cme auricular reconstruction for microtia: part i. …...cme auricular reconstruction for microtia:...

CME

Auricular Reconstruction for Microtia: Part I.Anatomy, Embryology, and Clinical EvaluationElisabeth K. Beahm, M.D., and Robert L. Walton, M.D.Houston, Texas, and Chicago, Ill.

Learning Objectives: After studying this article, the participant should be able to: (1) Understand external ear anatomyand embryology. (2) Develop an approach to evaluation of microtia, including otologic considerations.

In the first of a two-part series, we reviewissues pertinent to the anatomy, embryology,and criteria for comprehensive managementof children with microtia. The salient aspectsof external ear anatomy, including the nerveand blood supply, lymphatic drainage, and aes-thetic anatomic relationships, are described.An overview of the embryologic developmentof the external and middle ear and its relation-ship to auricular deformities is presented. Theclinical spectrum of microtia and its classifica-tion are discussed. The appropriate initial eval-uation of these patients and the rationale andcriteria for middle ear surgery are reviewed.Options for treatment, optimal timing, and co-ordination of the otologic and plastic surgicalmanagement of these children are discussed.The surgical techniques for external ear recon-struction, including autologous and prostheticmethods, both historic and contemporary, arebriefly discussed.

EXTERNAL EAR ANATOMY

The external ear is composed of three pri-mary components, the helix-antihelical com-plex, the conchal complex, and the lobule.The three-dimensional relief of the ear is sup-ported by the auricular cartilage, which is com-posed of highly convoluted elastic cartilage1

(Fig. 1).

Nerve Supply

Sensibility of the normal external ear is de-rived from several cranial and extracranial

branches. Cervical nerves (the great auricularnerve, C2 to C3) and the lesser occipital nerve(C2) innervate the posterior aspect of the au-ricle and lobule. These nerves have a variablesize and distribution, but in the majority ofdissections, the lesser occipital nerves havebeen found to be dominant and innervate thesuperior ear and the mastoid region, whereasthe inferior ear and a portion of the preauric-ular area are supplied by the great auricularnerve.2 The anterior surface and the tragus aresupplied by the trigeminal nerve (auriculotem-poral nerve V3). The auricular branch of thevagus nerve (Arnold’s nerve) provides sensibil-ity to the external auditory meatus (Fig. 2).

Vascular Supply

Two separate but intercommunicating arte-rial networks derived from the external carotidsystem supply the auricle.3 One network sup-plies the triangular fossa-scapha, and the othersupplies the concha. The triangular fossa-scapha network is derived from one subbranchof the upper auricular branch of the superficialtemporal artery and from branches of the pos-terior auricular artery, which come throughthe earlobe and triangular fossa and over thehelical rim. The conchal network is derivedfrom perforators (usually two to four vessels) ofthe posterior auricular artery. The superficialtemporal artery also sends several small auric-ular branches to supply the anterior surface ofthe ear. The rich communications between thesuperficial temporal and postauricular arterial

From the Department of Plastic Surgery, M. D. Anderson Cancer Center, and Section of Plastic Surgery, University of Chicago. Received forpublication August 13, 2001; revised November 16, 2001.

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systems allow for either system to support theear. Venous drainage flows through the poste-rior auricular veins into the external jugular,the superficial temporal, and the retroman-dibular veins (Fig. 3).

Lymphatic Drainage

The lymphatic drainage patterns of the ex-ternal ear are generally felt to reflect embryo-logic development. As such, it has traditionallybeen considered that the concha and meatusdrain into the parotid and infraclavicularlymph nodes, whereas the external auditorycanal and superior auricle drain into the mas-toid and superior cervical lymph nodes.4 Re-cent use of sentinel lymph node biopsy andlymphoscintigraphy in melanoma and otherneoplastic disorders, however, has demon-strated lymphatic drainage patterns in thehead and neck that are more unpredictableand less discrete than those describedclassically.5–7

Muscles

The anterior, superior, and posterior auric-ularis muscles constitute the extrinsic muscula-ture of the external ear. The intrinsic muscu-lature is largely vestigial and includes thehelicis major and minor, the tragicus, the an-titragicus, and the transverse and oblique mus-cles1 (Fig. 4).

