- Email: [email protected]
The Nagata technique for microtia reconstruction
Author’s Accepted Manuscript The Nagata Technique for Microtia Reconstruction Tom Shokri, David R. White
www.techgiendoscopy.com
PII: DOI: Reference:
S1043-1810(17)30037-4 http://dx.doi.org/10.1016/j.otot.2017.03.009 YOTOT759
To appear in: Operative Techniques in Otolaryngology - Head and Neck Surgery Cite this article as: Tom Shokri and David R. White, The Nagata Technique for Microtia Reconstruction, Operative Techniques in Otolaryngology - Head and Neck Surgery, http://dx.doi.org/10.1016/j.otot.2017.03.009 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Title: The Nagata Technique for Microtia Reconstruction Authors: Tom Shokri M.D., Division of Otolaryngology—Head & Neck Surgery, Department of Surgery, College of Medicine, The Pennsylvania State University, Hershey, Pennsylvania David R. White M.D., Department of Otolaryngology, Department of Pediatric Otolaryngology, Medical University of South Carline, Charleston, South Carolina, USA Correspondence to: Tom Shokri M.D., Division of Otolaryngology—Head & Neck Surgery, Department of Surgery, College of Medicine, The Pennsylvania State University MC H091 P.O. Box 850 Hershey, PA 17033. Email: [email protected] Keywords: Microtia, Autogenous rib cartilage, auricular reconstruction, Nagata technique Disclosures: None Abstract Multiple techniques for auricular reconstruction for microtia have been described. Reconstruction using autologous costal cartilage continues to be the most widely implemented technique for repair. Recreation of a three-dimensional framework mimicking the curves and contours of a normal ear, while also maximizing stability, is crucial in reconstructing the auricle. Additionally, soft tissue management, although generalized in approach, is specific to each patient and greatly influences surgical outcomes. In the present article, we discuss the Nagata technique for auricular reconstruction, a two-staged technique using costal cartilage grafts to rebuild the auricle.
Microtia Reconstruction: The Nagata Technique Microtia is a congenital anomaly of the ear resulting in abnormal external ear development. It is estimated to occur in approximately 0.03% of live births.1-3 The external ear develops from the first and second branchial arches at around 5 to 6 weeks of gestation continuing to develop through the second trimester. These arches form the 6 hillocks of His that eventually give rise to the helix, lobule, tragus, and antihelix that come to form the auricle.4 Surgical reconstruction of the auricle is a rewarding, though humbling, and uniquely challenging process. The goals of reconstruction include creation of an aesthetically natural appearing ear with a resilient framework and reduction of donor site morbidity. Surgical approaches to reconstruction have continued to evolve with refinements to techniques but the fundamental approach to repair has remained consistent. Historical perspective Ear reconstruction was first documented in the Sushruta Samhita, an ancient Sanskrit text, documenting local tissue transfer for repair of a lobular defect. In 1597, Tagliacozzi, an Italian surgeon, first described repair of ear deformities using post-auricular skin flaps. Then in 1845, Dieffenbach described repair of a middle third auricular defect with a post-auricular advancement flap that is still implemented today. Attempted microtia repair was first described in 1920 by Gillies, with sculpted homograft rib cartilage placement under the mastoid skin with overlying skin flap. In the 1930’s Pierce modified this method with use of rolled skin to reconstruct the helix and the addition of a skin graft for coverage. Gillies documented his efforts with use of maternal donor cartilage however the constructs showed a high rate of resorption. It was not until 1959, when Tanzer described subcutaneous implantation of an autogenous cartilage graft framework that the modern era of microtia reconstruction began. Techniques developed by Brent and Nagata later evolved through modifications and alterations to Tanzer’s, though the general principles of framework construction, tissue handling, and skin redraping remain. 5 Patient Evaluation and Preoperative Considerations The initial evaluation of a child presenting with microtia should include evaluation of facial symmetry and movement, dental occlusion, and an otologic evaluation with audiological testing and imaging. Microtia is associated with conductive hearing loss (CHL) in 80-90% of cases. Sensorineural hearing loss is less common
with an incidence of 10-15%. It is therefore crucial to assess the external auditory canal and hearing status. If aural atresia surgery is under consideration, it should be done after completed reconstruction to avoid manipulation of the delicate blood supply for the reconstructive process.6 The surgeon must be mindful of other associated hypoplastic features of the head and neck as associated anomalies occur in in approximately 50% of cases. These malformations are often in close proximity to, or arise from, the first and second embryologic branchial arches. Oculo-auriculo-vertebral spectrum disorders, are a range of disorders that develop due to disturbances in the embryonic structures that develop from these arches. These spectrum of disorders include Goldenhar syndrome, hemifacial microsomia, and oculoauricular vertebral dysplasia. Microtia is often associated with other craniofacial anomalies including cleft lip/palate, anopthalmia or micropthalmia, cardiac defects, abnormal limb development, renal malformations, and facial nerve dysfunction. Syndromes involving dysmorphogeneis of first or second branchial arches must therefore be considered when first evaluating a child with microtia. Radiologic imaging may include high-resolution computed tomography of temporal bones to assess atresia, cervical spine imaging to evaluate vertebral anomalies, renal ultrasound for genitourinary anomalies, and potentially panorex for malocclusion. If multiple congenital anomalies are found then the patient should be comprehensively evaluated by a multidisciplinary craniofacial team prior to surgical intervention. Timing of surgery The age at which a patient should undergo surgery for optimal reconstruction varies based on technique employed. The patient’s age will ultimately determine the extent of external ear maturation. The ear continues to grow until 10 years of age.7 However, it reaches 85% of its growth by age three.8 However, the rib cage does not adequately develop to allow for sufficient cartilage harvesting until five to six years old. This is the age that surgeons performing the Brent technique typically begin reconstruction.9-10 The contralateral unaffected ear, often used as a template for reconstruction, has by this time reached at least 90% of its adult size. In contrast, the Nagata or Firmin techniques require a larger amount of cartilage to be harvested for framework design. Therefore, surgeons implementing this technique may delay surgery until the child is at least nine or 10 years old and the chest circumference is at least 60 cm.10-15 Delaying surgery until the patient is
