Increased Intracranial Pressure, Generalized or Focal, and its Consequence—Mass-Movements and Herniations

Abstract

Consideration must first be given to rules of displacement within the intracranial space since they differ from those of the primarily elastic body cavities, such as the thorax and the abdomen. This is due to the rigid wall of the intracranial space, the skull, aptly described as a “closed box” in the English literature. The addition of volume—i.e., a space-occupying lesion—results in a displacement of other substances within this space. When a tumor develops, the volume of cerebrospinal fluid or blood must be reduced, or the brain itself must either undergo atrophy or (because it is essentially non-compressible) be forced out of the skull through the foramen magnum (Fig. 1). As the space-occupying lesion evolves, the adjacent ventricles are first distorted and compressed and then the reserve spaces of the arachnoidal sulci and cisterns (Fig. 2) are filled with brain tissue.