CSF hydrodynamic studies in man. 1. Method of constant pressure CSF infusion.

The constant pressure method for the study of the hydrodynamics of CSF is presented. By infusing artificial CSF at constant pressures and recording the resultant flow, it is possible to obtain information about the hydrodynamic conductance of the CSF outflow pathways. By lowering the infusion pressure below the pressure of the sagittal sinus all CSF produced can be collected and the CSF formation rate may thus be calculated. There is a rectilinear relationship between CSF pressure and the flow necessary to maintain the pressure. It is thus concluded that the arachnoidal villi, when once opened, are not further distended by pressure. This method makes possible indirect calculation of the pressure of the sagittal sinus and the pressure difference between the subarachnoid space and the sagittal sinus.