older is thought to reduce the risk of thoracic deformity due to rib graft harvesting. It is important to discuss the benefits of a properly formulated reconstructive plan over the negative impact expedited surgery may have. Autologous Rib Techniques Autogenous costochondral reconstruction is the oldest method by which microtia is repaired. Use of costochondral graft involves harvesting, carving, and assembling a framework of costal cartilage secured with carefully placed sutures. The sculpted framework is then implanted within a skin pocket in an aesthetically well positioned area. The subsequent stages modify and adjust the appearance of the auricular construct and elevate it away from the scalp to establish an anatomically correct auriculocephalic angle. There continues to be controversy surrounding techniques utilizing autogenous constructs, in particular the Brent and Nagata methods although the Firmin technique has gained popularity as well. The Nagata technique has fewer stages and has been shown to yield more consistent outcomes in the hands of some surgeons. This technique does require more cartilage and thus as previously mentioned must be deferred until an older age. Conversely, the Brent technique emphasizes limited use of cartilage in the hopes of mitigating the risk of any chest wall deformity. This means that children may undergo surgery earlier, which is often favored by parents due to an earlier intervention’s potential to limit psychosocial sequelae. Despite the technique employed, meticulous surgical planning and attention to detail is required to recreate an ear that is natural and cosmetically appropriate. Tanzer’s initial approach consisted of six stages which Brent later modified creating a four staged approach: (1) Fabrication of framework from contralateral costal cartilage and implantation into skin pocket, (2) lobule transposition, (3) ear elevation, and (4) creation of the conchal bowl and tragus; stages two and four may be combined for a possible three staged procedure.9-10 Nagata’s modification groups stages one, two, and four of Brent’s for a two staged procedure. There are additional changes to the sculpting of the framework, amount of cartilage used, and incisions based on the microtia type and remnant structures.11-15 Firmin’s technique maintained a two-staged procedure with further alterations to the framework and incisions. She created three particular frameworks, adding 1 to 3 cartilage segments to aid in projection depending on the extent of mastoid hypoplasia.16 During the planning stage, benefits, risks, and alternatives to surgery should be thoroughly discussed with the patient and parents. Engaging the patient in the overall process is crucial as their compliance throughout each
stage will help determine the final result of reconstruction. Realistic expectations of outcomes should be established. It may help to review photographs of reconstructed ears from prior patients with similar microtia types in order to set representative expectations (Figure 1). Nagata Stage I: Framework harvesting, fabrication, and implantation The first step in the Nagata reconstructive process is creating a template for the cartilaginous framework. A template is made by tracing the contours of the contralateral normal ear onto radiographic film or the transparent layer of an autoclavable sterilization envelope. The scaphoid and triangular fossa as well as the conchal bowl are cut out of the template to allow for carving of the cartilage. This template is used to help determine the position of the implanted framework and as a guide for carving (Figure 2). The distance from the lateral canthus to the root of the helix of the normal ear is measured and is usually the length of the normal ear or 6.5 cm. This determines the location of the template with respect to the lateral canthus. The vertical position of the template is then matched to both the superior aspect and lobule of the normal side. The distance between the helical rim to the lateral canthus and oral commissure are also marked on the film. It is important that the entire face and both ears be kept within the surgical field during preparation. This allows the contralateral unaffected side to be easily visualized permitting assessment of symmetry. The eyes and mouth are also included in the preparation field to allow visualization of important landmarks such as the lateral canthus and oral commissure. The ipsilateral rib cartilage is then harvested. The length of the xiphoid process to inferior margin of the costal cartilage is divided in thirds. A horizontal incision line is drawn at the inferior border of the superior third. This will approximate the inferior margin of the 7th costal cartilage and should be approximately 2 cm from the costal margin (Figure 3). The skin and fat are incised, exposing the fascia of the external oblique and rectus abdominis. An incision is then carried out between these two muscles and the intercostal muscles revealing the underlying 6th-9th costal perichondrium. The anterior aspect of the perichondrium is then incised and a perichondrial elevator is used to undermine the perichondrium, leaving the posterior perichondrium intact to stimulate cartilage growth and mitigate possible chest wall deformity. The radiographic film template is then used to determine the best donor site for the auricular frame.
