Cerebrospinal Fluid Flashcards
What is cerebrospinal fluid?
Clear, colorless fluid between the arachnoid and the pia mater in the brain and spinal cord. It is contained within the subarachnoid space.
What are the two components where CSF is made?
(1) Production by choroid plexus cells and ependymal lining cells (30%)
(2) Selective secretion from plasma into the ventricles and choroid plexus (70%)
(T/F) CSF is an ultrafiltrate of plasma.
False, CSF is NOT an ultrafiltrate of plasma
How much (volume) total CSF is contained within adults?
85-150 mL
How much (volume) total CSF is contained within neonates?
10-60 mL
Where does CSF circulate?
Circulates to brainstem and spinal cord
What are the functions of CSF?
(1) Protects the brain and spinal cord: acts as a mechanical buffer to prevent trauma; regulates volume of fluid present; helps with intercranial pressure
(2) Transports and exchange nutrients and waste: blood brain barrier (regulates the flow of particles between the blood and nervous system)
(3) Stable chemical environment: homostatic functions
What are some reasons why CSF may be collected?
(1) Infection
(2) Hemorrhage
(3) Neurologic disease
(4) Malignancy
(5) Tumor
(6) Treatments
Where in the spine is CSF collected in adults?
3rd or 4th lumbar interspace
Where in the spine is CSF collected in children?
4th or 5th lumbar interspace
What is the pressure reading that should be obtained prior to collecting CSF?
50 to 180 mmHg
If the pressure of CSF collection is between 50 and 180 mmHg, how much CSF can be collected?
About 20 mL
If the pressure of CSF collection is less than/greater than between 50 and 180 mmHg, how much CSF can be collected?
1 to 2 mL
What will happen if CSF remains at room temperature?
40% of WBCs in CSF will lyse in 2 hours
What storage temperature of CSF will yield the best recovery of viable organisms?
Room temperature
What will happen if CSF is refrigerated?
15% of WBCs in CSF will lyse
What are some other special considerations when testing CSF?
(1) Clotted specimens
(2) Low volume specimens
When testing CSF, what is tube 1 primarily used for?
Chemical, immunology, and serology
When testing CSF, what is tube 2 primarily used for?
Microbiological studies
When testing CSF, what is tube 3 primarily used for?
Cell counts and cytology studies
When testing CSF, what is tube 4 primarily used for?
Miscellanous testing
What is the color or normal CSF?
Colorless
Define xanthachromia
Yellow, orange, or pink discoloration
What is xanthachromia indicative of?
Bilirubin i.e. lysed blood cells present
Xanthachromia is neonates is indicative of what?
Increased bilirubin and increased protein due to immaturity of blood-brain barrier.
Define pleocytosis
An increase in the number of cells in CSF
What is the grading system used to determine the clarity of CSF?
Graded 0 (clear) to 4+ (cannot see through fluid)
What are some characteristics of a traumatic tap?
(1) Amount of blood decreases/clears progressively from first to last tube
(2) Streaking of blood in CSF during collection
(3) CSF may clot
(4) Usually no xanthrochromia
(5) No hemosiderin present
What are some characteristics of a hemorrhage CSF collection?
(1) Amount of blood is the same in all collection tubes
(2) Blood is evenly dispersed during collection
(3) CSF does not clot
(4) Xanthochromia present
(5) Present of hemosiderin-laden macrophages AKA siderophages
What is the reference range for total protein in CSF?
15-45 mg/dL
At what age do infants and adults generally often have higher protein concentration?
> 40 years old
What is total protein in CSF assessing?
Assesses the integrity of blood brain barrier
Increased total protein may indicate what?
(1) Contaminated specimen (blood)
(2) Altered capillary endothelial exchange
(3) Decreased reabsorption into the venous blood
(4) Increased synthesis in the central nervous system (CNS)
Decreased total protein may indicate what?
(1) Increased reabsorption through the arachnoid villi because of increased intracranial pressure
(2) Loss of fluid due to trauma or invasive procedures
What is the reference protein for permeability of blood brain barrier?
Albumin
(T/F) No albumin is synthesized in the CNS
True
What is the calculation for CSF/serum albumin index?
Albumin[CSF] (mg/dL)/Albumin[serum] (g/dL)
An CSF/serum albumin index of <9
Considered normal
CSF/serum albumin index of 9-14
Minimal impairment of blood brain barrier
CSF/serum albumin index of 15-100
Moderate to severe impairment
CSF/serum albumin index >100
Complete breakdown of barrier
(T/F) Immunoglobin G (IgG) is normally present in CSF in very large amounts
FALSE, IgG is present in very small amounts (~1 mg/dL)
What is the calculation for CSF IgG index?
