Microtia Aesthetics



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Microtia
Aesthetics


  • Width 55% of length

  • Helical rim protrudes 15 – 20mm from skull

  • Auriculocephalic angle 21 – 25

  • Conchalscaphal angle 75-105

  • Long axis tilted supero-posteriorly 20

  • Angle between ear axis and bridge of nose is about 15degrees

  • The ear is positioned 1 ear length 60-65mm) posterior to the lateral orbital rim between eyebrow and columella



Epidemiology
From Melnick’s study of 56000 pregnancies,

  • Any ear abnormality 1.1%

  • Severe abnormalities occur in 1 per 7000 births

  • Cultural variation - higher in Asians(1 in 4000), Navajo (1 in 1000)

  • Multifactorial inheritance

  • M:F 2:1

  • 10% bilateral

  • 50% had features of FAVS



Etiology

    1. Vascular accident in utero

    2. Prenatal infections and teratogens including isotretinoin, thalidomide, and maternal rubella.

  • 5% have immediate family history

  • 50% associated with syndromes

  1. FAVS, oculoauriculo vertebral dysplasia, Goldenhar

  2. Treacher Collins syndrome (ie, mandibulofacial dysostosis, Franceschetti syndrome)

    1. AD; TCF gene isolated to chromosome arm 5q; 1 in 50,000

    2. 60% of cases of TCS arise de novo

    3. abnormalities of the external ears, atresia of the external auditory canals and malformation of the middle ear ossicles, which result in bilateral conductive hearing loss

    4. lateral downward sloping of the palpebral fissures with colobomas of the lower eyelids and a lack of eyelashes medial to the defect;

    5. hypoplasia of the mandible and zygomatic complex

    6. cleft palate

  3. Nager syndrome (acrofacial dysostosis)

    1. atretic external auditory canals, down slanted palpebral fissures, a high nasal bridge, malar hypoplasia, and micrognathia

    2. Preaxial limb malformations include absent or hypoplastic thumbs, hypoplasia of the radius and shortened humeral bones

  4. Miller syndrome

    1. AR

    2. postaxial acrofacial dysostosis

60-70% of microtia isolated. Associated defects:



  1. facial clefts and cardiac defects are the most common (30 percent)

  2. anophthalmia or microphthalmia (14 percent)

  3. limb reduction defects or severe renal malformations (11 percent)

  4. holoprosencephaly (7 percent).



Evaluation

  • Head and neck examination emphasizing:

  1. facial asymmetry

  2. retrognathia or other airway concerns common to this group

  3. integrity of the facial nerve

  4. quality of non–hair-bearing skin in the vicinity of the auricle

  5. hairline

  6. position of the remnant auricle, and future lobule;

  7. condition of the contralateral ear.


Classification of external ear deformity

Tanzer (1977)

  1. Anotia (very rare)

  2. Complete hypoplasia (microtia)

a. with atresia of ext auditory canal

b. without atresia of ext auditory canal



  1. Hypoplasia of middle third auricle

  2. Hypoplasia of superior third

a. constricted (cup and lop)

b. cryptotia

c. hypoplasia of entire third


  1. Prominent ear


Even with extremely small microtic remnants a lobular component is almost always present, but vertically orientated and superiorly displaced.
Nagata

Based on surgical technique required for correction



  1. Lobule type (remnant ear and ear lobule without meatus, concha, tragus)

  2. Concha type (remnant ear, lobule, meatus, tragus)

  3. Small Concha (remnant ear and lobule with small indentation for concha)

  4. Clinical Anotia

  5. Atypical


Reconstruction
Staged reconstruction

Number of stages varies according to technique and amount of additional procedures.


Timing

  • Need to consider

  1. ongoing growth of ears

  2. contralateral ear characteristics

  3. Costal cartilage development

  4. Social ridicule

  5. Child’s cooperation

  6. middle ear reconstruction, if planned

    • should be done after auricular reconstruction as often leads to scarred, poorly vascularized tissue in the mastoid area and will compromise the quality of the soft-tissue cover for the framework.

  • At age 6 ribs area at satisfactory size, ear within 6 mm of full height, beginning of peer ridicule and child will probably cooperate

  • If the patient is small for age or the opposite ear is large may consider postponing surgery.

  • Tanzer showed comparable increases in height in both ears after reconstruction. i.e. the framework will grow concomitantly (he attributed this to intact perichondrium)


Preoperative


  • Preoperative photos

  • Xray film pattern is traced from the normal ear

    • Landmarks in relation to nose, lateral canthus can also be marked.

    • Patterns can be reversed and sterilized to use intraoperatively.




  • Position – height and vertical position of ear, vertical angulation in relation to nose, lateral canthus

  • In severe hemifacial microsomia, ear position is placed halfway between the vestige site and the markings from the comtralateral ear. (Brent)

  • Size – Tanzer designs the ear 2-3mm larger than the contralateral side; Brent keeps in the same or even slightly smaller


Stages of reconstruction (Brent)


  • Four-stage technique:

  1. framework placement;

  2. lobule transposition;

  3. tragus construction and conchal excavation;

  4. elevation of the ear framework with creation of the auriculocephalic sulcus.




  • Brent has modified this to include tragal reconstruction as part of Stage 1

  • Interval between stages 3 months (Tanzer = 4 months)


1. Cartilaginous framework

  • Contralateral rib cartilages harvested through a costal margin incision.

    • David Gillet takes split thickness contralateral ribs with periosteum

    • In bilateral cases, use shape of mother’s ears for template model

  • Synchondrotic region of the 6th and 7th ribs is used for the base plate.

  • helical rim from the first floating rib (usually 8th)

  • Harvesting the anterior surface perichondrium in continuity with the cartilage helps in shaping the framework and in its vascularization.

  • Leaving the posterior perichondrium in situ minimizes the deformation as many children lay down some new cartilage in this bed.

  • A rim of cartilage can be left along the edge of the rib cage to decrease visual deformity at the donor site.

  • Maximum relief of the construct is essential for the highest quality of reconstruction.