CEREBROSPINAL FLUID (CSF)

1. By
Dr KHALED ALGARIRI
CAMS- QASSIM UNIVERSITY
October 2019

2. INTRODUCTION
The cerebrospinal fluid (CSF) is a dynamic,metabolically
active fluid surrounding the brain and spinal cord and has
many important functions.
It is very valuable as a diagnostic aid in the evaluation of
inflammatory conditions, infections involving the brain,
spinal cord, and subarachnoid haemorrhage.

3. FORMATION OF CSF/ANATOMY
Both the brain and spinal cord are covered by three
protective membranes referred to as the meninges. The
outermost layer is called the dura mater and is composed
of tough connective tissue.
• The middle layer is the arachnoid named for it spider web
like appearance.
• The delicate inner most layer which is in direct contact
with the brain and spinal cord is called the pia mater. An
inflammation of the meninges is referred to as meningitis.
7/

4. FORMATION OF CSF/ANATOMY
Between the arachnoid layer and the pia mater is a
space called the subarachnoid space. It contains a
clear, colorless fluid referred to as Cerebrospinal Fluid
(CSF).
• CSF is produced in the ventricles of the brain by a
collection of rich vascular protrusions called the
choroid plexus.

6. Generally, the total volume of CSF
circulating throughout the adult Central
Nervous System (Brain and Spinal Cord) is
approximately 90 - 150 ml.
• In newborns this volume is 10 -60 ml.
• Excess CSF is continuously reabsorbed by
arachnoid villi and returned to the venous system
thus maintaining a consistent amount of fluid.

7. FUNCTIONS OF CSF
1-Protection : CSF protects the brain from damage by
buffering the brain. It acts as a cushion
2-Buoyancy: The actual mass of the human brain is about
1400 grams; however, the net weight of the brain suspended in
the CSF is equivalent to a mass of 25 grams. which allows
the brain to maintain its density without being impaired
by its own weight

8. FUNCTIONS OF CSF
3-Chemical stability/Homeostasis: CSF maintain the
distribution of necessary substance and waste product
between CNS and Blood stream
4-Prevention of brain ischemia: made by decreasing the amount of
CSF in the limited space inside the skull. This decreases total pressure .
transport of biomolecules to the brain
• Clearance of catabolites (CO2, lactate)
• Maintenance of constant intracranial pressure
5-Clearin of waste: Removes waste from the brain through the bllod
for elimination via kidneys.

9. BIOCHEMICAL COMPOSITION OF CSF

10. Examination of CSF
(Physical examination)
 Normal CSF is:
 Colorless
 Clear
 Free of clots
 Free of blood
 If CSF is cloudy (turbid)  perform microscopic
examination:
 is usually due to leucocytes
 may be due to micro-organisms

11. Blood & Hemoglobin pigments in CSF
Traumatic tap
 bright red color
 RBCS in decreasing
number as the fluid is sampled
Subarachnoid hemorrhage (SAH)
 Xanthochromia (hemoglobin
breakdown pigments) = RBCs lysis
& metabolism previously occurred
(at least 2 hr earlier)

12. CSF glucose test
A CSF glucose test measures the amount of
sugar (glucose) in the cerebrospinal fluid
(CSF). CSF is a clear fluid that flows in the
space surrounding the spinal cord and brain.

13.  Normal Values
The glucose level in the CSF should be 50 - 80 mg/100
mL (or greater than 2/3 of the blood sugar level).
Note: Normal value ranges may vary slightly among
different laboratories. Talk to your doctor about the
meaning of your specific test results

14. Abnormal CSF [Glucose]
 ↑ CSF [glucose]:
 Not clinically informative
 Provides only confirmation of hyperglycemia

15.  ↓CSF [glucose] (hypoglycorrhachia):
1)Disorder in carrier-mediated transport
•e.g. TB meningitis
2)Active metabolism of glucose by cells or organisms:
•e.g. acute purulent, amebic, & fungal meningitis
3)Increased metabolism by the CNS
•e.g. by CNS neoplasm
 In viral meningitis CSF [glucose] is usually normal

16. CSF/blood glucose ratio
Normal CSF glucose/ plasma glucose ratio is
approximately 0.6-0.7
 (N.B. Ratio is decreased if plasma glucose is more than 500
mg/dl due to saturation of the glucose carrier system to CSF
CSF/blood glucose ratio may be a better single indicator for
bacterial meningitis. Since the CSF glucose and blood glucose
values are promptly and easily obtained from a lumbar puncture

