How and where is CSF reabsorbed?

  • Reabsorbed by the arachnoid granulations:
    • Villi arising from the arachnoid mater
    • Project into venous sinuses and veins
  • Reabsorption occurs throughout the brain and spine
    • 90% by villi of the sagittal and sigmoid Dural sinuses
    • 10% by spinal villi
  • Reabsorption due to differences in pressure between CSF and veins
    • Pressure of CSF typically 15 cm H2O and venous blood typical 8cm H2O
    • Removal of CSF increases with rising intracranial pressure.
Structure of the arachnoid granulations