Cerebrospinal Fluid and Cranial Sinus Pressures: Relationship in Normal and Hydrocephalic Cats

PRESSURE has repeatedly been demonstrated to be an important factor in bulk absorption of cerebrospinal fluid (CSF). The dependence of absorption on pressure was shown to be linear above a critical threshold pressure and thereafter over a wide pressure range. 1-4 A similar, although quantitatively different, relationship was shown to exist in hydrocephalus. 5,6 Regardless of the route of absorption, be it through the arachnoid villi in the normal animal 7 or by an alternate transventricular pathway in hydrocephalus, 8,9 all CSF absorbed must ultimately find its way into the venous system. Consequently, the pressure instrumental in CSF absorption is actually the pressure gradient between the CSF and the venous systems. Furthermore, if venous pressure varies with CSF pressure, the change should also be linear but not parallel. The present work is a study of the pressure relationship between the CSF system and the venous system as reflected in