HEMIFACIAL MICROSOMIA

Some children are born with a condition called Hemifacial Microsomia. Another term used for this condition is Craniofacial Microsomia.

In Hemifacial Microsomia one side of the face does not grow normally. The elements principally involved are the mandible (lower jaw), and the ear. The zygomatic bone (cheek bone) may also fail to grow normally, whereas growth of the maxilla (upper jaw) is caused by the deficient growth of the mandible.

The degree of deformity varies greatly, from barely perceptible to most severe. In the lesser forms the only deformity may be a poorly developed external ear, or a slight asymmetry of the face caused by a minor degree of growth deficiency of the lower jaw.

 In the more severe cases the lower jaw may be very malformed or even absent on the affected side. The soft tissues are usually deficient also giving the face a very asymmetrical appearance.

Treatment of hemifacial microsomia has changed dramatically in the past few years, with the development of bone distraction techniques. A special apparatus is attached to the mandible in a relatively simple surgical procedure, allowing gradual lengthening of the short part of the jaw. As the lower jaw moves away from the upper jaw, the latter is now able to grow more normally. There is also evidence that bone distraction also helps soft tissues to develop.

Not all cases of hemifacial microsomia can be adequately treated by bone distraction techniques. In some cases bone needs to be added to the lower jaw from other parts of the body (bone grafting) in order to replace missing portions of the mandible. Sometimes soft tissues have to be added to the affected part of the face (mainly muscle, occasionally fatty tissue grafts) to produce a normal contour.

Orthodontic treatment plays a most important role in the care of children with hemifacial microsomia. The orthodontist is involved from the very beginning in their care, by helping to plan the distraction procedure, by making very specialized splints which will hold the lower jaw in the desired position and will allow the teeth of the upper jaw to extrude in a guided fashion, and finally by bringing the individual teeth in the desired position in order to normalize occlusion.