The 6th through 9th cartilages are harvested en
bloc. Morselization of extraneous cartilage into 2 to 3 mm blocks, and placement into the perichondrial defect,
has been described to further reduce the risk of thoracic deformity by stimulating cartilage regeneration. 17-18 These perichondrial pockets are then closed with 4-0 nylon. The donor site is closed in multiple layers. Meticulous closure of the rectus muscle and subcutaneous layers is important to further prevent postoperative chest wall deformity. The auricular cartilaginous framework is then sculpted from the synchondrosis of the 6th and 7th ribs. The helix and helical crus are then fabricated using cartilage from the 8th rib, and the 9th rib is used to reconstruct the antihelix, superior and inferior crus (Figure 4). Cartilage from the 6th rib is “banked” in the subcutaneous layer of the chest incision for use in the second stage. Components of the framework are then secured together using steel wire or clear 4-0 nylon. The risk of extrusion may be reduced by embedding suture into grooves in the framework, made by creating small incisions with a scalpel. Lobule transposition is then performed during the initial stage of reconstruction. Skin incisions divide the lobule into three separate skin flaps: the anterior and posterior skin flap of the lobule and the tragus skin flap. The posterior flap remains attached to the mastoid skin flap and the anteriorly based tragal flap is used to surface the tragus. A “lazy W-flap” is created by the margins of the mastoid and posterior lobule flap and the middle limbs of the “W” will eventually meet helping form the intertragal notch. This “W-flap” and the anterior lobule flap become transposed in a reciprocal manner resembling a z-plasty. The rudimentary auricular cartilage is removed and the subcutaneous pocket is formed. The skin is then extensively undermined below the subdermal plexus. The 3-D framework is then implanted into the subcutaneous pocket, a suction drain is positioned beneath the framework, and the flaps are secured over this construct with carefully positioned bolsters (Figure 5). Drains are removed in 48-72 hours, and bolsters may be removed in approximately 1-2 weeks. Stage II: Framework Elevation The second stage of repair is typically performed about six months after the first. An incision is made approximately 3-5 mm away from the framework, along the mastoid skin, paralleling the helical rim. The framework is elevated from the mastoid skin by dissection into the postauricular sulcus. Attention is paid to preserving the delicate vasculature and soft tissue of the cartilage framework. The postauricular skin is then undermined and advanced into the area of the postauricular sulcus allowing adequate projection of the ear
laterally, effectively lifting it away from the mastoid. The remaining standing cutaneous deformity is removed and the skin is further thinned and hair follicles are removed. The previously banked 6th rib cartilage is retrieved and thinned along it’s convexity into a crescent shape with a thickness of approximately 1 cm. This segment is then placed under the neoauricle, between the framework and mastoid, to ensure adequate projection and prevent future repositioning. It is then secured in place with 4-0 clear nylon suture. The graft is then covered with a well vascularized tissue to allow for overlying skin graft adherence and prevention of infection or extrusion. A temporoparietal fascia flap may be raised and subcutaneously tunneled to cover the posterior aspect of the neoauricle and cartilage graft. The retroauricular skin is then advanced forward and a split thickness skin graft is harvested from the parietal-occipital scalp, thigh, or groin area to cover the remaining exposed temporoparietal fascia flap. The skin graft is secured in place to create a new postauricular sulcus with 5-0 chromic sutures. A bolster is then secured into the sulcus with 4-0 polypropylene suture. The bolster is kept in place for approximately 1 week (Figure 6). Complications Potential complications for all microtia techniques employing autogenous costal cartilage for reconstruction are similar. Complications involving the donor site include: pneumothorax, atelectasis, and scarring. Meticulous dissection technique, as well as leaving posterior perichondrium intact, is important in order to avoid pneumothorax. One should check for pneumothorax or air leak from the thoracic cavity by filling the defect with sterile saline and requesting the anesthesiologist to administer Valsalva maneuver with positive pressure ventilation to sustain a pressure of 40 cm H20. The presence of a steady stream of air bubbles will confirm a defect in the pleura requiring repair. A red rubber catheter may be placed into the identified defect and both pleura and muscle should then be closed in a purse string fashion while the catheter remains on suction. The suture should be tied down during full lung expansion (Valsalva maneuver) as the catheter is removed. Bupivacaine intercostal nerve block may be used at the end of the procedure to help reduce donor site pain postoperatively. Postoperative pain control, in addition to respiratory therapy, will help reduce atelectasis by preventing splinting. Complications involving the recipient site include hematoma and infection of the cartilaginous framework. These have become less common with use of suction drains. However, postoperative assessment for excess
tension along the skin pocket is important in preventing skin necrosis and resultant framework exposure and subsequent cartilage loss. In the event that the graft becomes exposed due to skin breakdown, appropriate antibiotic coverage should include Staphylococcus and Pseudomonas species. The exposed site should be covered with moist dressings. A 1-2 mm exposure with intact perichondrium may be allowed to initially heal secondarily. Problems with scar contracture and resultant poor contouring may improve with time. Scar revision may be necessary and the patient should be educated regarding realistic outcomes.
