Strasinger_CSF Flashcards
CSF Functions
- provides nutrients to nervous tissue
- removes metabolic wastes
- produces mechanical barrier to cushion the brain and spinal cord against trauma
lines the brain and spinal cord
meninges
3 meninges layers
dura mater
arachnoid
pia mater
Which layer of the meninges lines the skull and vertebral canal
dura mater
hard mother
dura mater
which layer of the meninges is referred to as the spider-like filamentous inner membrane
arachnoid
thin membrane lining the surfaces of brain and spinal cord
pia mater
gentle mother
pia mater
How much CSF is produced every hour
20 mL
Where CSF is produced
choroid plexuses (of the two lumbar ventricles and the third and fourth ventricles)
Where the CSF flows through
subarachnoid space
where the subarachnoid space is located
between arachnoid and pia mater
normal volume of CSF in adults
90-150 mL
normal volume of CSF in neonates
10-60 mL
how is CSF volume maintained?
the circulating fluid is reabsorbed back into the blood capillaries in the arachnoid granulations/villae at a rate equal to its production.
arachnoid granulations:
one-way or two-way valve?
one-way:
The cells of the arachnoid granulations act as one-way valves that respond to pressure within the central nervous system (CNS) and prevent reflux of the fluid
How is CSF formed?
Choroid plexuses form CSF from plasma by mechanisms of selective filtration under
hydrostatic pressure and active transport secretion
T/F:
CSF does not resemble an ultrafiltrate of plasma
TRUE
cells that line the capillary walls throughout the body
endothelial cells
: these are loosely connected to allow passage of soluble nutrients and wastes between the plasma and tissues
tight-fitting structure of the endothelial cells in the choroid plexuses
blood-brain barrier (BBB)
T/F:
Diseases such as meningitis and multiple sclerosis disrupts BBB
True
: this then allows leukocytes, proteins, and additional chemical to enter CSF
procedure used for CSF collection
lumbar puncture
: between the third, fourth, or fifth lumbar vertebra
T/F:
Lumbar puncture is a complicated procedure
FALSE
: Lumbar puncture is not complicated but may require certain precautions.
: requires measurement of intracranial pressure and technique to prevent infection or neural tissue damage
number of tubes needed for CSF collection
3
Tube 1 from CSF collection is for:
chemical and serological tests
: frozen
: least affected by blood or bacteria introduced as a result of tap procedure
Tube 2 from CSF collection is for:
microbiology
Tube 3 from CSF collection is for:
cell count
: least likely to contain cells introduced by the tap
4th tube may be drawn from the CSF collection. This is for:
microbiology to better exclude skin contamination or for additional
serologic tests
T/F:
Excess CSF fluid drawn may be discarded
FALSE
Excess fluid should not be discarded and should be frozen until there is no further use for it.
Supernatant fluid left over after each section has performed its tests may be used for?
additional chemical or serologic tests
T/F:
CSF testing are ideally performed on a STAT basis
TRUE
Storage condition of CSF tube:
Hematology tubes
Refrigerated
Storage condition of CSF tube:
Microbiology tubes
Room temp
Storage condition of CSF tube:
Chemistry and serology tubes
Frozen
CSF appearance that may be a result of increased protein or lipid concentration and may be indicative of infection
cloudy, turbid, milky
If only one tube can be collected for CSF, where must it be tested first?
Microbiology
T/F:
It is not unusual for cell counts requested to be performed on both Tubes 1 and 4
TRUE
: this is to check for cellular contamination by the puncture
CSF supernatant is pink, orange, or yellow
Xanthochromia
most common cause of xanthochromia
presence of RBC degradation products
CSF color that would indicate there is a very slight amount of oxyhemoglobin
pink
CSF color that would indicate heavy hemolysis
orange
CSF color that would indicate conversion of oxyhemoglobin to unconjugated bilirubin
yellow
Other causes of xanthochromia other than presence of RBC degradation products
- elevated serum bilirubin
- presence of pigment carotene
- markedly increased protein concentrations
- melanoma pigment
T/F:
Xanthochromia that is caused by bilirubin due to immature liver function is also commonly seen in infants, particularly premature infants
TRUE
appearance of a normal CSF
crystal clear
causes of grossly bloody CSF
- intracranial hemorrhage
* due to puncture of a blood vessel during spinal tap procedure
visual examinations of CSF that would determine whether the blood is the result of hemorrhage or a traumatic tap
- uneven blood distribution
- clot formation
- xanthochromic supernatant
Blood from a cerebral hemorrhage will be (evenly/unevenly) distributed throughout the three CSF specimen tubes
evenly
: traumatic tap will leave the heaviest concentration of blood in tube 1, and gradually diminishing amounts in tubes 2 and 3.
T/F:
Fluid collected from a traumatic tap may form clots owing to the introduction of plasma fibrinogen into the specimen.
TRUE
: Bloody CSF caused by intracranial hemorrhage does not contain enough fibrinogen to clot
presence of web-like pellicle in CSF is associated with?
tubercular meningitis
: pellicles can be seen after overnight refrigeration of fluid
RBCs must usually remain in the CSF for approx. how many hours before noticeable hemolysis begins?
2 hours
T/F:
A xanthochromic supernatant would be the result of blood that has
been present longer than that introduced by the traumatic tap.
TRUE
: care should be taken; a recent hemorrhage would produce a clear supernatant, and introduction of serum protein from a traumatic tap could also cause the fluid to appear xanthochromic.
color of CSF (supernatant) from a recent hemorrhage
clear
how to examine a blood fluid for the presence of xanthrochromia?
centrifuge in a microhematocrit tube
examine against a white background
Other tests used for differentiation of blood CSF from intracranial hemorrhage or traumatic tap?
Microscopic Examination
: presence of ingested RBCs (erythrophagocytosis) or hemosiderin granules = intracranial hemorrhage
D-dimer Test
: detection of fibrin degradation product D-dimer by latex agglutination immunoassay indicates fibrin formation at a hemorrhage site
Cell count routinely performed on CSF specimens
leukocyte (WBC) count
In CSF analysis, cell count must be performed immediately. WBCs (particularly granulocytes and RBCs begin to lyse within ______, and leukocytes disintegrate after ____ hours.
1 hr; 2 hours
What percentage of leukocytes in the CSF begin to disintegrate after 2 hours?
40%
T/F:
Specimens that cannot be
analyzed immediately should be frozen.
FALSE
: refrigerated
Normal WBC count in normal adult CSF
0-5 WBCs/uL
T/F:
The number of leukocytes is higher in children as compared to adults
TRUE
:as many as 30 mononuclear cells/µL can be considered normal in newborns.
T/F:
Specimens that contain up to 200 WBCs or 400 RBCs/uL may appear clear
TRUE
: so it is necessary to examine all specimens microscopically
this is routinely used for performing CSF cell counts
Improved Neubauer Counting Chamber
This have not been used for performing CSF cell counts due to high background counts and poor reproducibility of low counts
Electronic cell counters
T/F:
The standard Neubauer calculation formula used for blood cell counts is also applied to CSF cell counts to determine the number of cells per microliter
TRUE
CSF Cell Count Formula
[(# of cells counted x dilution) / (# of cells counted x volume of 1 square)] = cells/uL
The CSF cell count formula can be used for both diluted and undiluted specimens
TRUE
: it also offers flexibility in the number and size of the squares counted
T/F:
Clear specimens may be counted undiluted, provided no overlapping of cells is seen during the microscopic examinatio
TRUE
Dilutions for total cell counts are made with _________
normal saline
:then, mixed by inversion, and loaded into the hemocytometer with a Pasteur pipette
What parts of the hemocytometer are cells counted for CSF analysis?
4 corner squares and center square on both sides of the hemocytometer
T/F:
Lysis of RBCs must be obtained before performing the WBC count on either diluted or undiluted specimens.
TRUE
reagent used to lyse RBCs
3% glacial acetic acid
reagent used to stain WBCs
methylene blue
: added to the diluting fluid
: this provides better differentiation between neutrophils and mononuclear cells
how often must diluents be checked for contamination?
biweekly
Diluents are checked for contamination by examining them in a counting chamber under what magnification?
400x
T/F:
Contaminated diluents should be discarded and
new solutions must be prepared
TRUE
Speed of cytocentrifuge must be checked ______ (how often?)
monthly
used to check speed of cytocentrifuge
tachometer
: timing is checked with a stopwatch
If nondisposable counting chambers are used for CSF cell count, they must be soaked in a bactericidal solution for how long?
at least 15 minutes
: then thoroughly rinsed with water and cleaned with isopropyl alcohol after each use
Differential count on a CSF specimen is performed:
(a) on a stained smear
(b) via counting chamber
a. on a stained smear
T/F:
In differential counting on a CSF specimen, to ensure that the maximum number of cells is available for examination, the specimen should be concentrated before
preparing the smear.
TRUE
Methods available for specimen concentration
prior to differential counting on CSF specimens
- sedimentation
- filtration
- centrifugation
- cytocentrifugation
Specimen concentration method/s that are not routinely used in the clinical laboratory but produce/s less cellular distortion
sedimentation
filtration
This is a specimen concentration method performed when there is no cytocentrifuge available
centrifugation
In concentrating CSF specimens via centrifugation, how long must be the specimen centrifuged?
5-10 minutes
: supernatant fluid is removed and saved for additional tests
: slides made from suspended sediment are allowed to air dry
:stain slides with Wright’s stain
In performing CSF cell count, if the cell count is low and finding 100 cells is not possible, what must be the manner of reporting?
report only the numbers of the cell types seen
In cytocentrifugation, how much CSF is used to combine with 1 drop of 30% albumin?
0.1 mL
:already produces adequate cell yield when processed with the cytocentrifuge
The purpose of adding albumin in cytocentrifugation
increases cell yield and decreases cellular distortion frequently seen on cytocentrifuged specimen
