1. CSF ANALYSIS

4. CSF Formation
Cerebrospinal fluid (CSF) is the liquid that surrounds the brain & spinal cord.
The brain & spinal cord are surrounded by the meninges that consist of three layers:
dura matter, arachnoid & pia matter
CSF flow between the arachnoid & pia matter in an area referred to as the subarachnoid space
The cerebrospinal fluid is formed mainly in the choroid plexuses of
the lateral, third, and fourth ventricles;
some originates from the ependymal cells lining the ventricles
and from the brain substance
Normal blood brain barrier is important for the normal chemistry results of CSF
Mechanism of formation:
Selective ultrafiltration of plasma
Active secretion by epithelial membranes

5. Functions of CSF
1- Physical support & protection of the CNS from trauma.
2- Supplying nutrients to the CNS & removal of metabolic wastes from CNS
3- Intra-cerebral transport (neuroendocrine role i.e. distribution of hypothamic hormones within the brain)

6. Clinical Indications for CSF Analysis
CSF is performed in cases of suspected:
1- CNS infections (infectious meningitis & encephalitis)
2- CNS malignancy (as malignant infiltrates as in leukemia ..etc)
3- CNS hemorrhages (as subarachnoid hemorrhage)
4- CNS demyelinating diseases (as multiple sclerosis)

7. Routine Laboratory CSF Analysis
Collection Lumbar puncture At interspace of vertebrate L3-4 or lower With complete aseptic techniques Sampling: Collected CSF sample is immediately divided into three tubes: Tube 1: Chemical Investigation (kept in freezer till performed) Tube 2: Microbiology Investigation (kept in room temperature) Tube 3: Microscopic Investigation (Cellular Counting – Differential – Cytology)

10. Normal CSF Analysis Normal Physical Examination Appearance & Color
Clear ,Colorless pH
7.4
Daily Secretion ml
Specific Gravity
Normal Microscopic Examination
Lymphocytes
1-5 /H.P.F
Normal Chemical Examination
Protein
15-45 mg/dl
Glucose
mg /dl
Chloride
mmol /L
Calcium
mmol/L
Phosphorus
mmol/L
Magnesium
mmol/L
Potassium
mmol/L
Normal Microbiological Examination
No pathogenic microorganisms

11. Physical examination of CSF
Normal CSF: Clear & colorless
Viscosity: equal to water (increased with increased proteins)
Color and/or turbidity of CSF: observed only in pathological circumstances.
Turbid CSF
Bacteria, WBCs cells or pus cells: suggestive of a CNS infection (menigitis or encephalitis)
Blood : suggestive of hemorrhage: subarachnoid or artifactual traumatic tap: DIFFERNTIATE?

12. Physical examination of CSF
Red & brown color :
Blood
Yellow colour
1- Jaundice (bilirubin in CSF)
2- Xanthochromia (hemoglobin breakdown pigments in CSF)
Xanthochromic CSF suggests that a subarachnoid hemorrhage has recently occurred
(at least within two hours prior to tapping).
The yellow color is due to bilirubin generated in the CNS by the breakdown of hemoglobin released from RBC's. (so jaundice should be excluded).

13. Microscopic examination of CSF
WBCs
Normal Total WBCs count: 1-5 lymphocytes /HPF
Normal differential WBCs Count: (in centrifuged cells)
- 62% lymphocytes
- 36% monocytes
- 2% neutrophils
Increased neutrophils: bacterial meningitis
Increased lymphocytes: aseptic and viral meningitis
RBCs
Normally CSF is blood free
RBCs in CSF: subarachnoid hemorrhage & malignancy
Artifact: traumatic tap (should be excluded)
(Traumatic tap bright red color RBCS in decreasing number as the fluid is sampled)

14. Chemical examination of CSF
In addition to the major ions, CSF contains oxygen, sugars (e.g. glucose, fructose), lactate, proteins (e.g. albumin, globulins), amino acids, urea, ammonia, glutamine, creatinine, lipids, hormones (e.g. insulin) and vitamins.

