PREPARED BY: MUHAMMAD ARIFF B. MAHDZUB BACHELOR MEDICINE AND SURGERY (MBBS) UNIVERSITY COLLEGE SHAHPUTRA, KUANTAN

1. 1
CEREBROSPINAL FLUID AND
INTRACRANIAL PRESSURE
PROBLEM BASED LEARNING (PBL)
PREPARED BY: MUHAMMAD ARIFF B. MAHDZUB
BACHELOR MEDICINE AND SURGERY (MBBS)
UNIVERSITY COLLEGE SHAHPUTRA, KUANTAN

2. The brain tissue is separated from the
plasma by three main interfaces
(a) blood–brain barrier (BBB),
(b) blood–cerebral spinal fluid barrier
(BCSFB)
(c) arachnoid cells underlying the dura
mater.

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

5. 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
(perivascular space).

6. MECHANISM OF FORMATION OF CSF
CSF is formed primarily by secretion
(active transportation) and also by
filtration from the net works of
capillaries and ependymal cells in the
ventricles called choroid plexus.

7. 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 30 percent less

8. 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].

9. ABSORPTION OF CSF THROUGH
ARACHNOID VILLI
The arachnoidal villi are fingerlike inward
projections of the arachnoidal membrane
through the walls into venous sinuses.
The endothelial cells covering the villi have
vesicular passages directly through the bodies
of the cells large enough to allow relatively
free flow of (1) cerebrospinal fluid, (2)
dissolved protein molecules, and (3) even
particles as large as red and white blood cells
into the venous blood.

10. REGULATION OF ABSORPTION
• Absorption of CSF occurs by bulk flow is
proportionate to CSF pressure.:
• At pressure of 112 mm (normal average):
filtration and absorption are equal.
• Below pressure of 68 mm CSF, absorption
stops

11. COMPOSITION OF CSF
Proteins(Less than plasma)=20-40 mg/100
ml
Glucose( Less than plasma )=50-65 mg/100
ml
Cholesterol= 0.2 mg/100 ml
Na+(more)= 147 meq/Kg H2O
Cl+(more) =
Ca+(less) = 2.3 meq/kg H2O
Urea(less) = 12.0 mg/100 ml
Creatinine = 1.5 mg/100 ml
Lactic acid = 18.0 mg/100 ml

12. 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

13. CIRCULATION OF CSF
Lateral ventricle
Foramen of Monro
[Interventricular foramen]
Thirdventricle
Subarachnoid space of Brain and Spinal cord
Fourth ventricle:
Cerebral aqueduct
Foramen of megendie and formen of lusch

15. 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
Transport hormones and hormone releasing
factors

16. Count. Function
 Remove metabolic wastes from CNS
 Serves as pathway for pineal secretion to
reach the pituitary gland.
 it protects against acute changes in
arterial and venous blood pressure;
 it is involved in intra-cerebral transport,
ex. hypothalamic releasing factors

17. INTRACRANIAL PRESSURE
• ICP typically means the supratentorial CSF
pressure measured in the lateral ventricles
or over the cerebral cortex.
• Normal ICP value is 7-15 mm Hg
• Intracranial hypertension is defined as a
sustained increase btwen20–25 mm Hg

18. MONORO-KELLIE HYPOTESIS
• The pressure-volume relationship between ICP,
volume of CSF, blood, and brain tissue,
and cerebral perfusion pressure (CPP) is known as
the Monro-Kellie doctrine or the Monro-Kellie
hypothesis.
• Since the cranium is a rigid structure with a fixed
volume, comprising of CSF, brain, and blood. An
increase in one of these components must be
accompanied by an equivalent reduction in
another to avoid a rise in ICP

19. • Initially, an increase in volume is met with
little or no change in ICP. Ultimately, there
is a point where minute increases in
volume can result in a dramatic rise in ICP.
• Compensatory mechanisms that prevent
the initial rise in ICP include:
a) displacement of CSF from the cranial to
spinal compartment,
b) decrease in production of CSF
c) increase in absorption of CSF
d) decrease in total cerebral blood volume

21. Absorption Of CSF

22. • Absorption of cerebrospinal fluid is mainly by
arachnoidal villi
• Arachnoidal villi:
– Microscopic fingerlike inward projection of
arachnoidal membrane through the walls and into
venous sinus
– Allow relatively free flow of
• CSF
• Dissolved protein molecules
• Particle as large as RBC & WBC