CSF Overview and Collection Flashcards
CSF provides a physiologic system to supply nutrients to the nervous tissue, _____ metabolic waste, and provides a ________ ______ to cushion the brain and spinal chord.
- removes metabolic waste
- mechanical barrier
What lines the brain and spinal chord?
Meninges
Name the three layers of the meninges?
- Dura mater (outside)
- Arachnoid (middle)
- Pia mater (inner)
Describe the three layers of the meniges?
- Dura mater - lines skull and verterbral canal
- Arachnoid - filamentous inner memebrane
- Pia mater - thin memebrane lining surfaces of the brain and spinal chord.
Where is CSF produced?
Choroid plexuses of the two lumbar ventricles and 3rd and 4th ventricles.
What are the choriod plexuses?
Capillary networks that form the CSF from plasma by selective filtration under hydrostatic pressure and active transport seceretion.
How much CSF is produced hourly in adults?
20 mL
CSF flows through the _________ ________ located between the arachnoid and pia mater.
subarachnoid space
To maintain a volume of _______ in adults and _______ in neonates, the circulating fluid is reacbsorbed back into the blood capilaries in the arachniod granulations/villae at a rate equal to its production.
- 90 - 150 mL
- 10 - 60 mL
The cells of the arachnoid granualtions act as one-way valves that respond to and prevent what?
- pressure in CNS
- prevent reflex of fluid
The choriod plexuses endothelial cells have very tight fitting junctures that prevent?
prevents the passage of many molecules
What is the tight fitting structure of endothilial cells in the choriod plexus called?
Blood-brain barrier
Give an example of two diseases that can disrupt the blood brain barrier?
- Meningitis
- Multiple sclerosis
How is CSF collected?
Which vertebrae?
- Lumbar puncture
- Between the 3rd, 4th or 5th vertebrae
What precaustions are taken prior to a lumbar puncture? (2)
- Measurement of intracranial pressure
- careful technique to prevent introduction of infection or damage of neural tissue
The volume of CSF that can be removed is based on? (2)
- volume avaiable in a patient (adult vs. neonate)
- opening pressure of CSF when needle first enters the subarachnoid space.
Specimens are collected on three sterile tubes. What tests is each tube used for and how is each preserved temperature wise?
- Tube 1 - chemical and serological tests; least affected by blood/bacteria introduced as a result of tap. FROZEN
- Tube 2 - Microbiology, ROOM TEMP
- Tube 3 - Cell count (hematology), FRIDGE
- Tube 4 - microbiology for additional testing and better exclusion of contamination.
Describe the appearance of CSF?
Crystal clear
A cloudy, turbid, or milky CSF specimen can be the result of?
- Increased protien / lipid concentration
- Infection (WBCs cause turbidity)
Xanthochromia is used to describe CSF that is?
- Pink
- Orange
- Yellow
What is the most common cause of xanthochromia?
Describe varying color changes?
RBC degredation products
- Pink - very slight oxyhemoglobin
- Orange - heavy hemolysis
- Yellow - oxyhemoglobin converted to unconjugated bilirubin
Apart from RBC degredation, what are other causes for xanthochomia in CSF? (4)
- Elevated serum bilirubin
- the presence of pigment carotene
- markedly increased [protein]
- melanoma pigment
Grossly Bloody CSF is indicative of?
- Intracranial hemorrhage
- blood vessel puncture from spinal tap
How do you differentiate between intracranial hemorrhage and a traumatic tap?
Three visual examinations of the collected specimens can usually determine this:
- Blood from cerebral hemorrhage is evenly ditributed
- Traumatic tap - blood heaviest conc. in forst tube, with decreasing amounts in tubes 2 and 3
Why might CSF from a truamatic tap form clots?
Does it clot from intracranial hemorrhage?
- Due to introduction of fibrinogen into specimen
- Bloody CSF from intracranial hemorrhage does not contain enough fibrinogen to clot.
What conditions damage the blood-brain barrier, allowing the filtration of protien and coagulation factors causing clot formation, but not bloody CSF? (3)
- Meningitis
- Froin syndrome
- Blockage of CSF circulation
How long can RBCs remain in CSF before noticable hemolysis?
2 hours
A classic web-like pellicle that can be seen in CSF after overnight refridgeration is associated with?
Tubercular meningitis
What is another way of differentiating intracranial hemmorage from traumatic tap? (2)
- D-Dimer test
- By latex agglutination immuno assay indicated formation of fibrin at hemorrhage site.