Conclusion The surgical correction of microtia is a humbling yet rewarding experience for the reconstructive surgeon. Each patient and malformation is unique. Therefore, careful consideration of the individual patient with regard to comfort level, deformity type, and appropriate surgical approach is crucial in management. Meticulous planning and a great attention to detail are required by the surgeon to achieve an optimal balance between desired aesthetic and functional results. The Nagata technique allows for detailed reconstruction of the ear while also optimizing auricular projection. It enables reconstruction of defects with complete anotia, low lying hairline, and secondary repair as well. Nagata’s method emphasizes the preservation of the vascular supply to the reconstructed region while attempting to mitigate the risk of cartilage graft resorption. Like other techniques using autologous cartilage, there is a significant learning curve with this technique and a requirement for some artistic ability. All techniques of microtia repair have their associated advantages and disadvantages. These should be thoroughly discussed with the patient and family prior to reconstruction.
Figure 1: Various patients at different stages of repair. Top left: Grade 3 lobular type microtia prior to intervention. Top Right: Implanted cartilage framework prior to lobule transposition; Brent technique. Bottom left: After transposition of lobule. Bottom Right: Following stage 2 with elevation of framework
Figure 2: Completed cartilage framework at left adjacent to original template drawn on sterile packaging sheet used for carving. Figure 3: Incision line for costal cartilage harvest approximating 7th rib.
Figure 4: Auricular
cartilaginous framework sculpted from synchondrosis of the sixth and seventh ribs. Helix and
helical crus are fabricated using cartilage from the eighth rib, and the ninth rib is used to reconstruct the antihelix, superior and inferior crus . Figure 5: Nagata technique for the first stage of microtia repair with a W-Shaped incision with depiction of anterior and posterior skin flaps of the lobule, the anterior skin flap of the tragus and the mastoid skin flap. Removal of remnant auricular cartilage and construction of the skin pocket with placement of 3-D framework.
Figure 6: Second stage with temporoparietal fascia (TPF) tunneled posteriorly. Crescent shaped cartilage construct placed to elevate framework. Fixation of cartilage block to soft tissue of the posterior surface of 3-D frame and to the temporal and mastoid surfaces. The TPF then overlies the posterior surface of the reconstructed auricle, the cartilage block and the temporal and mastoid surfaces. Skin of the temporal and mastoid surfaces is closed and the excess tissue excised. Exposed surface is covered with a skin graft.
Disclosures There are no disclosures to report.
References 1. Lucente FE, Lawson W, Novick NL: The External Ear, Philadelphia, 1995, WB Saunders. 2. Melnick M, Myrianthopoulos NC: External Ear Malformations: Epidemiology, Genetics and Natural History, New York, 1979, Alan R. Liss. 3. Aase JM, Tegtmeier RE: Microtia in New Mexico. Birth Defects 13:113, 1977. 4. Anatomy and embryology of the external ear and their clinical correlation. Park C, Roh TS - Clin Plast Surg - April 1, 2002; 29 (2); 155-74 5. Weerda, H. History of auricular reconstruction. Aesthetics and Functionality in Ear Reconstruction. 2010; 68: 1-24. 6. Jahrsdoerfer RA, Kesser BW. Issues on aural atresia for the facial plastic surgeon.Facial Plast Surg 1995;11(4): 274–7. 7. Andreoli SM, Mills JC, Kilpatrick LA, White DR, Patel KG. 30 CT measured normative cartilage growth in children requiring costochondral grafting. Otolaryngol Head Neck Surg. 2013 Dec;149(6):9248. Adamson JE, Horton CE, Crawford HH. The growth patterns of the external ear. Plast Reconstr Surg. 1965;36:466. 9. Brent B. The correction of microtia with autogenous cartilage grafts: I. The classic deformity. Plast Reconstr Surg. 1980;66(1):1-12. 10. Brent B. The correction of microtia with autogenous cartilage grafts: II. Atypical and complex deformities. Plast Reconstr Surg. 1980;66(1):13-21. 11. Nagata S. A new method of total reconstruction of the auricle for microtia. Plast Reconstr Surg. 1993;92(2): 187-201.
