CSF in Disease Diagnosis

Question 1

What is the total volume of cerebrospinal fluid (CSF) in adults?

Answer 1

Total volume in adults ≈135-150ml.

Question 2

Where is CSF produced?

Answer 2

CSF is produced by the choroid plexuses in the lateral ventricles.

Question 3

How does CSF flow through the brain and spinal cord?

Answer 3

CSF flows through the third and fourth ventricles into the sub-arachnoid space and surrounds the brain and spinal cord.

Question 4

How is CSF reabsorbed into the circulation?

Answer 4

CSF is reabsorbed into the circulation by arachnoid villi.

Question 5

What are the functions of CSF?

Answer 5

Functions of CSF include buoyancy, protection, chemical stability, and prevention of brain ischemia.

Question 6

What is the actual brain mass and the weight of the brain suspended in CSF?

Answer 6

The actual brain mass is 1400g, and the weight suspended in CSF is 25g.

Question 7

What conditions can CSF analysis help diagnose?

Answer 7

CSF analysis can help diagnose meningitis, encephalitis, CNS or metastatic tumors, syphilis, bleeding in the brain and spinal cord, Guillain-Barre syndrome, unexplained seizures, and infected skin at the lumbar puncture site.

Question 8

What are the contraindications for lumbar puncture?

Answer 8

Contraindications for lumbar puncture include severe pulmonary or lumbar disorders, focal neurologic deficits, and immunocompromised states.

Question 9

What are some possible complications of a lumbar puncture?

Answer 9

Possible complications of a lumbar puncture include post-tap headache, vomiting, epidural hematomas, subdural or subarachnoid hemorrhage, acute neurologic or respiratory deterioration, cerebral herniation, and infection or abscess formation.

Question 10

Describe the procedure for CSF collection and transport.

Answer 10

CSF collection and transport should be performed aseptically by an experienced medical officer, and the sample should be transported immediately to the lab.

Question 11

What preparation is necessary before performing a lumbar puncture?

Answer 11

Before performing a lumbar puncture, rule out contraindications, perform a CT scan if necessary, and inform the laboratory staff.

Question 12

What is the correct patient position for a lumbar puncture?

Answer 12

The patient should be positioned on their left side with their back on the edge of the bed and fully flexed (knee to chin) or in a sitting position for patients with pulmonary disorders or young infants.

Question 13

What is the landmark for needle insertion during a lumbar puncture?

Answer 13

The landmark for needle insertion is the plane of the iliac crest through the L4-L5 intervertebral space.

Question 14

What are the steps for sterilizing the site for a lumbar puncture?

Answer 14

Sterilize the site with tincture of iodine or methylated spirit in a circular outward motion.

Question 15

What type of bottles are used for CSF collection and what should they contain?

Answer 15

CSF collection bottles should include a sterile bottle, lithium heparin, EDTA bottle, and a fluoride oxalate bottle.

Question 16

What is the correct needle size for a lumbar puncture?

Answer 16

A 22G spinal needle with a stilette is used for a lumbar puncture.

Question 17

How is the CSF pressure measured during a lumbar puncture?

Answer 17

CSF pressure is measured with a manometer (90-180 mmH2O).

Question 18

What should be done after collecting the CSF sample?

Answer 18

After collecting the CSF sample, send it promptly for analysis, lie the patient flat for 15-30 minutes, check CNS observations and BP, and ask about headaches.

Question 19

Describe the appearance of normal CSF.

Answer 19

Normal CSF is clear and colorless.

Question 20

What does red or bloody CSF indicate?

Answer 20

Red or bloody CSF indicates a traumatic tap or subarachnoid hemorrhage (SAH).

Question 21

What does turbid or cloudy CSF suggest?

Answer 21

Turbid or cloudy CSF suggests acute pyogenic meningitis.

Question 22

What is xanthochromia and what can it indicate?

Answer 22

Xanthochromia is a pink/orange/yellow colored CSF and can indicate RBC lysis, SAH, ICH, or increased bilirubin levels.

Question 23

What does the presence of a coagulum or viscous CSF indicate?

Answer 23

A coagulum or viscous CSF indicates high protein content, often seen in TB meningitis or CNS tumors.

Question 24

What is the normal glucose level in CSF?

Answer 24

Normal glucose level in CSF is approximately 2/3 of fasting plasma glucose.

Question 25

What glucose level in CSF is often associated with bacterial and fungal meningitis?

Answer 25

A glucose level below 40mg/dl in CSF is often associated with bacterial and fungal meningitis and malignancy.

Question 26

What are some causes of high protein levels in CSF?

