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CEREBRAL CIRCULATION AND
CEREBROSPINAL FLUID [CSF]
Sultan Ayoub Meo
MBBS, PGC Med Ed, M.Phil, Ph.D
Professor, Department of Physiology
College of Medicine, King Saud University
CEREBRAL CIRCULATION
The Circle of Willis is
the joining area of
several arteries at the
bottom (inferior) side of
the brain. At the Circle
of Willis, the internal
carotid arteries branch
into smaller arteries that
supply
oxygenated
blood over 80% of the
cerebrum.
CEREBRAL CIRCULATION
CEREBRAL CIRCULATION
CEREBRAL CIRCULATION
CEREBRAL CIRCULATION
CEREBRAL CIRCULATION
The Circle of Willis is a vital formation of arteries at the base
of the brain OR
Grouping of arteries near the base of the brain which is
called the Arterial Circle of Willis.
It is named after an English physician named Thomas Willis,
who discovered it and then published his findings in his
1664, a seminal peace on the inner workings of the brain
entitled, Cerebri anatomi (from the Latin for “Anatomy of
the Brain”).
CEREBRAL CIRCULATION
The brain receives its blood
supply from four main
arteries:
the
two
internal carotid arteries
and the two vertebral
arteries.
The
clinical
consequences of vascular
disease in the cerebral
circulation is depend upon
which
vessels
or
combinations of vessels are
involved.
CEREBRAL CIRCULATION
The vertebral arteries unite to form Basilar artery
The basilar artery and the carotids form the circle of Willis
below the hypothalamus
The circle of Willis is origin of six large vessels supplying
the cerebral cortex
Substances injected into one carotid artery distributed
almost completely to the cerebral hemisphere on that side.
Normally no crossing over occurs probably because the
pressure is equal on both sides
CEREBRAL CIRCULATION
The arteries and arterioles supply blood to the brain are
highly specialized, include both vascular smooth muscle
and endothelial cells that are unlike vascular cells from the
peripheral circulation or other vascular beds.
The vascular smooth muscle is highly responsive to
changes in pressure, a process called myogenic activity,
that contributes to autoregulation of cerebral blood flow.
The endothelial cells in the brain circulation are also highly
specialized and provide a barrier to fluid movement called
the blood-brain barrier. When these normal cell processes
fail or altered such as in hypertension
CEREBRAL CIRCULATION
Fainting: Temporary loss of consciousness, weakness of
muscles, and inability to stand up, caused by sudden loss
of blood flow to the brain.
Fainting is a relatively common symptom caused by a
variety of problems relating to changes in blood
pressure.
The American Heart Association reports that fainting is
responsible for 3% of all visits to emergency rooms and
6% of all admissions to hospitals.
CEREBRAL CIRCULATION
Stroke: Stroke occurs when the blood supply to a part of
the brain is blocked resulting in the death of an area within
the brain.
If a large vessel is blocked the outcome may be rapidly fatal
or may lead to very severe disability.
If smaller blood vessels are blocked the outcome is less
severe and recovery may be good. The most common types
of disability are the loss of functions of one side of the body
and speech problems.
CEREBRAL CIRCULATION
Principal types of stroke:
Thrombotic: Stroke due to the blockage of an artery leading
to or in the brain by a blood clot.
Haemorrhagic: Stroke due to bleeding from a ruptured blood
vessel, usually a consequence of hypertension.
Embolic: Stroke due to the formation of a blood clot in a
vessel away from the brain. The clot is carried in the
bloodstream until it lodges in an artery leading to or in the
brain.
The thrombotic and haemorrhagic forms are common,
CEREBRAL CIRCULATION
Transient ischaemic attack: When blood supply to a part of
the brain is temporarily interrupted without producing
permanent damage.
Recovery may occurs within 24 hours.
Usually result from small blood clots or clumps from
plaques of atheroma which get carried into the blood
circulation producing transient blockages.
Occasionally these clots may get carried from the heart or
arteries leading to the brain (e.g. carotid arteries), rather
than from within the cerebral circulation itself.
CEREBRAL CIRCULATION
Dementia: This may result from repeated episodes of
small strokes which produce progressive damage to the
brain over a period of time.
The main clinical feature of dementia is a gradual loss of
memory and intellectual capacity.
Loss of motor function in the limbs and incontinence can
also occur.
CEREBRAL CIRCULATION
CEREBRAL CIRCULATION
CEREBRAL CIRCULATION
CEREBRAL CIRCULATION
CEREBROSPINAL FLUID
The cerebrospinal Fluid [CSF] is a clear,
colorless transparent, tissue fluid present in
the cerebral ventricles, spinal canal, and
subarachnoid spaces.
