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 1
Grade 2

9. Classification
Grade 3
Anotia

10. About Aural Atresia Absence of the ear canal
Patients who have microtia usually 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