Fluid movement in the brain

The composition of CSF is substantially different from plasma. Protein content is lower in CSF, but the extracellular fluid of the brain directly connects with the CSF flow, so proteins produced by cells in the brain can be found in CSF. Protein analysis of the CSF is a promising method for diagnosis of brain disease [16]. 

In the tissue of the CNS, under normal conditions, fluid flows within the gray matter are negligible flows can be significant within white matter. For example, flows of 10 fj,m/ min were measured in white matter, but not gray matter, in the periventricular tissue of cats [17]. This extracellular fluid (ECF) flow, which moves towards the ventricular surface, is presumably the result of fluid leakage from the capillaries that moves predominantly through white matter tracts. 

Surgical trauma and the introduction of osmotically active drug compounds may alter the normal fluid flow patterns by increasing the rate of 

Convective or pressure-driven fluid flow is remarkably efficient for carrying agents over large distances (i.e. 1 cm) and for mixing agents within the human body. 

Fluid flow can be introduced into the equations that describe solute movement in tissues. 

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