Cerebrospinal fluid (CSF) is a clear fluid that surrounds the brain and spinal cord. It is produced by specialized cells in the brain and acts as a cushion and filtration system. CSF composition is tightly regulated by the blood-brain barrier to protect the central nervous system. CSF analysis through lumbar puncture is important for diagnosing conditions like meningitis, tumors, and multiple sclerosis. Abnormalities in CSF properties including white blood cell count, glucose, protein, and presence of tumor cells or blood can indicate different diseases.

2. Cerebral Spinal Fluid
&
Clinical Importance

3. CEREBROSPINAL FLUID

4. CEREBROSPINAL FLUID

5. CEREBROSPINAL FLUID[CSF]
The cerebrospinal Fluid is a clear, colorless
transparent, tissue fluid present in the
cerebral ventricles, spinal canal, and
subarachnoid spaces.

6. Cerebrospinal Fluid (CSF)
• Blood Brain Barrier
• Occurs due to tight fitting endothelial cells
that prevent filtration of larger molecules.
• Controls / restricts / filters bloodcomponents
• Restricts entry of large molecules, cells,etc.
• Therefore CSF composition is unlike blood’

7. Cerebrospinal Fluid (CSF)
• Blood Brain Barrier
• Essential to protect the brain
• Blocks chemicals, harmful substances
• Antibodies and medications also blocked
• Tests for those substances normally
blocked can indicate level of disruption by
diseases: ie meningitis and multiple
sclerosis.

8. CEREBROSPINAL FLUID [FORMATION]
CSF is largely formed by the choroid plexus of the lateral
ventricle and remainder in the third and fourth ventricles.
About 30% of the CSF is also formed from the ependymal
cells lining the ventricles and other brain capillaries.
The choroid plexus of the ventricles actively secrete
cerebrospinal fluid.
The choroid plexuses are highly vascular tufts covered by
ependyma.

9. MECHANISM OF FORMATION OF CSF
CSF is formed primarily by secretion and also by filtration from
the net works of capillaries and ependymal cells in the ventricles
called choroid plexus.
Various components of the choroid plexus from a blood-
cerebrospinal fluid barrier that permits certain substances to enter
the fluid, but prohibits others.
Such a barrier protects the brain and spinal cord from harmful
substances.

10. MECHANISM OF FORMATION OF CSF
CSF is formed at a rate of about 550 milliliters each day,. About
two thirds or more of this fluid originates as secretion from the
choroid plexuses in the four ventricles, mainly in the two lateral
ventricles.
The entire cerebral cavity enclosing the brain and spinal cord
has a capacity of about 1600 to 1700 milliliters
About 150 milliliters of this capacity is occupied by
cerebrospinal fluid and the remainder by the brain and cord.

11. MECHANISM OF FORMATION
Less important transport processes move small amount of glucose
into the cerebrospinal fluid and both potassium and bicarbonate
ions out of the cerebrospinal fluid into the capillaries.
The resulting characteristics of the CSF are:
Osmotic pressure approximately equal to that of plasma sodium
ion concentration
Approximately equal to that of plasma chloride ion
About 15 per cent greater than in plasma potassium ion
approximately 40 per cent less glucose

12. MECHANISM OF FORMATION OF CSF
Rate of formation:
About 20-25 ml/hour
550 ml/day in adults. Turns over 3.7 times a day
Total quantity: 150 ml:
30-40 ml within the ventricles
About 110-120 ml in the subarachnoid space [of which
75-80 ml in spinal part and 25-30 ml in the cranial part].

13. Cerebrospinal Fluid (CSF)
 Specimen collection and handling
 Routinely collected via lumbar puncture between 3rd & 4th,
or 4th & 5th lumbar vertebrae under sterile conditions
 Intracranial pressure measurement taken before fluid is
withdrawn.

14. LUMBAR PUNCTURE

15. CEREBROSPINAL FLUID

16. COMPOSITION OF CSF
Proteins = 20-40 mg/100 ml
Glucose = 50-65 mg/100 ml
Cholesterol = 0.2 mg/100 ml
Na+ = 147 meq/Kg H2O
Ca++ = 2.3 meq/kg H2O
Urea = 12.0 mg/100 ml
Creatinine = 1.5 mg/100 ml
Lactic acid = 18.0 mg/100 ml

17. CHARACTERISTICS OF CSF
Nature:
Colour = Clear, transparent fluid
Specific gravity = 1.004-1.007
Reaction = Alkaline and does not coagulate
Cells = 0-3/ cmm
Pressure = 60-150 mm of H2O
The pressure of CSF is increased in standing, coughing,
sneezing, crying, compression of internal Jugular vein

18. Comparison of Average Serum and Cerebrospinal Fluid
Substance CSF Serum
Water Content (%) 99 93
Protein (mg/dL) 35 7000
Glucose (mg/dL) 60 90
Osmolarity (mOsm/L) 295 295
Sodium (mEq/L) 138 138
Potassium (mEq/L) 2.8 4.5
Calcium (mEq/L) 2.1 4.8
Magnesium (mEq/L) 2.0–2.5 1.7
Chloride (mEq/L) 119 102
pH 7.33 7.41

19. Cerebrospinal Fluid (CSF)
• CSF Lactate
• Normal values = 11-22 mg/dL
• Increase as result of hypoxia
• Bacterial meningitis. Head injury
• CSF Glutamine
• Normal 8-18 mg/dL
• Increased levels associated with increases in ammonia (toxin)
• CSF Enzymes
• Lactate dehydrogenase (LDH or LD)
• 5 isoenzyme types; LD1&LD2 are in brain tissue
• Creatine kinase (CPK or CK)
• Isoenzyme CK3/ CK-BB from brain tissue
• Following cardiac arrest, patients with CSF levels <17 mg/dL have favorable
outcome.

