Site and mechanism for compression of the venous system during experimental intracranial hypertension

Abstract

✓ The pressure gradient of the venous pathway between the cortical vein and superior sagittal sinus was measured in adult mongrel dogs by recording the pressures of the bridging vein, lateral lacuna (proximal portion), and superior sagittal sinus, together with the systemic blood pressure while gradually increasing the intracranial pressure up to the level of mean systemic blood pressure. The pressure gradient between the lateral lacuna and the superior sagittal sinus was also measured under increased intracranial pressure. Pressures of the bridging vein and lateral lacuna were constantly 50 to 250 mm H2O higher than the intracranial pressure, regardless of the level of intracranial pressure. An abrupt drop in the intraluminal pressure was observed at a point 1 to 2 mm proximal to the junction of the lateral lacuna and the superior sagittal sinus, regardless of the level of intracranial pressure. It is concluded that gradual stenosis of the parasagittal venous pathways took place 1 to 2 mm proximal to the junction between the lacuna and the superior sagittal sinus, and thus cortical venous pressure was maintained 50 to 250 mm H2O higher than intracranial pressure. The authors believe that an “intracranial venous pressure regulation mechanism” exists at the junction of the lateral lacuna and the superior sagittal sinus.