Hemifacial microsomia is a congenital problem which affects the development of the lower part of the face. It typically results in underdevelopment of the mouth, lower jaw, ear and cheek. The severity of the disorder varies from patient to patient, with some children being very severely affected and others having very subtle facial asymmetry. It occurs 1 in 4000 births.
Hemifacial microsomia is also known as 1st and 2nd brachial arch syndrome, oral-mandibular-auricular syndrome, lateral facial dysplasia, otomandibular dysostosis, Goldenhar syndrome, facio-auriculo-vertebral syndrome (FAV), oculo-auriculo-vertebral spectrum (OAV) and lateral facial dysplasia.
Cause of hemifacial microsomia
Researchers are still not sure exactly what causes this condition. However, most experts believe that this condition is the result of abnormal blood flow to the developing facial structures around the 4th week of gestation. This condition is not the result of anything that either parent does or fails to do. Although hemifacial microsomia sometimes runs in families, it is usually not an inherited condition. More commonly, this condition occurs sporadically or “by chance.”
Children with hemifacial microsomia frequently have a small, underdeveloped lower jaw or mandible. Not all children are affected to the same degree. In it’s most severe form, the mandible may lack a normal joint entirely and may be so underdeveloped that breathing and eating may be difficult. In milder forms, the mandible is only slightly small and functions normally.
Children with this disorder also frequently have an underdeveloped ear. Once again, the severity of the ear deformity varies, with some children having an absent or severely malformed ear and others having essentially a normal ear that is only slightly smaller than it should be.
In some children, the mouth may also be affected, making the corner of the mouth appear too wide. Other characteristics include weakness or paralysis of the facial muscles, skin tags on the cheek and ear and an underdeveloped cheek bone.
There is not a blood test to diagnose this condition. Hemifacial microsomia is most often diagnosed based on medical history and recognition of the characteristic physical traits. To confirm the diagnosis, it is important to have your child evaluated by an experienced craniofacial surgeon.
Surgical treatment for this condition depends on how severely your child is affected and what facial features are involved.
- Lower jaw: When the lower jaw is severely underdeveloped, surgery is sometimes needed to reconstruct the jaw joint and help the jaw function properly. This is often done by rebuilding the underdeveloped part of the jaw with a rib graft when you child is approximately 4-5 years old.
For less severely affected children, the small portion of the jaw may be lengthened surgically by a process called distraction osteogenesis. This also frequently done in early childhood.
For those children who have minor abnormalities, a combination of orthodontics and jaw surgery may be recommended to help balance the lower jaw and establish proper alignment of the teeth when your child is in their late teenage years.
- Ear: When the ear is badly malformed or absent, ear reconstrution may be required to build a new ear. There are several different approaches to ear reconstruction, but the most durable, long-term strategy is to construct a new ear using your child’s rib cartilage. This surgery most often requires 2-3 stages to complete. Ear reconstruction is done when your child is 6-8 years of age.
- Face asymmetry: When a child has asymmetry of the face, surgery may be recommended to help improve balance. This can be done by placing facial implants or by grafting fat or other soft tissue to the areas that appear to small.