[Analysis of the principal factors which influence cerebral circulation and intracranial cerebrospinal fluid dynamics]

Abstract

Cerebral blood flow and intracranial pressure dynamics are affected by two main factors. A first factor is represented by the action of cerebrovascular regulatory mechanisms (controls of cerebral blood volume and cerebral blood flow). Furthermore, intracranial circulation occurs within a rigid space, whose volume must, therefore, remain constant. This second factor explains the presence of a brain volume control, in order to maintain a normal value of intracranial pressure. The mean intracranial pressure value is mainly affected by the pressure-volume characteristic of the intracranial compartment, by the mean cerebral blood volume and by cerebrospinal fluid production and reabsorption processes. On the contrary, the pulsating intracranial pressure component is mainly affected by the intracranial pressure volume relationship and by cerebrovascular compliance; this last, in its turn, is modified by the action of regulatory mechanisms. A better understanding of the relationship occurring between cerebral hemodynamics, cerebrospinal fluid kinetics and intracranial pressure can be achieved with the aid of mathematical models. In particular, mathematical modelling allows the way intracranial pressure and cerebral blood flow are related to the main physical parameters of the intracranial compartment to be pointed out. Moreover, with a mathematical model it is possible to discriminate between the great number of different factors which act simultaneously "in vivo" on the cerebrovascular bed.