Microtia and Atresia - Combined Approach by Plastic and Otologic Surgery
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Remarkable progress in the development of new concepts and techniques used in reconstructive surgery of microtia/atresia of the external auditory canal (EAC) has been made since the beginning of the 21st century. Helical computed tomography has made a three-dimensional reconstruction of the soft tissue of the temporal bone surface and the cranium possible, and has laid the groundwork for a collaboration between plastic surgeons and otologists. This book presents the latest findings on reconstructive surgery performed jointly by plastic surgeons and otologists. Based on this concept, information on diagnosis, surgical procedures, outcomes, long-term results and psychology is discussed.
Collaborative surgery offers advantages not only in terms of a better reconstruction of morphology and function, but also in terms of the lower number of surgical procedures required which reduces the psychological pressure and economic burden on patients.

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Date de parution 14 octobre 2013
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EAN13 9783318023862
Langue English
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Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery
Advances in Oto-Rhino-Laryngology
Vol. 75
Series Editor
G. Randolph Boston, Mass.
Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery
Volume Editors
Kimitaka Kaga Tokyo
Hirotaka Asato Tochigi
95 figures, 67 in color, and 8 tables, 2014
_______________________ Kimitaka Kaga National Institute of Sensory Organs National Tokyo Medical Center 2-5-1 Higashigaoka Meguro-ku Tokyo 152-8902 Japan
_______________________ Hirotaka Asato Department of Plastic Surgery Dokkyo Medical University 880 Kitakobayashi, Mibu-Machi Shimotsuga-gun, Tochigi 320-0293 Japan
Library of Congress Cataloging-in-Publication Data
Microtia and atresia: combined approach by plastic and otologic surgery /volume editors, Kimitaka Kaga, Hirotaka Asato.
p. ; cm. –– (Advances in oto-rhino-laryngology, ISSN 0065-3071 ; vol. 75)
Includes bibliographical references and indexes.
ISBN 978-3-318-02385-5 (hard cover: alk. paper) -- ISBN 978-3-318-02386-2 (electronic version)
I. Kaga, Kimitaka, 1944- editor of compilation. II. Asato, Hirotaka, 1958-editor of compilation. III. Series: Advances in oto-rhino-laryngology; v. 75.0065-3071
[DNLM: 1. Ear Auricle-abnormalities. 2. Ear Auricle-surgery. 3. Otologic Surgical Procedures-methods. 4. Reconstructive Surgical Procedures-methods. W1 AD701 v.75 2013/WV 220]
RF127 23
617.8’059-dc23
2013021357
Bibliographic Indices. This publication is listed in bibliographic services, including Current Contents ® .
Disclaimer. The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publisher and the editor(s). The appearance of advertisements in the book is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
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All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
© Copyright 2014 by S. Karger AG, P.O. Box, CH-4009 Basel (Switzerland)
www.karger.com
Printed in Germany on acid-free and non-aging paper (ISO 9706) by Kraft Druck, Ettlingen
ISSN 0065-3071
e-ISSN 1662-2847
ISBN 978-3-318-02385-5
e-ISBN 978-3-318-02386-2
Contents
Introduction
Kaga, K. (Tokyo); Asato, H. (Tochigi)
Etiology and Gene Mutation
Abstract
Etiology and Genes
Matsunaga, T. (Tokyo)
Diagnosis
Abstract
Classification of Shapes (Auricle/External Auditory Canal)
Suzuki, Y. (Tochigi)
Imaging Diagnosis
Takegoshi, H. (Tokyo)
Audiometry
Kaga, K. (Tokyo)
Bone-Conduction Auditory Brainstem Response and Bone-Conduction Auditory Steady-State Response
Sakata, H. (Saitama)
Development of the Auricle and External Auditory Canal
Ozeki, H. (Kobe)
Development of Rib Cartilage
Oki, M.; Asato, H. (Tochigi)
Deciding on the Position for Auricular Reconstruction
Umekawa, K. (Tochigi)
Anomalies of the Auditory Ossicles
Ishimoto, S. (Tokyo)
Follow-Up of Psychological Changes in Patients Prior to Surgery
Kaga, K. (Tokyo)
Otitis Media and Subcutaneous Abscess while Awaiting Surgery
Sakata, H. (Saitama)
Deciding on the Timing and Method of Surgery
Watanabe, M.; Asato, H. (Tochigi)
Surgical Methods
Abstract
Reconstruction of the Auricle with Autogenous Rib Cartilage Grafts
Kaji, N.; Asato, H. (Tochigi)
Joint Surgery for Elevation of the Auricle and Construction of the EAC. 1. Design of Auricle Elevation in a Joint Surgery
Imanishi, M.; Asato, H. (Tochigi)