Anatomic Relationships

The relationships, dimensions, and propor-tions of the external ear have been thoroughlyreviewed by Tolleth8 (Fig. 5). Ear width is ap-proximately 55 percent of length. The longaxis of the ear is tilted posteriorly from the

vertical axis of the face at an angle rangingfrom 2 to 30 degrees. The axis of the ear andthe nasal bridge, although similar, are notidentical: the angle between them approxi-mates 15 degrees, with the ear more vertical.The helical rim protrudes 1 to 2 cm from theskull, with the projection increasing from su-perior to inferior. In a normal ear, the rim ispositioned 10 to 12 mm from the mastoid atthe superior helix, 16 to 18 mm from the mas-toid at midear, and 20 to 22 mm from themastoid in the lower third. Although thesemeasurements are most commonly used as areference in setback otoplasty to avoid the clas-sic “telephone” deformity, they must also becarefully assessed and reproduced for an ana-tomically correct ear reconstruction in patientswith microtia.

Embryology

Both the first (mandibular) and second (hy-oid) branchial arches contribute to auricular

FIG. 1. (Left) External ear anatomy. CH, crus helicis; H,helix; T, tragus; AT, antitragus; L, lobule; A, antihelix; TF,triangular fossa; SC, superior crus; C, cavum conchae; CY,cymba conchae; TA, tuberculum auriculae. (Center) Ear elas-tic cartilage anatomy, anterior surface. LT, lamina tragi; CU,cauda helicis. (Right) Ear elastic cartilage anatomy, posteriorsurface. TS, transverse sulcus; P, ponticulus.

FIG. 2. (Above) Sensory innervation of anterior surface ofthe external ear. (Below) Sensory innervation of posteriorsurface of the external ear.

2474 PLASTIC AND RECONSTRUCTIVE SURGERY, June 2002

development. The pinna begins developing be-tween the third to sixth weeks of embryoniclife, when hillocks appear on the arches, and isfully formed by the fourth month. The anteriorthree hillocks, derived from the first arch, formthe basis of the tragus, the helical root, and thesuperior helix. The second arch contributesthe posterior hillocks, which develop into theantihelix, antitragus, and lobule. The pinnadevelops around the external meatus, whichbegins to canalize at week 28 (Fig. 6). Thecavity of the middle ear begins to form in thefirst pharyngeal arch at 4 weeks. The middleear cleft is present at 8 weeks, and the cavity isfully formed at 30 weeks. The mastoid cellsdevelop after birth. The malleus and incusarise from the first arch cartilage by 8 weeks ofage, and begin to ossify at 4 months. Concur-rently, the stapes forms and ossifies from thesecond arch cartilage (with the exception ofthe medial lamina of the footplate, which isderived from the otic capsule).9

Microtia occurs as a broad range of deformi-ties, involving to variable degrees the first andsecond branchial arches. Failure of develop-ment or adverse events that occur early, duringthe sixth through eighth weeks of gestation,are felt to lead to the clinical spectrum ofmicrotia. Later gestational insults most often

result in less profound expressions of ear de-formity. The auricular deformities may be ac-companied by facial nerve abnormalities, mid-dle ear maldevelopment, mandibularhypoplasia, and lip and palatal clefts. The mostcommon clinical presentation of microtia (ap-proximately 60 to 70 percent) is that of anisolated deformity.10 Despite absence of otherreadily identifiable clinical manifestations,however, radiographic examination will oftendemonstrate pathologic disease in the mandi-ble (most notable in the condyle), temporalbone, and vertebra of these patients. Isolatedmicrotia is felt to represent the mildest form ofhemifacial microsomia.11–14

TYPES OF MICROTIA

A number of classification systems for micro-tia have been proposed. Microtic auricular de-formities are usually classified according to thevestigial structures present.13,15–19 Nagata hasproposed a concise categorization of this dis-order, directly pertinent to the surgical correc-tion of each deformity. This system defineslobule-type, concha-type, and small concha-type microtia20–24 (Fig. 7). Anotia, the mostsevere form of microtia, represents the com-plete absence of the external ear. Those mi-crotic ears with a remnant ear and lobule with-out the concha, acoustic meatus, and tragusare categorized as lobule-type microtia. In con-cha-type microtia, the lobule, concha, acousticmeatus, tragus, and incisura tragica are presentto variable degrees. Classically, the features ofsmall concha-type microtia include the rem-nant ear and lobule with only a small indenta-tion representing the concha. As certain micro-tia variants exist with a well-developed externalear save for hypoplasia of the middle third,

