Autologous Costochondral Reconstruction of Microtia
Kathleen C.Y. Sie
INTRODUCTION
The incidence of microtia ranges from 1:5,000 to 1:10,000. Eighty percent of patients with microtia have unilateral involvement; therefore, this chapter will focus on management of these patients. Infants born with microtia commonly have associated aural atresia and hearing loss. These malformations are obvious at birth, so the families are often eager to understand the abnormality and proceed with treatment of the ear and hearing loss. However, these anomalies are obvious at birth, and the interventions are typically deferred for several years and the otolaryngologist develops a relationship with the child and family. In order to adequately counsel these families, the otolaryngologist must understand the medical and developmental issues related to the ear anomalies, associated medical issues, treatment options, and timing of interventions.
At Seattle Children’s Hospital, we have developed a team approach to managing children with microtia. Pediatric audiologists monitor hearing status and make recommendations for amplification. An anaplastologist meets with the families interested in prosthetic management. After the otolaryngologist counsels the families about reconstructive options, our nurse reviews photographs of reconstructed ears with the child and family. Then, the pediatric otolaryngologist and facial plastic surgeon evaluate the child to assess the options for reconstruction.
Craig S. Murakami and I have worked together over the past 20 years to perform microtia reconstruction. Initially, we used the three-staged approach popularized by Brent. In 2010, we started using a modification of the two-staged approach as described by Nagata. More recently, Amit Bhrany has joined our team. Our current technique for microtia reconstruction using autogenous costal cartilage is presented.
HISTORY
Patients with microtia typically come to medical attention during infancy or early childhood. The parents should be asked about the results of newborn hearing screening and their observations of the child’s response to sound, speech, and language development. It is important to inquire about ear infections or middle ear effusions in the normally formed ear.
Past medical history should be reviewed to rule out other medical conditions that can be associated with microtia, including renal, cardiac, and vertebral anomalies. Family history may reveal a genetic predisposition for external ear anomalies. A family history of bleeding or anesthetic problems is important in preoperative planning. Social history, including school placement and extracurricular activities, is relevant since microtia reconstruction involves staged elective surgery. Each surgery is associated with postoperative activity restrictions that should be considered before scheduling.
PHYSICAL EXAMINATION
Physical examination should include careful inspection of the abnormal ear with accurate description of the pinna and inspection of the external auditory canal. Some patients with severe microtia may have a patent or stenotic ear canal. Patients with unilateral microtia are also more likely to have relatively minor anomalies of the contralateral “normal” ear.
A complete examination of the head and neck includes assessment of the position of the orbit, symmetry of the mandible, facial nerve function, and soft tissue status. It is helpful to think of the OMENS (ocular, mandibular, ear, nerve, soft tissue) plus (vertebral, cardiac, renal) classification. The position of the hairline and size of the chest should be considered when the plans are being made for surgical reconstruction.
It is also important to assess the overall size of the child, with attention to the chest. While I currently do not use objective measures, some surgeons measure the diameter of the chest several centimeters below the nipples. They use the criteria of 60 cm to proceed with reconstruction. I prefer that the child’s height is at least at the 50th percentile for an 8-year-old child. Waiting until the child is closer to the size of a 10-year-old child will provide more cartilage for creation of the framework.
INDICATIONS
Children with microtia should be followed carefully to monitor hearing, speech, and language development. As the child grows, ear-specific behavioral responses should be obtained to assess the hearing status of the microtic ear as well as the contralateral ear. Bone conduction thresholds must be obtained to rule out sensorineural hearing loss. The audiologic management of children with unilateral hearing loss is evolving. With our growing understanding of problems related to unilateral hearing loss, amplification options should be discussed with the family.
While management of the hearing is beyond the scope of this chapter, it is important for the microtia surgeon to consider options for management of the hearing when counseling patients and their families. Ideally, the surgeon, patient, and family will have a clear view of the overall treatment plan before embarking on the first surgical intervention. Children with craniofacial microsomia may benefit from the coordinated services of a craniofacial team.
