{
  "abstract": "Background and Objectives The intracranial venous system is closely coupled to intracranial pressure (ICP). Elevations in ICP can collapse low-pressure veins, acting as Starling resistors, a phenomenon described by the ‘waterfall effect,’ where venous outflow becomes dependent on ICP rather than the arterial-venous pressure gradient. Direct experimental characterization of ICP-venous coupling, particularly across cortical and dural venous structures, is limited. We developed a novel large-animal, endovascular model that allows simultaneous measurement of cortical vein, dural sinus, and arterial pressures during controlled ICP elevation, providing the first documentation of cortical venous pressures using an endovascular approach.Methods Five sheep were instrumented with ICP monitors, external ventricular drains for stepwise cerebrospinal fluid infusion, and brain tissue oxygenation (PbtO 2) probes. Endovascular catheterization of the internal carotid artery, superior sagittal sinus (SSS), and transverse sinus (TS) was performed using balloon-mounted microcatheters connected to pressure transducers. Transient balloon inflation within the SSS allowed distal pressure measurement, providing an indirect assessment of cortical venous ‘wedge’ pressure. ICP was gradually elevated while arterial, venous, and PbtO2 parameters were continuously recorded.Results ICP increased from 15.6 mmHg to 60.8 mmHg with stable PbtO 2. TS pressure remained <25 mmHg across all ICP levels. In contrast, SSS pressure closely tracked ICP once ICP exceeded 20 mmHg, remaining consistently slightly higher than ICP (mean +1.7 mmHg; range +1.2-2.4 mmHg), demonstrating that venous sinuses are compressible and not rigid structures. Cortical wedge pressures were markedly elevated above ICP (mean +17.9 mmHg; range +11.1-24.8 mmHg), with progressively widening gradients at higher ICP. Importantly, these results indicate that ICP can be assessed relatively accurately through SSS pressure, supporting the feasibility of a venous-based implanted sensor to be explored.Conclusions This is the first endovascular large-animal model to directly document cortical vein pressures and characterize intracranial venous behavior during controlled ICP elevation. The parallel rise of SSS pressure with ICP confirms that dural venous sinuses are deformable, challenging traditional assumptions of a rigid compartment. This platform establishes a foundation for venous-based implanted ICP sensors to be explored, as well as for further studies aimed at preserving cerebral perfusion during intracranial hypertension.Disclosures O. Doron: None. F. Fakhri: None. V. Nguyen: None. M. Bydon: None. I. Awad: None. A. Mansour: None. F. Goldenberg: None.Abstract O-049 Figure 1",
  "authors": [
    {
      "affiliations": [
        "Neurosurgery, University of Chicago, Chicago, IL"
      ],
      "name": "O Doron"
    },
    {
      "affiliations": [
        "Neurosurgery, University of Chicago, Chicago, IL"
      ],
      "name": "F Fakhri"
    },
    {
      "affiliations": [
        "Radiology, University of Chicago, Chicago, IL"
      ],
      "name": "V Nguyen"
    },
    {
      "affiliations": [
        "Neurosurgery, University of Chicago, Chicago, IL"
      ],
      "name": "M Bydon"
    },
    {
      "affiliations": [
        "Neurosurgery, University of Chicago, Chicago, IL"
      ],
      "name": "I Awad"
    },
    {
      "affiliations": [
        "Neurology, University of Chicago, Chicago, IL"
      ],
      "name": "A Mansour"
    },
    {
      "affiliations": [
        "Neurology, University of Chicago, Chicago, IL"
      ],
      "name": "F Goldenberg"
    }
  ],
  "title": "O-049 Brain wedge pressure in a novel endovascular large animal model - a platform for venous based intracranial pressure monitoring",
  "uid": "edf8bb53-4445-5dee-839e-2a8650d70b15"
}