FIG. 3. (Left) Arterial supply of the anterior auricular sur-face. The superficial temporal artery (STA) has upper, mid-dle, and lower terminal branches, the most superior (*) ofwhich provides an anastomotic network to the anteroauricu-lar surface with branches of the posterior auricular artery thatpenetrate anteriorly in the region of the triangular fossa (‘),concha (F), helical margin, and lobule (�). (Center) Arterialnetworks of the anterior auricular surface. The superficialtemporal and posterior auricular arteries contribute to thetriangular fossa-scapha network (vertical slashes) and the con-chal network (horizontal slashes). (Right) Arterial supply of theposterior auricular surface. Branches of the posterior auric-ular artery (PA) penetrate the cartilage at the triangular fossa(‘), cymba conchae, helical root (*), cavum conchae (F),and lobule (�) to anastomose with branches of the superficialtemporal artery. (Adapted from Park, C., Lineaweaver, W. C.,Rumly, T. O., et al. Arterial supply of the anterior ear. Plast.Reconst. Surg. 90: 38, 1992. Used with permission.)

FIG. 4. The auricular muscles. Three extrinsic muscles:anterior (A), superior (S), and posterior (P); and six intrinsicmuscles: helical muscles, large (HL) and small (HS), muscleof the tragus (T), muscle of the antitragus (AT), transversemuscle (TM), oblique muscle (O).

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small concha-type microtic ears are probablybest characterized by the presence of a smallconcha.

EPIDEMIOLOGY

The cause of microtia is felt to be heteroge-neous, including genetic aberrations, terato-gens, and vascular abnormalities.10 Excludingknown chromosomal anomalies, large multina-tional registries of congenital malformationssuggest the prevalence of microtia to be from0.76 to 2.35 per 10,000 births.10–13,25 It is gen-erally held that there is a lower incidence ofmicrotia among whites (and probably blacks)than in Hispanics and Asians. The proportionof anotia and microtia also varies betweenraces, with the lowest proportion of anotia seenin whites. In unilateral cases, the right sideappears to be more frequently affected thanthe left side, especially when the ear malforma-tion occurs as an isolated deformity. There is amale excess, again most pronounced in iso-lated forms of microtia. Anotia and microtiaare associated with other congenital malforma-tions, to a comparable degree. Among associ-ated malformations, facial clefts and cardiacdefects are the most common (about 30 per-cent of these infants are so affected), followedby anophthalmia or microphthalmia (14 per-cent), limb reduction defects or severe renalmalformations (11 percent), and holoprosen-cephaly (7 percent). A maternal parity effect isalso seen, with an increased risk at four or

more pregnancies. This is more pronouncedfor anotia than for microtia.25

Microtia has long been felt to represent oneend of the spectrum of hemifacial microso-mia.10,13 Although debates in the literature con-tinue, mounting evidence points to the com-monality of not only “isolated microtia” andhemifacial microsomia but also oculoauriculo-vertebral dysplasia and Goldenhar syndrome,as variants of the same condition, each ex-hibiting variable degrees of auricularmalformation.12,13,26

DIAGNOSTIC STUDIES AND EVALUATION IN

MICROTIA

Initial assessment of patients with microtiashould include a thorough physical examina-tion: evaluation of facial and ear structure, sym-metry, and animation, and dental occlusal re-lationships. A family history and subsequentgenetic study/counseling will address any syn-dromic issues. A complete audiologic evalua-tion and radiographic study of the temporalbones is critical in all patients with microtia.Classically, it has been held that a small exter-nal auditory canal is associated with a mixedhearing loss, whereas an atretic canal has beenlinked primarily to a conductive hearing loss.27

In addition, the presence of a tragus in a mi-crotic ear has been considered an indication ofa functional middle ear.28 A normal middle earis rarely found in conjunction with microtia,but the status of the middle ear is not directlyrelated to the external deformity. Although theseverity of the external deformity appears tocorrelate with the severity of the temporalbone abnormalities, no such association be-tween the severity of the dysmorphic featuresand the degree of hearing loss has been not-ed.10 It is therefore important to conduct a

FIG. 5. Variations in ear position. (Above, left) The aes-thetic ideal. (From Tolleth, H. Artistic anatomy, dimen-sions, and proportions of the external ear. Clin. Plast. Surg. 5:337, 1978. Used with permission.)

