copyright © 2014. f.a. davis company chapter 9 cerebrospinal fluid
Post on 19-Dec-2015
227 Views
Preview:
TRANSCRIPT
Copyright © 2014. F.A. Davis Company
CHAPTER 9CHAPTER 9
CEREBROSPINAL FLUIDCEREBROSPINAL FLUID
Copyright © 2014. F.A. Davis Company
Upon completing this chapter, the reader will be able to1.State the three major functions of cerebrospinal fluid (CSF).2.Distribute CSF specimen tubes numbered 1, 2, 3, and possibly 4 to their appropriate laboratory sections and correctly preserve them. 3.Describe the appearance of normal CSF and the causes of abnormally appearing CSF.4.Define xanthochromia and state its significance.5.Differentiate between CSF specimens caused by intracranial hemorrhage and a traumatic tap.
Learning ObjectivesLearning Objectives
Copyright © 2014. F.A. Davis Company
6. Calculate CSF total, white blood cell (WBC), and red blood cell (RBC) counts when given the number of cells seen, amount of specimen dilution, and the squares counted in the Neubauer chamber.
7. Describe the leukocyte content of the CSF in bacterial, viral, tubercular, and fungal meningitis.
8. Describe and state the significance of macrophages in the CSF.
9. Differentiate between the appearance of normal choroidal cells and malignant cells.
Learning Objectives Learning Objectives (cont’d)(cont’d)
Copyright © 2014. F.A. Davis Company
10.State the reference values for CSF total protein and name three pathologic conditions that produce an elevated CSF protein.
11.Determine whether increased CSF albumin or immunoglobulin is the result of damage to the blood-brain barrier or central nervous system production.
12.Discuss the significance of CSF electrophoresis, immunophoresis, and isoelectric focusing findings in multiple sclerosis and the identification of CSF.
13.State the reference values for CSF glucose and name the possible pathologic significance of a decreased CSF glucose.
Learning Objectives Learning Objectives (cont’d)(cont’d)
Copyright © 2014. F.A. Davis Company
14.Discuss the diagnostic value of CSF lactate and glutamine determinations.
15.Name the microorganism associated with a positive India ink preparation.
16.Discuss the diagnostic value of the bacterial and cryptococcal antigen tests.
17.Determine whether a suspected case of meningitis is of bacterial, viral, fungal, or tubercular origin, when presented with pertinent laboratory data.
18.Describe the role of the Venereal Disease Research Laboratories test and fluorescent treponemal antibody-absorption test for syphilis in CSF testing.
Learning Objectives Learning Objectives (cont’d)(cont’d)
Copyright © 2014. F.A. Davis Company
• Brain and spinal cord lined by meninges• Three layers of meninges
– Dura mater: outer– Arachnoid: middle– Pia mater: surfaces of brain and spinal cord
• Cerebrospinal fluid (CSF) produced in choroid plexuses of the four ventricles– 20 mL/min produced in adults– Volume adults 90 to 150 mL, neonates 10 to 60 mL
Formation and PhysiologyFormation and Physiology
Copyright © 2014. F.A. Davis Company
The MeningesThe Meninges
Copyright © 2014. F.A. Davis Company
• CSF flows through subarachnoid space between arachnoid and pia mater
• Reabsorbed into blood in arachnoid granulations/villae (one-way valves)
• Formation by selective filtration– Hydrostatic pressure and active transport– Not an ultrafiltrate– Very tight-fitting endothelial cells, prevent filtration of
large molecules—called the blood-brain barrier
Formation and PhysiologyFormation and Physiology
Copyright © 2014. F.A. Davis Company
Flow of Spinal Fluid Flow of Spinal Fluid Through the BrainThrough the Brain
Copyright © 2014. F.A. Davis Company
• Blood-brain barrier– Essential to protect brain– Chemicals and harmful substances do not pass– Antibodies and medications are excluded– CSF composition differs from plasma– Meningitis, multiple sclerosis disrupt membrane– Test for substances that pass through: cells, protein,
bacteria, immunoglobulins
Formation and PhysiologyFormation and Physiology
Copyright © 2014. F.A. Davis Company
• CSF collected between third to fifth lumbar vertebrae
• Three sterile tubes in this order1. Chemistry/serology2. Microbiology (avoid skin contamination)3. Hematology (avoid cells from tap)– Save leftover fluid/fourth tube for additional tests– Volume removed based on patient volume and
opening pressure
Specimen Collection Specimen Collection & Handling& Handling
Copyright © 2014. F.A. Davis Company
CSF Specimen Collection TubesCSF Specimen Collection Tubes
Copyright © 2014. F.A. Davis Company
• Usually STAT requests• Handle carefully to avoid repeat taps• Preservation
– Hematology– Refrigerate– Microbiology– Room temperature– Chemistry/serology– Frozen
Specimen CollectionSpecimen Collection& Handling & Handling
Copyright © 2014. F.A. Davis Company
• Crystal clear, cloudy/turbid, milky, xanthochromic, hemolyzed/bloody
• Cloudy = infection; milky = lipid or protein• Xanthochromic
– Pink, orange, yellow – RBC degradation products– Also jaundice, ↑ ↑ protein, carotene– Pathologic = cerebral hemorrhage
AppearanceAppearance
Copyright © 2014. F.A. Davis Company
