Prevalence of agenesis of frontal sinus in human skulls with metopism

The frontal bone is an anatomical structure of the skull separated by the metopic suture in the childhood. The scientific literature indicates that metopic suture consolidates with closure in the early stages of life. Metopism is the term used to describe a metopic suture that persists up to the adulthood. Persistent metopic suture is associated potentially with the agenesis of the frontal sinus. To investigate the prevalence of absent frontal sinuses in dry skulls with metopism. The present study was performed after the approval of the local Committee of Ethics in Research. The sample consisted of dry skulls (n=245), aging between 17 and 50 years old, of the Forensic Medical Institute of Goiânia, Brazil. The skulls underwent anthropological exam in the search for metopism. Radiographic exam was performed in the skulls with metopism to verify the presence or absence of the frontal sinus. The radiographic assessment was performed with a Mobile DaRt Evolution device (Shimadzu, Kyoto, Japan) with protocol set in 64 kV and 16 mA). From the 245 dry skulls, 17 presented metopism. The length of the metopic suture in the skulls, considering the distances between nasio and bregma craniometric landmarks, ranged between 114 mm and 137 mm. Radiographic exams were performed on 16 skulls (one skull was not analysed radiographically because of extensive destruction). Only one skull (6.25%) had the frontal sinus absent. Besides the agenesis, the present study also found four (12.5%) skulls with aplasia and eight (25.0%) hyperplasia of the frontal sinus in dry skulls with metopism. The present study found a low prevalence rate of the agenesis of frontal sinuses in dry skulls with metopism.