  Numerous mathematical models have emerged in the medical literature over the
past two decades attempting to characterize the pressure and volume dynamics
the central nervous system compartment. These models have been used to study he
behavior of this compartment under such pathological clinical conditions s
hydrocephalus, head injury and brain edema. The number of different pproaches
has led to considerable confusion regarding the validity, accuracy or
appropriateness of the various models. In this paper we review the mathematical
basis for these models in a mplified fashion, leaving the mathematical details
to appendices. We show at most previous models are in fact particular cases of
a single basic differential equation describing the evolution in time of the
cerebrospinal fluid pressure (CFS). Central to this approach is the hypothsis
that the rate change of CSF volume with respect to pressure is a measure of the
compliance of the brain tissue which as a consequence leads to particular
models epending on the form of the compliance funtion. All such models in fact
give essentially no information on the behavior of the brain itself. More
recent models (solved numerically using the Finite Element Method) have begun
to address this issue but have difficulties due to the lack of information
about the mechanical properties of the brain. Suggestions are made on how
development of models which account for these chanical properties might be
developed.
