Transmantle and transvenous pressure gradients in cerebrospinal fluid disorders.

Hydrocephalus is the symptomatic endpoint of a variety of disease processes. Simple hydrodynamic models have failed to explain the entire spectrum of cerebrospinal fluid (CSF) disorders. Physical principles argue that for ventricles to expand, they must be driven by a force, Fishman's transmantle pressure gradient (TMPG). However, the literature to date, reviewed herein, is heterogenous and fails to consistently measure a TMPG. The venous system, like CSF, traverses the cerebral mantle, and thus analogous transparenchymal and transvenous pressure gradients have been described, reliant on the differential haemodynamics of the deep and superficial venous systems. Interpreting CSF disorders through these models provides new insights into the possible pathophysiological mechanisms underlying these diseases. However, until more sophisticated testing is performed, these models should remain heuristics.