Answer 26

High protein levels in CSF are seen in bacterial and fungal meningitis, tuberculosis, tumors, subarachnoid hemorrhage, traumatic tap, abscess, and multiple sclerosis.

Question 27

How is glucose estimation in CSF performed in the lab?

Answer 27

Glucose estimation in CSF is performed using the oxidase or hexokinase method.

Question 28

How is protein estimation in CSF performed in the lab?

Answer 28

Protein estimation in CSF is performed using the sulpho salicylic acid or triacetic acid method, or by electrophoresis for suspected monoclonal gamopathy.

Question 29

What does an increased level of lactate in CSF indicate?

Answer 29

Increased lactate in CSF indicates bacterial and fungal meningitis.

Question 30

What conditions are associated with elevated lactate dehydrogenase in CSF?

Answer 30

Elevated lactate dehydrogenase in CSF is associated with bacterial and fungal meningitis, malignancy, and subarachnoid hemorrhage.

Question 31

What initial test is done when CSF is cloudy?

Answer 31

The initial test for cloudy CSF is a Gram smear.

Question 32

How should a Gram smear be prepared and stained?

Answer 32

A Gram smear should be prepared by centrifuging the sample, transferring the sediment to a slide, air drying, alcohol-fixing, and staining with Gram technique.

Question 33

What type of bacteria can be identified using a Gram smear?

Answer 33

Gram smears can identify G -ve intracellular diplococci (N. meningitidis), G +ve diplococci (S. pneumoniae), G -ve rods (H. influenzae, E. coli), and yeast cells (C. neoformans).

Question 34

What is the significance of finding yeast cells in a Gram smear?

Answer 34

The presence of yeast cells in a Gram smear indicates cryptococcal meningitis.

Question 35

How should CSF be cultured?

Answer 35

CSF should be cultured ASAP on chocolate agar, blood agar, and MacConkey agar, and incubated accordingly.

Question 36

What conditions make a CSF sample unsuitable for cell count?

Answer 36

Heavily blood-stained or clotting CSF samples are unsuitable for cell count.

Question 37

What stains are recommended for diluting CSF during cell count?

Answer 37

Isotonic 1% toluidine blue or isotonic methylene blue stains are recommended for diluting CSF during cell count.

Question 38

How is a CSF cell count performed using a counting chamber?

Answer 38

CSF cell count is performed using a modified Fuchs-Rosenthal ruled counting chamber and a microscope.

Question 39

What is the purpose of Ziehl-Neelsen staining in CSF analysis?

Answer 39

Ziehl-Neelsen staining is used when TB meningitis is suspected.

Question 40

What are the steps for preparing a Ziehl-Neelsen smear?

Answer 40

Ziehl-Neelsen smear preparation involves centrifuging CSF, transferring sediment to a slide, fixing with methanol, and staining with ZN stain.

Question 41

How is cryptococcal meningitis suspected and confirmed using CSF?

Answer 41

Cryptococcal meningitis is suspected with yeast cells on Gram smear and confirmed with India ink preparation.

Question 42

What culture media are used for growing different bacteria from CSF?

Answer 42

Chocolate and Blood agar cultures can identify N. meningitidis, S. pneumoniae, and H. influenzae.

Question 43

What are the typical appearance and lab findings for normal CSF?

Answer 43

Normal CSF is clear and colorless with <5x10^6/L lymphocytes, 0.15-0.4 g/L protein, and 2.5-4.0 mmol/L glucose.

Question 44

What are the typical appearance and lab findings for pyogenic bacterial meningitis?

Answer 44

Pyogenic bacterial meningitis CSF is purulent/cloudy with many pus cells, high protein, and very low glucose.

Question 45

What are the typical appearance and lab findings for viral meningitis?

Answer 45

Viral meningitis CSF is clear or slightly turbid with increased lymphocytes, normal or increased protein, and usually normal glucose.

Question 46

What are the typical appearance and lab findings for tuberculosis meningitis?

Answer 46

Tuberculosis meningitis CSF is clear or slightly turbid with increased lymphocytes, high protein, and reduced glucose.

Question 47

What are the typical appearance and lab findings for cryptococcal meningitis?

Answer 47

Cryptococcal meningitis CSF is clear or slightly turbid with increased lymphocytes, high protein, and reduced glucose.

Question 48

What causes hydrocephalus and what are its symptoms?

Answer 48

Hydrocephalus is caused by blockage of CSF flow, leading to symptoms like an enlarged head in infants and sun-setting eyes.

Question 49

How is hydrocephalus treated?

Answer 49

It is treated by addressing the primary cause and through the use of shunts for intermittent relief.