A Simple Geometric Model for Simulating Brain Herniation Using CT Craniometry

The intracranial space (ICS) is incompletely separated by the cerebral falx and the cerebellar tentorium into three compartments. To simulate brain herniation, defined as part of the brain shifting from one compartment to another, we proposed a simplified model of the supratentorial space (STS) based on computed tomographic (CT) images obtained from 50 subjects.After identifying skull regions, we manually outlined the STS regions on CT slices. Pertinent dimensions of the STS and its openings were measured. The average volumes of the ICS and the STS were 1326 and 1154 mL. The average length, width and height of the STS were 154.7, 136.1, and 90.3 mm. The average length and height of the subfalcine space (SFS) were 85.8 and 52.1 mm, while the average length and width of midbrain were 37.9 and 30.9 mm.Based on these data, we constructed a half sphere STS model with a diameter of 160 mm and a volume of 1072 mL. A 40 mm circle representing the tentorial incisura is removed from the center of its equatorial plane. This model is then divided into two compartments by its intact mid-sagittal plane, which had another 80 mm semicircle removed to simulate the SFS.