Joint Surgery for Elevation of the Auricle and Construction of the EAC. 2. Construction of the External Auditory Canal/Middle Ear
Kaga, K. (Tokyo)
Elevation of the Auricle without Canal/Tympanoplasty
Fukuda, N.; Fukayama, Y. (Tochigi)
Complications
Abstract
Postoperative Infection of the External Auditory Canal
Shinjo, Y. (Tokyo)
Skin Necrosis
Tamura, R.; Mizuguchi, K.; Asato, H. (Tochigi)
Facial Nerve Palsy
Ushio, M.; Kaga, K. (Tokyo)
Chest Wall Deformity at the Site of Costal Cartilage Harvesting
Nomura, H. (Tochigi)
Management of Postoperative Wounds
Abstract
Management of the Auricle
Kurabayashi, T. (Tochigi)
Postoperative Management of the Reconstructed External Auditory Canal
Kaga, K. (Tokyo)
Hair Removal
Watanabe, T.; Onomura, M.; Asato, H. (Tochigi)
Postoperative Hearing
Abstract
Effect of Lateralization of the Reconstructed Eardrum on Postoperative Hearing
Kaga, K. (Tokyo)
Temporal Bone Computed Tomography of Patients with Poor Postoperative Hearing Improvement after Surgery for Atresia of the External Auditory Canal
Hayashi, Y.; Kaga, K. (Tokyo)
Author Index
Subject Index
Introduction
In Japan and overseas, plastic surgeons and otologic surgeons have performed reconstructive surgery for microtia/atresia of the external auditory canal (EAC) independently. Pinnaplasty alone has been performed by plastic surgeons, and it was not unusual for plastic surgeons to tell patients that otorrhea might persist lifelong or facial paralysis might even develop if an otologist reconstructed the EAC. Furthermore, otolaryngological surgeries were performed mainly to improve hearing through reconstruction of the EAC, eardrum and ossicular chain, but the cosmetic shape of the ear was not always given special attention. However, remarkable advances in the concepts and techniques for reconstructive surgery of this congenital malformation have been made since the beginning of the 21st century and, hence, this book contains the latest findings about joint reconstructive surgery performed cooperatively by plastic surgeons and otologists.
Previously, we, the editors, discussed reconstructive surgery for microtia/atresia of the EAC while working at the plastic surgery and otolaryngology departments of the University of Tokyo Hospital, and we wanted to realize our ideal of achieving a natural-looking auricle and improving hearing with a single surgery. Helical computed tomography has enabled three-dimensional reconstruction of the soft tissues of the temporal bone surface and the cranium, which serves as a plan for collaborative surgery connecting the two departments. In other words, it has become possible to determine the construction site for the EAC in the mastoid section as well as the site for pinnaplasty. With this concept of planning, the plastic surgery department creates an auricle framework using costal cartilage, which will be embedded subcutaneously in the temporal region during the first stage of surgery. The second stage is a joint procedure involving the plastic surgery and otolaryngology departments, where the auricle is elevated and the EAC, ossicular chains and eardrum are reconstructed. Finally, a costal cartilage block is placed at the posterior part of the auricle and covered with a free skin flap. This joint surgery takes approximately 6 h. If the surgery is performed separately, more surgeries are necessary from each department, and a patient would undergo a total of four to six surgeries. In cases of bilateral microtia, the number of surgical procedures would double. Joint surgery is therefore advantageous not only for better reconstruction of morphology and function, but also in terms of the lower number of surgical procedures required, which there by reduces the psychological pressure and economic burden on patients.
Based on our concept of joint surgery, information on diagnosis, surgical procedures, outcomes, long-term results and psychology is presented in this book. We hope that readers will also find information on the activities of the association of patients with microtia/atresia of the EAC called ‘Blue Sky Association’. This book is to be referenced by plastic surgery departments, otolaryngology departments, speech therapists, school teachers and patients’ families. We hope this book will serve as a clinical textbook for those involved in surgical and audiological specialties of microtia/atresia of the EAC in the clinical setting.
We would like to thank Ms. Kayoko Sekiguchi, the secretary of Dr. Kaga, for her unlimited contribution in publishing this book.
