Published on 25/03/2015 by admin
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Last modified 25/03/2015
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Chapter 630 Congenital Malformations
Joseph Haddad, Jr.
The external and middle ears, derived from the 1st and 2nd branchial arches and grooves, grow throughout puberty, but the inner ear, which develops from the otocyst, reaches adult size and shape by mid-fetal development. The ossicles are derived from the 1st and 2nd arches (malleus and incus), and the stapes arises from the 2nd arch and the otic capsule. The malleus and incus achieve adult size and shape by the 15th wk of gestation, and the stapes achieves adult size and shape by the 18th wk of gestation. Although the pinna, ear canal, and tympanic membrane (TM) continue to grow after birth, congenital abnormalities of these structures develop during the 1st half of gestation. Malformed external and middle ears may be associated with serious renal anomalies, mandibulofacial dysostosis, hemifacial microsomia, and other craniofacial malformations. Facial nerve abnormalities may be associated with any of the congenital abnormalities of the ear and temporal bone. Malformations of the external and middle ears also may be associated with abnormalities of the inner ear and both conductive (CHL) and sensorineural hearing loss (SNHL).
Congenital ear problems may be minor and mainly cosmetic, or major, affecting both appearance and function. Any child born with an abnormality of the pinna, external auditory canal, or TM should have a complete audiologic evaluation in the neonatal period. Imaging studies are necessary for evaluation and treatment; in the patient with other craniofacial abnormalities a team approach with other specialists can assist in guiding therapy.
Severe malformations of the external ear are rare, but minor deformities are common. Isolated abnormalities of the external ear occur in approximately 1% of children. A pitlike depression just in front of the helix and above the tragus may represent a cyst or an epidermis-lined fistulous tract. These are common, with an incidence of approximately 8/1,000 children, and may be unilateral or bilateral and familial. The pits require surgical removal only if there is recurrent infection. Accessory skin tags, with an incidence of 1-2/1,000, can be removed for cosmetic reasons by simple ligation if they are attached by a narrow pedicle. If the pedicle is broad-based or contains cartilage, the defect should be corrected surgically. An unusually prominent or “lop” ear results from lack of bending of the cartilage that creates the antihelix. It may be improved cosmetically in the neonatal period by applying a firm framework (sometimes soldering wire is used) attached by Steri-Strips to the pinna and worn continuously for weeks to months. Otoplasty for cosmetic correction can be considered in children >5 yr of age, when the pinna has reached about 80% of its adult size.
The term microtia may indicate subtle abnormalities of the size, shape, and location of the pinna and ear canal, or major abnormalities with only small nubbins of skin and cartilage and absence of the ear canal opening; anotia
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