Site and Mechanism of Vascular Stenosis under Increased Intracranial Pressure — Intracranial Venous Pressure Regulation Mechanism

Abstract

Although many authors have suggested vascular congestion of venous system under increased intracranial pressure as a cause of CBF reduction, the exact site and mechanism of compression has remained obscure. The results of our previous investigations in dogs are summarized in Fig. 1. Cortical venous pressure (CVP), bridging venous pressure (bridging VP), and lateral lacunar pressure (lat lacuna P) were constantly 4–18 mmHg higher than ICP, regardless of the level of ICP, while superior sagittal sinus pressure (SSSP) is quite stable at low levels (4–6 mmHg). Thus, pressure gradients between the cortical arterial pressure and the CVP, gradually decrease as ICP is elevated, while the pressure gradient between the CVP and the SSSP continuously increases as ICP is elevated. These evidences indicate that vascular stenosis is taking place in the lateral lacuna of superior sagittal sinus.