MEASUREMENT OF THE DYNAMICS OF THE CEREBROSPINAL-FLUID SYSTEM IN THE RAT

A technique for intracranial pressure (ICP) monitoring in the rat that enables the measurement of the cerebrospinal outflow resistance (R(CS F)) and the intracranial pressure-volume index (PVI) is described. A p ermanent catheter placed into the cisterna magna through the occipital bone was used. ICP, R(CSF) and PVI were measured in ten LEW rats. The baseline ICP was 8 +/- 1.7 mm Hg (Mean +/- S.D.). The PVI was 0.0518 +/- 0.018 ml. The R(CSF) was 464 +/- 196 mm Hg ml(-1) min(-1) which is less than reported previously. The cannulation technique is easy and gives reliable pressure tracings. It enables ICP monitoring and estima tion of the dynamics of the cerebrospinal fluid (CSF) system during ex perimental surgical procedures in the rat.