cerebral circulation and cerebrospinal fluid [csf] sultan ayoub meo mbbs, pgc med ed, m.phil, ph.d...
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CEREBRAL CIRCULATION AND CEREBROSPINAL
FLUID [CSF]
Sultan Ayoub Meo MBBS, PGC Med Ed, M.Phil, Ph.D
Professor, Department of PhysiologyCollege of Medicine, King Saud University
CEREBRAL CIRCULATIONThe 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 CIRCULATIONThe 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 CIRCULATIONThe 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 CIRCULATIONThe 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 CIRCULATIONFainting: 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 CIRCULATIONStroke: 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 CIRCULATIONPrincipal 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 CIRCULATIONTransient 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 CSFCSF 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.
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 CSFRate 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 FORMATIONCSF 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 FORMATIONSecretion 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 concentrationApproximately 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 = 20-40 mg/100 mlGlucose = 50-65 mg/100 mlCholesterol = 0.2 mg/100 mlNa+ = 147 meq/Kg H2OCa+ = 2.3 meq/kg H2OUrea = 12.0 mg/100 mlCreatinine = 1.5 mg/100 mlLactic acid = 18.0 mg/100 ml
CHARACTERISTICS OF CSF
Nature:Colour = Clear, transparent fluidSpecific gravity = 1.004-1.007Reaction = Alkaline and does not
coagulateCells = 0-3/ cmmPressure = 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 CSFLateral ventricle
Foramen of Monro [Interventricular foramen]
Third ventricle:
Subarachnoid space of Brain and Spinal cord
Fourth ventricle:
Cerebral aqueduct
Foramen of megendie and formen of luschka
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 absorberA mechanical bufferAct as cushion between the brain and craniumAct as a reservoir and regulates the contents of the craniumServes as a medium for nutritional exchange in CNSTransport hormones and hormone releasing factorsRemoves the metabolic waste products through absorption
CSF AND INFLAMMATIONIncreased 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.
CSF AND INFLAMMATIONIncreased 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.
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 GLUCOSELow 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, encephalitisInflammatory conditions: Sarcoidosis, neuro syphilis, SLEInfiltrstive conditions:Leukamia, lymphoma, carcinomatous - meningitisAdministration of drugs in CSF (Therapeutic aim)Antibiotics: (In case of meningitis)AntimitoticsDiagnostic aim: Myelography, CisternographyAnaesthetics 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 cerebriSuspected spinal cord mass or intracranial mass lesion (based on lateralizing neurological findings or papilledema)Uncontrolled bleeding diathesisSpinal 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-gauge3. Manometer4. Three-way stopcock5. Sterile drapes6. 1% lidocaine without epinephrine in a 5-cc syringe with a 22 and 25-gauge needles7. Material for skin sterilization8. Adhesive dressing9. 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 PUNCTUREFind 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
HYDROCEPHALUSLHydrocephalus" 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