15. CSF Glucose
Normal CSF glucose: mg/dl
- The actual CSF glucose concentration may be:
1- Falsely low in the presence of hypoglycemia
Or 2- Incorrectly interpreted as normal when the patient is hyperglycemic
Accordingly, CSF glucose should always be compared with a simultaneous
plasma glucose that is drawn prior to lumbar puncture.
Normal CSF glucose/ plasma glucose ratio is approximately
(N.B. Ratio is decreased if plasma glucose is more than 500 mg/dl
due to saturation of the glucose carrier system to CSF

16. CSF Glucose cont. Elevated CSF / plasma glucose ratio (more than 0.7)
has no CSF diagnostic significance (occurs with hyperglycemia)
Decreased CSF / plasma glucose ratio(hypoglycorrhachia):
1- CNS septic (pyogenic) infections
Due to increased glycolysis by leukocytes and bacteria (with increase CSF lactate)
2- Brain tumors
due to increased metabolism of glucose by CNS
3- TB meningitis & sarcoidosis
Due to inhibition of glucose entry into the subarachnoid space
N.B. in viral CNS infections, CSF glucose is usually normal

17. CSF Protein cont.
Lumbar CSF protein: mg/dl (mostly albumin)
The majority of CSF protein is derived from the plasma by ultrafiltration
Certain proteins arise within the intrathecal compartment:
1- Immunoglobulins produced by CNS lymphocytes
2- Transthyretin (produced by choroid plexus)
3- Various structural proteins found in brain tissue

18. CSF Protein Decreased CSF protein:
Leak of CSF from a tear in the dura due to severe trauma
2- Otorrohea: leak of CSF from ear
3- Rhinorrohea: leak of CSF from nose

19. CSF Protein cont. Increased CSF protein:
1- Lysis of contaminant blood from traumatic tap
2- Increased permeability of epithelial membrane (blood-brain barrier)
in cases of:
- CNS bacterial or fungal infections
- Cerebral hemorrhages
2- Increased production by CNS tissue as in cases of:
- Multiple sclerosis (MS)
- Subacute sclerosing panencephalitis (SSPE)
3- Obstruction as in cases of :
- Tumors or abscess

20. So, it is essential to determine the source of IgG
CSF Protein cont.
Analysis of protein fractions: (Albumin & IgG)
1- Albumin of CSF
is obtained from blood by means of blood-brain barrier (as it is
produced solely by the liver)
In cases of increased permeability of BBB, albumin is increased in
CSF
2- IgG of CSF can be obtained:
from blood (By BBB) : increase in cases of increase permeab. of BBB
& by local synthesis from plasma cells within CSF (increased in cases of MS)
So, it is essential to determine the source of IgG
SEE NEXT SLIDE PLEAE !!!

21. CSF Protein cont. FIRST: CHECK INTEGRITY OF BLOOD BRAIN BARRIER (BBB)
BY CSF / serum albumin index calculation
CSF serum albumin index = CSF albumin (mg/dl) / serum albumin (g/dl)
Index less than 9 indicates intact BBB (no increased permeability of BBB)
SECOND: CSF IgG INDEX IS CALCULATED
CSF IgG / Serum IgG
CSF IgG index =
CSF albumin / serum albumin
Normal : less than 0.7
Increased in cases of demylineating diseases of CNS as : Multiple sclerosis (MS)

22. CSF serum /Albumin index
CSF Immunoglobulin
CSF IgG/Serum IgG
CSF IgG index:
Normally: < 0.7 =
CSF serum /Albumin index
CSF IgG can arise:
from plasma cells within CSF
& from the blood through BBB
↑CSF [IgG] without concomitant ↑ in CSF [Alb] suggests local production of IgG:
multiple sclerosis (MS)
subacute sclerosing panencephalitis (SPEE)

23. CSF Electrophoresis: Oligoclonal Banding

24. CSF lactate
CSF lactate is increased in cases of bacterial meningitis (due to increased glycolysis by bacteria & inflamatory cells)

25. CSF glutamine
The level of CSF glutamine reflects level of ammonia in that is normally removed in the CNS by formation of glutamine (amino acid glutamate + ammonia).
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

26. Enzymes in the CSF
CSF lactate dehydrogenase (LDH) may be elevated in bacterial meningitis.
CSF adenosine deaminase (ADA) elevations can occur in tuberculous meningitis.

27. 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

28. Interpretations of Results of CSF Chemical Analysis
Bacterial Meningitis
Viral Meningitis
Tuberculous Meningitis
Brain Tumor
Protein
Increased
Normal
Glucose
Decreased or
slightly affected