20. FUNCTIONS OF CSF
A shock absorber
A mechanical buffer
Act as cushion between the brain and cranium
Act as a reservoir and regulates the contents of the
cranium
Serves as a medium for nutritional exchange in CNS
Transport hormones and hormone releasing factors
Removes the metabolic waste products through absorption

21. INDICATIONS OF CSF EXAMINATION
Infections: meningitis, encephalitis
Inflammatory conditions: Sarcoidosis, neuro syphilis
Infiltrstive conditions:Leukamia, lymphoma, carcinomatous -
meningitis
Administration of drugs in CSF (Therapeutic aim)
Antibiotics: (In case of meningitis)Antimitotics
Diagnostic aim: Myelography, Cisternography
Anaesthetics are also given through the lumbar Puncture.

22. Cerebrospinal Fluid (CSF)
• Indications for analysis
• To confirm diagnosis of meningitis
• Evaluate for intracranial hemorrhage
• Diagnose malignancies, leukemia
• Investigate central nervous system disorders

23. Cerebrospinal Fluid (CSF)
• Four major categories of disease
• Meningeal infections
• Subarachnoid hemorrhage
• CNS malignancy
• Demyelinating disease

24. CSF AND INFLAMMATION
Increased inflammatory cells [pleocytosis] may be caused
by infectious and noninfectious processes.
Polymorphonuclear pleocytosis indicates acute suppurative
meningitis.
Mononuclear cells are seen in viral infections
(meningoencephalitis, aseptic meningitis), syphilis,
neuroborreliosis, tuberculous meningitis, multiple sclerosis,
brain abscess and brain tumors.

25. CSF & LOW GLUCOSE
Low glucose in CSF:
This condition is seen in suppurative tuberculosis
Fungal infections
Sarcoidosis
Meningeal dissemination of tumors.
Glucose is consumed by leukocytes and tumor cells.

26. CSF AND PROTEINS
Increased protein: CSF protein may rise to 500 mg/dl in
bacterial meningitis.
A more moderate increase (150-200 mg/dl) occurs in
inflammatory diseases of meninges (meningitis, encephalitis),
intracranial tumors, subarachnoid hemorrhage, and cerebral
infarction.
A more severe increase occurs in the Guillain-Barré syndrome
and acoustic and spinal schwannoma.

27. CSF AND PROTEINS
Multiple sclerosis: CSF protein is normal or mildly
increased.
Increased IgG in CSF, but not in serum [IgG/albumin index
normally 10:1].
90% of MS patients have oligoclonal IgG bands in the CSF.
Oligoclonal bands occur in the CSF only not in the serum.
The CSF in MS often contains myelin fragments and myelin
basic protein (MBP).
MBP can be detected by radioimmunoassay. MBP is not specific for
MS. It can appear in any condition causing brain necrosis, including
infarcts.

28. BLOOD IN CSF
Blood: Blood may be spilled into the CSF by accidental
puncture of a leptomeningeal vein during entry of the LP needle.
Such blood stains the fluid that is drawn initially and clears
gradually. If it does not clear, blood indicates subarachnoid
hemorrhage.
Erythrocytes from subarachnoid hemorrhage are cleared in 3 to
7 days. A few neutrophils and mononuclear cells may also be
present as a result of meningeal irritation.

29. CSF AND TUMOUR CELLS
Tumor cells indicate dissemination of metastatic or
primary brain tumors in the subarachnoid space.
The most common among the latter is
medulloblastoma.
They can be best detected by cytological
examination.
A mononuclear inflammatory reaction is often seen in

30. CSF AND XZNTHOCHROMIA
Xanthochromia [blonde color] of the CSF
following subarachnoid hemorrhage is due to
oxyhemoglobin which appears in 4 to 6 hours and
bilirubin which appears in two days.
Xanthochromia may also be seen with hemorrhagic
infarcts, brain tumors, and jaundice.

31. Cerebrospinal Fluid (CSF)
• Appearance
• Clots – indicates increased fibrinogen & usually due to traumatic tap, but may indicate
damage to blood-brain barrier. (see below)
• Pellicle formation in refrigerated specimen associated with tubercular meningitis.
• Pellicle formation - picture at right (pellicle in L. tube, R is normal)
• Milky – increased lipids
• Oily – contaminated with x-ray media

32. LUMBAR PUNCTURE
Place the patient in the lateral decubitus position lying on
the edge of the bed and facing away from operator.
Place the patient in a knee-chest position with the neck
flexed.
The patient's head should rest on a pillow, so that the
entire cranio-spinal axis is parallel to the bed.
Sitting position is the second choice because there may be
a greater risk of herniation and CSF pressure cannot be
measured

33. Differential Diagnosis of Meningitis
by Laboratory Results
Bacterial Viral Tubercular Fungal
Increased WBC count Increased WBC count Increased WBC count Increased WBC count
Neutrophils Lymphs Lymps & Monos Lymphs & Monos
Marked ↑ protein Mod. ↑ protein Mod-Marked ↑ protein Mod-Marked ↑
protein
Marked ↓ glucose ↔ normal glucose ↓ glucose Normal to ↓ glucose
Lactate > 35
mg/dL
Lactate normal Lactate > 25 mg/dL Lactate > 25
mg/dL
+ gram stains Pellicle formation + India ink with
Cryptococcus
neoformans
+ bacterial
antigen tests
+ immunological
test for C. neo.