Also known as metopic craniosynostosis, trigonocephaly is a congenital developmental defect wherein the two bones of the forehead fuse together prematurely. The condition may be noticeable at birth, or may only become apparent around one year of age.
The premature fusion of the frontal (metopic) suture causes a prominent ridge down the center of the forehead, which appears as a protrusion of the central forehead so that the head looks triangular when viewed from above. In children with this condition, the eyes may also appear very close set and slanted upward at the outer corners, and there is a possibility for a wide variety of additional cosmetic abnormalities.
Besides affecting the appearance, trigonocephaly can in some cases cause functional problems as well. This is because when the forehead bones fuse prematurely, it can cause other areas of the skull to grow abnormally in order to make room for the growing brain. In severe cases, this can affect vision, hearing, speech, and even breathing.
A reconstructive craniofacial surgeon may be able to reshape central portion of the forehead to avoid further distortion of the face and skull. This operation is usually scheduled between 8 to 10 months of age. However, if the condition is not so severe as to affect function, some people may live with the cosmetic differences their entire lives, or may even choose to have cosmetic forehead reshaping as adults (though there is less that safely can be done in adulthood to change the shape of the skull).