Cerebrospinal fluid: normal values, abnormalities

Question 1

DEFINE

CSF:

Answer 1

Cerebrospinal fluid (CSF) is an ultrafiltrate of plasma contained within the ventricles of the brain* and the *subarachnoid spaces of the cranium and spine.

It performs vital functions, including providing nourishment, waste removal, and protection to the brain.

Adult CSF volume is estimated to be 150 ml, with a distribution of 125 ml within the subarachnoid spaces and 25 ml within the ventricles.

CSF is predominantly secreted by the choroid plexus,

Its secretion varies between individuals with adult production, usually ranging between 400 to 600 ml per day. The constant secretion of CSF contributes to complete CSF renewal four to five times per 24-hour period in the average young adult.

The reduction of CSF turnover may contribute to the accumulation of metabolites* seen in aging and *neurodegenerative diseases.

Question 2

• CSF:*
• has concentration of what elements?*

Answer 2

When compared to plasma,

CSF has a higher concentration of sodium, chloride, and magnesium but a lower concentration of potassium and calcium.

Unlike plasma, CSF has only trace amounts of cells, protein, and immunoglobulins.

No cells can pass through the blood-CSF barrier, although small numbers of white blood cells are usually introduced to the CSF indirectly.

Question 3

CSF:

Function: 2

Answer 3

CSF assists the brain by providing protection, nourishment, and waste removal.

CSF provides hydromechanical protection of the neuraxis through two mechanisms.

1st CSF acts as a shock absorber, cushioning the brain against the skull.

2nd CSF allows the brain and spinal cord to become buoyant, reducing the effective weight of the brain from its normal 1,500 grams to a much lesser 50 grams.

• The reduction in weight lessens the force applied to the brain parenchyma and cerebral vessels during mechanical injury.
• Another function of CSF is to maintain homeostasis of the interstitial fluid of the brain.

Question 4

CSF:

• Produced by:*
• Total CSF volume:*
• Pressure:*
• Glucose:*

Answer 4

• Produced by choroids plexus 500ml/day.
• T_otal CSF volume_ 140ml (80-180)
• pressure: 5–18 cmH2O

or

50-180 mmH2O

-Glucose: 40–85 mg/dL.

(66% of plasma glucose level)

Question 5

• CSF:*
• Protein total:*
• LDH:*
• Lactate:*
• Leukocytes (adult/child):*

Answer 5

-Protein (total): 15–45 mg/dL.

- LDH: 1/10 of serum level.

• Lactate: less than 35 mg/dL.
• Leukocytes (WBC): 0–5/μL (adults / children);

up to 30/μL (newborns).

Question 6

CSF:

• Gram stain:*
• Culture:*
• Gross appearance:*

Answer 6

• Gram stain: negative.
• Culture: sterile.

-Gross appearance: clear and colorless