CSF is produced by the choroid plexus in the brain ventricles and circulates through the brain and spinal cord. It serves functions like protecting the brain, transporting nutrients and waste. CSF is analyzed to distinguish between infectious diseases, hemorrhaging, immune disorders and tumors. A lumbar puncture collects CSF for analysis. The blood-brain barrier normally prevents substances crossing from blood to brain but is disrupted by injury or inflammation. Hydrocephalus is excess CSF in the brain which can be communicating within ventricles or non-communicating due to blockage.
3. Cerebrospinal fluid (CSF) is found in the subarachnoid space of
the brain (within the ventricles) and spinal canal. It is produced by
the choroid plexus in the ventricles of the brain and the cerebral
vessels, at the rate of 500 ml/day. Production matches reabsorption
so, at any one time in an adult, the average volume of CSF is about
150 ml.
Clear colorless and transparent fluid
Circulates through cavity of the brain, subarachnoid space
and central canal of spinal cord.
Part of extracellular fluid (ECF)
4. CSF is covered by three membranes, they are
1. Pia meter (Inner membrane)
2. Arachnoid meter (center membrane)
3. Dura meter (Outer membrane)
6. Protects & lubricates the brain
Provides nutrients ,remove waste
Modulates pressure changes
serves as a chemical buffer to maintain
constant ionic environment
Serves as a transport medium for
nutrients and metabolites ,endocrine substansis and even
neurotransmitters
7. The CSF is formed mainly in the brain ventricles, and that the majority of
the remaining CSF is probably produced by the ependymal surface of
ventricles.
It is generally accepted that CSF flows unidirectional from the brain
ventricles to the subarachnoid space with the
exchange of various substances between the CSF and interstitial
compartments.
Choroid plexuses are the main site of CSF production.
Then, passage of the plasma ultra filtrate through the endothelium,
facilitated by hydrostatic pressure. Then, passing into the ventricles. An
active metabolic process which transforms the ultra filtrate into secretion
CSF.
10. WHY?
CSF analysis can accurately distinguish between a wide
range of CNS diseases.
Conditions found by CSF analysis can be placed into
four main categories:
1- infectious diseases.
2- hemorrhaging.
3- immune response disorders.
4- tumors.
12. LUMBER PUNCTURE:
A lumbar puncture (or LP, and
colloquially known as a spinal
tap) is a diagnostic procedure that
is performed in order to collect a
sample of cerebrospinal fluid
(CSF) for biochemical ,
microbiological and cytological
analysis.
13. Proper angle of entry through
the L3-L4 interspace.
Spinal cord terminates at L1;
needle entry must occur distal to
this location.
18. In normal cases, CSF is clear and colorless.
In cases of malady, the appearance change according to
the case.
We will discuss some of these in the following:
1- Xanthochromic :
(Bright red or yellow)
This indicates the presence of blood.
The appearance of fresh blood in all
tubes supports the diagnosis of a subarachnoid
hemorrhage.
2- Turbid :
This indicates the presence of white
cells
and is suggestive of a CNS infection.
19. Physiological barrier to
flow of substances from
blood to brain tissue
The BBB functions to
preserve a stable
environment for neurons of
the CNS
20. Lipid soluble molecules will cross
easily.
High CO2/low O2 produce vasodilation
and decrease resistance of BBB.
Injury or inflammation:
Decreases the resistance of BBB (allows
some antibiotics to be used for treatment).
21. Tight junctions.
Surrounded by astrocytes.
Carrier mediated transport of glucose and amino acids.
Brain capillary
22. Selected brain areas are not protected by the BBB –
the circumventricular organs (CVO) bordering on the
3rd and 4th ventricles.
– Parts Of The Hypothalamus - Median Eminence .
– Neurohypophysis.
– Pineal Gland.
– Area Postrema.
– Sub fornical Organ.
– Sub Commissural Organ.
23. 1- CSF Glucose:
CSF glucose is derived from blood glucose hence,
ideally CSF glucose level should be compared with
fasting plasma glucose level for adequate clinical
interpretation.
Decrease duo to hypoglycemia , tuberculosis.
Increase duo to high blood sugar.
2- CSF Pressure:
Increase duo to increases intra cranial
Pressure.
Decrease due to shock, fainting or
diabetic coma.
3- CSF Protein :
Increase duo to blood in CSF ,tumor.
Decrease duo to rapid CSF production.
24.
25. Communicating and Noncommunicating.
Acute and chronic.
Congenital and acquired.
(A)1- Non-communicating (obstructive):
CSF circulation is blocked at or proximal to fourth ventricular outlet foramina.(enlargement of
ventricles proximal to the block).
2- Communicating (non-obstructive):
Due to excessive formation of CSF or lack of absorption.
The obstruction of CSF flow is in the subarachnoid space from prior bleeding or meningitis.
This causes thickening of the arachnoid leading to blockage of the return-flow channels.
26. (B) 1- Acute :
hydrocephalus caused by tumor.
Develops within days or few weeks.
Manifests with rapid progression of symptoms.
Requires early attention and treatment .
2- Chronic :
Over months (or even years).
Subtle signs of memory impairment, walking difficulty and urinary incontinence.
Chronic hydrocephalus can present acutely because of changes in the pathophysiology of the CSF
absorption or flow.
(C) 1-Congenital :
Present at birth or few weeks/months after birth.
2- Acquired:
Infection (post-meningitis).
Post – hemorrhagic (SAH,IVH).
Tumors.
