Cerebrospinal Fluid Analysis Flashcards

Comprehensive practice questions covering the formation, physiology, collection, appearance, and diagnostic testing of Cerebrospinal Fluid (CSF) as presented in LEC 10.

What are the three primary functions of Cerebrospinal Fluid (CSF)?

1. Supply nutrients to the nervous system.

2. Remove metabolic waste.

3. Produce a mechanical barrier to cushion the brain and spinal cord against trauma.

What are the three layers of the meninges from outermost to innermost?

Dura Mater, Arachnoid Mater, and Pia Mater.

How is the Dura Mater described in the lecture notes?

It is the outer layer that lines the skull and vertebral canal.

What is the characteristic appearance of the Arachnoid Mater?

It is a filamentous, spiderweb-like inner membrane.

Where specifically does Cerebrospinal Fluid (CSF) flow?

In the subarachnoid space, which is located between the Arachnoid Mater and the Pia Mater.

What is the function of the Choroid Plexus?

It is the specific part of the brain that produces CSF by selective filtration.

What is the normal rate of CSF production?

$$20\,mL/hr$$

What is the function of the Arachnoid Villi?

They reabsorb CSF to regulate the total amount in circulation.

Between which vertebrae is a lumbar puncture typically performed?

Between the 3rd, 4th, or 5th vertebrae.

What is the total volume of CSF in adults versus neonates?

Adults: $90-150\,mL$; Neonates: $10-60\,mL$

In a standard three-tube CSF collection, what is the destination for Tube 1?

Chemistry and Serology.

Which laboratory section receives Tube 2 of a CSF collection?

Microbiology.

What is Tube 3 traditionally used for in CSF collection?

Hematology (Cell Count).

If only one tube of CSF is collected, what is the priority order for laboratory sections?

1. Microbiology, 2. Hematology, 3. Chemistry/Serology.

Why is Microbiology the first priority when only one CSF tube is available?

To maintain sterility and prevent contamination of the specimen.

What are the storage requirements for CSF if there is a delay in testing for Chemistry/Serology?

Frozen.

How should CSF for Microbiology be stored if testing is delayed?

Room temperature.

What is the recommended storage temperature for CSF Hematology samples if testing is delayed?

Refrigerator temperature.

If there is any excess CSF fluid that needs to be stored, what is the required method?

It must be frozen.

How quickly do WBCs and RBCs begin to lyse in a CSF specimen?

WBCs and RBCs begin to lyse within an hour.

What percentage of WBCs in CSF disintegrate within 2 hours?

$$40\%$$

What is the normal appearance of Cerebrospinal Fluid?

Crystal clear.

What concentration of WBCs or RBCs can cause CSF to appear hazy, turbid, or cloudy?

WBCs $> 200/\mu L$ or RBCs $> 400/\mu L$

What does the term 'Xanthochromia' refer to in CSF analysis?

A supernatant that is pink, orange, or yellow due to the presence of RBC degradation products.

What causes pink Xanthochromia in a CSF sample?

A slight amount of oxyhemoglobin.

Yellow Xanthochromia indicates the conversion of oxyhemoglobin to what substance?

Bilirubin.

What does an oily appearance in CSF suggest?

The presence of radiographic contrast media.

The presence of a pellicle in the CSF is distinctive of which condition?

Tubular Meningitis.

How do you distinguish the blood distribution of a Traumatic Tap versus an Intracranial Hemorrhage?

Traumatic Tap shows an uneven distribution (highest in tube 1), while Intracranial Hemorrhage shows equal distribution across all tubes.

Which condition involves clot formation in the CSF: Traumatic Tap or Intracranial Hemorrhage?

Traumatic Tap (due to fibrinogen from a punctured blood vessel).

What is the normal WBC count for adults in CSF?

$$0-5\,WBCs/\mu L$$

What is the normal WBC count for neonates in CSF?

$$0-30\,WBCs/\mu L$$

What diluting fluid is used for a CSF WBC count, and what is the purpose of its components?

$3\%$ Acetic Acid (to lyse RBCs) and Methylene Blue (to stain and appreciate WBC morphology).

What is the standard diluent for a total CSF cell count?

Normal Saline Solution (NSS).

