CSF Flashcards

1
Q

Neuroendocrine role/transport function of CSF

A

CSF is involved in the distribution of hypophyseal hormones in the brain and the clearance of hormones from the brain and blood

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2
Q

Description of (normal) CSF

A

Clear, colorless, free of clots and free of blood

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3
Q

Average total CSF volume in

  • Adults
  • neonates
A
Adults = 90-150 mLs (~8% of total CNS cavity volume)
neonates = 10-60 mLs
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4
Q

Formation of CSF

A

-Formed predominantly at the Choroid plexus (70%) deep within the brain/by ependymal lining the ventricles and (30%) formed as interstitial fluid.
=result of selective ultrafiltration of plasma and active secretion by the epithelial membranes

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5
Q

Rate of CSF formation

A

=500 mL/day (0.4 mL/minute) = resorption must occure

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6
Q

Resorption of CSF

A

Occurs at out-pouchings in the dura/dural sinuses called ***arachnoid villi (=granulations) that protrude through the dura to the venous sinuses of the brain and into the bloodstream.
–They act as one-way valves to maintain an excretion volume equal to the production volume–
Also, small amounts of resorption occur along the perineurial lymphatics.

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7
Q

Circulation of CSF

A

Begins in the Lateral ventricles –> 3rd ventricle –> 4th ventricle, through the ventricular foramina (three small openings in the 4th ventricle) –> Intracranial and subarachnoid spaces.

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8
Q

Communicating Hydrocephalus

A

=impaired resorption

-Usually occurs after bacterial meningitis or subarachnoid hemorrhage - CNS pressure and CSF volume ^^.

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9
Q

Obstructive Hydrocephalus

A

=blockage of any of the ventricles or the foramina

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10
Q

Function of the Blood-Brain Barrier

A

=Prevent passage of plasma constituents into CSF

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11
Q

Blood-Brain Barrier is composed of

A

Capillary epithelium and fenestrated choroidal capillaries

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12
Q

Factors that significantly influence a substance’s access to the brain and CSF

A
  • Molecular weight (entry=inversely related to size)
  • Protein binding (highly protein bound sub.s enter less readily than unbound sub.s)
  • Lipid solubility (Lower lipid soluble sub.s enter less readily than highly soluble ones (=alcohol, CO))
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13
Q

Lab investigations of CSF are indicated for cases of suspected

A
  • -Dx of disease states = Meningeal CNS infections, demyelinating diseases, CNS malignancy, hemorrhage into the CNS, and
  • -Therapy
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14
Q

CSF specimens are obtained by

A

Lumbar puncture (between L3-4 or lower) using aseptic technique.

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15
Q

Normal pressure of CSF

A

= 90-180 mm/Hg - minor changes can occur due to coughing, respiration or straining.

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16
Q

Increased CNS pressure due to (5)

A
  • CHF
  • Inflammation of meninges
  • Mass lesions
  • Obstruction of intracranial venous sinuses
  • Cerebral edema
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17
Q

Decreased CNS pressure due to (4)

A
  • Partial/complete sinus blockage
  • Circulatory collapse
  • Dehydration
  • CSF leakage
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18
Q

3-4 tubes of CSF are drawn if pressure is adequate. from first to last the tubes are used for what analysis?

A

1st = chemical and immunologic studies
2nd = microbiologic examination
3rd (and/or 4th) = cell count and differential

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19
Q

CSF may appear cloudy/turbid due (6)

A
  • wbcs > 200 cells/uL
  • rbcs > 400 cells/uL
  • presence of microorganisms
  • presence of contrast media
  • aspiration of epidural fat during lumbar puncture
  • an increased CSF protein level (>45 mg/dL)
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20
Q

Clots in CSF may be caused by

A

Increased fibrinogen, which may be due to

  • traumatic tap
  • subarachnoid block
  • suppurative meningitis
  • tuberculous meningitis (may appear on CSF in these cases after refrigeration for 12-24 hours)
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21
Q

Two most common causes of blood and Hgb pigments to be seen in CSF =

A
  • Traumatic tap = artifactual presence of blood/derivatives due to interdiction of blood vessels during the lumbar puncture - As the tubes are drawn, there will be a gradual clearing.
  • Subarachnoid hemorrhage = breakdown of CNS barrier and Circulatory system from trauma - All tubes collected will have the same degree of discoloration.
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22
Q

Traumatic tap characteristics (3)

A
  • Clear supernatant
  • (-) D-dimer (no fibrinogen)
  • May have clots present
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23
Q

