Hemifacial Microsomia - Introduction
1. Description of HFM
Hemifacial Microsomia (HFM) is the most common craniofacial birth defect after cleft lip and palate. It occurs in approximately in 1:5000 or 1:6000 live births and displays a wide spectrum of abnormalities. HFM is essentially an abnormality of development of the embryonic first and second branchial arches. It is usually unilateral and always asymmetrical.
Synonyms which are also in common usage are craniofacial microsomia, oculo-auriculo-vertebral-dysplasia or facial-oculo-auriculo vertebral dysplasia. Goldenhar syndrome is a term liked by pediatricians but only really refers to a small sub group of HFM patients.
2. Etiology
The etiology of HFM is not known. There does not appear to be a clearly inherited gene. Poswillo in animal experiments was able to induce a similar condition by creating a hematoma in the embryonic stapedial artery system. Similar but bilateral examples have also occurred following the use of retinoids in humans during pregnancy (eg, thalidomide) and this has been repeated experimentally in animals.
3. Growth
It is not clear whether the facial deformity of Hemifacial microsomia gets worse with age and growth or not.
