How much CSF is normally produced?

  • Normal rate of production is 0.3-0.4ml/min or 20ml/hour or 500ml/day
  • Results in effective replacement of CSF volume 3x daily
  • Production is largely independent of ICP:
    • Raised ICP is compensated by increased absorption of CSF reducing total volume
    • Decreased when CPP <70 mmHg due to reduction in choroid plexus blood flow