FIG. 6. Embryology of the external ear. (Left) Hillock for-mation in an 11-mm human embryo. (Middle) Hillock con-figuration in a 15-mm embryo at 6 weeks’ gestation. (Right)Adult auricle depicting the hillock derivations.


complete radiographic and audiologic evalu-ation for every child with microtia, regardlessof clinical presentation. It must be remem-bered that the middle ear is formed laterembryologically than is the external ear.Thus, although patients with relatively minorunilateral deformities often hear and speakwell, attempts to correlate function with thepresence or absence of certain anatomicremnants of the hypoplastic external ear re-main unreliable.

Sensorineural, conductive, and mixed(sensorineural and conductive) hearing lossmay be present in the microtic ear. The pre-dominant hearing deficit in microtia/auralatresia is conductive hearing loss (80 to 90percent). However, sensorineural hearingloss has been found to account for 10 to 15percent of the hearing loss in these childrenand should not be overlooked.10,28,29 To eval-

uate these patients, and before any ear sur-gery, audiometric studies, including an audi-tory brainstem response, are performed todetermine the degree of sensorineural andconductive hearing losses. In the case of anassociated atretic external auditory canal, thestatus of the middle ear and the need to ruleout a cholesteatoma are of great concern.The middle ear deformity may range fromminor ossicular chain disruption (the stapesis usually normal) to complete loss of thetympanic cavity. A high-resolution computedtomographic scan of the temporal bone willbest evaluate the status of the ossicles andmiddle ear cleft, providing critical anatomicinformation for any proposed otologic sur-gery.30 Nuclear magnetic resonance imagingmay also be helpful in defining the course ofthe facial nerve, which is often displaced inmiddle ear malformations.28,29

FIG. 7. Types of microtia. Anotia (above, left); lobular type microtia (above); intermediate deformities having elements of bothlobule and helix (center); isolated tragal element with external auditory meatus (center, right); and deformities having conchal,tragal, ear canal, lobule, and helical elements (including “cup” ear, “lop ear,” “crumpled ear,” and conchal and small conchalmicrotia) (below).


CONSIDERATIONS FOR OTOLOGIC SURGERY

It is well accepted, and intuitively obvious,that binaural hearing affords improved soundlocalization and speech perception. Traditionhas held that middle ear reconstruction is notindicated for unilateral microtia with normalhearing in the contralateral ear. This is basedon the observation that patients with microtiaoften fail to achieve true binaural hearing fol-lowing middle ear surgery because they con-tinue to rely almost exclusively on the normalear. This approach is also supported by exper-imental observations suggesting that the audi-tory neural structures critical for binaural pro-cessing develop only if binaural hearing isundisturbed early in life.31 As such, the classictreatment of children with unilateral microtiahas focused primarily on the preservation ofthe normal ear, with amplification of the af-fected one. Conversely, more recent studieshave demonstrated that children with unilat-eral hearing loss from any cause are at risk fordelayed language development, attention defi-cit, and poor school performance.32 In addi-tion, the plasticity in the developing auditorysystem may be greater than originally sug-gested, as a number of patients may exhibitbinaural processing, albeit subnormal, even af-ter long-term deprivation.33–35 These consider-ations have led to an increased interest in mid-dle ear exploration in an attempt to improvehearing in children with congenital auriculardeformities.

Middle ear surgery, in experienced hands,results in some hearing improvement in ap-proximately 70 percent of cases. These inter-ventions, although encouraging, entail certainrisks, such as injury to the facial nerve and adecrease in sensorineural hearing levels.30,36–38

This potential morbidity suggests that middleear surgery should be undertaken only when afinal air-bone gap of 30 dB or better may beexpected.38 Many authorities argue that be-cause of the modest hearing obtained with sur-gical intervention, the risks do not warrantsurgical intervention. In addition, some degra-dation of hearing may occur postoperatively,usually as a result of stenosis of the new exter-nal auditory canal. In approximately one-thirdof these patients, surgical revision will be re-quired. Although long-term studies are scarce,in suitable candidates it appears that a speechreception threshold of 30 dB can be achievedin greater than two-thirds of patients. The risk

of facial nerve injury in experienced handsapproximates that of cholesteatoma surgeryand the risk of sensorineural hearing loss iscomparable to that reported for stapedectomy,suggesting a favorable risk/benefit ratio formiddle ear exploration in selectedpatients.36–39

