trigonocephaly

Trigonocephaly is a form of craniosynostosis in which the metopic suture closes prematurely, resulting in a triangular or keystone-shaped forehead and a narrow frontal region. It is the characteristic facial and cranial appearance seen with metopic craniosynostosis, one of several patterns of abnormal skull growth due to early suture fusion.

Causes and pathophysiology: Trigonocephaly arises from early fusion of the metopic suture during infancy. This restricts transverse growth of the frontal bones and redirects growth to the sides and back of the skull, producing the distinctive triangular forehead. It can occur as an isolated (nonsyndromic) finding or as part of a craniosynostosis syndrome; genetic factors may be involved in some cases.

Clinical features: The hallmark is a midline, keel-like metopic ridge and a triangular, vertically narrow forehead and frontal region. Some children have mild hypotelorism (closely spaced eyes) and shallow orbits. Overall brain development is typically normal in nonsyndromic cases, but severe or associated intracranial pressure issues may influence development if untreated.

Diagnosis: Diagnosis is based on physical examination and imaging. Computed tomography (CT) with three-dimensional reconstruction is commonly used to confirm metopic suture closure, assess skull growth, and distinguish trigonocephaly from other craniosynostosis patterns. Additional evaluations may be done to rule out associated syndromes.

Management and prognosis: Management often involves surgical correction in infancy to improve skull shape and, when necessary, to prevent or relieve elevated intracranial pressure. Surgical options include open frontoorbital remodeling or less invasive endoscopic metopic suturectomy with postoperative helmet therapy. Timing is typically in the first year of life. Prognosis for isolated trigonocephaly is generally good with appropriate treatment, though some patients may require further refinement or monitoring for potential cosmetic or developmental issues.