Facial cleft

A facial cleft is an opening or gap in the face, or a malformation of a part of the face. Facial clefts is a collective term for all sorts of clefts. All structures like bone, soft tissue, skin etc. can be affected. Facial clefts are extremely rare congenital anomalies. There are many variations of a type of clefting and classifications are needed to describe and classify all types of clefting. Facial clefts hardly ever occur isolated; most of the time there is an overlap of adjacent facial clefts.

The cause of facial clefts is still unclear.

It is possible that facial clefts are caused by a disorder in the migration of neural crest cells.

Another theory is that facial clefts are caused by failure of the fusion process and failure of inwards growth of the mesoderm.

Other theories are that genetics play a part in the development of facial clefts or that they are caused by amniotic bands.

There are different classifications about facial clefts. Two of the most used classifications are the Tessier classification and the Van der Meulen classification. Tessier is based on the anatomical position of the cleft and Van der Meulen classification is based on the embryogenesis.

In 1976 Paul Tessier published a classification on facial clefts based on the anatomical position of the clefts. The different types of Tessier clefts are numbered 0 to 14. These 15 different types of clefts can be put into 4 groups, based on their position: midline clefts, paramedian clefts, orbital clefts and lateral clefts. The Tessier classification describes the clefts at soft tissue level as well as at bone level, because it appears that the soft tissue clefts can have a slightly different location on the face than the bony clefts.

The midline clefts are Tessier number 0 ("median craniofacial dysplasia"), number 14 (frontonasal dysplasia), and number 30 ("lower midline facial cleft", also known as "median mandibular cleft"). These clefts bisect the face vertically through the midline. Tessier number 0 bisects the maxilla and the nose, Tessier number 14 comes between the nose and the frontal bone. The Tessier number 30 facial cleft is through the tongue, lower lip and mandible. The tongue may be absent, hypoplastic, bifid, or even duplicated. People with this condition are frequently tongue-tied.

...
Wikipedia