Hemifacial Microsomia

Hemifacial microsomia (HFM) is a condition in which part of one side of the face is underdeveloped and does not grow normally. The eye, cheekbone, lower jaw, facial nerves, muscles, and neck may be affected. Other findings may include hearing loss from underdevelopment of the middle ear; a small tongue; and macrostomia (large mouth). HFM is the second most common facial birth defect after clefts. The cause of HFM in most cases is unknown. It usually occurs in people with no family history of HFM, but it is inherited in some cases. HFM is part of a group of conditions known as "craniofacial microsomia". It is not known whether the conditions included in the group really are different conditions or part of the same problem with different degrees of severity. Treatment depends on age and the specific features and symptoms in each person.