Variations of the External Ear Severely Deformed Cup Ear and Mini Ear
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97 Ear Aman Deep1, Martin M. Mortazavi2 and Nimer Adeeb1 1Children’s of Alabama, Birmingham, Alabama, USA 2University of Washington School of Medicine, Seattle, Washington, USA Anatomical observations are very important for determining grades of dysplasia. Grade I anomalies entail minor variations the shape, position, and variations of the ear. An anatomical that do not warrant the use of skin and cartilage to repair the variation can be an isolated anomaly or part of a syndrome and structural defect. The category includes macrotia, anomalies of its effect can range from no defect to complex hearing loss. The the pinna (protruding ear, cryptotia, Darwin’s tubercle, satyr ear has a very complex structure and careful observations can ear, Stahl ear, shell ear, Mozart ear, and lop ear), absent helical help in the diagnosis of anomalies and syndromes. The purpose cleft, and anomalies of the lobule and tragus. Grade II dyspla- of this chapter is to describe anatomical variations of the ear. sia or second‐degree microtia includes anomalies where some normal ear features are detectable and reconstruction requires the use of additional skin and cartilage. This grade covers Variations of the external ear severely deformed cup ear and mini ear. In Grade III dysplasia, no normal ear features are detectable and complete reconstruc- Various classifications are used in the literature to describe tion is required. This category includes microtia (unilateral or anomalies of the external ear. Recently, Hunter and Yotsuyanagi bilateral) with external acoustic meatus atresia, and anotia or (2005) published a classification modified from the Weerda complete absence of the ear. classification (Table 97.1). They divided the anomalies into three Microtia Microtia is a congenital anomaly where the pinna is underde- Table 97.1 Classification of anomalies of external ear. Adapted from Hunter veloped (Luquetti et al. 2012). It ranges from mild structural and Yotsuyanagi (2005). abnormality to absence of the ear/anotia (Fig. 97.1). Terminol- ogies ranging from “microtia”/“microtia/anotia” to “microtia‐ Grade of dysplasia Types anotia” are used in the literature. It can occur as an isolated anatomical anomaly or as part of a syndrome. Sufferers are pre- Grade I 1. Enlarged ear dominantly male. Microtia is unilateral in 77–93% of cases with 2. Anomalies of pinna: cryptotia, protruding ear, satyr ear, Stahl ear, Darwin’s tubercle, Shell 60% involvement of the right ear. The incidence is 0.8–2.4 per ear, Mozart ear, lop ear 10,000 live births. Hispanics and Asians have a higher preva- Lop ear is divided into mild and moderate lence than African Americans and Europeans. The highest inci- malformation: dence of 8.3 per 10,000 live births has been reported in Navajo 1. Mild anomalies: helical folding lies above Indians (Luquetti et al. 2012). the Darwin tubercle: (a) hiding helix; and (b) Various risk factors have been reported including mater- constricted helix type IV A 2. Moderate anomalies: helical folding lies nal diabetes mellitus, low birth weight, advanced maternal above the Darwin tubercle: (a) absence of age, exposure to thalidomide, retinoic acid derivatives, and helix or cleft in helix; (b) anomalies of lobule; mycophenolate mofetil. There is some association of microtia and (c) anomalies of tragus with autosomal trisomies (18, 21, and 22) and trisomy 13 and Grade II 1. Cup ear 18 mosaicism. Single‐gene disorders, for example SIX1 and 2. Mini ear EYA1 and chromosomal translocation 6p24, are also reported to Grade III 1. Microtia (unilateral or bilateral) with external be associated with microtia. canal atresia Herman Marx (1926) proposed the first and most frequently 2. Anotia used classification system for the condition. He divided microtia Bergman’s Comprehensive Encyclopedia of Human Anatomic Variation, First Edition. Edited by R. Shane Tubbs, Mohammadali M. Shoja and Marios Loukas. © 2016 John Wiley & Sons, Inc. Published 2016 by John Wiley & Sons, Inc. 1167 1168 Bergman’s Comprehensive Encyclopedia of Human Anatomic Variation Figure 97.1 Variations of microtia: (a) typical ear; (b–d) first‐degree dysplasia; (e) second‐degree dysplasia; and (f–i) third‐degree dysplasia. Source: Luquetti et al. (2012). Reproduced with permission from John Wiley & Sons. into three grades based on identification of auricular land- classification was based on embryological variations and surgi- marks. Rogers (1968) added grade IV microtia (anotia) to the cal classification as well as other external ear deformities and existing Marx classification. Tanger (1978) published a surgi- minor anomalies. Hunter and Yotsuyanagi (2009) recently pub- cal approach‐based classification system, and Weerda (1988) lished a classification to standardize the terminologies referring modified both of these systems and developed a new one. His to the external ear (Table 97.2). Table 97.2 Classifications