dimensional ultrasound to better examine the fetal ear for purposes of prenatal diagnosis and genetic counseling. Cao and Vacanti et al have provided promising advances in the technique of microtia reconstruction. This group has evaluated a tissue-engineered autologous cartilage to use in place of harvested rib cartilage. Autologous chondrocytes are harvested and seeded into a mesh that is shaped in the form of the normal ear. This new framework is then inserted under the microtic vestige as a first-stage procedure. If successful in the long term, this form of cartilage harvesting may replace present-day rib harvesting. The future of microtia surgery holds much promise. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
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