Chapter 10 CSF

where is CSF formed

lateral, 3rd, and 4th ventricles of the brain

what is the normal volume of CSF present (adult & infant)

• 90-150 mL in adults

• 10-60 mL in infants

how much CSF is produced (per day and per hour)

• 500 mL/day

• 20 mL/hour

what are 3 major functions of CSF

1. supply nutrients to nervous tissue and remove metabolic waste

2. maintain intracranial pressure

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

where is a lumbar puncture/spinal tap performed?

intervertebral space between L3-L4 or L4-L5

CSF tube 1

frozen

chemistry (glucose, protein), serology

CSF tube 2

room temperature

gram stain, AFB stain (tuberculosis), india ink preparation, bacterial culture (BA, CHOC), fungal culture, culture for tuberculosis

CSF tube 3

may refrigerate up to 4 hours

hematology (total cell count, differential count)

CSF tube 4

may refrigerate up to 4 hours

cytology, immunology, additional tests

what does normal CSF look like

clear and colorless, viscosity similar to water

CSF that is turbid, hazy, milky, or cloudy may contain….?

WBCs, microorganisms, protein

• could indicate meningitis or disorders affecting BBB

CSF that is oily-appearing may contain…?

radiographic contrast media

CSF that is clotted may contain…?

protein & clotting factors

• associated with a traumatic tap

• disorders affecting the BBB including neurosyphilis (dementia) and meningitis

CSF that is bloody red, pink, or smoky may contain…?

RBCs

• traumatic tap

CSF that is xanthochromic may contain…?

bilirubin, carotene, protein, melanin, hemoglobin, or protein and associated with various disorders

CSF that is pellicle may contain….?

protein or clotting factors

define xanthochromia

CSF is yellow, pink, or orange 

what causes xanthochromia

• RBC degradation

• pink - slight amount of oxyhemoglobin

• orange - heavy hemolysis

• yellow - conversion of oxyhemoglobin to unconjugated bilirubin

• elevated serum bilirubin

• carotene

• increased protein

• melanoma pigment

A xanthochromic CSF specimen appears:

yellow and clear

what is the main difference between CSF specimens due to a hemorrhage and CSF specimens due to a traumatic tap?

hemorrhage specimens will all appear the same amount of pink or red

traumatic tap specimens will gradually become more clear

Differential counts on CSF are performed on:

stained smears prepared form concentrated specimens

what are the lab results for normal CSF

(appearance, WBC, protein, glucose, lactate, and other tests)

• clear

• < 8 WBCs

• 15-45 mg/dL protein

• 50 -80 mg/dL glucose

• 11-22 mg/dL lactate

what are the lab results for bacterial meningitis CSF

(appearance, WBC, protein, glucose, lactate, and other tests)

• turbid

• elevated

  • > 1000-2000 WBCs

  • neutrophils

• elevated protein

• decreased glucose

• lactate level >35 mg/dL

• positive gram stain and bacterial antigen tests

what are the lab results for fungal meningitis CSF

(appearance, WBC, protein, glucose, lactate, and other tests)

• clear

• elevated

  • <500 WBCs

  • lymphocytes AND macrophages/monocytes present

• moderate-elevated protein

• normal-decreased glucose

• lactate level >25 mg/dL

• positive for Cryptococcus neoformans (PCR, imm test, india ink)

what are the lab results for viral meningitis CSF

(appearance, WBC, protein, glucose, lactate, and other tests)

• clear

• elevated 

  • <300 WBCs

  • lymphocytes present

• moderate protein elevation

• normal glucose level

• normal lactate level 

• PCR test positive for enterovirus, herpes simplex, or parechovirus

what are the lab results for tubercular CSF

(appearance, WBC, protein, glucose, lactate, and other tests)

• pellicle

• elevated

  • lymphocytes and monocytes present

• moderate to elevated protein

• decreased glucose

• lactate > 25 mg/dL

• PCR positive for Mycobacterium tuberculosis

identify this cell and what it indicates

macrophage

• appears within 2-4 hours after RBCs enter CSF

• frequently seen after repeated taps

identify this cell and what it indicates

increased macrophages

• previous hemorrhage

identify this cell and what it indicates

dark blue or black iron-containing hemosiderin granules

• degradation of phagocytized RBCs

identify this cell and what it indicates

yellow hematoidin crystals inside macrophages

• further degeneration

identify this cell 

choroidal cells and capillary endothelial cells (from spinal wall)

Increased and vacuolated macrophages are seen in the CSF following:

previous hemorrhage

Which cells are considered an abnormal finding in CSF

tumor/blast cells

what is CSF protein normal range

15 mg/dL - 45 mg/dL

what are some proteins present in CSF

• albumin

• prealbumin (transthyretin)

• alpha globulins

• transferrin

• gamma globulins

• fibrinogen

• beta lipoprotein

what can cause elevated CSF protein

• damage to BBB

• immunoglobulin production within the CNS

• decreased normal protein clearance from fluid

• neural tissue degradation

what can cause abnormal elevated CSF protein

• meningitis

• hemorrhage

• primary CNS tumors 

• multiple sclerosis

• neurosyphilis 

• Guillan-Barre syndrome

• Cushing disease

• diabetes

what can cause abnormal decreased CSF protein

• CSF leakage/trauma

• recent puncture

• rapid CSF production

• water intoxication

CSF/serum albumin index

CSF albumin (mg/dL) / serum albumin (g/dL)

normal CSF/serum albumin index

< 9

A complete breakdown of the blood–brain barrier is indicated by a CSF/serum albumin index of…?

> 100

What laboratory finding is most suggestive of blood-brain barrier damage in a cerebrospinal fluid (CSF) analysis?

CSF/serum albumin index >9

an IgG index value of > 0.70 indicates…?

IgG production within the CNS

• typically becomes an autoimmune disease

Primary purpose for performing CSF protein electrophoresis is to?

detect oligoclonal bands, which represent inflammation within the CNS

• gamma region

The presence of two or more oligoclonal bands in the CSF that are not present in the serum can be a valuable tool in diagnosing?

Multiple sclerosis, accompanied by increased IgG index

presence of what protein in CSF indicates recent destruction of the myelin sheath (demyelination) → MS

Myelin basic protein (MBP)

The normal CSF glucose is:

60 to 70% of the blood glucose

• 50-80 mg/dL

what is normal lactate level of CSF

11-22 mg/dL

CSF lactate level >35 mg/dL indicates…?

bacterial meningitis

elevated CSF lactate level can also indicate…?

tissue destruction due to hypoxia or any condition that decreases oxygen flow to tissues

how is glutamine produced

ammonia and a-ketoglutarate by brain cells

• removes toxic metabolic waste product ammonia from CNS

what is normal CSF glutamine level

8-18 mg/dL

CSF glutamine test is often ordered  for patients with …?

coma of unknown origin

what organism is associated with positive india ink test

Cryptococcus neoformans

• fungal meningitis

• AIDS

• thickly capsulated

identify this organism

star-burst pattern gram stain

Cryptococcus neoformans

• causes infection in immunocompromised (AIDS/HIV) patients after breathing in the fungus

what is a more sensitive test than india ink to detect Cryptococcus neoformans

latex agglutination tests are more sensitive, but should be confirmed with a positive india ink stain AND culture

what are some advantages of PCR molecular diagnostic testing in meningitis

–detect the cause of meningitis with a small amount of the pathogen’s DNA

–Universal PCR detects pathogens with increased sensitivity and specificity.

does PCR test for DNA or RNA

–PCR assays are based on the amplification of regions of ribosomal RNA (rRNA) genes to detect and differentiate causative pathogens of meningitis.