What is the normal index range for CSF IgG?
0.30 to 0.70
What does an increase CSF IgG index represent?
Increased intrathecal production, multiple sclerosis, and/or inflammatory neurological disorders
What does a decreased CSF IgG index represent?
Compromised blood-brain barrier
What are the four predominate bands in normal CSF pattern for protein electrophoresis?
(1) Transthyretin (TTR)
(2) Albumin
(3) Two distinct transferrin bands (T-transferrin only present in CSF)
What is the primary purpose for protein electrophoresis in CSF?
Detect oligoclonal bands
When oligoclonal bands are present in CSF and absent in serum, what condition is that indicative of?
Multiple sclerosis
What is the reference range for CSF glucose?
50-80 mg/dL
How does glucose enter CSF?
(1) Active transport by endothelial cells
(2) Simple diffusion along concentration gradient
What is the normal value for CSF/plasma glucose ratio?
~6
What is increase glucose indicative of?
Hyperglycemia, traumatic tap (blood contamination)
What is decreased glucose indicative of?
(1) Decreased/defective transport across blood-brain barrier and increased glycolysis within CNS
(2) Hypoglycemia
(3) Meningitis
(4) Tumor
What is the reference range for lactate in CSF?
10-22 mg/dL
Increased lactate in CSF is indicative of what?
Anaerobic metabolism within CNS due to tissue hypoxia/decreased oxygenation
What is the range for lactate in CSF for someone who may have viral meningitis?
~25 - 30 mg/dL
What is the range for lactate in CSF for someone who may have bacteria/fungal meningitis?
> 35 mg/dL
What is a normal CSF WBC count in adults?
0-5 WBCs/uL
What is a normal CSF WBC count in children?
0-10 WBCs/uL
What is a normal CSF WBC count in neonates?
0-30 WBCs/uL
What is a normal CSF RBC count?
None (0)
What is the WBC differential procedure for CSF?
(1) Scan slide on 10x; helps in detecting abnormalities - plasma cells, malignant cells, cell clumps, etc.
(2) Perform differential on 100x; may not be about to count 100 cells depending on total cell count
What are some infectious causes of seeing neutrophils in CSF?
Meningitis, cerebral abscess
What are some non-infectious causes of seeing neutrophils in CSF?
Hemorrhage, tumor, intrathecal treatment (drug administration in spinal cord)
What is the most common cell found in CSF?
Lymphocytes
What are some infectious causes of seeing lymphocytes in CSF?
Meningitis (viral, tuberculosis, fungal, syphilitic), HIV/AIDS
What are some non-infectious causes of seeing lymphocytes in CSF?
Multiple Sclerosis, Guillain-Barre syndrome, lymphoma, drug abuse
What are some infectious causes of seeing monocytes in CSF?
Meningitis
What are some non-infectious causes of seeing monocytes in CSF?
Tumor
What are some characteristics of lymphocytes within a microscopic examination of CSF?
(1) High N:C ratio
(2) Oval/round nuclear shape
(3) Smaller in overall size
(4) Dense chromatin pattern
What are some characteristics of monocytes within a microscopic examination of CSF?
(1) Low N:C ratio
(2) Irregular nuclear shape
(3) Larger in overall size
(4) Less dense chromatin pattern
Identify the following indicated CSF cell
Plasma Cell
(T/F) Plasma cells are not normally in CSF
True
What are some infectious causes of seeing plasma cells in CSF?
Tuberculous and Syphilitic Meningitis
What are some non-infectious causes of seeing plasma cells in CSF?
Multiple Sclerosis, Guillain-Barre syndrome
What are some infectious causes of seeing eosinophils in CSF?
Parasitic infections, fungal infections, Idiopathic eosinophilic meningitis
What are some non-infectious causes of seeing eosinophils in CSF?
Allergic reaction, lymphoma, leukemia
What are some infectious causes of seeing macrophages in CSF?
Tubercular meningitis, fungal meningitis
What are some non-infectious causes of seeing macrophages in CSF?
Response to RBCs and lipids in CSF, treatments
What are some results of seeing malignant cells within CSF?
CNS tumor, metastasis (melanoma, lung, breast, GI, leukemia, lymphoma
Microscopically, what is the difference between choroid plexus/ependymal cells and malignant cells?
(1) Distinct borders
(2) Chromatin evenly dispersed
(3) “Window” between cells
What common staining technique is used for microbial testing?
Cytospin slide with gram stain
(T/F) It is okay to start a patient on antibiotics prior to CSF collection
FALSE, you should always collect the CSF specimen prior to starting antibiotics
What is the gold standard for testing CSF for bacterial and fungal meningitis?
CSF gram stain and culture