Kimitaka Kaga , Tokyo Hirotaka Asato , Tochigi
Etiology and Gene Mutation
______________________
Abstract
The external ear is composed of the auricle and the external auditory canal and develops from the first and second branchial arches.
The etiology of an external ear anomaly is considered to involve direct and indirect inhibition of the modulation of expression or function of the genes involved in morphogenesis of the external ear at an early stage of gestation period (the first trimester). Microtia may be caused by monogenic mutation, or abnormalities in the gene expression site or the mechanism of gene expression regulation due to chromosomal translocation. Familial recessive heredity of microtia was reported to be due to mutation of the HOXA1 gene which plays an important role in morphogenesis of the second brachial arch. Microtia and atresia of the external auditory canal are observed in patients which chromosomal aberrations of four types of trisomy (13, 18, 21, 22 chromosomes) and three types of chromosomal deletions (5p-, 18p-, 18q-). On the other hand, it is argued to be induced by environmental factors or multifactorial heredity rather than monogenic heredity.
Etiology and Gene Mutation
Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 2–8 (DOI: 10.1159/000350491)
______________________
Etiology and Genes
Tatsuo Matsunaga
National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan
Understanding the etiology of microtia/atresia of the external auditory canal (EAC) is indispensable for explaining the condition to patients and their family members, planning surgery, predicting complications and coping with them in time, and for genetic counseling. The etiology of microtia/atresia of the EAC is classified into hereditary factors that influence the development of the external ear and environmental factors. Given that the auricle and the EAC develop from the same origin, microtia and atresia of the EAC often coexist, with atresia of the EAC being observed in nearly 74% of patients with microtia [ 1 , 2 ].
Elucidation of Etiology Based on Investigation of Syndromes
Great progress was made in understanding the etiology of microtia and atresia of the EAC through studies of patients with microtia and atresia of the EAC that are syndromic complications of other anomalies (e.g. facial cleft, cardiac anomaly, anophthalmia, microphthalmia, limb deficiencies, and kidney malformations are commonly observed). This is because patients with the same underlying cause are easily identified based on characteristics other than the external ear, which makes genetic analysis more simple.
Microtia and atresia of the EAC are observed in patients with chromosomal aberrations of four types of trisomy (13, 18, 21, 22 chromosomes) and three types of chromosomal deletions (5p-, 18p-, 18q-) [ 1 ].
Given that anomalies of the first and second branchial arches and hemifacial microsomia, or Goldenhar syndrome (which is accompanied by epibulbar dermoid), complicated by anomalies of the upper limbs and kidney, presents sporadic cases in monozygotic twins, it is argued to be induced by environmental factors or multifactorial heredity rather than monogenic heredity [ 3 ]. Vascular injury due to injury of the stapedial artery at the embryonic stage is also a hypothesized cause. Mutation of the SALL1 gene was identified in patients with Townes-Brocks syndrome, which is autosomal-dominant heredity accompanied by anomalies of the first and second branchial arches, kidneys, limbs and anus [ 4 ]. In addition, mutation of the TCOF1 gene was identified in patients with Treacher-Collins syndrome, which is autosomal-dominant heredity presenting anomalies of the first and second branchial arches [ 5 ]. Bilateral microtia, severe hearing loss, and partial cleft palate were reported as autosomal-recessive heredity due to mutation of the HOXA2 gene, a homeobox gene that plays an important role in fetal development [ 6 ]. Microtia, small teeth and severe hearing loss accompanied by a severe inner ear anomaly were also reported as autosomal-recessive heredity due to mutation of the FGF3 gene [ 7 ]. In addition, various causative genes have been identified in syndromes accompanied by microtia and atresia of the EAC.
Risk Factors of Nonsyndromic Microtia and Atresia of the External Auditory Canal
It is considered that multifactorial heredity and environmental factors are strongly involved in the etiology of microtia and atresia of the EAC that develops without complication by other anomalies, but it is difficult to identify patient groups with the same etiology based on symptoms, so the cause has not been elucidated. Heredity is considered to be involved in some patients because 9-34% of the diseases are familial, and they might be multifactorial heredity, chromosome aberration, or recessive or dominant monogenic heredity [ 8 , 9 ]. Reported risk factors of environmental origin include anemia, drug use during pregnancy (antiepileptic: trimethadione; follicular hormone: estriol; ovulatory agent: clomiphene citrate; vitamin A; etc.), paternal age, maternal diabetes, and pregnancy toxemia [ 2 , 10 , 11 ].
