pediatrics
Congenital Jaw Abnormalities
Micrognathia (small mandible)
Micrognathia may occur in > 700 genetic syndromes. Pierre Robin sequenceis a common manifestation of micrognathia characterized by a U-shaped cleft soft palate and upper airway obstruction caused by glossoptosis (a tongue that falls to the back of the throat); conductive hearing loss may also be present. Feeding can be difficult, and sometimes cyanosis develops because the tongue is posterior and may obstruct the pharynx. Prone positioning during feeding may help, but uncoordinated swallowing may require nasogastric gavage feedings or a gastrostomy tube. If cyanosis or respiratory problems persist, tracheostomy or surgery to affix the tongue in a forward position (eg, sewing it to the inner lower lip) may be required. Otologic evaluation is indicated. About one third of patients with micrognathia have associated anomalies that suggest an underlying chromosomal defect or genetic syndrome. Some of the diagnoses to be considered include Treacher Collins syndrome (associated with downward slant of the eyes, Coloboma , malformed pinna [ Surgical extension of the mandible can improve appearance and function. In the typical procedure, called distraction osteogenesis, an osteotomy is done and a distraction (separator) device is attached to both pieces. Over time, the distance between the two pieces is widened, and new bone grows in between to enlarge the mandible. 