CSF is a clear fluid found in the brain ventricles, spinal canal, and subarachnoid spaces. It is produced by the choroid plexus in the ventricles at a rate of 0.3 mL/min and circulates through the brain and spinal cord. CSF contains water, electrolytes, proteins, and sugars and acts to protect the brain, remove waste, and regulate cranial pressure. CSF is absorbed into the venous sinuses and any blockages can cause hydrocephalus. CSF is analyzed to diagnose infections, inflammatory conditions, and cancers of the central nervous system.

2. Introduction
• CSF is clear, colorless and
transparent fluid present in
the cerebral ventricles,
spinal canal, and
subarachnoid spaces.
• Circulates through cavity of
the:
– Brain
– Subarachnoid space
– Central canal of spinal cord
• Part of Extracellular fluid
(ECF)

3. Properties
• Volume : approximately 150 mL
• Rate of formation: approximately 0.3 mL/min
• Specific gravity
• Nature
: 1.005
: Alkaline

4. Composition
Inorganic substances
1.Sodium
2.Calcium
3.Potassium
4.Magnesium
5.Chlorides
6.Phosphate
7.Bicarbonates
8.Sulfates
Cerebrospinal Fluid
Water - 99.13% Solids - 0.87%
Organic substances
1.Proteins
2.Amino acids
3.Sugar
4.Cholesterol
5.Urea
6.Uric acid
7.Creatinine
8.Lactic acid
Lymphocytes in CSF : 6/ cu mm

5. Continued…
• As CSF is part of ECF therefore it contain
more amount of Sodium than Potassium.
• Contains some lymphocytes.
• CSF secreted by ventricles does not contain
any cell.
• The lymphocytes are added when it flows in
the spinal cord.

6. Formation of CSF
• Site of formation
– Formed by the choroid plexus
situated within the
ventricles.
– The choroid plexus are tuft of
capillary projections present
inside ventricles and covered
by:
• Pia matter
• Ependymal covering.

8. Mechanism of formation
• Formed by process of secretion.
• Uses energy.
• Active transport mechanism is involved in secretion.

9. Substances affecting the formation of CSF
•Pilocarpine, ether and extracts of pituitary gland
stimulates the secretion of CSF by stimulating
choroid plexus.
•Pilocarpine is a medication used to treat increased
pressure inside the eye and dry mouth
•Injection of isotonic saline also stimulates CSF
formation.

10. Continued…
• Injection of hypotonic saline
– Causes greater rise in capillary pressure and
intracranial pressure,
– Fall in osmotic pressure leading to increase in CSF
formation.
• Hypertonic saline
– Decreases CSF formation
– Decreases CSF pressure

11. Circulation of CSF

12. Absorption of CSF
• Mostly absorbed by the Arachnoid villi
into Dural sinuses and Spinal veins.
• Small amount is absorbed along the
perineural spaces into cervical lymphatics
and in to the perivascular spaces.
• Normally, 500 mL of CSF is formed
everyday and equal amount is absorbed.
• Absorption is done by filtration due to
pressure gradient between hydrostatic
pressure in the subarachnoid space fluid
and the pressure that exists in the Dural
sinus blood.

13. FUNCTIONS OF CSF
Protection
Nutrition
Removal of waste
Lubrication

14. Continued…
• Regulation of Cranial Content Volume
– Is very essential because
– When substances are absorbed into the venous sinuses,
intracranial pressure is raised,
– Intracranial pressure in turn interferes with the cerebral
circulation causing Asphyxia.
• It is prevented by greater absorption of CSF to give
space for increasing cranial contents.
• Medium of Exchange
• CSF is the medium through which substances like :
– Nutritive substances
– Waste materials
are exchanged between blood and brain tissues.

15. Collection of CSF
• Collected by :
– Cisternal puncture or
– Lumbar puncture
• In Cisternal puncture
– CSF is collected by passing needle between
Occipital bone and Atlas, so it enters the
cisterna magna.

16. Continued…
• In Lumbar puncture
– The Lumbar puncture needle is
introduced into the subarachnoid
space in the Lumbar region
, between the third and fourth Lumbar
spines.
– Uses of Lumbar puncture
• Collecting CSF for diagnostic purpose.
• Injecting drugs for spinal anesthesia,
analgesia and chemotherapy.
• Measuring pressure exerted by CSF.

17. Blood–Cerebrospinal Fluid Barrier
Barrier between the blood and cerebrospinal fluid .
• Exists at the Choroid plexus and Similar to Blood-
Brain Barrier(BBB)
• Allows the movement of only those substances,
which are allowed by BBB.

18. Substances which can pass through
Blood-Cerebrospinal Fluid Barrier
• Oxygen
• Carbon dioxide
• Water
• Glucose
• Amino acids
• Electrolytes
• Drugs such as L-dopa, 5-hydroxytryptamine
sulfonamides, tetracycline and other lipid soluble
drugs.
• Anesthetic gases such as ether, nitrous oxide
which are lipid soluble

19. Substanes which can’t pass through
Blood-Cerebrospinal Fluid Barrier
• Injurious chemical agents.
• Pathogens such as bacteria.
• Drugs such as Penicillin and the
Catecholamines.
• Dopamine also can’t pass therefore
Parkinsonism is treated with L-dopa instead
of dopamine.

20. Continued…
• Bile pigments
– However barrier is not well developed in infants.
– The bile pigments enter the brain tissues .
– During jaundice in infants, the bile pigments
enter the brain and causes damage of Basal
ganglia leading to Kernicterus.

21. CSF disorders
• Hydrocephalus
– Abnormal accumulation of CSF in the skull with
enlargement of head.
• 2 types of Hydrocephalus
1. non-communicating
2. communicating

22. 1. Non-communicating Hydrocephalus or
Internal Hydrocephalus
Due to the obstruction of any of the foramen
through which CSF escapes results in dilation of
ventricular cavity.
2. Communicating Hydrocephalus or External
Hydrocephalus
3. Due to blockage of Arachnoid villi.
Symptoms of Hydrocephalus:
 Headache, Vomiting Atrophy of brain Mental weakness
Convulsions

23. INDICATIONS OF CSF
EXAMINATION
1. Infections: meningitis, encephalitis.
2. Inflammatory conditions: Sarcoidosis,
Neurosyphilis, SLE.
3. Infiltrative conditions: Leukemia, lymphoma
4. Administration of drugs in CSF (Therapeutic
aim): Antibiotics
5. Anticancer drugs
6. Anesthetic drugs