Congenital Malformations

Published on 25/03/2015 by admin

Filed under Pediatrics

Last modified 22/04/2025

Print this page

This article have been viewed 1390 times

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.

Pinna Malformations

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 indicates complete absence of the pinna and ear canal. Microtic ears often are more anterior and inferior in placement than normal auricles, and the location and function of the facial nerve may be abnormal. Surgery to correct microtia is considered for both cosmetic and functional reasons; children who have some pinna can wear regular glasses, a hearing aid, and earrings and feel more normal in appearance. If the microtia is severe, some patients may opt for creation and attachment of a prosthetic ear, which cosmetically closely resembles a real ear. Surgery to correct severe microtia may involve a multistage procedure including carving and transplantation of autogenous cartilage rib grafts, and local soft tissue flaps. Cosmetic reconstruction of the auricle usually is performed between 5-7 yr of age, and is performed before canal atresia repair in children deemed appropriate for this surgery.

Congenital Stenosis or Atresia of the External Auditory Canal

Stenosis or atresia of the ear canal often occurs in association with malformation of the auricle and middle ear; minor stenoses may occur in isolation. In some genetic syndromes, such as trisomy 21, ear canals are narrow. Audiometric evaluation of these children should be undertaken as early in life as possible. Most children with significant CHL secondary to bilateral atresia wear bone conduction hearing aids for the 1st several yr of life. Diagnosis, evaluation, and surgical planning often are aided by CT, and sometimes MRI, of the temporal bone. Mild cases of ear canal stenosis do not require surgical enlargement unless the patient develops chronic external otitis or severe cerumen impaction that affects hearing.

Reconstructive ear canal and middle-ear surgery for atresia usually is considered for children >5 yr of age who have bilateral deformities resulting in a significant CHL. The aim of reconstructive surgery is to improve hearing to a point where the child may not need a hearing aid or to provide an ear canal and pinna so that the child can derive improved benefit from an air-conduction hearing aid. CT evidence of an adequate middle-ear cleft, ossicles, and mastoid is required to perform the surgery; the position of the facial nerve, which often is in an abnormal location in these children, also must be considered. The use of bone-anchored hearing aids (BAHA) may provide an option for some of these children when they are older. These devices are approved by the U.S. Food and Drug Administration for surgical placement in children aged 5 yr and older. Prior to that age they can be worn with a soft band around the head.

Congenital Middle-Ear Malformations

Children may have congenital abnormalities of the middle ear as an isolated defect or in association with other abnormalities of the temporal bone, especially the ear canal and pinna, or as part of a syndrome. Affected children usually have CHL but may have mixed CHL and SNHL. Most malformations involve the ossicles, with the incus most commonly affected. Other less common abnormalities of the middle ear include persistent stapedial artery, high-riding jugular bulb, and abnormalities of the shape and volume of the aerated portion of the middle ear and mastoid; all present problems for a surgeon. Depending on the type of abnormality and the presence of other anomalies, surgery may be considered to improve hearing.

Congenital Inner Ear Malformations

Congenital inner ear malformations have been identified and classified as a result of improvements in imaging modalities, especially CT and MRI. As many as 20% of children with SNHL may have anatomic abnormalities identified on CT or MRI. Congenital malformations of the inner ear usually are associated with SNHL of various degrees, from mild to profound. These malformations may occur as isolated anomalies or in association with other syndromes, genetic abnormalities, or structural abnormalities of the head and neck. Enlarged vestibular aqueducts have been identified on imaging studies in association with SNHL; although no therapy exists for this condition, it may be associated with progressive SNHL in some children, and, therefore, diagnosis may have some prognostic value.

Congenital perilymphatic fistula (PLF) of the oval or round window membrane may present as a rapid-onset, fluctuating, or progressive SNHL with or without vertigo and often is associated with congenital inner ear abnormalities. Middle ear exploration may be required to confirm this diagnosis, because no reliable nonoperative diagnostic test exists. It may be necessary to repair a PLF to prevent possible spread of infection from the middle ear to the labyrinth, to stabilize hearing loss, and to improve vertigo when present.

Congenital Cholesteatoma

A congenital cholesteatoma usually appears as a white, round, cystlike structure medial to an intact TM. Cysts are seen most commonly in the anterior-superior portion of the middle ear, although they can present in other locations and within the TM or in the skin of the ear canal. Affected children often have no prior history of otitis media (OM). One theory for the pathogenesis is that the cyst derives from a congenital rest of epithelial tissue that persists beyond 33 wk of gestation, when it ordinarily would disappear. Other theories include squamous metaplasia of the middle ear, entrance of squamous epithelium through a nonintact eardrum into the middle ear, ectodermal implants between the 1st and 2nd branchial arch remnants, and residual amniotic fluid squamous debris. Congenital or acquired cholesteatoma should be suspected when deep retraction pockets, keratin debris, chronic drainage, aural granulation tissue, or a mass behind or involving the TM is present. Besides acting as a benign tumor causing local bone destruction, the keratinaceous debris of a cholesteatoma is a good culture medium and may become a focus of infection for chronic OM. Complications include ossicular erosion with hearing loss, bone erosion into the inner ear with dizziness, or exposure of the dura, with consequent meningitis or a brain abscess. Cholesteatoma should be removed surgically after CT scan and hearing evaluation, and appropriate antibiotic therapy. A second-look procedure 6-9 months after primary surgery is often recommended to prevent further recurrence. Congenital cholesteatoma is an aggressive disease, and early surgical removal and close monitoring will help prevent permanent damage to the middle and inner ear.

Davids T, Gordon KA, Clutton D, et al. Bone-anchored hearing aids in infants and children younger than 5 years. Arch Otolaryngol Head Neck Surg. 2007;133:51-55.

Ozgen B, Oguz KK, Atas A, et al. Complete labyrinthine aplasia: clinical and radiologic findings with review of the literature. AJNR Am J Neuroradiol. 2009;30:774-780.

Mylanus EA, Rotteveel LJ, Leeuw RL. Congenital malformation of the inner ear and pediatric cochlear implantation. Otol Neurotol. 2004;25:308-317.

van Wijk MP, Breugem CC, Kon M. Non-surgical correction of congenital deformities of the auricle: a systematic review of the literature. J Plast Reconstr Aesthet Surg. 2009;62:727-736.

Related

Nelson Textbook of Pediatrics Expert Consult