12. 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(2):221-30; discussion 267-8. 13. 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 93:231, 1994. 14. 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 93:243, 1994. 15. Nagata S: Modification of the stages in total reconstruction of the auricle. Part IV: Ear elevation for the constructed auricle. Plast Reconstr Surg 93:254, 1994. 16. Firmin F. Ear reconstruction in cases of typical microtia. Personal experience based on 352 microtic ear corrections. Scand J Plast Reconstr Surg Hand Surg. 1998;32(1):35-47. 17. Kawanabe Y, Nagata S. A new method of costal cartilage harvest for total auricular reconstruction: Part I. Avoidance and prevention of intraoperative and postoperative complications and problems. Plast Reconstr Surg 2006;117:2011-18. 18. Kawanabe Y, Nagata S. A new method of costal cartilage harvest for total auricular reconstruction: Part II. Evaluation and analysis of the regenerated costal cartilage. Plast Reconstr Surg 2007;119:308-15.
www.techgiendoscopy.com
PII: DOI: Reference:
S1043-1810(17)30037-4 http://dx.doi.org/10.1016/j.otot.2017.03.009 YOTOT759
To appear in: Operative Techniques in Otolaryngology - Head and Neck Surgery Cite this article as: Tom Shokri and David R. White, The Nagata Technique for Microtia Reconstruction, Operative Techniques in Otolaryngology - Head and Neck Surgery, http://dx.doi.org/10.1016/j.otot.2017.03.009 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Title: The Nagata Technique for Microtia Reconstruction Authors: Tom Shokri M.D., Division of Otolaryngology—Head & Neck Surgery, Department of Surgery, College of Medicine, The Pennsylvania State University, Hershey, Pennsylvania David R. White M.D., Department of Otolaryngology, Department of Pediatric Otolaryngology, Medical University of South Carline, Charleston, South Carolina, USA Correspondence to: Tom Shokri M.D., Division of Otolaryngology—Head & Neck Surgery, Department of Surgery, College of Medicine, The Pennsylvania State University MC H091 P.O. Box 850 Hershey, PA 17033. Email: [email protected] Keywords: Microtia, Autogenous rib cartilage, auricular reconstruction, Nagata technique Disclosures: None Abstract Multiple techniques for auricular reconstruction for microtia have been described. Reconstruction using autologous costal cartilage continues to be the most widely implemented technique for repair. Recreation of a three-dimensional framework mimicking the curves and contours of a normal ear, while also maximizing stability, is crucial in reconstructing the auricle. Additionally, soft tissue management, although generalized in approach, is specific to each patient and greatly influences surgical outcomes. In the present article, we discuss the Nagata technique for auricular reconstruction, a two-staged technique using costal cartilage grafts to rebuild the auricle.
Microtia Reconstruction: The Nagata Technique Microtia is a congenital anomaly of the ear resulting in abnormal external ear development. It is estimated to occur in approximately 0.03% of live births.1-3 The external ear develops from the first and second branchial arches at around 5 to 6 weeks of gestation continuing to develop through the second trimester. These arches form the 6 hillocks of His that eventually give rise to the helix, lobule, tragus, and antihelix that come to form the auricle.4 Surgical reconstruction of the auricle is a rewarding, though humbling, and uniquely challenging process. The goals of reconstruction include creation of an aesthetically natural appearing ear with a resilient framework and reduction of donor site morbidity. Surgical approaches to reconstruction have continued to evolve with refinements to techniques but the fundamental approach to repair has remained consistent. Historical perspective Ear reconstruction was first documented in the Sushruta Samhita, an ancient Sanskrit text, documenting local tissue transfer for repair of a lobular defect. In 1597, Tagliacozzi, an Italian surgeon, first described repair of ear deformities using post-auricular skin flaps. Then in 1845, Dieffenbach described repair of a middle third auricular defect with a post-auricular advancement flap that is still implemented today. Attempted microtia repair was first described in 1920 by Gillies, with sculpted homograft rib cartilage placement under the mastoid skin with overlying skin flap. In the 1930’s Pierce modified this method with use of rolled skin to reconstruct the helix and the addition of a skin graft for coverage. Gillies documented his efforts with use of maternal donor cartilage however the constructs showed a high rate of resorption. It was not until 1959, when Tanzer described subcutaneous implantation of an autogenous cartilage graft framework that the modern era of microtia reconstruction began. Techniques developed by Brent and Nagata later evolved through modifications and alterations to Tanzer’s, though the general principles of framework construction, tissue handling, and skin redraping remain. 5 Patient Evaluation and Preoperative Considerations The initial evaluation of a child presenting with microtia should include evaluation of facial symmetry and movement, dental occlusion, and an otologic evaluation with audiological testing and imaging. Microtia is associated with conductive hearing loss (CHL) in 80-90% of cases. Sensorineural hearing loss is less common