Development of the Ear
Development of the ear is a key area directly linked with the clinical pathology of microtia and atresia of the EAC. The ear is composed of three parts – the external ear, middle ear, and inner ear. Formation of these parts starts at an early stage of fetal development, and they are ultimately functionally integrated after their respective routes of development. Given that the external ear and middle ear develop from adjacent origins, concomitant anomalies of the external and middle ear are often observed. However, the inner ear develops from an origin distinct from that of the external and middle ear, and combined anomalies of the external, middle and inner ear are rare. In some patients who develop an inner ear anomaly in association with external and middle ear anomalies, the presence of genetic factors common to the external, middle, and inner ear or environmental factors that influence their development is presumed. We previously reported on a family with dominant heredity of an external/middle/inner ear anomaly, which suggested the presence of such heredity factors [ 12 ].

Fig. 1. Development of the external, middle, and inner ear. a Gestation week 4. b gestation week 5. c Gestation month 3. d Gestation month 7. Adapted from Moore et al. [ 23 , p 444].
The inner ear is the oldest in terms of phylogeny. The membranous labyrinth of the inner ear is derived from otocyst of the ectoderm tissues, whereas the bony labyrinth is derived from the surrounding mesenchymal tissues ( fig. 1 ). Involvement of the homeobox gene in the development of the inner ear has been demonstrated, and abnormalities in genes such as Hox, Kreisler, Fgf3, Otx1 , Nkx5-1, Hmx3, Pax2, Ngn1 , and Dlx5 are known to cause abnormal morphogenesis of the inner ear [ 13 , 14 ].
The middle ear develops mainly from the first and second branchial arches and the first pharyngeal pouch ( fig. 1 ). Epithelial-mesenchymal interactions are required for development of the middle ear, and genes such as ET-1 and Fgf8 coordinate epithelial-mesenchymal interactions. Eya1, Prx1, Hoxa1, Hoxa2, Dlx1, Dlx2, Dlx5 , and Gsc are involved in formation of mesenchymal tissues derived from the neural crest and play a key role in morphogenesis of the middle ear [ 15 ].

Fig. 2. Development of the auricle. a Gestation week 6. b Newborn. Adapted from Moore et al. [ 23 , p 445].
The external ear is composed of the auricle and the EAC. The EAC develops from the first branchial groove in gestation week 4. The epithelial cells at the EAC base proliferate around gestation month 3 to form an EAC plug. This EAC plug is absorbed by gestation month 7, and the EAC and the tympanic membrane form ( fig. 1 ). Atresia of the EAC occurs due to disordered absorption of the EAC plug. Development of the auricle starts with formation of the auricular hillocks in gestation week 6. Three auricular hillocks at both the first and the second branchial arches, or a total of six auricular hillocks, encircle the first branchial groove. They develop and fuse in gestation week 7, and the characteristic morphology of the auricle is complete by the end of embryology month 4 ( fig. 2 ). This process is complex and congenital anomalies such as auricular anomaly, preauricular sinuses, and auricular appendages are likely to occur.
The Hox gene, one of the homeobox genes related to segmentation, and the Gsc gene are involved in sequencing of the first and second branchial arches [ 16 - 18 ], and both deficit and duplication of branchial arch-derived tissues have been observed in gene knockout mice. Anomalies of the middle ear and the external ear were also observed in the presence of abnormalities in the Dlx2, Otx2 and Prx1 genes, other homeobox genes, as well as the retinoic acid receptor gene, and the significance of these genes in morphogenesis of the external ear and middle ear has been demonstrated [ 19 - 21 ].
Etiology of Microtia/Atresia of the External Auditory Canal
As explained above, the external ear develops from the first and second branchial arches, and the etiology of an external ear anomaly is considered to involve direct and indirect inhibition of the modulation of expression or function of the genes involved in morphogenesis of the external ear at an early stage of gestation period (the first trimester).
Table 1. Summary of representative syndromes presenting external ear anomaly

Microtia often occurs as a nonhereditary anomaly in boys, and is often accompanied by occlusion or stenosis of the EAC [ 2 , 11 ]. Reported environmental causes of external ear anomalies include pregnancy-induced hypertension syndrome, anemia, and use of folic acid (vitamin B 9 ) antagonists [ 2 ]. Higher parity (4 or more) is also listed as a risk factor [ 1 ]. Microtia may be induced by the use of the antiepileptic hydantoin, isotretinoin [ 10 ], for treating recurrent cystic acne, and thalidomide during pregnancy, as well as rubella infection during early pregnancy.