The current approach to middle ear surgeryinvolves careful evaluation of the status of theossicles, mastoid, and facial nerve with specificselection criteria to establish those patientswho will be appropriate candidates for surgicalexploration.32,36–40 A rating system suggested byAguilar and Jahrsdoerfer assigns a cumulativepoint scale to identify those patients who willbenefit from middle ear surgery. In this system,one point is given for the presence of each ofthe following: an open oval window, an ade-quate middle ear space, a normal facial nervecourse, a malleus-incus complex, adequatemastoid pneumatization, an incus-stapes con-nection, good external ear appearance, andcanal stenosis with a malleus bar. Two pointsare given for presence of the stapes. A score of8 or more suggests a good surgical candidate,with an anticipated success rate of approxi-mately 60 percent. A score of 5 or less contra-indicates surgery, as does a predominately sen-sorineural hearing loss, complete lack ofpneumatization of the mastoid, or obstructionof the mandibular condyle and/or glenoidfossa.40

In bilateral microtia, early and conscientioususe of bone-conductive hearing aids is imper-ative for social hearing and speech develop-ment. Traditional dictates have held that ifadequate auditory acuity is not achieved withthe use of hearing aids by approximately 1 yearof age, middle ear exploration on the mostfavorable side should be performed.40 How-ever, as previously noted, not all patients arefavorable candidates for surgery. This is espe-cially true in bilateral deformities, which areoften more severe, and carry higher risks forsurgical intervention. If otologic surgery isdeemed appropriate, the anticipated successrate approximates only 50 percent in bilateralcases.37,38,41 The hearing deficits in many ofthese children are either not treated surgicallyor the surgical intervention is delayed untillater in childhood.

Most of the hearing deficits in children withbilateral microtia are managed primarily withhearing aids. There have been a number ofadvances in conductive hearing devices, but a


major limitation of hearing aids has been theirfixation to the mastoid. Bone aids have beentraditionally applied transcutaneously to intactskin. The aids are applied with adhesives, head-bands, or spectacles, which pose numerousproblems for young children. The small size ofthe nose and lack of an external ear provideslittle support for spectacles, and adhesives aredifficult to use and may lead to dermatitis orlocal skin reactions.32 During the 1980s, bone-anchored hearing aids secured with an os-seointegrated implant were developed. The im-plant is usually composed of a ceramic with atitanium and/or gold core that is compatiblewith magnetic resonance imaging. These im-plants were initially used in adults with dis-charging ears, but have been studied in chil-dren with congenital deformities 2 years of ageand older. The bone-anchored hearing aid hasdemonstrated marked improvement over con-ventional aids in hearing threshold levels, aswell as in aiding previously refractory ears,likely because of its improved anchorage to themastoid. These implants are well tolerated inchildren with congenital deformities, with min-imal adverse effects, and the success of theseimplants has obviated the need for middle earexploration in certain cases. These aids have afunctioning and retention rate of over 95 per-cent on long-term follow-up, with a soft-tissuereaction rate of about 30 percent (these infec-tions rarely lead to implant removal).42–48 Thelocation for securing a conductive hearing aidmust be carefully considered in the planningof auricular reconstruction to ensure good co-aptation and hearing, and avoidance of surgi-cal incision sites. Unfortunately, a purely im-plantable bone conduction aid, which mightobviate a number of these issues, has remainedlargely in the experimental realm, and is notyet a central part of the clinical strategy.49–51

If middle ear reconstruction is deemed ap-propriate, it must be carefully coordinated withthe auricular reconstruction, taking into ac-count canal position, the vascular axis of theflaps, and location of the incisions used inexternal ear reconstruction. This may requirean additional stage in the auricular reconstruc-tion. Flexibility on the part of both the otolo-gist and the plastic surgeon is necessary. Brent,in his extensive experience, prefers to delaythe middle ear surgery until the auricular re-construction is completed, and this has beenthe standard approach to management in mostpatients.52–56 Others have proposed integrated

protocols in which the atresia repair and theauricular reconstruction are divided intostages, beginning with initial placement of thecartilage framework, followed by the atresiarepair in a three- to five-stage procedure.57,58

Both approaches appear to work well. How-ever, for either technique to be successful, ajoint management plan customized to meetthe reconstructive goals of each individual pa-tient is crucial.

