Hemifacial Microsomia (HFM)
This is the second most common type of facial anomaly, after cleft lip and cleft palate. Hemifacial microsomia is known by a variety of other names, including craniofacial microsomia, first and second pharyngeal arch syndrome, Goldenhar syndrome, and lateral facial dysplasia. It occurs when soft tissue and bone from the pharyngeal arches on one side of a child's face fails to develop fully. The result is that facial and jaw bones in the area are smaller than normal. Although it generally occurs on just one side of the face, it can also appear on both sides.Children with HFM have several common facial features. They may have one-sided (unilateral) or two-sided (bilateral) underdevelopment of the eye, cheekbone, lower jaw, facial nerve and muscles. Bits of skin and cartilage may occur in front of the ears. There may be hearing loss from underdevelopment of the middle ear. The soft palate (the fold of tissue at the back of the mouth that separates the mouth from the nasal cavity) may move to the unaffected side because of muscle weakness on the affected side. The tongue may be small with nerve weakness on the affected side. In about 40 percent of children with HFM, the nerve responsible for moving the facial muscles is weak on the affected side or, rarely, on both sides. About a third of children with the disorder have macrostomia, literally 'large mouth,' because of an opening at the corner of the mouth. Typically, microtia and atresia are part of hemifacial syndrome.