Strasinger AUBF - CSF Ultimate Reviewer

CSF

A major fluid of the body, provides a physiologic system to supply nutrients to the nervous tissues, remove metabolic wastes, and produce a mechanical barrier to cushion the brain and spinal cord against trauma

Meninges

Lines the brain and the spinal cord

Dura mater

Outer layer meninges that lines the skull and vertebral canal

Hard mother

Translates to dura mater

Arachnoid

Filamentous inner membrane (meninges)

Spiderweb-like

Translates to arachnoid

Pia mater

Thin membrane lining the surfaces of the brain and spinal cord (meninges)

Gentle mother

Translates to pia mater

Choroid plexuses

CSF is produced in the _____ of the two lumbar ventricles and the third and fourth ventricles

20mL/hr

Adults produce this amount of CSF

Subarachnoid space

CSF flows through the ____ located between the arachnoid and pia mater

90- 150 mL

Maintaining volume of CSF in adults

10- 60 mL

Maintaining volume of CSF in neonates

Cells of the arachnoid granulations

Acts as a one-way valves that respond to pressure within the central nervous system and prevent reflux of the fluid

Choroid plexuses

Capillary networks that form the CSF from plasma by mechanisms of selective filtration under hydrostatic pressure and active transport secretion

Blood-brain barrier

Tight-fitting structure of the endothelial cells in the choroid plexuses

CSF

Routinely collected by lumbar puncture between the third, fourth (adult) or fifth (pediatric) lumbar vertebra

Slowly

Elevated pressure requires CSF to be withdrawn ___

3

CSF is collected in ___ sterile tubes

Chemical, serologic tests

Tube 1 is for ____ which is least affected by blood or bacteria introduced as a result of the tap procedure

Microbiology

Tube 2 is for ____

Cell count, hematology

Tube 3 is for ___ which is least likely to contain cells introduced by the spinal tap procedure

Skin contamination

Fourth tube may be drawn for microbiology laboratory to better exclude _____ or for additional serologic tests

Refrigeration

Hematology tubes are maintained by _____

Room temp

Microbiology tubes remain at _____

Frozen

Chemistry and serology tubes are ____

Crystal- clear

Normal CSF appearance

Cloudy, turbid, milky CSF

Result of an increased protein or lipid concentration; may also be indicative of infection, cloudiness caused by presence of WBCs

Xanthochromia

Used to describe CSF supernatant that is pink, orange or yellow

Presence of RBC degradation products

Most common cause of xanthochromia

Xanthochromia

Caused by elevated serum bilirubin, presence of the pigment carotene, increased protein concentrations and melanoma pigment

Oily CSF

Due to radiographic contrast media

RBCs, hemorrhage, traumatic tap

Causes of Bloody CSF

Xanthochromic

Due to hemoglobin, bilirubin or RBC degradation, carotene, protein, melanin

Clotted appearance

Due to protein (disorders affecting blood-brain barrier), clotting factors introduced by traumatic tap

Pellicle appearance

Due to protein (disorders affecting blood-brain barrier), clotting factors (tubercular meningitis)

1

A traumatic tap will leave the heaviest concentration of blood in tube ___

Fibrinogen

Fluid collected from traumatic procedure may form clots due to the introduction of plasma ___ into the specimen

Xanthochromic supernatant

Result of blood that has been present longer than that introduced by the traumatic tap

Microhematocrit

To examine a bloody fluid for the presence of xanthochromia, the fluid should be centrifuged in a ____ tube

White

Xanthochromic supernatant must be examined against a ___ background

Leukocyte count

Cell count commonly performed on CSF specimens

RBC count

Usually determined only when a traumatic tap has occurred and a correction for leukocytes or protein is desired

RBC count

Can be calculated by performing a total cell count and a WBC count and subtracting the WBC count from the total count

1

Cell count should be performed immediately because WBCs and RBCs begin to lyse within __ hour,

2

40% of the leukocyte disintegrate after __ hours

0 to 5

Normal adult CSF contains ___ WBCs/uL

30 mononuclear cells/uL

Normal WBCs in newborn CSF

Neubauer counting chamber

Routinely used for performing CSF cell counts

Electronic cell counters

Not used for performing CSF cell counts, due to high background counts and poor reproducibility of low counts

Automation

Increases precision, standardization, and faster turnaroundtime for results

Normal saline

Dilutions for total cell counts are made with _____, mixed by inversion, and loaded into the hematocytometer

