Congenital Malformations

Introduction:

Given the complex embryology and developmental biology of the head and neck, a vast number of congenital malformations are possible, ranging from merely cosmetic to life-threatening in severity. Although it is not feasible to discuss all of the potential developmental anomalies in an introductory text, this chapter will provide an overview of some of the more commonly encountered conditions. Due to the number and diversity of malformations covered, discussion will be organized by organ.

Craniofacial:

A multitude of craniofacial abnormalities exist, many of which are part of syndromes or sequences that include anomalies of other organ systems. From an otolaryngologic standpoint, one of the primary concerns in patients with craniofacial anomalies is airway patency. Alterations in craniofacial structure, such as jaw, palate, and tongue size or positioning can cause airway obstruction and may require emergent intervention in the neonatal period. Other otolaryngologic problems that may be encountered in syndromic patients include Eustachian tube dysfunction, recurrent acute otitis media, hearing loss, and speech delay or difficulty. Patients with craniofacial syndromes benefit from treatment by a multidisciplinary team that includes otolaryngologists, plastic and reconstructive surgeons, psychologists, speech therapists, and audiologists. Some of the more commonly seen craniofacial conditions are summarized below.

Cleft lip/palate – Incidence of cleft lip and/or palate in the United States is estimated to be 1 in 600 live births, with patients of Native American and Asian ethnicity and male sex being at higher risk. Cleft lip and/or palate may be unilateral (more common) or bilateral. Several fetal risk factors have been associated with cleft development, including alcohol or tobacco exposure, folic acid deficiency and maternal diabetes. Approximately 15% of cleft lip and 33% of cleft palate cases are associated with syndromes. Important issues to be addressed in cleft lip and/or palate patients include feeding difficulties, airway patency, chronic otitis media, and speech problems. Surgical repair may require multiple staged procedures, depending on the severity of the defect.

Pierre-Robin sequence – This disorder comprises a constellation of anomalies, including micrognathia (small jaw), glossoptosis (posteroinferior displacement of the tongue), and cleft palate. Many cases are also associated with ophthalmologic and otologic problems. Airway obstruction and obstructive sleep apnea are frequently present in the neonatal period due to the tongue and jaw abnormalities in these patients. This can lead to respiratory distress as well as feeding difficulty, aspiration, and failure to thrive. Long-term sequelae of chronic airway obstruction include cor pulmonale and pulmonary hypertension. Mandibular distraction osteogenesis is a surgical intervention that can be performed to improve airway patency in certain patients. With appropriate therapy in infancy, mortality rates are low and prognosis is good.

Goldenhar syndrome/hemifacial microsomia – Goldenhar syndrome is a rare, sporadic disorder of first and second branchial arch development, resulting in abnormalities of the midface, ear, eyes, vertebrae and other organs. In the majority of cases, only one side of the body is affected, and in most bilateral cases, one side is more severely affected than the other. Goldenhar syndrome is considered a subdivision of a group of disorders known as oculo-auriculo-vertebral spectrum, which also includes hemifacial microsomia. Surgical interventions may include mandibular distraction osteogenesis.

Branchio-oto-renal syndrome – This is an autosomal dominant disorder that, as the name suggests, involves anomalies of the kidneys, ears, and neck. Patients may have hypoplastic kidneys or renal agenesis, preauricular pits or tags, external ear malformations, hearing loss, and branchial cleft anomalies.

Trisomy 21 – Also known as Down syndrome, trisomy 21 is associated with a characteristic facies, but can present with a wide variety of dysmorphic facial features. Incidence of Down syndrome is estimated to be 1 in 650 live births, with increasing risk as maternal age increases. The abnormalities in craniofacial development in trisomy 21 patients predispose them to conditions such as obstructive sleep apnea and Eustachian tube dysfunction with chronic serous otitis media.

Treacher Collins syndrome – This rare autosomal dominant disorder is also known as mandibulofacial dysostosis. Patients have a characteristic facial appearance that includes abnormalities of the eyes, ears, face, mandible, and oral cavity. Intelligence is generally normal. Mandibular hypoplasia and palatal defects may cause airway obstruction that requires surgical intervention. Conductive hearing loss is often present due to malformation or absence of middle ear structures; however, the inner ear is usually normal and patients benefit from the use of hearing aids. If microtia is present, it may be corrected surgically (see below).

Ear:

Many of the common congenital ear abnormalities that cause conductive hearing loss are discussed in Conductive Hearing Loss; therefore, this section will focus primarily on external malformation.

As discussed in The Ear, the auricle is composed of several structural subunits. Absence or malformation of one or more of these subunits results in microtia. Although microtia may occur as part of a syndrome, it is commonly an isolated, unilateral abnormality. Severity of microtia is classified into three grades. Grade I microtia consists of mild dysmorphism, usually involving the helix or antihelix. Conditions such as protuberant pinna, cupped ear deformity, and low-set ears fall into this category. All of the major auricular subunits are present in this grade. Grade II microtia consists of dysplastic anomalies resulting in deficiencies in one or more of the auricular subunits. Lop ear deformities are the most common Grade II anomalies. Grade III deformity is the most severe, wherein most of the auricular subunits are missing.