HISTORY OF AURICULAR RECONSTRUCTION

Early attempts at external ear reconstructionwere rather crude and were primarily directedtoward the reconstruction of partial losses re-sulting from trauma.59 Because of the paucityof knowledge on grafting and flap physiology,and the lack of anesthesia, one can easily sur-mise that these attempts were fraught withhigh complication rates and less-than-ideal re-sults. Nevertheless, as experience with movingand shaping tissue was gained, legitimate in-roads were made. In 1597, Tagliacozzi appliedhis now classic pedicled arm flap technique inthe reconstruction of a monk’s ear, and in themid 1800s Dieffenbach used a folded mastoidflap to repair a traumatic ear defect.

Until the mid-twentieth century, total earreconstruction for microtia remained an elu-sive goal and was deemed impossible by mostsurgeons. The experimental and clinical use ofautogenous costal cartilage reported by Pierceand others in the early 1930s ushered in a newera in reconstruction that could be uniquelyapplied to ear reconstruction.60 Most ear re-constructive techniques have been derivedfrom the formula that uses a framework placedbeneath the skin to create an ear form. Numer-ous materials have been used to fabricate theear framework, but autologous cartilage haslong been considered the standard material.Modern auricular reconstruction has beencredited to Tanzer, who thoroughly detailedthe principles, techniques, and critical evalua-tion of total ear reconstruction using carvedautologous costal cartilage.61,62 Borrowing fromthese principles, Brent, Nagata, and othershave refined the technique of ear reconstruc-tion to an art form.20–24,52–56 A history of earreconstruction through the mid-twentieth cen-tury is nicely chronicled by Converse.59

TIMING OF AURICULAR RECONSTRUCTION

The primary factors considered in determin-ing the most appropriate timing for auricular


reconstruction include the age of external earmaturity, the availability of adequate donor-siterib cartilage, and the school age and risk of peerderision.61 Although ear width will continue toincrease until age 10, it has been established that85 percent of ear development is attained by 3years of age.63,64 Rib cartilage is rarely of sufficientsize until the age of 5 to 6 years, which coincideswith the beginning of school. In addition, theautologous cartilage construct will usually grow ata rate comparable to the normal ear, and some-times to a size slightly larger that the native ear.The cartilage framework is thus carved to matchthe dimensions of the opposite normal ear or, invery young patients, it is made slightly larg-er.26,62,65 Brent noted that with a minimum 5-yearfollow-up, 48 percent of the reconstructed earsgrew at the same rate, 41.6 percent grew severalmillimeters larger, and 10.3 percent lagged sev-eral millimeters behind the native ear.66 Weigh-ing all these factors, Brent and many others haverecommend performing ear reconstruction be-tween the ages of 4 and 6 years, during pre-school, to complete the reconstruction beforethe child enters first grade. However, some sur-geons, especially those using the Nagata tech-nique, may delay the surgery until a later age.The recommended age of surgery in Japan is 10years; a chest circumference (at the level of thexiphoid) of at least 60 cm is also an acceptablecriterion. This may relate to the relatively largevolume of cartilage needed for reconstruction asrequired by the Nagata technique.20–24,67

CHOICE OF AURICULAR FRAMEWORK

There has been continued debate over theuse of autologous versus nonautologous auric-ular frameworks. Proponents of each of thedifferent framework materials cite legitimatereasons for their specific material preferences.These include the number of operative proce-dures and donor-site morbidity (more with au-tologous cartilage constructs), erosion or mi-gration of the implant, and infectiouscomplications or exposure of the implant(more with alloplastic constructs).

Autologous costal cartilage is the most com-monly used and preferred material for ear re-construction. It has a demonstrated trackrecord for durability and stability over time butis not without shortcomings. Harvest of thecostal cartilage results in a visible anteriorchest-wall deformity in most patients, and al-though local application of Marcaine into theharvest site may ameliorate it somewhat, con-

siderable pain and discomfort is present in theinitial postoperative period. The cartilageframework is usually harvested from the syn-chondrosis of the sixth, seventh, and eighthribs. Preservation of perichondrium on the sur-face of the cartilage may help with constructadherence to the recipient site and promotegraft viability. The entire perichondrial sleevehas been elevated with the costal cartilagegraft, but because of problems of significantchest-wall depression and deformity, most au-thors prefer to leave at least some remnant ofthe perichondrium in situ to support cartilageregeneration at the harvest site. To satisfy theneeds of both the construct and the chest-walldonor site, the superficial perichondrium isusually harvested with the graft, leaving theposterior perichondrium at the donorsite.52,61,62,68,69 Most authors advocate harvest ofthe contralateral cartilage. Fukuda andYamada prefer harvesting the ipsilateral carti-lage, placing the superficial perichondriumside down to enhance contact with the mastoidsurface and construct stability.70

