85 Cerebrospinal fluid (CSF) pressure

Cerebrospinal fluid pressure: CSF production, lumbar opening pressure, causes of raised and low pressure.

Cerebrospinal fluid (CSF) is the clear fluid that surrounds the brain and spinal cord and fills the brain ventricles. It cushions the brain, removes waste products and helps keep the chemical environment of the nervous system stable. About 400–600 mL of CSF is produced each day, mostly by the choroid plexus in the ventricles, and it is continuously reabsorbed into the venous blood, so that only about 150 mL is present at any time. The CSF pressure is the pressure of this fluid; it is usually measured as the opening pressure at lumbar puncture and closely reflects intracranial pressure when the CSF pathways are open.

Nervous systemLumbar punctureIntracranial pressure

CSF production≈ 400–600 mL/day

CSF volume≈ 150 mL

Raised (adults)> 25 cmH₂O

Low< 6 cmH₂O

Figure 1. Lumbar CSF opening pressure in adults, measured lying on the side and relaxed (10 cmH₂O ≈ 7.4 mmHg). Obesity, straining and position affect the value.

CSF composition

CSF is formed by active secretion of sodium by the choroid plexus, with chloride and water following. Compared with plasma, it contains more sodium and chloride and much less protein, potassium, calcium and glucose. Analysis of CSF (cells, protein, glucose, microbiology) is essential in diagnosing meningitis, encephalitis, subarachnoid haemorrhage and some neurological diseases.

Raised CSF pressure

Idiopathic intracranial hypertension: mainly in young women with obesity; headache and visual disturbance with swelling of the optic discs; in adults the diagnostic opening pressure is above 25 cmH₂O
Meningitis and encephalitis, brain tumours, bleeding, cerebral venous sinus thrombosis
Hydrocephalus: blocked flow or reduced reabsorption of CSF
Some medicines (tetracyclines, high doses of vitamin A, retinoids)

Low CSF pressure

Low pressure is usually caused by a CSF leak: after lumbar puncture or spinal anaesthesia, after surgery, or spontaneously. The typical symptom is a headache that appears or worsens on standing and improves on lying down.

Seek emergency care

for sudden severe headache, headache with fever and neck stiffness, headache with vomiting and drowsiness, or headache with visual loss or double vision.

References

Sakka L, Coll G, Chazal J. Anatomy and physiology of cerebrospinal fluid. Eur Ann Otorhinolaryngol Head Neck Dis. 2011;128(6):309–316. doi:10.1016/j.anorl.2011.03.002
Friedman DI, Liu GT, Digre KB. Revised diagnostic criteria for the pseudotumor cerebri syndrome in adults and children. Neurology. 2013;81(13):1159–1165. doi:10.1212/WNL.0b013e3182a55f17

This article is for general information and does not replace a consultation with a doctor. Measurements must be interpreted by a physician together with symptoms and other tests.

Published on 1 May 2024

Medical Book