Treatment for microtia is elective surgery. Depending on whether the external ear defects are associated with middle or inner ear abnormalities, functional restoration may or may not be possible. However, cosmetic improvement can be achieved via auricular reconstruction. For grade III microtia, in which often only a lobule remnant is present, reconstruction involves a multi-stage procedure. Autologous rib cartilage is harvested, shaped, and grafted into the appropriate position. After the graft has taken, further steps include repositioning the pre-existing lobule (if present), elevating the cartilage graft with postauricular skin grafting, and fine-tuning of the reconstruction. Microtia surgery is usually delayed until the patient is at least 6 years of age to allow for sufficient rib cartilage development, and to ensure better size and shape matching with the contralateral, normal ear.

Ear canal atresia and stenosis may be associated with defects of the external and middle ear. In addition to causing conductive hearing loss, severe canal stenosis can increase risk of cholesteatoma development. Reconstruction for aural atresia is attempted only if cochlear function and inner ear anatomy is normal. If repair is to be attempted in conjunction with microtia reconstruction, the canal is typically reconstructed after the external ear. The outcomes for canal atresia repair depend on the severity of disease and patient anatomy; success rates for restoring near-normal hearing have been reported to be as high as 90% for appropriately selected patients.

Nose:

Nasal malformations are of particular concern in the neonate as infants are obligate nasal breathers for up to the first five months of life; therefore, occlusion of the nasal cavities may result in respiratory distress. While neonates can breathe through the mouth temporarily (such as when crying), sustained oral breathing may not be possible. Additionally, feeding may present particular difficulty, as the act precludes intake of air through the oral cavity. Patients may present with symptoms of dyspnea, stertor, cyanotic episodes, or failure to thrive. Others may be brought to attention due to failed attempts at passing suction catheters or feeding tubes through the nasal passages. The main categories of congenital nasal malformation include congenital nasal masses and obstructive bony malformations.

Midline nasal masses are relatively uncommon congenital disorders. The most common of these is the nasal dermoid cyst. Like dermoid cysts elsewhere in the body, they result from entrapment of epithelium in deeper tissues. It is thought that anterior skull base defects are responsible for their development. The cysts are composed of ectodermal and mesodermal elements and frequently contain hair and other skin appendages. The gross appearance of a dermoid cyst may be as a midline mass, pit, or tract. If a mass is present, it is generally firm, noncompressible, and does not expand with crying or Valsalva (negative Furstenberg test). The most common location of a nasal dermoid cyst is the lower third of the nasal bridge, where it may cause widening of the nasal dorsum. An intracranial connection may be present in up to 45% of cases, which can result in complications such as meningitis and cerebrospinal fluid leakage.

It is important to note that a congenital nasal mass should never be biopsied prior to obtaining radiographic studies, as the presence of intracranial elements (e.g., meninges or brain tissue in an encephalocele) must be excluded before intervention. MRI is most sensitive for evaluation of soft tissue and whether intracranial extension is present, although CT is useful for visualizing skull base defects. The treatment of nasal dermoid cyst is surgical excision. The surgical approach depends on the location and extent of the lesion; those with intracranial components typically require a craniotomy. Recurrence rates after surgery are low, provided that all dermal elements are completely excised.

Other than nasal dermoid cysts, the differential diagnosis for midline nasal masses includes encephalocele and nasal glioma. Encephaloceles are herniations of intracranial elements (meninges with or without brain tissue) through defects in the skull. Unlike dermoid cysts, they are soft, compressible masses that expand with crying or Valsalva (positive Furstenberg test). Gliomas are generally isolated anomalies that may occur intranasally, extranasally, or have components of both. They are firm and noncompressible with a negative Furstenberg test and may be covered with telangiectasias. Both encephaloceles and gliomas are treated with surgical excision and carry a good prognosis.

The primary congenital bony obstructive nasal defect is choanal atresia, which has an incidence of one in every 5000-8000 live births. Either unilateral or bilateral atresia may occur, although the former is more common. Unilateral choanal atresia is more common in the right choana than the left. Choanal atresia has a female predilection and is associated with additional developmental anomalies in up to two-thirds of cases. It is one of the components of the CHARGE association, which includes coloboma (ocular), heart malformations, atresia (choanal), retardation of growth or development, genitourinary malformation, and ear malformations or deafness.

CT is the preferred imaging modality for evaluation of choanal atresia. The diagnosis is made based on measurements of the posterior choanal orifice and posterior vomer on CT. Bilateral choanal atresia often requires temporizing measures to secure the airway until surgery can be performed. Specialized feeding nipples may be used to allow oral breathing while feeding. In some cases, intubation or tracheostomy may be required. Surgical treatment of choanal atresia is usually approached endoscopically or transnasally, following which the atretic plate is opened either with instruments or laser. Stents are sometimes placed, along with topical mitomycin C to prevent scarring and restenosis; however, recurrence rates have been reported to be as high as 45%.

Larynx:

Congenital malformations of the larynx include laryngeal webs, subglottic stenosis, laryngeal clefts, and bifid epiglottis. Additional discussion of pediatric laryngeal conditions, both congenital and acquired, can be found in Pediatric Stridor.

Neck:

See Pediatric Neck Masses for a discussion of congenital neck conditions, such as branchial cleft anomaly and thyroglossal duct cyst.