Cronin and later Ohmori et al. described useof the Silastic framework for auricular recon-struction.71–75 The initial aesthetic results wereoften excellent, and donor-site deformity was anonissue. Long-term follow-up, however, demon-strated spontaneous exposure of the implantwith failure of the reconstruction in many cases.In addition, minor abrasions or trauma also re-sulted in exposure and failure. The complica-tions entailed in this technique have promptedCronin and Brauer to abandon the use of sili-cone implants for ear reconstruction.

The use of porous polyethylene has beenrecently advocated by Reinisch.76 A total of 116patients over an 8-year period demonstrated aninitial high complication rate. With techniquemodification, however, good short-term (2years) results were reported. The inertness andporous quality of porous polyethylene providebetter tissue anchorage, a major advantageover smooth Silastic implants. The perfor-mance of these constructs over time has notbeen established, and this technique remainsto be proved safe and reliable.

Elisabeth K. Beahm, M.D.Department of Plastic SurgeryM. D. Anderson Cancer Center1515 Holcombe Blvd., Box 443Houston, Texas [email protected]


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Self-Assessment Examination follows onthe next page.


Self-Assessment Examination

Auricular Reconstruction for Microtia: Part Iby Elisabeth K. Beahm, M.D., and Robert L. Walton, M.D.

1. SENSIBILITY TO THE EXTERNAL AUDITORY CANAL IS PROVIDED BY WHICH OF THE FOLLOWINGNERVES?A) Lesser occipital nerveB) Maxillary division of trigeminal nerveC) Auriculotemporal nerveD) Auricular branch of vagus nerveE) Greater auricular nerve

2. THE CONCHAL VASCULAR NETWORK IS DERIVED PRIMARILY FROM WHICH OF THE FOLLOWINGSOURCES?A) Subbranch of the upper auricular branch of the superficial temporal arteryB) Occipital arteryC) Perforating branches of the postauricular arteryD) Direct branches of the superficial temporal arteryE) Mastoid artery

3. THE CONCHA AND MEATUS PORTIONS OF THE EXTERNAL EAR PREFERENTIALLY DRAIN TO WHICH OFTHE FOLLOWING LYMPH NODES?A) Parotid and infraclavicular lymph nodesB) Superior cervical lymph nodesC) Postauricular lymph nodesD) Posterior cervical lymph nodesE) Submandibular lymph nodes

4. THE TRAGUS IS DERIVED FROM WHICH OF THE FOLLOWING EMBRYONIC PRECURSORS?A) The hyoid archB) The first branchial archC) The second branchial archD) The first branchial cleftE) The posterior hillocks

5. WHICH OF THE FOLLOWING STATEMENTS ABOUT MICROTIA IS TRUE?A) The incidence of microtia varies from 5.20 to 10.55 per 10,000 births.B) Anotia and microtia are rarely associated with other congenital malformations.C) There is a female preponderance for microtia.D) In unilateral microtia, the right side predominates.E) Limb reduction defects are the most common associated malformations.

6. THE PRESENCE OF WHICH ONE OF THE FOLLOWING EXTERNAL EAR PARTS IS ASSOCIATED WITH AFUNCTIONAL MIDDLE EAR?A) LobuleB) HelixC) ConchaD) TragusE) Antitragus

7. AT WHAT AGE WILL THE EXTERNAL EAR ATTAIN 85 PERCENT OF ITS ADULT SIZE?A) 2 yearsB) 3 yearsC) 5 yearsD) 8 yearsE) 10 years

8. WHICH OF THE FOLLOWING REPRESENTS THE MAJOR SHORTCOMING OF THE SILASTIC FRAMEWORKFOR AURICULAR RECONSTRUCTION?A) Migration of the implantB) Poor definitionC) CostD) ExposureE) Temporal arteritis

To complete the examination for CME credit, turn to page 2626 for instructions and the response form.

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