Microtia Diagnosis and Management

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

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

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

Anatomy of the External Ear

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

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

Classification Grade 1 Grade 2

Classification Grade 3 Anotia

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

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

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

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

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

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