Microtia in some patients is hereditary, and it may be caused by monogenic mutation, or abnormalities in the gene expression site or the mechanism of gene expression regulation due to chromosomal translocation. Hereditary factors that are restricted only to external ear anomalies have not been reported. Familial recessive heredity of microtia including partial cleft palate was reported to be due to mutation of the HOXA1 gene, which plays an important role in morphogenesis of the second branchial arch [ 6 ]. A familial recessive heredity due to mutation of the HOXA1 gene that presents as external/inner ear anomaly, sensorineural hearing loss, bilateral disturbance of lateral gaze, facial palsy, circulatory organ anomaly, and mental retardation has also been identified [ 13 ]. Developmental disorders including an external ear anomaly were observed in animals presenting with site-nonspecific overexpression of morphogenesis factors Hox1.1 and Hox2.2 [ 22 ]. Microtia, inner ear aplasia, and small teeth are observed in a mode of recessive heredity due to mutation in fibroblast growth factor 3 (FGF3) [ 7 ]. Table 1 summarizes representative syndromes presenting with external ear anomalies.
Prospect of Elucidation of Etiology and Clinical Applications
Hereditary exploration will continue to identify the causes of syndromes associated with microtia/atresia of the EAC. Hereditary mechanisms of external ear formation will be clarified in more detail through creation and study of animal models, and prevention and early detection of complications will become more common and effective. Statistical analysis will also be performed for risk factors of nonsyndromatic microtia/atresia of the EAC, and it is predicted that taking evidence-based preventive measures may become possible. Examination of the interactions between hereditary factors and environmental factors may enable more accurate prediction of recurrence risk and potential preventive measures, and therapeutic methods other than surgery may be developed in the future.
References
1 Harris J, Kallen B, Robert E: The epidemiology of anotia and microtia. J Med Genet 1996;33:809-813.
2 Okajima H, Takeichi Y, Umeda K, Baba S: Clinical analysis of 592 patients with microtia. Acta Otolaryngol Suppl 1996;525:18-24.
3 Schinzel AA, Smith DW, Miller JR: Monozygotic zwinning and structural defects. J Pediatr 1979;95: 921-930.
4 Kohlhase J, Taschner PE, Burfeind P, Pasche B, Newman B, Blanck C, Breuning MH, ten Kate LP, Maaswinkel-Mooy P, Mitulla B, Seidel J, Kirkpatrick SJ, Pauli RM, Wargowski DE, Devriendt K, Proesmans W, Gabrielli O, Coppa GV, Wesby-van Swaay E, Trembath RC, Schinzel AA, Reardon W, Seemanova E, Engle W: Molecular analysis of SALL1 mutations in Townes-Brocks syndrome. Am J Hum Genet 1999;64:435-445.
5 The Treacher Collins Collaborative Group: Positional cloning of a gene involved in the pathogenesis of Treacher Collins syndrome. Nat Genet 1996;12:130-136.
6 Alasti F, Sadeghi A, Sanati MH, Farhadi M, Stollar E, Somers T, Van Camp G: A mutation in HOXA2 is responsible for autosomal-recessive microtia in an Iranian family. Am J Hum Genet 2008;82:982-992.
7 Tekin M, Hismi BO, Fitoz S, Ozdag H, Cengiz FB, Sirmaci A, Aslan I, Inceoğle B, Yüksel-Konuk EB, Yilmaz ST, Yasun O, Akar N: Homozygous mutations in fibroblast growth factor 3 are associated with a new form of syndromic deafness characterized by inner ear agenesis microta and microdontia. Am J Hum Genet 2007;80:338-344.
8 Llano-Rivas I, Goncalez-del Angel A, del Castillo V, Reyes R, Camevale A: Microtia: a clinical and genetic study at the National Institute of Pediatric in Mexico City. Arch Med Res 1999;30:120-124.
9 Tasse C, Bohringer S, Fischer S, Lüdecke HJ, Albrecht B, Hom D, Janecke A, Kling R, König R, Lorenz B, Majewski F, Maeyens E, Meinecke P, Mitulla B, Mohr C, Preischi M, Umstadt H, Kohlhase J, Gillessen-Kaesbach G, Wieczorek D: Oculo-aurichulo-vertebral spectrum (OAVS): clinical evaluation and severity scoring of 53 patients and proposal for a new classification. Eur J Med Genet 2005;48:397-411.
