Lecture 5 Flashcards
What is CSF
clear and colorless
surrounds the brain
formed by ependymal cells
how is csf produced
chroid plexus
ultrafiltrate of plasma
clinical importance of csf
changes are systemic changes with a lag compared to serum - especially for glucose and serum
What are the three layers of the meninges
Dura Mater: outermost and closest to the skull.
Arachnoid: middle layer with spider web-like appearance.
Pia Mater: delicate inner layer attached to the CNS.
functions of csf
support - acts as cushion , absorbs shock
Excretion - removes waste
environment - maintains control environment
transport- nutrients and hormones
what is the BBB
-physiological barrier separating the ECF and CNS parenchyma
has selective permeability with some needing active transport - glucose
-factors like molecular weight, protein binding and lipid solubility affect how things cross
what can affect BBB permeability
inflammation
neovascularity
toxins
developmental stages
changes are important for diagnosing CNS diseases
why would you need to look at the csf
Trauma: Intracranial bleeding, subarachnoid hemorrhage.
Infectious Diseases: Meningitis (bacterial, viral, fungal), encephalitis, AIDS, Lyme disease.
Inflammatory Diseases: Multiple sclerosis.
Malignancy: Tumors, metastatic cancer.
Hydrocephalus: Obstructed CSF leading to increased brain pressure
What tubes are used for csf
-collected via lumbar puncture between c3 and c4
3 tubes collected for different tests
1- chem glu pt
2-micro - c&s
3- hem - cell count
What do you look for in a macroscopic examination of CSF
Color
normal - colorless
Xanthochromia - yellow =old blood breakdown
Red- blood present - traumatic tap
Transparency
cloudy- cells, bacteria high protein
Clots- poor puncture
Pellicle- TB meningitis
What do you look for in a microscopic examination
micro - gram for bacterial, viral or TB
Hem for cell count, diff staining (wright stain for cancer)
Biochemical testing of CSF - glucose
routine biochem test - glu and tp
plasma glucose take 2 hours to be reflected in csf
Glucose is decreased in
Bacterial meningitis - bacterial eat the glucose
Fungal and TB meningitis
glucose normal or slightly decreased in
Viral meningitis, MS and subarachnoid hemorrhage
Glucose is measured by
glucose oxidase method- glucose in csf reacts with O2 and H2O-= gluconic acid and h2o2 which react with chromogen = glucose concentration
Hexokinase - phosphorylation of glucose to g6p by hexokinase and G6P is oxidized by NAD to NADH increase in ABs at 340 proportional to concentration
Sources of Error in measurement methods
Glucose Oxidase- affected by reducing substances like ascorbic acid, bilirubin, glutathione, uric acid, and hemoglobin, can
lead to falsely low glucose readings
Hexokinase method- not affected much by reducing substances but hexoses like fructose and gross hemolysis can impact
Blood contamination - blood in CSF falsely increases glucose as there is a higher glucose presence in blood
Delayed Analysis- glycolysis in csf sample can decrease glucose if there is delay in processing
why is protein measurement in csf important
indicated neurological disease
-in healthy people protein cant get into csf due to BBB
-normal RI can vary due to method and instrument used.
When will you see increase protein in csf
Bacterial, Fungal, and TB Meningitis: Marked elevation due to the increased
permeability of the BBB.
Viral Meningitis: Moderate elevation.
Multiple Sclerosis: Mild to moderate elevation
Subarachnoid Hemorrhage: due to the presence of blood in CSF.
Tumors, Abscesses, and CNS Degenerative Diseases: due to increased production or decreased
clearance of proteins.
when would you see Decreased Protein Levels
CSF Leak or Hyperthyroidism (increase production leading to dilution)
Measurement Methods for TP in CSF
Turbidimetric method: proteins in CSF cause turbidity and when mixed with acids like trichloroacetic acid the degree of turbidity is measure photometrically
Dye binding methods: prot bind to coomassie brilliant blue or Ponceau S = color change measured spectrophotometrically
Electrophoresis
-proteins separated based on size and charge which helps with MS diagnosis (olig)
Sources of Error when measuring TP
Contamination - blood contamination falsely increases
method errors - different methods diff answers makes sure everything is consistent
significance of decreased CL in CSF
Tuberculous Meningitis: A marked reduction in CSF chloride can be seen, - diagnostic marker.
Bacterial Meningitis: Mild to moderate decrease.