with an incidence of 10-15%. It is therefore crucial to assess the external auditory canal and hearing status. If aural atresia surgery is under consideration, it should be done after completed reconstruction to avoid manipulation of the delicate blood supply for the reconstructive process.6 The surgeon must be mindful of other associated hypoplastic features of the head and neck as associated anomalies occur in in approximately 50% of cases. These malformations are often in close proximity to, or arise from, the first and second embryologic branchial arches. Oculo-auriculo-vertebral spectrum disorders, are a range of disorders that develop due to disturbances in the embryonic structures that develop from these arches. These spectrum of disorders include Goldenhar syndrome, hemifacial microsomia, and oculoauricular vertebral dysplasia. Microtia is often associated with other craniofacial anomalies including cleft lip/palate, anopthalmia or micropthalmia, cardiac defects, abnormal limb development, renal malformations, and facial nerve dysfunction. Syndromes involving dysmorphogeneis of first or second branchial arches must therefore be considered when first evaluating a child with microtia. Radiologic imaging may include high-resolution computed tomography of temporal bones to assess atresia, cervical spine imaging to evaluate vertebral anomalies, renal ultrasound for genitourinary anomalies, and potentially panorex for malocclusion. If multiple congenital anomalies are found then the patient should be comprehensively evaluated by a multidisciplinary craniofacial team prior to surgical intervention. Timing of surgery The age at which a patient should undergo surgery for optimal reconstruction varies based on technique employed. The patient’s age will ultimately determine the extent of external ear maturation. The ear continues to grow until 10 years of age.7 However, it reaches 85% of its growth by age three.8 However, the rib cage does not adequately develop to allow for sufficient cartilage harvesting until five to six years old. This is the age that surgeons performing the Brent technique typically begin reconstruction.9-10 The contralateral unaffected ear, often used as a template for reconstruction, has by this time reached at least 90% of its adult size. In contrast, the Nagata or Firmin techniques require a larger amount of cartilage to be harvested for framework design. Therefore, surgeons implementing this technique may delay surgery until the child is at least nine or 10 years old and the chest circumference is at least 60 cm.10-15 Delaying surgery until the patient is
older is thought to reduce the risk of thoracic deformity due to rib graft harvesting. It is important to discuss the benefits of a properly formulated reconstructive plan over the negative impact expedited surgery may have. Autologous Rib Techniques Autogenous costochondral reconstruction is the oldest method by which microtia is repaired. Use of costochondral graft involves harvesting, carving, and assembling a framework of costal cartilage secured with carefully placed sutures. The sculpted framework is then implanted within a skin pocket in an aesthetically well positioned area. The subsequent stages modify and adjust the appearance of the auricular construct and elevate it away from the scalp to establish an anatomically correct auriculocephalic angle. There continues to be controversy surrounding techniques utilizing autogenous constructs, in particular the Brent and Nagata methods although the Firmin technique has gained popularity as well. The Nagata technique has fewer stages and has been shown to yield more consistent outcomes in the hands of some surgeons. This technique does require more cartilage and thus as previously mentioned must be deferred until an older age. Conversely, the Brent technique emphasizes limited use of cartilage in the hopes of mitigating the risk of any chest wall deformity. This means that children may undergo surgery earlier, which is often favored by parents due to an earlier intervention’s potential to limit psychosocial sequelae. Despite the technique employed, meticulous surgical planning and attention to detail is required to recreate an ear that is natural and cosmetically appropriate. Tanzer’s initial approach consisted of six stages which Brent later modified creating a four staged approach: (1) Fabrication of framework from contralateral costal cartilage and implantation into skin pocket, (2) lobule transposition, (3) ear elevation, and (4) creation of the conchal bowl and tragus; stages two and four may be combined for a possible three staged procedure.9-10 Nagata’s modification groups stages one, two, and four of Brent’s for a two staged procedure. There are additional changes to the sculpting of the framework, amount of cartilage used, and incisions based on the microtia type and remnant structures.11-15 Firmin’s technique maintained a two-staged procedure with further alterations to the framework and incisions. She created three particular frameworks, adding 1 to 3 cartilage segments to aid in projection depending on the extent of mastoid hypoplasia.16 During the planning stage, benefits, risks, and alternatives to surgery should be thoroughly discussed with the patient and parents. Engaging the patient in the overall process is crucial as their compliance throughout each