What is the formula used for correcting the CSF WBC count in a traumatic tap?

Subtract $1$ white cell for every $750$ RBCs counted.

What is the normal Lymphocyte to Monocyte ratio in an adult CSF differential count?

$$70:30$$

Which cell type is predominantly found in the CSF differential of children?

Monocytes.

In which conditions is Lymphocytic Pleocytosis commonly observed?

Viral, tubercular, and fungal meningitis.

An increased number of neutrophils in CSF is primarily associated with which condition?

Bacterial Meningitis.

Which cell type in CSF is associated with parasitic infections and some fungal infections like C. immitis?

Eosinophils.

What does an increased number of macrophages containing phagocytized RBCs (erythrophages) indicate?

Previous hemorrhage.

Where are plasma cells often found in CSF analysis?

Multiple Sclerosis.

What is the normal range for total CSF protein?

$$15-45\,mg/dL$$

What is the identified protein that is found ONLY in CSF and not in serum?

B2-Transferrin, also known as 'Tau'.

Which CSF protein is considered the major CSF protein and is used to evaluate Blood Brain Barrier (BBB) integrity?

Albumin.

What is the preferred turbidimetric method for CSF protein that precipitates both albumin and globulin?

$3\%$ Trichloroacetic Acid (TCA).

What dye is used in the dye-binding method for CSF protein, and what color change occurs?

Coomassie Brilliant Blue; the dye turns from red to blue when protein binds.

What is the formula for the CSF/Serum Albumin Index?

$$\frac{\text{CSF Albumin (mg/dL)}}{\text{Serum Albumin (g/dL)}}$$

What albumin index value indicates an intact Blood Brain Barrier?

$$< 9$$

What is the significance of a CSF/Serum IgG Index value of $\\ge 0.77$?

It indicates increased IgG production within the CNS, such as in Multiple Sclerosis.

What finding in agarose gel electrophoresis is valuable for the diagnosis of Multiple Sclerosis?

The presence of $2$ or more oligoclonal bands in the CSF that are not present in the serum.

What is the normal value for CSF glucose relative to blood glucose?

$60-70\%$ of Blood Glucose.

When should a blood glucose specimen be drawn relative to a spinal tap?

$2$ hours prior to the spinal tap.

Why is CSF glucose significantly decreased in bacterial, tubercular, and fungal meningitis?

Because the bacteria or fungi utilize the glucose for energy.

What is the normal range for CSF Lactate?

$$10-22\,mg/dL$$

How do CSF Lactate levels differentiate between types of meningitis?

Viral ($< 25\,mg/dL$), Tubercular/Fungal ($> 25\,mg/dL$), and Bacterial ($> 35\,mg/dL$).

Which chemical test is frequently performed in CSF but not in blood as an indirect measure of ammonia?

CSF Glutamine.

In CSF Glutamine physiology, what substance decreases as ammonia increases?

Alpha-ketoglutarate (it is converted into glutamine).

Elevation of which LDH isoenzymes is associated with bacterial meningitis?

LD4 and LD5.

Which CSF enzyme is elevated in cases of intracerebral and subarachnoid hemorrhage?

Aspartate Aminotransferase (AST).

What are the common causative agents of bacterial meningitis in adults according to the transcript?

S. pneumoniae, N. meningitidis, H. influenzae, and E. coli.

What are the common causative agents of bacterial meningitis in neonates?

S. agalactiae and L. monocytogenes.

What is the purpose of India Ink staining in CSF analysis?

To detect the presence of Cryptococcus neoformans (fungal infection).

What characteristic pattern does Cryptococcus neoformans produce in gram stain?

A star-burst pattern.

What does the Limulus Lysate Test detect in body fluids?

Gram-negative bacterial endotoxin.

What reagent is used in the Limulus Lysate Test?

Horseshoe Crab Blood (containing amoebocytes).

Which serologic test is recommended by the CDC for detecting active cases of neurosyphilis in CSF?

VDRL.

Why is the RPR test not recommended for CSF serologic examination?

Because it is less sensitive than VDRL.

In meningitis diagnosis, which type is specifically associated with normal glucose levels?

Viral Meningitis.

What is the clinical significance of elevated CSF Glutamine levels?

Liver disorders and Reye's Syndrome.