Cerebrospinal fluid
production 20ml/h
average adult volume = 150ml
neonates = 2ml/kg
recirculation
- secreted by the choroid plexuses
- exits at foramen of Luschka and foramen of Magendie (who?)
- reabsorbed by arachnoid villi
If production > absorption, then thanks to the Monro-Kellie doctrine, ICP ↑
VP shunts may be placed for congenital/acquired causes of ↓ absorption or Raised ICP