stage will help determine the final result of reconstruction. Realistic expectations of outcomes should be established. It may help to review photographs of reconstructed ears from prior patients with similar microtia types in order to set representative expectations (Figure 1). Nagata Stage I: Framework harvesting, fabrication, and implantation The first step in the Nagata reconstructive process is creating a template for the cartilaginous framework. A template is made by tracing the contours of the contralateral normal ear onto radiographic film or the transparent layer of an autoclavable sterilization envelope. The scaphoid and triangular fossa as well as the conchal bowl are cut out of the template to allow for carving of the cartilage. This template is used to help determine the position of the implanted framework and as a guide for carving (Figure 2). The distance from the lateral canthus to the root of the helix of the normal ear is measured and is usually the length of the normal ear or 6.5 cm. This determines the location of the template with respect to the lateral canthus. The vertical position of the template is then matched to both the superior aspect and lobule of the normal side. The distance between the helical rim to the lateral canthus and oral commissure are also marked on the film. It is important that the entire face and both ears be kept within the surgical field during preparation. This allows the contralateral unaffected side to be easily visualized permitting assessment of symmetry. The eyes and mouth are also included in the preparation field to allow visualization of important landmarks such as the lateral canthus and oral commissure. The ipsilateral rib cartilage is then harvested. The length of the xiphoid process to inferior margin of the costal cartilage is divided in thirds. A horizontal incision line is drawn at the inferior border of the superior third. This will approximate the inferior margin of the 7th costal cartilage and should be approximately 2 cm from the costal margin (Figure 3). The skin and fat are incised, exposing the fascia of the external oblique and rectus abdominis. An incision is then carried out between these two muscles and the intercostal muscles revealing the underlying 6th-9th costal perichondrium. The anterior aspect of the perichondrium is then incised and a perichondrial elevator is used to undermine the perichondrium, leaving the posterior perichondrium intact to stimulate cartilage growth and mitigate possible chest wall deformity. The radiographic film template is then used to determine the best donor site for the auricular frame.
The 6th through 9th cartilages are harvested en
bloc. Morselization of extraneous cartilage into 2 to 3 mm blocks, and placement into the perichondrial defect,
has been described to further reduce the risk of thoracic deformity by stimulating cartilage regeneration. 17-18 These perichondrial pockets are then closed with 4-0 nylon. The donor site is closed in multiple layers. Meticulous closure of the rectus muscle and subcutaneous layers is important to further prevent postoperative chest wall deformity. The auricular cartilaginous framework is then sculpted from the synchondrosis of the 6th and 7th ribs. The helix and helical crus are then fabricated using cartilage from the 8th rib, and the 9th rib is used to reconstruct the antihelix, superior and inferior crus (Figure 4). Cartilage from the 6th rib is “banked” in the subcutaneous layer of the chest incision for use in the second stage. Components of the framework are then secured together using steel wire or clear 4-0 nylon. The risk of extrusion may be reduced by embedding suture into grooves in the framework, made by creating small incisions with a scalpel. Lobule transposition is then performed during the initial stage of reconstruction. Skin incisions divide the lobule into three separate skin flaps: the anterior and posterior skin flap of the lobule and the tragus skin flap. The posterior flap remains attached to the mastoid skin flap and the anteriorly based tragal flap is used to surface the tragus. A “lazy W-flap” is created by the margins of the mastoid and posterior lobule flap and the middle limbs of the “W” will eventually meet helping form the intertragal notch. This “W-flap” and the anterior lobule flap become transposed in a reciprocal manner resembling a z-plasty. The rudimentary auricular cartilage is removed and the subcutaneous pocket is formed. The skin is then extensively undermined below the subdermal plexus. The 3-D framework is then implanted into the subcutaneous pocket, a suction drain is positioned beneath the framework, and the flaps are secured over this construct with carefully positioned bolsters (Figure 5). Drains are removed in 48-72 hours, and bolsters may be removed in approximately 1-2 weeks. Stage II: Framework Elevation The second stage of repair is typically performed about six months after the first. An incision is made approximately 3-5 mm away from the framework, along the mastoid skin, paralleling the helical rim. The framework is elevated from the mastoid skin by dissection into the postauricular sulcus. Attention is paid to preserving the delicate vasculature and soft tissue of the cartilage framework. The postauricular skin is then undermined and advanced into the area of the postauricular sulcus allowing adequate projection of the ear
