Fig. 3

CSF pressure and outflow during a standard infusion test. The arachnoid granulations dominated outflow both under baseline and (elevated) plateau ICP, with 60.0% and 80.3% of the fluid leaving through the granulations. The cribriform plate plays a much less prominent role at plateau than at baseline ICP (40.0% vs. 19.7%). Secretion from capillaries and flow in PVS are small compared to flow to the AG and cribriform plate. At baseline, (arterial) paravascular flow is small at 0.04 mL/min into the SAS. The capillary secretion rate is 0.07 mL/min. Flow in paravenous spaces will thus be 0.03 mL/min to balance out the capillary secretion (data now shown). During infusion, capillary filtration ceases due to the assumption that net absorption is impossible