Characteristics of Subarachnoid hemorrhage (3)

A
  • Xanthochromic supernatant
  • Erythrophages on microscopic examination
  • No clots
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24
Q

Xanthochromia

A

=pink, yellow or orange color of CSF supernatant
RBCs lyse in CSF due to decreased protein and lipid levels (compared to plasma) - after hemolysis, CSF will change from a cloudy/hazy pink-red –> clear pink-red, then through various shades as Oxyhgb –> Methgb –> Bilirubin (after 12 hrs).
-Decrease in discoloration over the 1st 2 days, complete clearing in 2-4 weeks. May also be due to
- CSF protein (>150 mg/dL) / TT w/ plasma contam. of protein
- Contamination by merthiolate (skin disinfectant)
- Carotenoids (hypercarotenemia)
- Melanin (Meningeal Melanosarcoma)
- Rifampin therapy

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25
Q

Normal cell counts in CSF

A

Adults =

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26
Q

Causes of increased segs (4)

A
  • meningitis (***bacterial, early viral, early tuberculous)
  • cerebral abscess
  • post-seizure
  • post-CNS hemorrhage
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27
Q

Causes of increased lymphs (2)

A
  • meningitis (***viral, tuberculous, fungal, bacterial (unusual organisms))
  • degenerative disorders
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28
Q

Causes of increased plasma cells (4)

A
  • ***MS
  • tuberculous meningitis
  • conditions associated with lymphocytic rxns
  • syphilitic meningoencephalitis
29
Q

Causes of increased eos ( >10%) (5)

A
  • ***intracranial shunt
  • parasitic infections
  • fungal infections
  • Rickettsial infections
  • foreign material (myelography)
30
Q

Causes of increased monos (3)

A
  • tuberculous meningitis
  • fungal meningitis
  • chronic bacterial meningitis
31
Q

Causes of increased macrophages (3)

A
  • meningitis (fungal, tuberculous)
  • foreign substance
  • recovery after subarachnoid hemorrhage - will contain phagocytized rbcs (erythrophages) in ~ 2 days, and hemosiderin (=siderophages) after 48 hours.
32
Q

Other cells CSF may contain (4)

A
  • Lupus Erythematous cells
  • Leukemic cells (**ALL)
  • Tumor cells (primary CNS tumors, metastatic neoplasms (lung, breast, GI tract, melanoma)
33
Q

Most proteins are present in CSF in ___ concentrations

A

low

34
Q

Methodology for measuring TP and normal values

A

Turbidimetric = sulfosalicylic acid, trichloracetic acid
Colorimetric = dye-binding (Coomassie brilliant blue/Ponceau S), modified biuret.
–Normal values–
> 6 months = 15-45 mg/dL
neonates = 30-140 mg/dL

35
Q

Elevated CSF protein (>65 mg/dL) caused by (5)

A
  • Plasma contamination from traumatic tap
  • Increased perm. of blood-CSF barrier
  • Decreased resorption (at the arachnoid villi)
  • Obstruction of CSF circulation
  • Increased Ig synthesis in lymphs and plasma cells of the CNS (*MS)
36
Q

Decreased CSF protein (

A
  • Leakage of CSF from dural tear (from trauma) (=rhinorrhea/otorrhea)
  • Removal of large volume of CSF
  • Increased intracranial pressure
  • Hyperthyroidism
37
Q

CSF/serum albumin index evaluates

A

Blood-CSF barrier
= CSF albumin (mg/dL) / Serum albumin (g/dL)
Normal range = 4 - 8
Index of >9 reflects impairment of blood-CSF barrier

38
Q

CSF/serum IgG index reflects

A

Intrathecal production of IgG and increased plasma IgG cross-over from breakdown of the blood-brain barrier
= CSF IgG (mg/dL) / serum IgG (g/dL)
Normal range = 3 - 8

39
Q

CSF IgG index evaluates

A

IgG synthesis by correcting for Ig derived from plasma crossover
= CSF IgG/serum IgG X serum alb/CSF alb
Normal range = 0 - 0.8
> 0.8 indicates increased IgG synthesis

40
Q

Oligoclonal bands in the gamma region during CSF protein Electrophoresis is present in

A
  • **70 - 90% of patients with MS

- Can also be present in HIV, neurosyphilis, brain tumors

41
Q

Myelin Basic Protein (MBP) is used as an aid in the Dx of _____;
It is a component of the ______ _____ ______ and is released during _____________.