17. Protein in CSF
 Proteins, mostly albumin are found in the CSF
(0.15-0.45 g/L)
 Source of CSF proteins:
• 80% from plasma by ultrafiltration
• 20% from intrathecal synthesis

18.  ↑ CSF [total protein]:
 Must be compared to the serum [protein]
 Useful nonspecific indicator of pathological states:
 Lysis of contaminant blood (traumatic tap)
 ↑ premeability of the epithelial membrane due to:
Bacterial or fungal infection
Cerebral hemorrhage
 ↑ production by CNS tissue in:
Multiple sclerosis (MS)
Subacute Sclerosing Panencephalitis (SSPE)
 Obstruction e.g. in:
 Tumors
 Abscess

19. Albumin in CSF
Albumin is produced solely in the liver
Its presence in CSF must occur through BBB
 Measured by the protein electrophoresis method

20. CSF Immunoglobulin
 CSF IgG can arise:
 from plasma cells within CSF
 from the blood through BBB
 ↑ [IgG] and normal [Alb] of CSF suggests local
production of IgG, e.g.,
 Multiple sclerosis (MS)
 Subacute sclerosing panencephalitis (SSPE)

21. CSF LACTATE
In neonates (10-40mg/dl) .
In adult or older children (10-22 mg/dl)
 Measurement of lactate concentrations in cerebrospinal fluid
(CSF) may be useful as part of the investigation of inborn errors
of metabolism in which lactic acidosis occurs.
 This includes disorders of gluconeogenesis, pyruvate
dehydrogenase complex, the Krebs cycle and the mitochondrial
electron transport chain.
 Levels greater than 35 mg/dl are frequently seen with bacterial
meningitis (due to increased glycolysis by bacteria &
inflammatory cells), whereas in viral meningitis, lactate levels
remain lower than 25 mg/dl.

22. CSF LACTATE cont
CSF lactate levels remain elevated during initial
treatment but fall rapidly when treatment is successful,
thus offering a sensitive method for evaluating the
effectiveness of antibiotic therapy.
Measurement of lactate in CSF has also been advocated
for investigating children with unexplained neurological
disease

23. Otorrhea & Rhinorrhea
Otorrhea: leakage of CSF from the ear
Rhinorrhea: leakage of CSF into the nose

24. CSF GLUTAMINE
Normal range 8-18 mg/dL
 Glutamine is produced in the CNS by the brain cells from ammonia and
alpha-ketoglutarate. This process serves to remove the toxic metabolic waste
product ammonia from the CNS.
 Glutamine synthesis helps to protect the CNS from the toxic effects of
increased ammonia.
 Ammonia production is increase dramatically in patients with liver
failure.
 Accordingly, CSF glutamine production is increased in cases of hepatic
encephalopathy

25. CSF ENZYMES
Lactate dehydrogenase
 LDH – LD1, LD2, LD3, LD4, LD5
 -Increase LD5 in metastatic brain tumor.
 -Increase all fractions in primary brain tumor such as
 Meningioma ( extra- exial)
 Glioblastoma (intra – exial)
 -Increase LD4,LD5 in bacterial meningitis.

26. CSF ENZYMES
 CK – BB:
 -Increase in:
 epileptic patient
 Brain tumor
 cerebral infarction

27. CSF ENZYMES
CSF adenosine deaminase (ADA) elevations
can occur in tuberculous meningitis.

28. Other Chemical Components of CSF
 CSF [Calcium], [Potassium] & [Phosphates] are lower than their
levels in the blood
 CSF [Chloride] & [Magnesium] are higher than their levels in the
blood
 Abnormal CSF [Chloride]
 marked  in acute bacterial meningitis
 slight  in viral meningitis & brain tumors

29. How the Test is Performed
LUMBAR PUNCTURE
A lumbar puncture is a medical procedure where a needle is
inserted into the lower part of the spine to test for conditions
affecting the brain, spinal cord or other parts of the nervous
system

30. CSF is collected by lumbar puncture
between third, fourth, fifth lumbar vertebrae.
It requires certain precautions and careful
technique to prevent the introduction of
infection or the damaging of neural tissue.
Lumbar puncture

31. Risk Factors

38. CSF is collected in three sterile tubes
•Tube 1 – used for chemical and serologic test:
centrifuge and use supernatant for chemistry analysis (glucose,
protein, enzymes and chloride) kept in freezer till performed.
• Tube 2 – used for microbiology lab kept in room
temperature
•Tube 3 – used for hematology (cell count) Cell
counts done as soon as possible after the fluid is collected as
cellular degradation occurs rapidly. If postponed, refrigerate for
up to one hour.