- microscopic finding of marophages w/ ingested RBCs or hemosiderin granules indicates intracranial hemorrhage
What cell count is routiely done on CSF?
When is an RBC cell count done?
- WBC count
- determined only when traumatic tap occured and need to correct leukocytes or protiens.
Why should a cell count be performed immediately?
WBCs (esp. granulocytes) and RBCs begin to lyse w/i 1 hour anf 40% WBCs disintegrate after 2 hours
Normal CSF range for WBCs?
0 - 5 WBCs uL (number is higher in children as manay as 30 mononuclear cells/ uL in neonates)
Calculation of CSF Cell counts?
Can this be used on diluted and undiluted specimens?
- Nebauer calculation
- # cells counted x dilution factor / # of sqs. counted (5) x vol. of sq. (0.1) = cells /uL
- Yes
What is used for the lysis of RBC cells prior to performing the WBC count?
Glacial acetic acid
Correction for contamination calculation?
- WBC (added) = WBC (blood) x RBC (CSF) / RBC (Blood)
- Calculate artificially added WBCs by comparing WBC to RBC ratio in periperal blood and compare with ratio of contaminating RBCs.
QC: How often should all diluents be checked?
How often is centrifuge checked?
How are non-disposable counting chambers cleanned?
- Bi-weekly, under microcopic examination for contaminants
- monthly using a tachometer for speed and w/ a timer for timing
- bactericidal solution soak for 15 minutes then rise w/ water and isopropyl alcohol
Differential: to ensure that the maximum number of cells are available for examination, what should be done with the specimen prior to smear prep?
Concentrated prior to prep of smear.
How many cells are counted for the CSF differential?
100
Why is albumin added for the cytocentrifugation?
The addition of albumin increases cell yield and decreases cellular distortion
What cells arefound in normal CSF and their ratios in adults and children?
- Lymphocytes and monocytes
- Adults have predminance of lymp. to mono at 70:30
- Children have predominance of lymp to mono at 70:30
What is Pleocytosis?
The presence of increased #s of normal cells and is considered abnormal, as is finding immature leukocytes, eos, plasma cells, marcrophages, increased tissue, and malignant cells.
A high WBC count, with the majority of cells being neutrophils is indicative of?
Bacterial menigitis
A moderately elevated CSF WBC count with a high percentage of lyphocytes and monocytes suggests?
Menigitis of viral, tubercular, fungal or parasitic origin
These cells are from the epitelial lining of the choroid plexus?
Choroidal cells
These cells are from the lining of the ventricles and neral canal?
Ependymal cells
These cells represent the lining from the arachnoid. They are usually seen in clusters with systemic malignancies.
Spindle-shaped cells
Lymphoblasts, myeloblasts, and monoblasts in the CSF are frequently seen in the case of?
Acute leukemia
What is the most frequenly performed test on CSF?
Protien determination
What are the normal values for total CSF protien?
15 - 45 mg/dL
What protein makes up the majority of SF protien?
Albumin
Abnormally values of protien are indicative of?
fluid leaking from the CNS
What conditions damage the blood brain barrier?
- Menigitis
- Hemorrhage
What test is used to determin whether IgG is elevated due to its prodution in the CNS or defect in the blood-brain barrier?
It evaluates the integrity of the blood brain barrier
Serum/albumin index
CSF/serum albumin index = CSF albumin (mg/dL) / Serum albumin (g/dL)
Serum/albumin index: What value represents an intact blood brain barrier?
index value <9
Index increases relative to the damage to the blood-brain barrier
What values are indicative of IgG production within the CNS?
>0.7
The presence of what in CSF that are not present in serum is indicative of multiple sclerosis?
- Oligoclonal bands (CSF Protein Electrophroesis)
- Bands appear in gamma region
Myelin Basic Protein (MBP) in the CSF is indicative of?
Recent destruction of the myelin sheath that protets the axons of neurons.
Measurement of what in CSF can be used to monitor the progression of Multiple Sclerosis?
This also measures the effectiveness of current and future treatments.
MBP
How does glucose enter the CSF?
What is the normal value CSF glucose compared to plasma glucose?
What is run for comparison?
- Seletive transport across the BB barrier.
- 60 - 70% of plasma glucos (e.g. if plasma glucose is 100 mg/dL, CSF glucose wuld approx. be 65 mg/dL)
- Blood glucose test
