Hemifacial microsomia is a congenital defect of tissues and structures on one side of face. In this condition the tissues of one side of face are underdeveloped. The structures primarily affected are ear, mouth and jaw and in some cases eye, cheek or part of skull is also affected. Sometimes both the sides of face are involved. It is frequent congenital birth defect of face after cleft lip and palate. Reported cases vary from 1 in every 3000 or 5000 newborns. Females are less affected than males. The right side malformation is more common than left side.
Hemifacial microsomia is known by other names such as lateral facial palsy, branchial arch syndrome, first and second branchial arch anomaly etc. The etiology of this condition is uncertain although physicians believe it is caused by some vascular problem in face during the first trimester of fetal development. The visible signs and symptoms are underdeveloped upper and lower jaw, absence of external ear, facial asymmetry, one eye smaller than other, flat forehead, etc.
Treatment depends on severity of abnormality. It may involve corrective surgery, grafting, use of hearing aids, etc. The precise timing of treatment is important with respect the growth of child.
What Causes Hemifacial Microsomia?
The exact cause of hemifacial microsomia remains unclear. Researchers believe the developmental defect occurs during the first trimester of pregnancy. Doctors believe some vascular problem is the underlying cause. Vascular problem such as hemorrhage from stapedial artery leading to hematoma is believed my many doctors.
Due to interrupted blood supply to the facial area during developmental stage of fetus, the structures and tissue of face develop irregularly and some are malformed. Some parts of face develop slowly. It is not linked with any diet or deficiency during pregnancy. In vast majority of cases the condition is not inherited and it occurs randomly.A person having hemifacial microsomia has very rare chance of having child with similar problem.
Signs And Symptoms Of Hemifacial Microsomia
The signs and symptoms of hemifacial microsomia may vary from person to person. This condition is more common in males as compared to females. In some cases the defect is not noticeable whereas in some people the abnormality of face is obviously seen.
In milder case, the child may have small jaw and a skin tag in front of the ear on one side of face. The facial structures on one side and the tissues may be underdeveloped. For example:
- Jaw: The upper and lower jaw of one side may be underdeveloped. Some people may have crooked jaw, overcrowding of teeth may be present. The mouth may open limitedly.
- Orbit: One eye may be smaller than other. However, the person vision is not compromised. In some people however, the underdeveloped eye may have impaired vision.
- Ear: There can be excess of skin in the form of skin tag in front of the ear. The external ear may be malformed and underdeveloped. In some cases the inner ear is absent and hence patient suffers from impaired hearing.
- Flat forehead and cheekbones.
- Facial paralysis or weakness on one side of face due to nerve involvement.
Majority of children have facial anomalies but there is no other associated medical ailment.
Treatment Options For Hemifacial Microsomia
Treatment of hemifacial microsomia may vary from one child to another. In some children having minor anomaly hearing aid or orthodontic procedure may only be necessary. However, if there is major defect on one side of face, patient may need surgical reconstruction and repair. For example if there is severe malformation of lower jaw, surgery may be required to reconstruct a bone graft from rib or some other bone.
In some cases other techniques may be used instead of bone graft and surgery. Surgery to reconstruct external ear may be needed if the external ear is absent. It is done between 6 to 8 years of age. Surgery to correct asymmetry of face may also be undertaken as the child reaches adolescence period.