What is the normal CSF opening pressure? What can lead to physiological variation?

  • Normal CSF opening pressure 5-20 cm H2O
    • May be up to 25 cm H2O in obese
    • Opening pressure >25 cm H2O diagnostic of intracranial hypertension
  • Meniscus fluctuates:
    • 2-5mm with pulse
    • 4-10mm with respiration
  • Must be measured in the lateral decubitus position:
    • Levels vary with gravity
    • Can be 20-40 cm H20 if measured in the sitting position
  • Opening pressure sure never be lowered by >50%