The drainage of cerebrospinal fluid in hydrocephalic rats

Cerebrospinal fluid plateau pressures and transverse sinus plateau pressures were measured in response to a series of constant-rate infusions into the CSF in 10-day-old control and hydrocephalic H-Tx rats. In control rats the venous pressure increased with CSF pressure but to a lesser extent and around 60% of the total resistance to absorption was due to the concurrent rise in venous pressure with a hydrostatic gradient maintained between CSF and venous blood. In hydrocephalic rats the same infusion rates resulted in an increase in venous pressure which was the same magnitude as the rise in CSF pressure, resulting in zero hydrostatic gradient from CSF to blood. This suggests that CSF drainage does not take place by this route in hydrocephalic rats and that alternative drainage routes must be operating.