Metopic synostosis, or trigonocephaly, is a non-syndromic type of craniosynostosis that occurs when the metopic suture fuses before birth. In this text; We try to explain the causes, symptoms and treatment of trigonocephaly.

The skull consists of several ‘plates’ of bone that form when we are born. These bones are held by structures called sutures, which have connective tissue between them, and they are not tightly connected to each other. As babies grow, the sutures gradually fuse (stick) together, usually completing the bonding process after all head growth has finished. When a child has craniosynostosis, the sutures fuse before birth.

It may affect one or several sutures. The metopic suture extends from the anterior fontanel (soft spot) to the forehead and to the top of the nose. Metopic synostosis is also known as trigonocephaly. Trigonocephaly means triangle in Greek.

What causes metopic synostosis?

The cause of metopic synostosis is not yet known. The condition may have a genetic basis, as it appears to be passed from parent to child in a small number of families. There also appears to be a link between a mother taking an anti-epileptic drug called sodium valproate during pregnancy and her baby being born with metopic craniosynostosis.

Another theory for the cause of trigonocephaly is that the baby’s position in the womb may affect skull development.

Metopic synostosis is more common in men, but it is unknown why this is the case. More and more babies are being born with metopic craniosynostosis

What are the signs and symptoms of trigonocephaly?

The main symptom of metopic synostosis is the abnormal shape of the forehead, which is pointed and triangular. There may also be a bony prominence on the early fused suture extending from the forehead from the anterior fontanelle to the top of the nose. This early fusion of the metopic suture often brings the eyes closer together than normal.

Children with metopic synostosis may have developmental delay – meaning they reach ‘developmental milestones’ later than other children of a similar age. Over time, many children catch up with their peers in developmental milestones, so they do not need extra support at school. There is currently no evidence that this developmental delay is a direct result of craniosynostosis – it just appears to be an association. Corrective surgery does not alter the progression of development.

How is trigonocephaly diagnosed?

Because children with metopic synostosis have a characteristic appearance, there is no need for specific diagnostic tests. Imaging scans such as x-ray  ,  CT  , or  MRI may be recommended to monitor bone growth before, during, and after treatment   .

In most cases, genetic testing will not be helpful because the gene mutation that causes metopic craniosynostosis has not yet been identified.

How is trigonocephaly treated?

Although metopic synostosis mainly affects the skull, treatment is best given in a specialist center where a multidisciplinary team approach can be applied.

In most cases, initial skull reshaping surgery occurs within the first few years of life. There are different types of surgery depending on the child’s age at diagnosis.

What happens after long-term follow-up of patients with metopic synostosis?

The general outlook for children with metopic synostosis is that the majority live normal lives. Children can sometimes develop behavior problems at school age, but with the input and support of professionals these problems are overcome in most cases.