A

MS
myelin nerve sheath
demyelination

42
Q

Beta-2-Transferrin is present only in ___; used in the Dx of ___ in otorrhea and rhinorrhea.

A

CSF

CSF

43
Q

Protein 14-3-3 may be detected in patients with ___________-_____ disease

A

Creutzfeldt-Jakob

44
Q

Normal CSF glucose is

A

60-70% of plasma values = 50-80 mg/dL in the fasting state

45
Q

Decreased CSF glucose caused by (4)

A
  • Acute or chronic meningitis (***bacterial, tuberculous, fungal, amebic, parasitic)
  • viral meningoencephalitis
  • systemic hypoglycemia
  • mechanisms (impaired Gluc transport, increased glycolytic activity in CNS, ***Gluc utilization by microorganisms and wbcs)
46
Q

primary source of CSF Lactate is

A

CNS anaerobic metabolism
-Increased more in bacterial/tuberculous/fungal meningitis than in viral meningitis
-Used in the routine evaluation of pt.s with severe head injury
Normal range = 9 - 26 mg/dL

47
Q

Increased CSF Lactate caused by (3)

A
  • traumatic brain injury
  • cerebral edema
  • any condition associated with tissue hypoxia of the CNS
48
Q

Lactate Dehydrogenase is significantly higher in _________ meningitis than in _______ meningitis.

A

bacterial

aseptic

49
Q

Creatine Kinase (CK) is normally present at the __ __ isoenzyme; Increased CSF __-__ may be due to (3)

A
CK BB
""
anoxia
ischemia
subarachnoid
50
Q

CSF ammonia is increased in

A

hepatic encephalopathy (=secondary to advanced liver disease)

51
Q

CSF glutamine protects the CNS from _______ toxicity.
Glutamine is formed when _____-____________ combines with _________ in ______ tissue;
Glutamine levels reflect ______ _______ ______
Increased levels are associated with __________ encephalopathy

A
ammonia
Alpha-ketoglutarate 
ammonia 
brain
brain ammonia levels
hepatic
52
Q

Tumor markers in CSF (not performed routinely) (3)

A
  • CEA(carcinoembryonic antigen)–metastatic meningeal carcinoma
  • AFP–embryonal carcinoma
  • HCG(human chorionic gonadotropin)–choriocarcinoma metastatic to CNS
53
Q

Immunological tests for neurosyphilis (2)

A

CSF FTA-ABS (CSF fluorescent treponemal antibody with abs)
-good sensitivity, poor specificity
CSF VDRL (CSF venerial disease research laboratory test) - poor sensitivity, good specificity

54
Q

Cryptococcal Antigen (latex agglutination) (false - (2), false + (1) due to?)

A

false (-)s = may occur in early stages of cryptococcal infection, in patients with nonencapsulated variants of C. neoformans, and prozone effect
false (+) = rheumatoid factor

55
Q

Latex agglutination for bacterial infection with (4) are best applied in cases of partially treated __________ in which the _______ stain has been _________.

A
H. influenzae
S. pneumoniae
N. meningitidis
GBS
meningitis
Gram's 
negative
56
Q

Binax NOW =

A

Strep. pneumo antigen test

57
Q

Gram’s stain is the

A

single most valuable exam of CSF

58
Q

Acridine orange =

A

fluorescent stain

  • useful in some patients with symptoms but a negative GS
  • Diff. Ameba (red) from wbcs (green) in cases of PAM
59
Q

Fluorescent auramine-rhodamine - for

A

Mycobacterium TB

60
Q

India Ink prep is for ______________, but the ______ ___________ is a better test.

A

C. neoformans

latex agglutination

61
Q

Most common cause of meningitis in: 3 mo - 18 yrs:

A

H influenzae

62
Q

MCC of meningitis: > 3 months

A

N. meningitidis

63
Q

MCC of meningitis in: > 3 months

A

S. pneumoniae

64
Q

MCC of meningitis in: newborns, elderly, immune compromised

A

Listeria monocytogenes

65
Q

MCC of meningitis in: newborns

A

GBS

66
Q

MCC of meningitis in: nb - 1 month

A

E. coli and other gram (-) bacilli

67
Q

PCR and sequencing is useful in diagnosis of __________ meningitis
RT-PCR = _________
PCR nucleic acid amplification test for ____.

A

bacterial
viruses
TB

68
Q

Functions of CSF

A
  • Physical support and protection;
  • Provides a controlled chemical environment (=supplies nutrients to tissues, removes wastes) -constituent levels are maintained within narrow limits;
  • Intra- and Extracerebral support = buoyant cushion for the brain