A thickening of the frontal bones characterizes Hyperostosis frontalis interna. This condition is found typically postmortem in post-menopausal women who undergo cadaveric dissection. Live patients commonly are asymptomatic, but may experience increased intracranial pressure, headaches, vertigo, visual and personality changes. Previous case studies report variable amounts of thickness in ostoses, but most remain localized to the frontal bone and extradural space. In contrast, our 79 year-old female cadavers exhibited circumferential thickening of the skull with subdural involvement. We found multiple ostoses bilaterally throughout the calvaria, but primarily endocranially along the frontal and parietal bones. We believe that this case is unique in describing bone growth beneath the dura mater. Using measurement software, we found dural thickening to be approximately doubled while the skull circumference was consistent with normal measurements. Thus, the dura mater may play a role in the development of Hyperostosis frontalis interna in exceptional situations.
