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)

1st and 2nd branchial arches

Hillocks 1-6

1-3: 1st branchial arch

4-6: 2nd 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

Final position: 20 weeks

EAC:

1st branchial cleft

Epithelial plug: weeks 4-5

Begins recanalization: week 21

Open with formed TM: week 28

MICROTIA ETIOLOGY

Vascular

Stapedial artery insult

Teratogens

Retinoic acid inhibitors

Thalidomide

Mycophenolate mofetil

Genetic

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:

future reconstruction difficult

dislodgment

remove at night

cost

Magnetic:

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

http://www.youtube.com/watch?v=LHHe_q3DNas

Stelarc

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 5th 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.