The central nervous system pressure histogram in hydrocephalus and hydromyelia.

This work makes proposals on the relationship between intracranial pressure (ICP) and hydrocephalus that changes over time with the evolution of the disease. This includes the cerebrospinal fluid (CSF) filling mechanism that leads to an increase in mode pressure if excess fluid volume exacerbates the obstructive process. Elevation in mode occurs because pressure in the central nervous system (CNS) represents a state of reduced flow, rather than an abnormality of volume. Diseases that cause elevated mode pressure by means of a primary edema can lead to hydrocephalus if there is sufficient time and obstruction to flow for the filling mechanism to act. Hydrocephalus is driven primarily by labile pressure due to restricted compliance, it can expand skeletal compartments and deplete parenchyma volume as it advances. This hypothesis applies existing principles of water balance. It is part of a series of works that propose a spectrum of hydrocephalic disorders including developmental forms such as achondroplasia with other conditions such as functional trapped fourth ventricle, arachnoid cyst, syringomyelia and normal pressure hydrocephalus (NPH). Links between the conditions can be made by understanding the continuously variable pressure profile local to the cavity that is subject to filling. Fluid lesions of the brain or spine that arise from developmental malformations of the skull have a physiological component. Changes form part of the mechanisms that may compensate the disease process.