Trigonocephaly is the term used to describe the shape that results from craniosynostosis of the metopic suture. The metopic suture runs from the top of the head at the fontanel, or soft spot, down the center of the forehead stopping just above the nose. A ridge can usually be seen running down the center of the forehead and the forehead will look narrow. Often, the eyes are spaced closer together than is normal. The most characteristic finding is when viewed from above is that the forehead will have a triangular shape like the bow of a boat.

The incidence of trigonocephaly is somewhere between one in 2,500 to one in 3,500 births. Trigonocephaly has been reported to occur when mothers have taken Valproic Acid (Depakene, Depakote, and Convulex) for seizures. Not all children require treatment. Sometimes it can be very difficult to determine if a child has significant trigonocephaly, or not. Those who are very mildly affected may not require any surgery. The metopic suture is different from all the other sutures of the skull because it is the only one that actually normally fuses shut, beginning this process well before a year of age. Therefore, x-rays showing that this suture has fused are not all that helpful. In some children, as the suture normally closes it can create a very prominent ridge. When this occurs, children may just have a ridge running down the center of their forehead without producing the triangular-shaped forehead.  Only those children who have overt trigonocephaly need treatment. Children with an isolated ridge running down their foreheads do not require surgery (see Publications, Book Chapters #3).  The treatment for this condition is discussed in the Treatment section.