Cerebral Edema or Brain Tumor: due to
altered electrolyte transport across the blood-brain barrier.
Increased CSF Chloride:
Dehydration or Hyperchloremic Acidosis: Elevated chloride levels can be
observed.
Measurement Methods: of csf CL
Ion-Selective Electrodes (ISE):
o Chloride levels are most accurately measured using ion-selective electrodes,
rapid and precise readings.
Sources of Error in CL measurement
Contamination: contamination with plasma or other fluids can alter chloride
levels.
Sample Handling: Delays or improper storage can lead to changes in electrolyte
concentrations, affecting the accuracy of the results.
CSF Immunoglobulin
IgG
-diagnosis of inflammatory
and autoimmune diseases of the central nervous system
Oligoclonal Bands (OCBs):
bands of immunoglobulins detected in the CSF but not in
the serum, indicative of intrathecal antibody production.
Clinical Significance:
of OLIG
Multiple Sclerosis (MS): The presence of OCBs is a hallmark of MS, found in
approximately 90% of patients. diagnostic criteria for MS.
Other Inflammatory CNS Conditions: OCBs can also be present in conditions like
neurosyphilis, chronic CNS infections, and autoimmune encephalitis.
Measurement Methods: of OLIG
Isoelectric Focusing (IEF) with Immunoblotting:
The gold standard for detecting OCBs where you separate proteins by their
isoelectric point and identifyimmunoglobulines with specific antibodies.
Sources of Error for OLIG
Blood Contamination: The presence of plasma proteins can complicate the
interpretation of OCBs.
Cross-Contamination: handle carefully to avoid cross-contamination
between patient samples, which could lead to false-positive results.
CSF Cytology and Flow Cytometry what does it do
examination of cells in the CSF
Normal Findings: in cytology
Lymphocytes and Monocytes: In a healthy individual, CSF predominantly contains small
numbers of lymphocytes and monocytes.
Clinical Significance: of looking at cells
Malignant Cells:
in CNS Tumors: finding malignant cells for primary brain tumors or metastasis to the CNS
Leukemia and Lymphoma: detected in the CSF in
patients with hematological malignancies
Clinical Significance: of looking at cells
Infectious Agents:
Fungal Infections: Fungal elements like Cryptococcus can be identified.
Bacterial Infections: Gram-negative bacteria or acid-fast bacilli in cases of
tuberculosis can be detected.
how is Flow Cytometry used for CSF testing
immunophenotyping
cells, looking at cell populations, useful in leukemia and lymphoma.
Sources of Error: in flow cytometery
Sample Handling: processing delays lead to cell lysis, resulting in poor-quality samples for cytological examination.
Contamination: Care must be taken to avoid contamination with external cells or
pathogens.
Subarachnoid Hemorrhage (SAH):
what will you see in CSF
Xanthochromia: yellow CSF due to the breakdown of hemoglobin to bilirubin is a key feature of SAH. detected spectrophotometrically.
Elevated Protein: Due to the presence of blood, protein levels are elevated.
Multiple Sclerosis (MS):
what will you see in CSF
Oligoclonal Bands (OCBs): , the presence of OCBs in the CSF but not
in the serum is indicative of MS.
Increased IgG Index: The IgG index is calculated to assess intrathecal IgG synthesis, which is elevated in MS.
Bacterial Meningitis
what will you see in CSF:
Elevated CSF protein, decreased glucose, increased WBC count mostly neutrophils.
Gram stain and culture are used for pathogen ID.
Viral Meningitis
what will you see in CSF:
Normal or slightly elevated protein, normal glucose, and increased WBC count
with a lymphocytic predominance.
PCR is used for viral pathogen detection.
Guillain-Barré Syndrome (GBS):
what will you see in CSF:
Albuminocytologic Dissociation: Elevated CSF protein with a normal cell count is
characteristic of GBS.
- Electrophysiological Studies: Complementary to CSF analysis, these studies help
confirm the diagnosis
What is CSF Protein Electrophoresis used for
to identify specific protein patterns in the CSF, aiding
in the diagnosis of various neurological conditions
Normal Protein Patterns: in CSF protein electrophoresis
Albumin: The most prominent protein in the CSF
- Prealbumin, Transferrin, and Transthyretin: present in smaller quantities.
Clinical Significance:
* Oligoclonal Bands (OCBs)
in CSF protein electrophoresis
presence can indicate
multiple sclerosis and other inflammatory CNS diseases.
