Cerebrospinal Fluid Physiology
Production and Volume
- The choroid plexus is the primary site of CSF production, located within the cerebral ventricles 1, 3
- CSF production is an active metabolic process that consumes energy 3
- Total CSF volume in adults is approximately 140 mL, which remains relatively constant regardless of height or weight 2
- Daily CSF production ranges from 500-800 mL, resulting in complete renewal approximately 4 times daily 1, 2
Circulation Pathway
- CSF flows from the lateral ventricles through the foramina of Monro into the third ventricle 1, 3
- It continues through the aqueduct of Sylvius into the fourth ventricle 1, 3
- From the fourth ventricle, CSF exits through the foramina of Magendie and Luschka to the base of the brain 1, 3
- CSF then travels in two directions: caudally to the base of the spinal cord (lumbar sac) and rostrally over the cerebral convexities 1, 2
Composition and Pressure
- Normal CSF pressure ranges from 6-25 cmH₂O, with a population mean of approximately 18 cmH₂O 2
- Glucose level in CSF is approximately 2/3 of the serum glucose level 1
- CSF contains various inflammatory markers and proteins that can be used as biomarkers for neurological conditions 4, 1
Physiological Functions
- Transports nutrients to the brain and central nervous system 1
- Plays a role in immune surveillance of the central nervous system 2
Blood-CSF and Blood-Brain Barriers
- The blood-CSF barrier is formed by tight junctions between epithelial cells of the choroid plexus 5
- It regulates the entry of substances into the CSF and is distinct from the blood-brain barrier 1
- The blood-brain barrier (BBB) is formed by tight junctions between endothelial cells of cerebral capillaries 6, 5
- Transport across these barriers occurs through various mechanisms including: