Cerebrospinal fluid CSF INTRODUCTION CSF is a clear colourless and transparent alkaline fluid that circulates through ventricles of brain subarachnoid space and central canal of spinal cord ID: 779594
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Slide1
DR. SHUBHANGI SAXENA SHMCNYS
Cerebrospinal fluid(CSF)
Slide2INTRODUCTION
CSF is a clear, colourless, and transparent, alkaline fluid that circulates through ventricles of brain, subarachnoid space and central canal of spinal cord.The entire cerebral cavity enclosing the brain and spinal cord has capacity of about 1600-1700 millilitres, about 150 ml of its capacity is occupied by CSF and remainder by the brain and spinal cord.
Slide3CSF composition and properties.
PROPERTIES Volume : 130-150 ml of which 30-40 ml is in the ventricular system and remaining in subarachnoid space. Rate of formation : 0.2- 0.3 ml/min
Daily secretion : 500-550 ml
Pressure (average) : in lateral lying position-130 mm H2O .
In sitting position 200 mm H2O.
Specific gravity : 1.005
Reaction : alkaline
Slide4COMPOSITIONS
Composition of CSF and blood
CONSTITUENT
CFS
BLOOD
Na
+
(
mEq
/L)
148
136-145
K
+
(
mEq
/L)
2.9
3.5-5
Cl
−
(
mEq
/L)
120-130
100-106
Ca
+2
(
mEq
/L)
2.3
4.7
Protein (mg %)
15-45
Glucose (mg %)
50-75
70-100
pH
7.3
7.4
Slide5The CSF differ from blood in having a lower concentration of K+ , glucose and protein and a higher concentration of Na+ and Cl−
CSF normally lacks blood cells.
Slide6FORMATION OF CSF
50% by choroid plexuses in the ventricles.40% by blood vessels of meningeal and ependymal lining of ventricles.10% by blood vessels of brain and spinal cord.Mainly formed by the choroid plexus, which are covered by specialized ependymal cells. The choroid plexus are located in the cerebral ventricles ( lateral, third and fourth).
Slide7Slide8Slide9Slide10CIRCULATION OF CSF
Slide11CSF formed in the lateral ventricle
through interventricular foramina (of monra) Into third ventricle fluid flow through cerebral aqueduct
(of
sylvius
)
Into fourth ventricle
foramen of
magendie
,
foramin
of
luschka
Then some CSF passes into the central canal of spinal cord
But most escape into the subarachnoid space
(surrounding the brain and spinal cord)
Slide12Slide13Ventricles of brain
Slide14Slide15ABSORPTION OF
CSF
Slide16Mainly 80 % by arachnoid villi into venous sinuses and spinal veins.
From subarachnoid space It flows upward towards cerebrum, where almost all arachnoid villi are located and is absorbed through these villi into the cerebral venous sinuses.
Slide17FUNCTIONS OF CSF
Slide18Protective function : CSF protects the brain from shock.The specific gravity of brain and CSF is more or less same, brain floats in CSF. When head receives a blow
CSF acts like a cushion
And prevent the movement of brain against the skull bone
Prevent the damage of brain.
Slide19Medium of exchange : CSF is the medium through which many substances particularly the nutritive substances and waste materials are exchanged between blood and brain tissues. It acts as a reservoir to regulate the contents of cranium i.e it can compensate for fluctuations in the amount of blood within skull, therefore at any moment if blood volume of brain increases then CSF drains away. Conversely, if brain blood volume shrinks more CSF is retained.
Thus, CSF keeps the total volume of cranial content constant.
Transport hormones and hormones releasing factors.
Slide20CLINICAL ASPECTS
Slide21(A) Causes of increase in CSF pressure
Physiological pathologicalPHYSIOLOGICAL : Increase in venous pressure for example following coughing or crying or compression of internal jugular vein. Queckenstedt’s sign : compression of internal jugular vein decrease absorption of CSF, as a result CSF pressure increases.
Slide22PATHOLOGICAL :
Increase in rate of fluid formation eg: inflammation of meninges. Increased resistance to absorption through arachnoids villi for example : brain tumors, hemorrhage or infection (cellular elements block the absorption)
(B)
CAUSES OF DECREASE IN CSF PRESSURE
Decrease in venous pressure
Decrease in rate of fluid formation
Slide23(C) The effect of I.V injection of hypertonic solutions on the CSF pressure.
I.V injection of 50ml of 10% NaCl solution causes fall in CSF pressure for 2 hours due to absorption of fluid from CSF into the plasma. However effect is temporary, because Na+ and Cl− eventually move into the CSF themselves and equilibrium is re-established. Uses : it is of value in conditions of raised intracranial pressure caused by cerebral tumors therefore helpful in :
Relieving
papilloedema
(optic disc swelling that is caused by increased intracranial pressure).
Restoring consciousness.
Intracranial operations made easier as bulging of the brain is prevented.
Slide24(D) HYDROCEPHALUS
It refers to an abnormal accumulation of CSF in the cranium.CAUSES :Obstruction to CSF circulation.Excessive production of CSF.Interference with absorption of CSF .
TYPES :
Internal or non External or communicating
communicating hydrocephalus
hydrocephalus
Slide25Internal or non communicating hydrocephalus:
When obstruction is within the ventricular system or in the roof of 4th ventricle. It results in the dilatation of the ventricle.Common side of blocks are : foramina of monra, aqueduct of sylvius, foramen of magendie, foramin of luschka
and within ventricular system itself.
External or communicating hydrocephalus:
Excess of fluid accumulation in subarachnoid space.
Cause – when rate of CSF formation is more than rate of its absorption.
Slide26HYDROCEPHALUS
Slide27Slide28Slide29CSF
Collection
Slide30CSF Collection
cisternal lumbar puncture puncture CSF is collected by passing needle is Introduce a needle between occipital into the subarachnoid
bone and atlas, so that it space in the lumbar
enters the
cisterna
magna region between the
3
rd
and 4
th
lumbar spine
Slide31CISTERNAL PUNCTURE
Slide32LUMBAR PUNCTUREPosture of the body :
The reclining body is bent forwardSo as flex the vertebral column as far as possibleThe body is brought near the edge of the table
Slide33Slide34POSTURE
Slide35PROCEDURE
The highest point of the iliac crest is determined by palpationA line is drawn on the back of the subject by joining the highest point of iliac crest of both sidesOpposite the mid point, this line can cross the 4th lumbar spine
After determining the area of 4
th
lumbar spine, 3
rd
lumbar spine is palpated
Slide36Then the needle is introduced through the soft tissue space between the 2 spines
So that the needle reaches the subarachnoid space
Slide37Slide38Slide39Reason for selecting the site :
spinal cord will not be injured because it terminates below the lower border of the 1st lumbar vertebra The cauda equina may be damaged. Even if it is injured, it can regenerate The subarachnoid space is wider in this site, it is because the pia
matter is reduced very much.
Slide40Slide41Collection of CSF
Slide42USES
Collecting CSF for diagnostic purpose
Injecting drugs for spinal anesthesia, analgesia, chemotherapy
Measuring pressure exerted by CSF
Slide43ABNORMAL CSF
In cerebral/ subarachnoid hemorrhage-CSF contains blood. In purulent meningitis – CSF is cloudy, cell count high and consist mostly of neutrophils. chemically, the sugar concentration falls sharply and protein concentration rises. All these features are due to the acute inflammation of the meninges.
In tubercular meningitis, protein concentration rises but the sugar and chloride concentration falls.
In viral encephalitis, rise of the protein, concentration may be the only abnormality.