The metopic suture: Natural history

Area of Science:

• Craniofacial development
• Pediatric neurosurgery
• Evolutionary biology

Background:

• The metopic suture (MS) is a key cranial suture. Premature closure causes trigonocephaly; persistence (metopism) is a normal variant.
• Data on MS closure timing and metopism prevalence in healthy children are limited.
• Trigonocephaly prevalence has increased, while metopism prevalence has decreased over recent decades.

Purpose of the Study:

• To document the age of onset and completion of metopic suture closure.
• To determine the prevalence of metopism in children.
• To analyze trends in trigonocephaly and metopism prevalence and their potential relationship.

Main Methods:

• Analysis of 3D-CT scans from 477 children with head trauma to study MS closure patterns.
• Review of clinical series of patients with synostosis over four decades.
• Comparative anatomy and paleoanthropology data review.

Main Results:

• Metopic suture closure typically begins at 4 months and completes by 9 months.
• Metopism prevalence stabilizes after age 1 at 5.1%, being more common in girls (F/M ratio 2.1).
• Trigonocephaly incidence has steadily increased, paralleling a decrease in metopism prevalence.

Conclusions:

• The findings provide normative data for metopic suture closure and metopism prevalence.
• The study suggests a potential evolutionary link between bipedalism, pelvic structure, and metopic suture persistence.
• The rise in cesarean sections may be a factor in the declining prevalence of metopism and increasing trigonocephaly.