Mount Fuji sign following subdural haematoma evacuation.

To cite: Saglam M, Sivrioglu AK, Kara K, et al. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/ bcr-2013-009091 DESCRIPTION An 88-year-old man was admitted to the emergency department with a head injury because of a fall. He had a loss of consciousness. Bilateral subdural haematoma and fracture of the left parietal bone were shown on the CT imaging. The left subdural haematoma was evacuated in operation and a drainage catheter was placed in the subdural space. His vital findings were normal in the postoperative period. However, the patient’s general condition broke down in the postoperative sixth hour. After that, cranial CT examination was performed again. Upon CT imaging evident-increased air densities were observed in the subdural space. These findings were consistent with the Mount Fuji sign in tension pneumocephalus (figure 1). The left drainage catheter that did not work was changed in reoperation and a new drainage catheter was placed in the right subdural space. In the control CT examination, a significant decrease in the amount of air densities was observed (figure 2). The Mount Fuji sign in tension pneumocephalus is described as bilateral subdural hypoattenuating air collections which cause compression and separation of the frontal lobes. The compressed frontal lobes and the widening of the interhemispheric space between the tips of the frontal lobes have the appearance of the silhouette of Mount Fuji. The most common causes of a tension pneumocephalus are evacuation of subdural haematoma, skull base surgery, paranasal sinus surgery, posterior fossa surgery in the sitting position and head trauma. It was believed that nitrous oxide, which was used as an anaesthetic, diffused into air-filled spaces and expanded the gaseous volume.