laterally, effectively lifting it away from the mastoid. The remaining standing cutaneous deformity is removed and the skin is further thinned and hair follicles are removed. The previously banked 6th rib cartilage is retrieved and thinned along it’s convexity into a crescent shape with a thickness of approximately 1 cm. This segment is then placed under the neoauricle, between the framework and mastoid, to ensure adequate projection and prevent future repositioning. It is then secured in place with 4-0 clear nylon suture. The graft is then covered with a well vascularized tissue to allow for overlying skin graft adherence and prevention of infection or extrusion. A temporoparietal fascia flap may be raised and subcutaneously tunneled to cover the posterior aspect of the neoauricle and cartilage graft. The retroauricular skin is then advanced forward and a split thickness skin graft is harvested from the parietal-occipital scalp, thigh, or groin area to cover the remaining exposed temporoparietal fascia flap. The skin graft is secured in place to create a new postauricular sulcus with 5-0 chromic sutures. A bolster is then secured into the sulcus with 4-0 polypropylene suture. The bolster is kept in place for approximately 1 week (Figure 6). Complications Potential complications for all microtia techniques employing autogenous costal cartilage for reconstruction are similar. Complications involving the donor site include: pneumothorax, atelectasis, and scarring. Meticulous dissection technique, as well as leaving posterior perichondrium intact, is important in order to avoid pneumothorax. One should check for pneumothorax or air leak from the thoracic cavity by filling the defect with sterile saline and requesting the anesthesiologist to administer Valsalva maneuver with positive pressure ventilation to sustain a pressure of 40 cm H20. The presence of a steady stream of air bubbles will confirm a defect in the pleura requiring repair. A red rubber catheter may be placed into the identified defect and both pleura and muscle should then be closed in a purse string fashion while the catheter remains on suction. The suture should be tied down during full lung expansion (Valsalva maneuver) as the catheter is removed. Bupivacaine intercostal nerve block may be used at the end of the procedure to help reduce donor site pain postoperatively. Postoperative pain control, in addition to respiratory therapy, will help reduce atelectasis by preventing splinting. Complications involving the recipient site include hematoma and infection of the cartilaginous framework. These have become less common with use of suction drains. However, postoperative assessment for excess
tension along the skin pocket is important in preventing skin necrosis and resultant framework exposure and subsequent cartilage loss. In the event that the graft becomes exposed due to skin breakdown, appropriate antibiotic coverage should include Staphylococcus and Pseudomonas species. The exposed site should be covered with moist dressings. A 1-2 mm exposure with intact perichondrium may be allowed to initially heal secondarily. Problems with scar contracture and resultant poor contouring may improve with time. Scar revision may be necessary and the patient should be educated regarding realistic outcomes.
Conclusion The surgical correction of microtia is a humbling yet rewarding experience for the reconstructive surgeon. Each patient and malformation is unique. Therefore, careful consideration of the individual patient with regard to comfort level, deformity type, and appropriate surgical approach is crucial in management. Meticulous planning and a great attention to detail are required by the surgeon to achieve an optimal balance between desired aesthetic and functional results. The Nagata technique allows for detailed reconstruction of the ear while also optimizing auricular projection. It enables reconstruction of defects with complete anotia, low lying hairline, and secondary repair as well. Nagata’s method emphasizes the preservation of the vascular supply to the reconstructed region while attempting to mitigate the risk of cartilage graft resorption. Like other techniques using autologous cartilage, there is a significant learning curve with this technique and a requirement for some artistic ability. All techniques of microtia repair have their associated advantages and disadvantages. These should be thoroughly discussed with the patient and family prior to reconstruction.
Figure 1: Various patients at different stages of repair. Top left: Grade 3 lobular type microtia prior to intervention. Top Right: Implanted cartilage framework prior to lobule transposition; Brent technique. Bottom left: After transposition of lobule. Bottom Right: Following stage 2 with elevation of framework
Figure 2: Completed cartilage framework at left adjacent to original template drawn on sterile packaging sheet used for carving. Figure 3: Incision line for costal cartilage harvest approximating 7th rib.
Figure 4: Auricular
cartilaginous framework sculpted from synchondrosis of the sixth and seventh ribs. Helix and
helical crus are fabricated using cartilage from the eighth rib, and the ninth rib is used to reconstruct the antihelix, superior and inferior crus . Figure 5: Nagata technique for the first stage of microtia repair with a W-Shaped incision with depiction of anterior and posterior skin flaps of the lobule, the anterior skin flap of the tragus and the mastoid skin flap. Removal of remnant auricular cartilage and construction of the skin pocket with placement of 3-D framework.
Figure 6: Second stage with temporoparietal fascia (TPF) tunneled posteriorly. Crescent shaped cartilage construct placed to elevate framework. Fixation of cartilage block to soft tissue of the posterior surface of 3-D frame and to the temporal and mastoid surfaces. The TPF then overlies the posterior surface of the reconstructed auricle, the cartilage block and the temporal and mastoid surfaces. Skin of the temporal and mastoid surfaces is closed and the excess tissue excised. Exposed surface is covered with a skin graft.
Disclosures There are no disclosures to report.
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