Cerebrospinal Fluid

About the Cerebrospinal Fluid

Cerebrospinal fluid CSF is a clear fluid produced by choroid plexus in the brain ventricles at approximately 500 mL daily, with approximately 150 mL circulating at any time. It flows from lateral ventricles through the foramen of Monro to the third ventricle, through the cerebral aqueduct of Sylvius to the fourth ventricle, then through the foramina of Luschka and Magendie to the subarachnoid space, where it is absorbed by arachnoid granulations into the venous system. CSF cushions the brain, maintains constant chemical environment, and removes metabolic waste via the glymphatic system. Normal CSF is clear and colorless, with very few white cells, a low protein content, and a glucose level roughly two thirds of that in blood, so changes in these values help diagnose meningitis and other disorders. Lumbar puncture at L3 to L4 obtains CSF for diagnosis. Elevated CSF opening pressure suggests intracranial hypertension. Hydrocephalus is excess CSF from overproduction, obstruction, or impaired absorption, treated with shunt placement. CSF rhinorrhea or otorrhea indicates skull base fracture.