There are three main options for management of microtia: (1) no intervention, (2) prosthetic management, either adhesive or implant retained, and (3) reconstruction, with either alloplastic or autogenous frameworks. The advantages and disadvantages of these approaches are presented in Table 39.1. It is important for patients and families to review photographs of expected outcomes of reconstruction so that they will have realistic expectations. Hearing management should be considered when formulating a plan for comprehensive management of the ear and hearing.
CONTRAINDICATIONS
The patient must participate in the decision to proceed with autogenous rib reconstruction. This requires that the child be developmentally capable of understanding the process. In order for patients and families to have realistic expectations of surgical outcomes, they should review photographs of reconstructed ears. It is also
important that the patient and family have a stable social situation. If the patient has significant psychosocial issues, it may not be the appropriate time to embark on elective reconstructive surgery.
important that the patient and family have a stable social situation. If the patient has significant psychosocial issues, it may not be the appropriate time to embark on elective reconstructive surgery.
TABLE 39.1 Options for Microtia Management | ||||||||||||||||||||||||
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TABLE 39.2 Perioperative Management for Patients Undergoing Autogenous Rib Reconstruction of Microtia | |||||||||||||||
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Local factors such as the hairline should be considered. A low hairline will result in hair growth over the reconstructed ear. In general, these patients are less favorable candidates for autogenous costal cartilage reconstruction though adjunctive measures such as surgical epilation or postoperative epilation can be considered. Children with severe mandibular asymmetry may be candidates for early mandibular reconstruction. Consideration should be given to associated medical issues.
PREOPERATIVE PLANNING
The goal of ear reconstruction is to create an ear that will be symmetric to the contralateral ear for the patient’s lifetime. Therefore, the surgeon must be able to harvest sufficient cartilage to create an appropriate-size framework. Some surgeons require a chest diameter of at least 60 cm. However, chest diameter does not allow the surgeon to determine the thickness of the costal cartilage. The amount of cartilage required is dependent upon the technique for creating the framework. The minimum age of surgical reconstruction using autogenous costal cartilage depends upon the size of the child and the size of the contralateral ear. In general, the ideal age to start autogenous costal cartilage reconstruction of microtia is probably between 8 and 10 years of age. Conversely, the costal cartilage starts to ossify as patients approach skeletal maturity. So the decision to proceed with microtia repair should be made prior to the late teenage years. For patients who are favorable candidates for atresia repair, we prefer to complete microtia reconstruction prior to atresia repair though there is increasing interest in performing atresia repair prior to auricular reconstruction.
A standardized set of preoperative photographs should be taken. The expected postoperative course and activity limitations (Table 39.2) should be reviewed in detail with the family as part of the consent process. See Table 39.3 for complications associated with the procedures. Children who are anxious about surgery may benefit from consultation with a child life specialist.
SURGICAL TECHNIQUE
There are several types of microtia, and each presents the reconstructive surgeon with unique challenges. The techniques presented here will focus on reconstruction of class 3 (lobule-type) microtia. We operate with two surgical teams; one team harvests the cartilage while the other excises the cartilaginous remnant and prepares the recipient bed during the first-stage surgery. At the second surgery, one team harvests the banked rib cartilage and skin graft while the second team elevates the ear and performs local advancement flaps.
Stage 1
Preparation
A template is created from the normal contralateral ear. Unexposed radiographic film is used because it is sufficiently rigid to be placed in the skin pocket and it can be autoclaved.
Preoperative antibiotics are administered intravenously prior to surgery. The patient is anesthetized and an oral RAE tube is inserted. The tube should be secured in the midline so the table can be turned 180 degrees allowing the two surgical teams to work simultaneously on either side of the patient. The face and both ears are included in the surgical field. The desired position of the new ear should be drawn on the patient (Fig. 39.1). Although measurements from the ear to the lateral orbital rim and oral commissure can be compared to the contralateral side, the underlying hemifacial macrosomia may cause some asymmetry in the measurements. We prefer to compare the position of the superior and inferior limits of the ear to be reconstructed with the contralateral ear.
