Hyperostosis frontalis interna and frontal bone thickness among various age groups - differences between males and females.

Hyperostosis frontalis interna (HFI) represents an abnormality of the frontal cranial bone that is characterized by bilateral, nodular thickening of its inner lamina and may sometimes be associated with neuropsychiatric symptoms such as headaches and depression. The aim was to assess prevalence, sex and age differences of HFI and frontal bone thickness by means of MRI. This retrospective study included 908 subjects who were divided into male and female groups and further subdivided into three groups, youngest (≤45 years), middle-aged (46- 65 years) and the oldest group (65 years). The thickness of the frontal bone was measured on the T2-weighted axial images at the top level of the lateral ventricles as a mean from both sides. We considered 10mm or thicker frontal bone as HFI. The total prevalence of HFI was 8.1%, with a more frequent occurrence in women (p0.05). In males, there was no difference in the frontal bone thickness between different age groups (p0.05), while in females we found differences between the youngest and the oldest group, and also between the middle-aged and the oldest group (p0.05). The female respondents had a thicker frontal bone, which was statistically significant only in the oldest group (p0.001). Frontal bone thickness was age-dependent only in women (Spearman's Rho 0.11; p≤0.01). In women, unlike in men, there is an age-related progression of HFI with increasing prevalence, with 16.4% occurrence in the oldest group.