ICP during head movement: significance of the venous system

It is thought that the internal jugular veins (IJV) are the primary route for cranial venous outflow in supine position and the vertebral venous plexus when upright. Previous studies have noted a greater increase in intracranial pressure (ICP) when subjects turn their head in one direction compared to the other, but no clear cause had been investigated. We hypothesised that in the supine position, head turning and consequently obstructing the IJV draining the dominant transverse sinus (TVS) would lead to a greater rise in ICP compared to turning to the non-dominant side. A prospective study in a large-volume neurosurgical centre. Patients undergoing continuous ICP monitoring as part of their standard clinical management were recruited. Immediate ICP was measured in different head positions (neutral, rotated to the right and left) when supine, seated, and standing. TVS dominance was established by consultant radiologist report on venous imaging. Twenty patients were included in the study, with a median age of 44 years. Venous system measurements revealed 85