 FIGURE 39.1 Determining the position of the ear. A template created from the contralateral ear is used to determine the position of the ear to be reconstructed. |
The area around the microtia and the area of the anticipated chest incision on the contralateral side are infiltrated with lidocaine with epinephrine. The placement of the chest incision is important to allow adequate exposure with the smallest possible incision.
Harvest of Costal Cartilage
We have gone to considerable effort to minimize donor site morbidity. With careful placement of the chest incision, we are reliably able to harvest an adequate amount of cartilage through a 2.5-cm incision. The incision should be made just lateral to the genu of the synchondrosis at the inferior aspect of the superior limb of the synchondrosis (Fig. 39.2).
The rectus and lateral oblique muscles are divided beyond the medial and lateral extents of the skin incision. After exposure of the costal cartilages, the floating cartilage with light attachment to the superior cartilage is separated at the point of attachment. The cartilage is dissected laterally, including the surrounding perichondrium. In general, a segment 8 cm in length is desirable though the length is sometimes defined by the location of the bony-cartilaginous junction. The more inferior floating cartilage is also harvested to create the antihelical fold.
The area of the synchondrosis is then addressed. Lidocaine with epinephrine is infiltrated into the intercostal muscles between the two limbs of the synchondrosis. Perichondrial incisions are made at the superior and inferior aspects of the cartilage so that the superficial perichondrium is left adherent to the excised
synchondrosis. The deep perichondrium is separated from the deep aspect of the costal cartilage and left in situ. The inferior limb is defined by making the lateral incision at the bony cartilaginous junction in a beveled fashion to avoid a sharp demarcation at the donor site. Care must be taken to carry this incision through the cartilage only, leaving the deep perichondrium intact. Once the lateral incision is made, the dissection between the cartilage and perichondrium is carried toward the midline under direct vision. When using a small incision, the inferior limb must be replaced into the chest wound so that the superior limb can be defined in a similar fashion. When both limbs are identified, the deep aspect of the synchondrosis must be freed from the underlying soft tissue. The area of attachment should be palpated to ensure that the synchondrosis is free of any soft tissue attachment. The final cut can be performed with placement of heavy Mayo scissors using manual guidance. Care must be taken to maximize the size of the cartilaginous segment removed.
synchondrosis. The deep perichondrium is separated from the deep aspect of the costal cartilage and left in situ. The inferior limb is defined by making the lateral incision at the bony cartilaginous junction in a beveled fashion to avoid a sharp demarcation at the donor site. Care must be taken to carry this incision through the cartilage only, leaving the deep perichondrium intact. Once the lateral incision is made, the dissection between the cartilage and perichondrium is carried toward the midline under direct vision. When using a small incision, the inferior limb must be replaced into the chest wound so that the superior limb can be defined in a similar fashion. When both limbs are identified, the deep aspect of the synchondrosis must be freed from the underlying soft tissue. The area of attachment should be palpated to ensure that the synchondrosis is free of any soft tissue attachment. The final cut can be performed with placement of heavy Mayo scissors using manual guidance. Care must be taken to maximize the size of the cartilaginous segment removed.
 FIGURE 39.2 Position of the chest incision. A: Position of costal cartilages drawn on chest. Asterisks marking area of anticipated incision. B: Attached floater removed. C: Lateral aspect of the superior limb of the synchondrosis divided and elevated with single hook. D: Inferior limb of synchondrosis elevated and delivered through chest incision. |
Once the cartilage is removed, hemostasis should be obtained and the wound inspected for evidence of pneumothorax. The wound should be filled with saline and the anesthesiologist is asked to deliver an airway pressure of 30 to 40 cm H2O to simulate a Valsalva maneuver. There may be initial air bubbles mobilized from the peripheral aspect of the wound. If a pleural defect is identified, a red rubber catheter should be placed through the defect, and it should be repaired with a purse-string suture. The suture is tied down as positive pressure is administered and the red rubber catheter removed. If possible, local soft tissue should be recruited to provide another layer of closure over the repair site.
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