Clinical Significance:
Increased Alpha-2 Globulin:
in CSF protein electrophoresis
Acute Phase Response:
An increase in alpha-2 globulin indicates acute phase response in CNS infections or inflammation.
Clinical Significance:
Monoclonal Bands:
in CSF protein electrophoresis
CNS Lymphoma or Paraproteinemia: presence of monoclonal
immunoglobulin bands suggest CNS lymphoma or systemic
paraproteinemia with CNS involvement.
Interpretation of Abnormal Patterns
in CSF protein electrophoresis
Albuminocytologic Dissociation:
o Seen in Guillain-Barré Syndrome (GBS), marked increase in
CSF protein without a corresponding increase in cell count.
Beta-2 Transferrin:
o Specific for CSF, used to confirm the presence of CSF in nasal or ear
discharge, in cases of suspected CSF leak.
Sources of Error
in CSF protein electrophoresis
Sample Contamination: Contamination with blood or plasma can introduces extraneous
proteins, complicating the interpretation of results.
- Degradation of Proteins: Improper storage or delays in analysis can lead to protein degradation, affecting the accuracy of electrophoresis.
CSF lactate
critical marker used to distinguish between different types of meningitis and other conditions affecting the central nervous system.
Clinical Significance:
* Elevated Lactate Levels:
Bacterial Meningitis: Significantly elevated lactate levels (>3.5 mmol/L) are often
indicative of bacterial infection.
o Fungal and Tuberculous Meningitis: moderate
o Hypoxia and Ischemic Conditions: due to anaerobic metabolism
under conditions of reduced oxygen supply.
Normal Lactate Levels: mean
helps with differential diagnosis.
Sources of Error while measuring lactate
Delay in Analysis: Lactate levels can increase if the CSF sample is not analyzed promptly
due to ongoing glycolysis by cells in the fluid.
- Blood Contamination: Can falsely elevate lactate levels if the sample is contaminated
with blood.
CSF Cell Count and Differential needed to
diagnosing infections,
hemorrhages, and inflammatory conditions affecting the CNS.
there are no RBCs in a persons csf
Clinical Significance:
* Elevated WBC Count (Pleocytosis):
in cell count
Bacterial Meningitis: Marked increase, mostly neutrophils.
o Viral Meningitis: Increase with lymphocytes
o Fungal and TB Meningitis: Lymphocytes
.
o Subarachnoid Hemorrhage and CNS Malignancies: increase in both WBCs and RBCs.
Measurement Methods of cell count
manual under a microscope
automated
Sources of Error:
in cell count
Traumatic Tap: Can introduce blood into the CSF sample,
- Sample Handling: Delays lead to cell lysis, which may affecting count accuracy
increase of Myelin Basic Protein (MBP): means
demyelinating diseases such as MS
Lactate Dehydrogenase (LDH):
o Increased LDH
indicate cell damage or breakdown, seen in bacterial meningitis, CNS tumors, and
subarachnoid hemorrhage. distinguished between viral and bacteria (higher)
-can increase after traumatic brain injury reflecting extent of damage
ISOENZYMES can pinpoint source if from brain or systemic circulation
: Increased CK-BB Isoform
Specific for the brain, elevated
indicate CNS injury or infarction
can increase after traumatic brain injury reflecting extent of damage
Neurotransmitters:
* Serotonin (5-HT):
decreased
depression, anxiety disorders, and other
psychiatric conditions
Neurotransmitters: Dopamine:
o Decreased Levels:
Parkinson’s disease and other movement disorders
Glutamate:
o Increased Levels
h excitotoxicity in conditions like stroke,
traumatic brain injury, and epilepsy
o Beta-Amyloid (Aβ42)
Tau Protein:
Beta-Amyloid (Aβ42) Decreased levels indicate Alzheimer’s deposition of amyloid plaques in the brain.
Tau Protein: increased levels markers of neurofibrillary tangles and neuronal injury in Alzheimer’s disease.
ELISA (Enzyme-Linked Immunosorbent Assay):
csf biomarkes
o Alpha-Synuclein
o DJ-1 Protein
o Alpha-Synuclein-hallmark of Parkinson’s disease can be seen at different levels in CSF
o DJ-1 Protein- biomarker for Parkinson’s disease,
reflecting oxidative stress and neuronal damage.
o Neurofilament Light Chain (NFL)
axonal damage increased in ALS and motor diseases