of microtia. Adapted from Luquetti et al. (2012). Grade/type Description Grade/degree Description Herman Marx Classification Weerda Classification Grade I Auricle is abnormal but all Grade I Macrotia, prominent ear, and cryptotia; landmarks are identifiable First‐degree Malformations Scaphoid ear, transverse cleft(coloboma), Stahl ear; Satyr ear; Darwin tubercle, defromed tragus and antitragus, helix crus absence; Lobular deformities: aplastic, hypoplastic and hyperplastic lobe, lobular fixation and lobular cleft; Deformity of cup ear I, IIa, IIb. Grade II Auricle is abnormal and few Grade II Deformity of cup ear III; landmarks are identifiable Second‐degree malformations Microtia: hypopastic upper pinna, hypoplastic middle pinna, and hyoplastic or aplastic lower pinna Grade III Anotia Grade III Grade III unilateral or bilateral microtia; Third‐degree Malformations Anotia Tanger Classification Hunter Classification Type I Complete absence of ear Microtia All normal ear components are present and the (anotia) First‐degree median longitudinal length of ear is greater than two standard deviations below the mean Type II Complete hypoplasia of ear Microtia Presence of few normal ear components and median with and without external Second‐degree longitudinal length of ear is greater than two acoustic meatus atresia standard deviations below the mean (microtia) Type III Hypoplastic middle third of Microtia Some auricular structures are present but these auricle Second‐degree structures do not conform to recognized ear component Type IV Hypoplastic superior third of Anotia Ear is completely absent auricle, cup and lop ear and cryptotia Type V Prominent ear Chapter 97: Ear 1169 Figure 97.3 Protruding ear. Source: Hunter and Yotsuyanagi (2005). Reproduced with permission from Figure 97.2 Macrotia. John Wiley & Sons. Source: Bauer (1997). Reproduced with permission from Elsevier. assess protrusion is to measure the gap between the rim of the Macrotia helix and a point on the mastoid perpendicular to the helix rim. Macrotia is an abnormal enlargement of the pinna (Fig. 97.2): Any variation in shape or position of the mastoid can influence an ear with length for age measurement above the 97th percen- the measurement; this is the biggest drawback of the method. tile. An adult ear has a width range of 3–4.5 cm and length range Another widely used method is to measure the auriculocephalic of 5.5–7 cm, and the term macrotia is used when the ear meas- angle. If this is greater than 30–40 degrees, various authors ures more than these values. Feingold and Bossert (1974) pro- regard it as indicating protrusion. In the auriculocephalic angle posed a gold standard measurement. The curves were based on method any variation of temporal bone convexity or soft tissue the measurements they made of Caucasian children in Boston. above the bone can change the measurement, so it is not fool- According to Feingold and Bossert, the ear grows about 10% proof. Smith (1978) described the protruding ear as a result of a of its length and 40% of its height between the ages of 6 and developmental defect in the posterior auricular muscle. One role 14 years. The ear can be divided into three parts: of the posterior auricular muscle is to draw the pinna towards 1. Upper third: the part of the ear above inferior crus, which the skull, and dysfunction of this muscle causes the pinna to comprises 33% of the total height of the ear. protrude. According to the author, the protruding pinna should 2. Middle third: inferior crus to incisura, which comprises 43% be considered a part of the neuromuscular defect and not artic- of the height of the ear. ular cartilage dysmorphogenesis. Association of protruding ears 3. Lower third: incisura to the tip, which comprises 23% of the with myotonic dystrophy and congenital muscular dystrophy total height. has been frequently reported in the literature. Anencephaly, tri- In true macrotia, the upper third of the ear is most commonly somy 8 syndromes, 18p syndrome, 4p syndrome, and Langer‐ enlarged. Giedion syndrome are also associated with protruding ears. Protruding ear Cryptotia Protruding ear is one of the most common anatomical varia- In cryptotia, the upper pole of helix cartilage is buried under tions. It is defined as an ear with a >40 degree angle in relation the fold of the skin which results in loss of the auriculoce- to the mastoid bone (Fig. 97.3). According to Carey (1993), the phalic sulcus (Fig. 97.4). This is more common in the Japanese gap between the mastoid bone and the helix in protruding ear is than the Caucasian population; its incidence in the former is greater than 2 cm. Driessen et al. (2011) found a sex difference about 1 in 400 births. The term cryptotia was introduced by in protrusion of the ear. In males, for an ear to be prominent, Sercer (1934). Altmann (1955) used the phrase “pocket ear” the protrusion should be greater than 21.5 mm for the upper for this anomaly. Gosserez and Piers (1959) called it “congen- or 20.0 mm for the lower part of the ear.