10 Lynberg MC, Khoury MJ, Lammer EJ, Waller KO, Cordero JF, Erickson JD: Sensitivity, specificity, and positive predictive value of multiple malformations in isotretinoin embryopathy surveillance. Teratology 1990;42:513-519.
11 Suutarla S, Rautio J, Ritvanen A, Ala-Mello S, Jero J, Klockars T: Microtia in Finland: comparison of characteristics in different populations. Int J Pediatr Otorhinolaryngol 2007;71:1211-1217.
12 Matsunaga T, Hirota E: Familial lateral semicircular canal malformation with external and middle ear abnormalities. Am J Med Genet A 2003;116A:360-367.
13 Tischfiled MA, Bosley TM, Salih MA, Alorainy IA, Sener EC, Nester MJ, Oystreck DT, Chan WM, Andrews C, Erickson RP, Enqle EC: Homozygous HOXA1 mutations disrupt human brainstem, inner ear, cardiovascular and cognitive development. Nat Genet 2005;37:1035-1037.
14 Fekete DM: Development of the vertebrate ear: insights from knockouts and mutants. Trends Neurosci 1999;22:263-269.
15 Mallo M: Formation of the middle ear: recent progress on the developmental and molecular mechanisms. Dev Biol 2001;231:410-419.
16 Chisaka O, Musci TS, Capecchi MR: Developmental defects of the ear, cranial nerves and hindbrain resulting from targeted disruption of the mouse homeobox gene Hox-1.6. Nature 1992;355:516-520.
17 Rijli FM, Mark M, Lakkaraju S, Dierich A, Dollé P, Chambon P: A homeotic transformation is generated in the rostral branchial region of the head by disruption of Hoxa-2, which acts as a selector gene. Cell 1973;75:1333-1349.
18 Kuratani S, Satokata I, Blum M, Komatsu Y, Haraguchi R, Nakamura S, Suzuki K, Kosai K, Maas R, Yamada G: Middle ear defects associated with the double knosk out mutation of murine goosecoid and Msx1 genes. Cell Mol Biol (Noisy-le-grand) 1999;45:589-599.
19 Qiu M, Bulfone A, Martinez S, Meneses JJ, Shimamura K, Pedersen RA, Rubenstein JL: Null mutation of Dlx-2 results in abnormal morphogenesis of proximal first and second branchial arch derivatives and abnormal differentiation in the forebrain. Genes Dev 1995;9:2523-2538.
20 Matsuo I, Kuratani S, Kimura C, Takeda N, Aizawa S: Mouse Otx2 functions in the formation and patterning of rostral head. Genes Dev 1995;9:2646-2658.
21 ten Berge D, Brouwer A, Korving J, Martin JF, Meijlink F: Prx1 and Prx2 in skeletogenesis: roles in the craniofacial region, inner ear and limbs. Development 1998;125:3831-3842.
22 Kaur S, Singh G, Stock JL, Schreiner CM, Kier AB, Yager KL, Mucenski ML, Scott WJ Jr, Potter SS: Dominant mutation of the murine Hox-2.2 gene results in developmental abnormalities. J Exp Zool 1992;264:323-336.
23 Moore KL, Persaud TVN, Torchia MG: The Developing Human. Clinically Oriented Embryology, ed 9. Philadelphia, Elsevier Saunders, 2011.
Tatsuo Matsunaga National Institute of Sensory Organs, National Tokyo Medical Center 2-5-1 Higashigaoka, Meguro-Ku Tokyo 152-8902 (Japan) E- Mail matsunagatatsuo@kankakuki.go.jp
Diagnosis
______________________
Abstract
Diagnostic procedures of microtia/atresia of the external auditory canal include: (1) classification of shapes of the auricle and the external auditory canal by shape, (2) imaging assessment for revealing the condition of the external canal and middle ear by CT, and reconstructing the surface of temporal bone to confirm the positions for pinnaplasty and auditory canalplasty in order, (3) auditory assessment by pure tone audiometry, air and bone conduction ABR and ASSR and sound lateralization test, (4) evaluation of development of the auricle and the external auditory canal and rib cartilage for pinnaplasty and auditory canalplasty, (5) deciding on the correct position for auricular reconstruction for later auditory canalplasty, (6) evaluation of anomalies of the auditory ossicles for improving hearing by tympanoplasty, and (7) psychological changes in patients before and after pinnaplasty and auditory canalplasty.
