MICROTIA Emily Tignor, MD Faculty Advisor: Shraddha Mukerji, MD The University of Texas Medical Branch Department of Otolaryngology Grand Rounds Presentation October 30, 2013
DISCUSSION TOPICS Embryology Etiology Presentation Associated Anomalies Classification Management
AURICLE EMBRYOLOGY Week 5 (inner ear week 3) 1 st and 2 nd branchial arches Hillocks 1-6 1-3: 1 st branchial arch 4-6: 2 nd branchial arch Multiple theories of embryogenesis of final auricular structure
AURICLE EMBRYOLOGY Traditional theory: 1 = tragus, 2,3 = helix, 4,5 = anti helix, 6 = anti tragus and lobule Other theories: 4-6 form 85% of the auricle
AURICLE EMBRYOLOGY
AURICLE and EAC EMBRYOLOGY Migration: Starts anterior Migrates dorsal and cephalic: weeks 8-12 EAC: Final position: 20 weeks 1 st branchial cleft Epithelial plug: weeks 4-5 Begins recanalization: week 21 Open with formed TM: week 28
MICROTIA ETIOLOGY Vascular Teratogens Genetic Stapedial artery insult Retinoic acid inhibitors Thalidomide Mycophenolate mofetil Chromosomal: XO, Trisomy 13, 15, 18, 21, 22 Other mutations: Treacher Collins syndrome, neural crest cell migration failure
MICROTIA Definition: The abnormal development of the external ear that results in a malformed auricle -Kelley & Scholes, 2007 Incidence: 0.83-17.4/10,000 live births Strongly associated with hearing loss 80% have conductive hearing loss 20% have sensorineural hearing loss Associated with psychological stigma and burden
MICROTIA: PRESENTATION More common in males: Male: Female ratio = 2.5:1 More common in Japanese, Hispanic, Native American Prevalence increased at high altitudes Multiparity
MICROTIA: PRESENTATION Unilateral in 90% of cases Bilateral in only 10% of cases Right side > Left side (60% right) Hearing loss normally in affected ear can be bilateral or in the ear without microtia
MICROTIA: ASSOCIATED ANOMALIES 50% microtia cases associated with other anomalies Common associated anomalies: Congenital aural atresia (CAA) Present in almost all cases of severe microtia Cholesteatoma (Associated with CAA) Hemifacial microsomia Acrofacial Dysostosis
MICROTIA: ASSOCIATED ANOMALIES Associate anomalies: Goldenhar syndrome
MICROTIA: ASSOCIATED ANOMALIES Associated anomalies: Treacher Collins Syndrome
MICROTIA: CLASSIFICATION Marx Classification Type 1: Mild deformity All structural components of auricle present
MICROTIA: CLASSIFICATION Type 2: Atypical microtia Some auricular structures Helical changes Auditory meatus patent
MICROTIA: CLASSIFICATION Type 3: Classic microtia Few auricular structures CAA Conchal or lobular remnant (MC is lobular)
MICROTIA: CLASSIFICATION Type 4: Anotia No auricular structures CAA
MICROTIA: AUDIOLOGY Hearing status Degree of microtia associated with degree of middle ear deformity CHL common in microtic ear Non microtic ear can have hearing loss Protect normal hearing ear Lower threshold for ventilation tubes Bilateral hearing loss Indication for bone anchored hearing aids
MICROTIA: MANAGEMENT Observation Type 1 microtia Prior to surgery: 5-8 years Advantages: no risk, possibility for future reconstruction Disadvantages: cosmesis, psychosocial issues Main focus: hearing and speech
MICROTIA: MANAGEMENT Prosthesis Adhesive: possible removal of microtic ear Magnetic: microtic ear removed, anchors placed in a 2 step surgical procedure Usage: failed or cannot have reconstruction
MICROTIA: MANAGEMENT Prosthesis Advantages: cosmesis Disadvantages: Adhesive: Magnetic: future reconstruction difficult dislodgment remove at night cost no future reconstruction remove at night/daily maintenance cost surgery
MICROTIA: MANAGEMENT Reconstruction Types: Autogenous rib: four step procedure Medpor: porous polyethylene, more difficult procedure Advantages: cosmesis, low maintenance Autogenous rib: lower risk for extrusion/infection Medpor: no donor site morbidity Disadvantages: surgery, flap failure, scar Autogenous rib: donor site morbidity, pneumothorax Medpor: higher risk for extrusion/infection
MICROTIA: MANAGEMENT Reconstruction Autogenous rib reconstruction stages 1: Cartilage implantation 2: Lobule transfer 3: Creation of post auricular sulcus 4: Tragus reconstruction Complications: Hematoma Pneumothorax
MICROTIA: MANAGEMENT Reconstruction: Autogenous Medpor
SUMMARY Microtia is auricular failure to develop Embryology: branchial arches 1-2 Etiology: mainly sporadic, possible genetic causes Associated anomalies: 50% of cases commonly associated with CAA
SUMMARY Type 1: minimal deformity Type 2: helix deformity Type 3: no recognizable auricular structures Type 4: no auricle Management: observation, prosthesis, reconstruction Monitor hearing and speech
NEW DEVELOPMENTS Vacanti Mouse: biodegradable scaffolding Stelarc http://www.youtube.com/watch?v=lhhe_q3d Nas
RESOURCES Genc, S., Kahraman, E., Ozel, H., Arslan, I., Demir, A., & Selcuk, A. (2012). Microtia and congenital aural atresia. Journal of Craniofacial Surgery, 23 (6): 1733-1735. Hitchinson, J., Caldarelli, D., & Gould, H. (1981). Classification and multidisciplinary management of microtia. Otolaryngology Clinics of North America, 14(4): 885-893. Kelley, P., & Scholes, M. (2007). Microtia and congenital aural atresia. Otolaryngology Clinics of North America, 40: 61-80. Luquetti, D., Heike, C., & Cox, T. (2012). Microtia: epidemiology and genetics. American Journal of Medical Genetics, 158(1): 124-139. Murakami, C., Quatela, V., Sie, K., & Shvidler, J. (2010). Chapter 192: Microtia reconstruction. Cummings Otolaryngology 5 th Edition: 2741-2751 Parisier, S., Fayad, J., Kimmelman, C., Sclafani, A., & Alexiades, G. (2008). Chapter 62: Pediatric otorhinolaryngology: microtia, canal atresia, and middle ear anomalies. Ballenger's Otolaryngology: 759-767. Wieczorek, D. (2013). Human facial dysostoses. Clinical Genetics 83(6): 499-510. Saim, A., Cao, Y., Weng. Y., Chang, C., Vacanti, M., & Eavey, R. (2000). Engineering autogenous cartilage in the shape of a helix using an injectable hydrogel scaffold. Laryngoscope, 110(10pt1): 1694-1697. Giardini-Rosa, R., Joazeiro, P., Thomas, K., Collavino, K, Weber, J. & Waldman, S. (2013). Development of scaffold-free elastic cartilaginous constructs with structural similarities to auricular cartilage. Tissue Engineering, In process of publishing.