The physics of the cranial cavity, hydrocephalus and normal pressure hydrocephalus: mechanical interpretation and mathematical model.

It is intended for this research, to provide some basis for the understanding of the rational mechanics of the cranial content. There are many interesting and controversial facts derived from the experimental and clinical-pathological observations of hydrocephalus and increased intracranial pressure. For instance, in some patients a moderate increase of intracranial pressure is accompanied by hydrocephalus and mental changes, while in others, with high intracranial pressure, the ventricles and mental functions remain unaltered. What then is the parameter that changes the size of the ventricles and impairs brain function? It is shown how the transmission of intraventricular pressure throughout the brain parenchyma creates a stress distribution that varies in magnitude; how during the production, maintenance, and reversal of hydrocephalus, and normal pressure hydrocephalus the stress is distributed throughout the brain; and how in the presence of a sudden increase of intracranial pressure nature has arranged additional mechanisms for protecting the brain. It is important to recognize that some aspects of intracranial physiopathology can be explained through classical concepts of physics, prior to attempting to interpret such processes solely in terms of biological or auto-regulatory phenomena.