CEREBROSPINAL FLUID
CEREBROSPINAL FLUID
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.
FORMATION & CIRCULATION OF CSF
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 bloodcerebrospinal 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.
MECHANISM OF FORMATION OF CSF
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.
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].
MECHANISM OF FORMATION
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.
Additional small amount of fluid is secreted by the
ependymal surfaces of all the ventricles and by the
arachnoidal membranes
Small quantity comes from the brain itself through the
perivascular spaces that surround the blood vessels
passing through the brain.
MECHANISM OF FORMATION
Secretion by the Choroid Plexus. The choroid plexus, is
a cauliflower-like growth of blood vessels covered by a thin
layer of epithelial cells.
Secretion of fluid by the choroid plexus depends mainly on
active transport of sodium ions through the epithelial cells
lining the outside of the plexus.
The sodium ions in turn pull along large amounts of chloride
ions because the positive charge of the sodium ion attracts
the chloride ion's negative charge. The two of these together
increase the quantity of osmotically active sodium chloride
in the cerebrospinal fluid, which then causes almost
immediate osmosis of water through the membrane, thus
providing the fluid secretion.
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
ABSORPTION OF CSF THROUGH
ARACHNOID VILLI
The arachnoidal villi are fingerlike inward projections of the
arachnoidal membrane through the walls into venous sinuses.
villi form arachnoidal granulations can protruding into the
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.
COMPOSITION OF CSF
Proteins
Glucose
Cholesterol
Na+
Ca+
Urea
Creatinine
Lactic acid
=
=
=
=
=
=
=
=
20-40 mg/100 ml
50-65 mg/100 ml
0.2 mg/100 ml
147 meq/Kg H2O
2.3 meq/kg H2O
12.0 mg/100 ml
1.5 mg/100 ml
18.0 mg/100 ml
CHARACTERISTICS OF CSF
Nature:
Colour
=
Specific gravity =
Reaction
=
Cells
Pressure
=
=
Clear, transparent fluid
1.004-1.007
Alkaline and does not
coagulate
0-3/ cmm
60-150 mm of H2O
The pressure of CSF is increased in standing, coughing,
sneezing, crying, compression of internal Jugular vein
(Queckenstedt’s sign
CIRCULATION OF CSF
Circulation: CSF is mainly formed in choroid pleaxus of the
lateral ventricle.
CSF passes from the lateral ventricle to the third ventricle
through the interventricular foramen (foramen of Monro).
From third ventricle it passes to the fourth ventricle through
the cerebrol aqueduct. The circulation is aided by the arterial
pulsations of the chroid plexuses.
From the fourth ventricle (CSF) passes to the sub arachnoid
space around the brain and spinal cord through the foramen
of magendie and foramina of luschka.
CIRCULATION OF CSF
Lateral ventricle
Foramen of Monro [Interventricular foramen]
Third ventricle:
Cerebral aqueduct
Fourth ventricle:
Foramen of megendie and formen of luschka
Subarachnoid space of Brain and Spinal cord
CIRCULATION OF CSF
Circulation: CSF slowly moves cerebromedullary
cistern and pontine cisterns and flows superiorly
through the interval in the tentorium cerebelli to
reach the inferior surface of the cerebrum. It moves
superiority over the lateral aspect of each cerebrol
hemisphere.
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
CSF AND INFLAMMATION
Increased inflammatory cells [pleocytosis] may be
caused by infectious and noninfectious processes.
Polymorphonuclear
suppurative meningitis.
pleocytosis
indicates
acute
Mononuclear cells are seen in viral infections
(meningoencephalitis, aseptic meningitis), syphilis,
neuroborreliosis,
tuberculous
meningitis,
multiple
sclerosis, brain abscess and brain tumors.
CSF AND INFLAMMATION
Increased inflammatory cells [pleocytosis] may be
caused by infectious and noninfectious processes.
Polymorphonuclear
suppurative meningitis.
pleocytosis
indicates
acute
Mononuclear cells are seen in viral infections
(meningoencephalitis, aseptic meningitis), syphilis,
neuroborreliosis,
tuberculous
meningitis,
multiple
sclerosis, brain abscess and brain tumors.
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.
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.
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.
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.
Leukemia Cells in CSF
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.
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
addition to the tumor cells.
INDICATIONS OF CSF EXAMINATION
Infections: meningitis, encephalitis
Inflammatory conditions: Sarcoidosis, neuro syphilis, SLE
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.
