1. 05/08/13 1E. S. MOKGWANE; 4TH YR MED

2. CHARECTERISTICS OF NORMAL CSF
Total Volume: 150ml
Colour: colourless, like water
Transparency: clear, like water
Osmolality at 37o C: 281mOsm/L
Specific Gravity: 1.006 to 1.008
Presure: 80-100 mm H2O
05/08/13 2E. S. MOKGWANE; 4TH YR MED

3. ACID-BASE BALANCE
pH 7.31
pCO2 47g mmHg
HCO3 22g mEq/L
Sodium 138 – 150 mEq/L
Potassium 2.7 to 3g mEq/L
Chloride 116 to 127 mEq/L
Calcium 2.0 to 2.5 mEq/L
Magnesium 2.0 to 2.5 mEq/L
Lactic Acid 1.1 to 2.8 mmol/L
05/08/13 3E. S. MOKGWANE; 4TH YR MED

4. APPEARANCE
1. BRIGHT RED
•Recent haemorrhage involving the subarachnoid
•Damage to a blood vessel during puncture
05/08/13 4E. S. MOKGWANE; 4TH YR MED

5. APPERANCE
2. XANTHOCROMIA
•Suggests subarachnoid haemorrhage in recent past
(days).
Rarely Xanthochromia may be due to:
• Severe Jaundice
• Carotenaemia
• Rifampicin
05/08/13 5E. S. MOKGWANE; 4TH YR MED

6. APPERANCE
3. TURBID
white cells present
suggest bacterial infection.
05/08/13 6E. S. MOKGWANE; 4TH YR MED

7. APPERANCE
4. PIGMENTS
• Oxyhaemoglobin – Released with lysis of red cells
detected in the supernatant fluid within 2h after SAH.
• Bilirubin – maximum at 48hrs after SAH.
05/08/13 7E. S. MOKGWANE; 4TH YR MED

8. TOTAL PROTEIN
0.5% or 1/200 that of plasma
Typical reference values for a lumbar tap:
Age g/L
<1 month <1.9
1-3 months <0.95
3-12 months <0.5
1-10 years <0.4
>10 years <0.7
05/08/13 8E. S. MOKGWANE; 4TH YR MED

9. TOTAL PROTEIN IS RAISED IN:
1. Infection (white cells, pus) e.g. bacterial meningitis
2. Blood Contamination
3. Chronic inflammatory diseases of the CNS.
4. Froin’s syndrome
5.Lysis of contaminated blood from traumatic tap
6.Increased permeability of the epithelial membrane
7.Increased production by CNS tissue
05/08/13 9E. S. MOKGWANE; 4TH YR MED

10. DECREASED CSF GLUCOSE
• Disorder in carrier –mediated transport of glucose into
CSF
• Active metabolism of glucose by cells or organisms
• Increased metabolism by CNS eg Brain tumor, diffuse,
meningeal neoplasia.
05/08/13 10E. S. MOKGWANE; 4TH YR MED

11. SUMMARY OF A TYPICAL CSF
FINDINGS
NORMAL BACTERIA VIRAL TB
Cells 0-5 >1000 <1000 <500
Polymorphs 0 Predominate Early +/- Increased
Lymphocytes 5 Late Predominate Increased
Glucose 60-80 Decreased Normal Decreased
CSF Plasma:
Glucose ratio
66% <40% Normal <30%
Protein 5-40 Increased +/- Increased Increased
Culture Negative Positive Negative +TB
05/08/13 11E. S. MOKGWANE; 4TH YR MED

12. END
05/08/13 12E. S. MOKGWANE; 4TH YR MED