Number of cells per uL

Number of cells counted multiplied by the dilution factor equals the ____

3% glacial acetic acid

Used to lyse the RBCs

Methylene blue

Stains the WBCs providing better differentiation between neutrophils and mononuclear cells

4 corner square, center square

WBCs are counted in the _____ and the _____ in both sides of the hematocytometer

Neubauer formula

Used when counting different squares

Biweekly

All diluents should be checked ____ for contamination by examining them in a counting chamber under 400x magnification

Tachometer

Speed of cytocentrifuge should be checked monthly with a ____

Stopwatch

Timing of the cytocentrifuge should be checked with a ____

Nondisposable counting chambers

These must be soaked in a bacterial solution for at least 15 minutes, thoroughly rinsed with water and cleaned with isopropyl alcohol after every use

Stained

Differential count should be performed on a ____ smear

Methods for concentration

Sedimentation, filtration, centrifugation and cytocentrifugation

6mm

Cells present in cytometer are forced into a monolayer within a ___ diameter circle on the slide

Filter paper blotter

Fluid is absorbed by the ____, producing a more concentrated area of the cells

30% albumin

0.1 mL of CSF combined with one drop of ____ produces an adequate cell yield when processed with the cytocentrifuge

Albumin

Increases the cell yield and decreases cellular distortion

Cellular distortion

Include cytoplasmic vacuoles, nuclear clefting, prominent nucleoli, indistinct nuclear and cytoplasmic borders, and cellular clumping that resembles malignancy

0.2 mL saline, 30% albumin

Daily control slide for bacteria is prepared by using ___ and two drops of the ___ being used then stained and examined

Too many

Chamber count should be repeated if ____ cells are seen on the slide

Not enough

New slide should be prepared if ____ cells are seen on the slide

70:30

Predominance of lymphocytes to monocytes in adults

Microbiology

If only one tube can be collected, it must be tested first by ___

Calculating CSF Cell Counts

Number of cells counted × dilution

----------------------------------------------- = cells/m L

Number of cells counted × volume of 1 square

Microbiology testing

Role is to identify the causative agent in meningitis

CSF culture

Confirmatory test for meningitis rather than a diagnostic procedure

Microbiology testing

Methods include gram stain, acid-fast stain, india ink preparation, and latex agglutination tests

Gram stain

Routinely performed on CSF from all suspected cases of meningitis

Concentrated specimens

All smears and cultures should be performed on ____ because often only a few organisms are present at the onset of disease

1500g, 15

CSF should be centrifuged at ___ for ___ minutes

Blood cultures

Should be taken because the causative agent is often present in both the CSF and the blood

CSF gram stain

One of the most difficult slides to interpret because the number of organisms present is usually small, and can be easily overlooked, giving a false-negative result

False-positive results

Caused by precipitated stain or debris is mistaken for microorganisms

Acid-fast or fluorescent antibody stains

Not routinely performed on specimens unless tubercular meningitis is suspected

Cryptococcus neoformans

India ink preparation is used to detect this yeast (fungi)

Latex agglutination tests

Detect the presence of C. neoformans antigen in serum and CSF provide a more sensitive method than the India ink preparation

Rheumatoid factor

Interference by ___ is the most common cause of false-positive reactions (detection of C. neoformans)

Lateral flow assay (LAF)

Can provide a rapid method for detecting C. neoformans

Lateral flow assay (LAF)

Procedure utilizes a reagent strip coated with monoclonal antibodies that react with the cryptococcal polysaccharide capsule

Latex agglutination, ELISA

Provides a rapid means for detecting and identifying microorganisms in CSF

Naegleria fowleri

An opportunistic parasite found in ponds, small lakes, and even chlorinated pools that enters the nasal passages and migrates along the olfactory nerves to invade the brain

Motile trophozoites

Seen microscopically by examining a wet prep of CSF

Nonmotile trophozoites

Seen on cytocentrifuged stained smears accompanied by increased WBCss and no bacteria

Serologic testing

Is performed to detect the presence of neurosyphilis

Venereal Disease Research Laboratories (VDRL)

Procedure recommended by the CDC to diagnose neurosyphilis

Fluorescent treponemal antibody-absorption (FTA-ABS)

More sensitive test for syphilis

Rapid Plasma Regain (RPR) test

Not recommended because it is less sensitive than the VDRL

Meningitis

Significance of finding WBCs in CSF

Meningitis

Significance of finding microorganisms in CSF

Protein

Indicates disorders affecting blood-brain barrier or production of IgG within the CNS if found in CSF