CONTRA-INDICATIONS FOR LP
Local skin infections over proposed puncture site
(absolute contraindication)
Raised intracranial pressure (ICP); exception is
pseudotumor cerebri
Suspected spinal cord mass or intracranial mass lesion
(based on lateralizing neurological findings or
papilledema)
Uncontrolled bleeding diathesis
Spinal column deformities (may require fluoroscopic
assistance)
Lack of patient cooperation
LUMBAR PUNCTURE
A lumbar puncture also called a spinal tap is a
procedure where a sample of cerebrospinal fluid is
taken for examination.
CSF is mainly used to diagnose meningitis [an
infection of the meninges].
It is also used to diagnose some other conditions
of the brain and spinal cord.
PRECAUTIONS FOR LUMBAR PUNCTURE
 Asked to sign a consent form
 Ask about taking any medicines
 Are allergic to any medicines
 Have / had any bleeding problems
 Ask about medications such as aspirin or warfarin
 Ask the female patient might be pregnant
 Empty the bladder before the procedure
LUMBAR PUNCTURE
1. Material for sterile technique [gloves and mask
are necessary]
2. Spinal Needle, 20 and 22-gauge
3. Manometer
4. Three-way stopcock
5. Sterile drapes
6. 1% lidocaine without epinephrine in a 5-cc
syringe with a 22 and 25-gauge needles
7. Material for skin sterilization
8. Adhesive dressing
9. Sponges - 10 X 10 cm
LUMBAR PUNCTURE [Complications]
Post lumbar puncture headache occurs in 10% to 30% of
patients within 1 to 3 days and lasts 2 to 7 days.
The pain is relieved by lying flat.
Treatment consists of bed rest and fluid with simple
analgesics.
LUMBAR PUNCTURE [Complications]
Headache following a lumbar puncture is a common and
often debilitating syndrome.
Continued leakage of cerebrospinal fluid from a puncture
site decreases intracranial pressure, which leads to
traction on pain-sensitive intracranial structures.
The headache is characteristically postural, often
associated with nausea and optic, vestibular, or otic
symptoms. Although usually self-limited after a few days,
severe postural pain can incapacitate the patient.
Management is mainly symptomatic, but definitive
treatment with the epidural blood patching technique is
safe and effective when done by an expert operator.
LUMBAR PUNCTURE
Patient usually lie on a bed on side with knees pulled
up against the chest.
It may also done with sitting up and leaning forward on
some pillows. Sterilize the area.
push a needle through the skin and tissues between
two vertebra into the space around the spinal cord
which is filled with CSF.
CSF leaks back through the needle and is collected in a
sterile container.
As soon as the required amount of fluid is collected the
needle is taken out and a plaster is put over the site of
needle entry.
LUMBAR PUNCTURE
Sent the sample to lab to be examined under
the microscope to look for bacteria.
It is also 'cultured' for any bacterial growth
The fluid can also be tested for protein, sugar
and other chemicals if necessary.
Sometimes also measure the pressure of the
fluid. This is done by attaching a special tube to
the needle which can measure the pressure of
the fluid coming out.
LUMBAR PUNCTURE
CEREBROSPINAL FLUID
CEREBROSPINAL FLUID
CEREBROSPINAL FLUID
CEREBROSPINAL FLUID
CEREBROSPINAL FLUID
CEREBROSPINAL FLUID
LUMBAR PUNCTURE
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
LUMBAR PUNCTURE
Find the posterior iliac crest and palpate the L4 spinous
process, and mark the spot with a fingernail.
Prepare the skin by starting at the puncture site.
Anesthetize the skin using the 1% lidocaine in the 5 mL
syringe with the 25-gauge needle. Change to 22-gauge
needle before anesthetizing between the spinous process.
Insert in the midline with the needle parallel to the floor
and the point directed toward the patient's umbilicus
LUMBAR PUNCTURE
Advance slowly about 2 cm or until a "pop'' (piercing a
membrane of the dura) is heard.
Then withdraw the stylet in every 2- to 3-mm advance of
the needle to check for CSF return.
If the needle meets the bone or if blood returns (hitting
the venous plexus anterior to the spinal canal), withdraw
to the skin and redirect the needle.
If CSF return cannot be obtained, try one disk space
down
HYDROCEPHALUSL
Hydrocephalus" means excess water in the cranial vault.
This condition is frequently divided into communicating
hydrocephalus and noncommunicating hydrocephalus.
In communicating hydrocephalus fluid flows readily from
the ventricular system into the subarachnoid space,
in noncommunicating hydrocephalus fluid flow out of one
or more of the ventricles is blocked.
HYDROCEPHALUSL