10: cerebrospinal fluid

what are the functions of cerebrospinal fluid?

• supply nutrients to nervous tissue

• remove metabolic waste

• maintain intracranial pressure

• produce mechanical barrier to cushion brain and spinal cord

what is the outer layer of the meninges?

dura mater

what is the middle layer of the meninges?

arachnoid

what is the surface of the brain and spinal cord?

pia mater

where is CSF produced?

choroid plexuses of the four ventricles

how much CSF is produced per hour in adults?

20 mL

what is the volume of CSF in adults?

90 to 150 mL

what is the volume of CSF in neonates?

10 to 60 mL

CSF flows through subarachnoid space between ________ and ________

arachnoid; pia mater

where is CSF reabsorbed into the blood?

arachnoid granulations/villae

the blood-brain barrier is formed by very tight-fitting ________ cells

endothelial

diseases such as ________ and ________ can disrupt the blood-brain barrier

meningitis; multiple sclerosis

CSF is collected between the ________ and ________ lumbar vertebrae

third; fifth

which kind of testing is the first CSF collection tube used for?

chemistry/serology

which kind of testing is the second CSF collection tube used for?

microbiology

which kind of testing is the third CSF collection tube used for?

hematology

volume from the fourth CSF collection tube is removed based on which factors?

patient volume and opening pressure

hematology CSF samples can be refrigerated for how long?

up to 4 hours

microbiology CSF samples must remain at which temperature and must be tested within how long?

room temperature; 1 hour

how must chemistry/serology CSF samples be preserved?

frozen

CSF that is cloudy indicates what?

infection

CSF that is milky indicates what?

lipids or protein

CSF that is pink, orange, or yellow is termed what?

xanthochromic

what usually causes xanthochromia in CSF?

RBC degradation products

the first, pink, stage of xanthochromia is caused by what?

slight oxyhemoglobin

the second, orange, stage of xanthochromia is caused by what?

heavy hemolysis

the third, yellow, stage of xanthochromia is caused by what?

conversion of oxyhemoglobin to conjugated bilirubin

other causes of xanthochromia may include elevated serum ________, presence of the pigment ________, markedly increased ________ concentrations, and ________ pigment

bilirubin; carotene; protein; melanoma

a pathological cause of xanthochromia is ________ hemorrhage

cerebral

xanthochromia caused by bilirubin due to immature liver function is common in ________

premature infants

in a traumatic tap, how does blood appear within the collection tubes?

most concentrated in first tube, diminishes in second and third

in a cerebral hemorrhage, how does blood appear within the collection tubes?

evenly distributed between all tubes

in CSF, granulocytes lyse within ________

1 hour

in CSF, 40% of leukocytes disintegrate after ________

2 hours

what is the normal WBC count in adult CSF?

0-5 WBCs/microliter

what is the normal WBC count in neonate CSF?

up to 30 mononuclear cells/microliter

which counting chamber is used for CSF WBC counts?

Neubauer

before performing a differential count on CSF, the sample must be ________

concentrated

cytocentrifugation forces cells onto a slide in a ________

monolayer

for cytocentrifugation, ________mL CSF is mixed with one drop ________% albumin

0.1; 30

how does albumin help in cytocentrifugation?

increases cell yield and decreases cellular distortion

cytocentrifugation uses ________ charged slides to attract cells

positively

a daily control slide for bacteria should be prepared using 0.2 mL ________ and two drops of ________% albumin stained to check for bacterial contamination

saline; 30

in adults, the normal ratio of lymphocytes to monocytes in CSF is ________

70:30

in children, the normal ratio of lymphocytes to monocytes in CSF is ________

30:70

occasional ________ in CSF are normal

neutrophils

________ is the term for an increased number of normal cells in CSF

pleocytosis

pleocytosis of ________ occurs in bacterial meningitis

neutrophils

pleocytosis of ________ occurs in viral, tubercular, fungal, and parasitic tuberculosis; HIV and AIDS; multiple sclerosis; degenerative disorders; and parasitic infections

lymphocytes

________ may be found in early cases of viral, tubercular, and fungal meningitis; cerebral hemorrhage; cerebral abcess; CNS infarction; injections of medications or radiographic dye; metastatic tumors; repeated lumbar punctures; and multiple sclerosis

monocytes

________ may be found in parasitic infections; fungal infections; coccidioidal meningitis; and introducing medications and shunts in the CNS

eosinophils

________ may be found in acute leukemia

blast forms

________ may be found in disseminated lymphomas

lymphoma cells

________ in CSF are clinically significant alongside RBCs in spinal fluid

macrophages

________ may be found in multiple sclerosis; guillain-barre syndrome; sarcoidosis; parasitic infections; syphilitic meningitis; and tuberculous meningitis

plasma cells

________ cells may be found in metastatic carcinomas

malignant

neutrophils in CSF often contain ________ and ________

phagocytized bacteria; vacuoles

while ________ primarily occur in bacterial meningitis, ________ and ________ primarily occur in viral, fungal, and tubercular meningitis

neutrophils; lymphs; monos

________ may be seen in viral meningitis

reactive lymphs

multiple sclerosis causes ________ or fewer lymphocytes per microliter, both normal and reactive

50

________ and ________ are commonly seen in HIV and AIDS

lymphs; monos

what is the purpose of macrophages in CSF?

remove cellular and other debris

after a hemorrhage, macrophages enter the CSF within ________ hours to phagocytize RBCs

2

which cells may appear after repeated lumbar punctures?

macrophages

________ cells tend to be uniform in shape and size, while ________ cells tend to have irregular shapes and sizes

choroidal; malignant

________ cells line the ventricles and neural canal and have less defined cell membranes in clumps

ependymal

abnormal chemistry CSF results indicate alterations in the ________ of the blood-brain barrier or increased ________ or ________ by neural cells in response to a pathologic condition

permeability; production or metabolism

what is the normal protein level in adult CSF?

15 to 45 mg/dL

protein levels in infants and people over 40 are ________

increased

the predominant protein in CSF is ________, with ________ coming in second

albumin; prealbumin

the alpha globulins in CSF include ________ and ________

haptoglobulin; ceruloplasmin

a major beta globulin in CSF is ________

transferrin

the normal percentage of glucose in CSF is roughly ________% to ________% that of plasma glucose

60; 70

glucose levels that are ________ are clinically significant

decreased

blood should be drawn ________ hours before spinal tap to get an accurate comparison of glucose levels

2

elevated CSF glucose levels are always a result of ________ elevations

plasma

in bacterial meningitis, glucose levels are markedly ________ with increased ________

decreased; neutrophils

in tubercular meningitis, glucose levels are ________ with increased ________

decreased; lymphocytes

in viral/fungal meningitis, glucose levels are ________ with increased ________

normal; lymphocytes

in bacterial, tubercular, and fungal meningitis, lactate levels are ________ due to tissue hypoxia and metabolic changes

>25 mg/dL

in viral meningitis, lactate levels are ________

<25 mg/dL

lactate levels remain elevated in meningitis until ________

treatment becomes effective

microbiology tests are useful for identifying ________ in meningitis

the causative agent

bacterial meningitis cultures can take ________

24 hours

tubercular meningitis cultures can take ________

up to 6 weeks

myelin basic protein in CSF indicates ________

demyelination

glutamine in CSF indicates ________

liver disorders causing increased blood and CSF ammonia