Overview: Hemifacial Microsomia (HFM) is the second most common craniofacial birth difference, characterized by underdevelopment of one half of the face. The extent of facial difference can range from mild to severe with variable functional deficit however, in all cases of HFM, there is some degree of underdevelopment of the mandible (lower jaw).
Causes: Although the exact cause of HFM is unknown, it is thought that a combination of both genetic and environmental factors lead to a change in facial development early in pregnancy. Possible contributing factors could be gene mutations or certain medications taken after conception. While HFM is not normally passed down from parent to child as an inherited condition, families who have a child with HFM do have about a 3% chance of having another child with the condition.
Signs and Symptoms: Children with HFM are most frequently noted to have a small lower jaw and ear on one side of the face, lending to an overall facial asymmetry, with poor jaw opening and malocclusion. In severe cases, the affected external ear and ear canal may be entirely missing, with resulting hearing loss. Expanded facial differences can include unilateral (one-sided) facial palsy (paralysis), small cheek bone, clefting of the corner of the mouth causing widening (macrostomia), cleft lip and/or palate, skin tags in front of the ear, small tissue growths on the eye (epibulbar dermoids) and small, malformed eye. Resulting functional deficits are generally seen in feeding, chewing, breathing, sight, hearing and speech.
Treatment: Treatment for HFM is multifactorial and differs for each patient. Main areas of treatment include addressing breathing issues including lengthening the lower jaw or surgical placement of a breathing tube; addressing feeding problems with jaw lengthening surgery, cleft lip and/or palate repair and macrostomia correction; evaluating and treating hearing loss; surgically reconstructing the small or missing ear or replacing it with a custom prosthetic; evaluating need for facial reanimation surgery; surgical removal of preauricular (in front of the ear) skin tags; reconstructing the jaws and repositioning the dentition to address facial asymmetry, jaw dysfunction and malocclusion; assessing and treating speech issues; monitoring for vision problems; and surveillance for spinal, renal (kidney) and heart issues.