Oral-facial clefts, including cleft lip and/or cleft palate, are the most common craniofacial birth defects, affecting approximately 135,000 newborns worldwide each year. The costs of caring for a child with an oral-facial cleft is more than $100,000 and creates significant financial and healthcare burdens for these families. Infants born with an oral-facial cleft may have feeding, swallowing, breathing, speech, and hearing complications. Therefore, a multidisciplinary team, including surgical, dental, speech, genetic, and nutrition experts, is typically involved in patient care. This chapter will discuss the pathogenesis, epidemiology, clinical manifestations, diagnosis, treatment, and prevention of oral-facial clefts.
PATHOGENESIS OF ORAL-FACIAL CLEFTS
Development of the lip and palate results from the growth and fusion of facial prominences and involves cell migration, proliferation, differentiation, and apoptosis. At approximately the fourth week of embryonic development in humans, the medial nasal processes that originate from the frontonasal process merge with each other and with the bilateral maxillary processes to form the upper lip and the primary palate. Later, around the sixth week, the bilateral maxillary processes project downward along the sides of the tongue; then as the tongue descends into the oral cavity, the processes elevate above the tongue and fuse to form the secondary palate, separating the oral and nasal cavities. Disruptions at any stage of these developmental processes can lead to an oral-facial cleft.
EPIDEMIOLOGY OF ORAL-FACIAL CLEFTS
The prevalence of oral-facial clefts varies according to geographic location and ethnic background. In general, Native American and Asian populations present the highest reported birth prevalence rates of ~2 to 3 per 1000 live births, whereas Caucasians present a prevalence of ~1 per 1000 births, and African populations present the lowest prevalence of 0.3 per 1000 births.
Oral-facial clefts have been categorized as syndromic or nonsyndromic based on the presence of additional structural abnormalities. Up to 44% to 64% of all cleft cases present with associated anomalies, and to date, over 500 syndromes including chromosomal abnormalities have been reported in association with an oral cleft. Relatively common syndromic forms of oral-facial clefts include Stickler syndrome, 22q11.2 deletion syndrome, Van der Woude syndrome, and ectodermal dysplasia ectrodactyly and clefting (EEC) syndrome, most of which are associated with cleft palate rather than cleft lip and palate (Table 178-1). The most common anomalies associated with cleft palate are congenital heart defects, hydrocephaly, urinary tract defects, and polydactyly. Midline (median) clefts are commonly associated with syndromic forms of clefts (eg, frontonasal dysplasia, holoprosencephaly, or other disruptions in frontonasal development). For these reasons, children with midline clefts of the lip require careful examination that should include computed tomography (CT) or magnetic resonance imaging (MRI) of the central nervous system. The majority of cleft lip and palate cases (approximately 70–75%) are isolated, also referred to as nonsyndromic, while approximately 50% of cleft palate cases are isolated.