Diagnosis
Kaga K, Asato H (eds): Microtia and Atresia – Combined Approach by Plastic and Otologic Surgery. Adv Otorhinolaryngol. Basel, Karger, 2014, vol 75, pp 10–12 (DOI: 10.1159/000350495)
______________________
Classification of Shapes (Auricle/External Auditory Canal)
Yasutoshi Suzuki
Department of Plastic Surgery, Dokkyo Medical University, Shimotsuga-gun, Tochigi, Japan
Classification of Shapes of the Auricle
Microtia is a congenital anomaly of the auricle in which the components of the auricle are small or missing. The severity and states vary. Its incidence is 1 in 10,000-15,000 births, and male patients outnumber female patients (approximately 2:1). Microtia develops more frequently on the right than the left side (approximately 5:3), and the reported incidence of bilateral microtia is approximately 10%. Many cases are complicated by stenosis or occlusion of the EAC in addition to the morphological abnormality of the auricle.
Auricular shape in microtia can be classified by conventional methods using the characteristics of the residual auricle, and by methods using qualitative differences related to embryology in addition to quantitative differences. The former includes the three-grade classification of Marx [ 1 ] and the five-grade classification of Ogino et al. [ 2 ] ( table 1 ), and the 10-type classification of Fukuda [ 3 ] is an example of the latter. These criteria are widely used in Japan for diagnosis, treatment and surgery of microtia. In addition, Asato and Kaga classified microtia into five types from the perspective of simultaneous reconstruction of the EAC with auricular projection, in addition to auricular reconstruction by costal cartilage transplantation ( fig. 1 , 2 ). The incidence of lobule-type (a) microtia is highest, accounting for approximately 60% of cases, followed by the concha-type (c) and the small-concha type (b), with a combined incidence of approximately 15%. Atypical-type (d) and anotia-type (e) microtia, which are not included in a, b or c are rare.

Fig. 1. Correlation between classification systems for microtia.

Fig. 2. Classification of microtia according to Asata and Kaga. a Lobule type. b Small concha type. c Concha type. d Atypical type. e Anotia type.
Table 1. Clinical classification of microtia

Classification of the External Auditory Canal by Shape
Many cases of microtia are complicated by atresia of the EAC, which may occur as complete occlusion or EAC stenosis, which is incomplete occlusion. Atresia or stenosis of the EAC is either limited to cartilage or osseous occlusion. Stenosis is classified as: (1) stenosis of the entire bone, (2) stenosis of the lateralis osseous, and (3) stenosis of the cartilage.
Osseous occlusion is often observed in microtia patients and is commonly complicated by a middle ear anomaly. In such cases, a deformation or deficit of the auditory ossicle or osseous adhesion to the surrounding tissues is observed, and formation of the middle ear cavity and development of the tympanic antrum are variable. From the viewpoint of treatment and prognosis, classification of cases by combining development of the middle ear with the occlusion of the EAC has been reported. The grading system of Jahrsdoerfer et al. [ 4 ] is especially useful, where higher scores indicate expected improvement of auditory acuity (see ‘Imaging diagnosis’, this vol., p. 15).
References
1 Marx H: Die Missbildungen des Ohres. Denker-Kahler’sche Handbuch der Hals-Nasen und Ohren-heilkunde, Gehörogan 1. Berlin, Julius Springer, 1926, pp 131-169.
2 Ogino Y, Nishimura Y, Horii M, et al: Congenital microtia – multidirectional tomographic and remnant auricular forms. Pract Otol 1976;69:792-801.
3 Fukuda O: Shoujishou no bunrui; in Soeda S (eds): Zusetsu rinshou keiseigekagaku kouza 4. Tokyo, Medical View, 1988, pp 16-17.
4 Jahrsdoerfer RA, Yeakley JW, Aguilar EA, et al: Grading system for the selection of patients with congenital aural atresia. Am J Otol 1992;13:6-12.
Yasutoshi Suzuki Department of Plastic Surgery, Dokkyo Medical University 880 Kitakobayashi, Mibu-Machi Shimotsuga-gun, Tochigi 320-0293 (Japan) E- Mail ysuzuki-tky@umin.ac.jp

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