Microtia

1. Microtia Diagnosis and Management

2. About Microtia • Congenital anomaly of the external ear, usually evident at birth • A small, abnormally shaped or absent external ear • Occurs in 1 every 6,000 to 12,000 births • Higher risk with higher maternal age

3. About Microtia • More common in males • More common on the right ear • Reasons for the above are unknown

4. About Microtia • Possible causes: • in utero tissue ischemia secondary to obliteration of the stapedial artery • Ischemia due to actual hemorrhage into the local tissues • Genetic influences • Medications such as thalidomide and isotretinoin • May present in syndromes such as Goldenhar Syndrome or Treacher Collins Syndrome

5. Anatomy of the External Ear

6. About Microtia • Grading: • Grade I – malformation of the pinna, with most of the characteristics of the pinna, such as the helix, triangular fossa, and scaphae, are present with relatively good definition • Grade II – pinna less developed than in Grade I, the helix may be underdeveloped, with the other structures with less definition

7. About Microtia • Grading: • Grade III - pinna is essentially absent except for a vertical sausage-shaped skin remnant • Superior aspect of the remnant consists of underlying unorganized cartilage • Inferior aspect of this remnant consists of a relatively well-formed lobule • Anotia – total absence of the pinna

8. Classification Grade 2 Grade 1

9. Classification Grade 3 Anotia

10. About Aural Atresia • Absence of the ear canal • Patients who have microtiausually have aural atresia • Microtia and aural atresia tend to occur together because the outer ear and the middle ear evolve from a common embryologic origin • Patients with aural atresia have no hearing on the affected ear

11. Embryology of External Ear • 7th week of gestation • First and Second branchial arches  six Hillocks of His • 1 – Tragus (first/mandibular arch) • 2 - Crus of Helix (rest are from second/hyoid arch) • 3 - Ascending Helix • 4 - Upper Helix, Scapha, & Antihelix • 5 - Descending Helix, Middle Scapha & Antihelix • 6 - Inferior Helix, Antitragus • Lobule

13. Considerations • Inner ear in microtia is almost always functional, and thus hearing loss is basically conductive (the affected ear can still hear by some degree) • In unilateral microtia, the unaffected ear is usually normal, so speech development is usually at par with age • The MD should reassure the parents of the patient and outline the plan of management for the child

14. Management • Auricular Reconstruction is usually performed at 6-8 years in children with unilateral microtia • Pinna is 85-90% of its adult size by this age • At this age the patient is usually large enough that rib size is sufficient to harvest an adequate rib graft • Surgery may be done earlier if the child has adequate rib size, and postponed if not

15. Management • Auricular Reconstruction is usually performed at 6-7 years in children with bilateral microtia • The usual goal is to fix at least one ear, and achieve adequate hearing without assistive devices • Ear canal and middle ear may be evaluated for reconstruction using CT scans of temporal bones • External ear reconstruction is usually done prior to middle ear reconstruction to preserve the skin and blood vessels • Bone-anchored Hearing Aids (BAHAs) may be used if the child is not a candidate for surgery

16. Management • Auricular Reconstruction • Stage I: Auricular Reconstruction • Stage II: Lobule Transposition • Stage III: Postauricular Skin Grafting • Stage IV: Tragal Reconstruction and Soft Tissue Debulking