Tubes of CSFTubes of CSF
Copyright © 2014. F.A. Davis Company
• Blood vessel punctured during tap• Differentiate from cerebral hemorrhage• Uneven blood distribution in tubes with
traumatic tap– Erythrophagocytosis, hemosiderin granules– Hemorrhage = even distribution in all tubes– Traumatic tap = decreasing tubes 1 through 3
Traumatic TapTraumatic Tap
Copyright © 2014. F.A. Davis Company
• Clot formation– Clots present = traumatic tap (plasma)– Hemorrhage does not have enough fibrinogen– Other causes of clot formation
• Nonbloody CSF = damage to blood-brain barrier• TB meningitis: web-like pellicle after refrigeration
• Xanthochromia– Not present in a recent traumatic tap– Indicates older hemorrhage– D-dimer test for hemorrhage
Traumatic Tap Traumatic Tap (cont’d)(cont’d)
Copyright © 2014. F.A. Davis Company
• White blood cell (WBC) and total cell count• Red blood cell (RBC) count seldom done• Granulocytes lyse within 1 hour; STAT
– Normal adult 0 to 5 WBCs/µL– Neonates up to 30 mononuclear cells/µL
• Neubauer counting chamber– Automated cell counters can be used
• Body fluid specific automation is available
Cell CountCell Count
Copyright © 2014. F.A. Davis Company
Neubauer Counting Chamber Neubauer Counting Chamber
Copyright © 2014. F.A. Davis Company
• Standard Neubauer calculation formula (cells/µL)
Number of cells counted × dilutionNumber of cells counted × volume of 1 square
= cells/µL• Can be used for diluted and undiluted samples
Calculating CSF Cell CountCalculating CSF Cell Count
Copyright © 2014. F.A. Davis Company
• Example# cells counted × dilution × 1 μL = cells/µL
1 μL (0.1 × 10) (volume counted) </exeq)
Calculating CSF Cell Count Calculating CSF Cell Count (cont’d)(cont’d)
Copyright © 2014. F.A. Davis Company
• Total cell count– Clear specimens count undiluted unless overlapping
cells are seen– Load with transfer pipette– Dilute with normal saline if necessary
• WBC count– Dilute with 3% acetic acid; methylene blue helps to
see cells; undiluted rinse transfer pipette with acetic acid, gently rotate pipette
Calculating CSF Cell Count Calculating CSF Cell Count (cont’d)(cont’d)
Copyright © 2014. F.A. Davis Company
• Commercial cell controls are available• Check diluents for contamination biweekly• Monthly check on cytocentrifuge speed and
timing• Soak nondisposable chambers in bactericidal
solution for 15 minutes; rinse; clean with isopropyl alcohol
Quality ControlQuality Control
Copyright © 2014. F.A. Davis Company
• Valuable diagnostic aid• Stained smear only• Must concentrate specimen
– Sedimentation, filtration, centrifugation, and cytocentrifugation
• 100 cells should be counted, classified, and reported in terms of percentage
Differential CountDifferential Count
Copyright © 2014. F.A. Davis Company
• Cytocentrifuge– Forces cells onto a slide in a monolayer– Filter paper absorbs moisture– 0.1 mL CSF to 1 drop 30% albumin
• Albumin increases the cell yield and decreases the cellular distortion
– Positively charged slides to attract cells– Daily control of 0.2 mL saline and two drops of
albumin stained for bacterial contamination
CytocentrifugationCytocentrifugation
Copyright © 2014. F.A. Davis Company
• Normal lymphocytes and monocytes• Adults: normal lymphocytes:monocytes = 70:30• Children’s ratio is reversed• Occasional neutrophils are normal• Pleocytosis: increased amounts of normal cells• Pleocytosis of normal cells is valuable in determining the
cause of meningitis– Neutrophils = bacterial– Lymphocytes = viral, tubercular, fungal, parasitic
Cellular ConstituentsCellular Constituents
Copyright © 2014. F.A. Davis Company
Prominent Cells Seen in CSFProminent Cells Seen in CSF
Type of Cell Major Clinical Significance Microscopic FindingsLymphocytes Normal All stages of development may be found Viral, tubercular, and fungal
meningitis
Multiple sclerosis Neutrophils Bacterial meningitis Granules may be less prominent than in blood Early cases of viral, tubercular,
and fungal meningitisCells disintegrate rapidly
Cerebral hemorrhage Monocytes Normal Found mixed with lymphocytes Viral, tubercular, and fungal
meningitis
Multiple sclerosis
Copyright © 2014. F.A. Davis Company
Prominent Cells Seen in CSF Prominent Cells Seen in CSF (cont’d)(cont’d)
Type of Cell Major Clinical Significance
Microscopic Findings
Macrophages RBCs in spinal fluid from hemorrhageContrast media
May contain phagocytized RBCs appearing as empty vacuoles or ghost cells, hemosiderin granules, and hematoidin crystals
Blast forms Acute leukemia Lymphoblasts, myeloblasts, or monoblastsLymphoma cells Disseminated lymphomas Resemble lymphocytes with cleft nucleiPlasma cells Multiple sclerosis Traditional and classic forms seen Lymphocyte reactions Reactive lymphsEpendymal, choroidal, and spindle-shaped cells
Diagnostic procedures Seen in clusters with distinct nuclei and distinct cell walls
Malignant cells Metastatic carcinomas Primary central nervous system carcinoma
Seen in clusters with fusing of cell borders and nuclei
Copyright © 2014. F.A. Davis Company
NeutrophilsNeutrophils
• Primarily in bacterial meningitis
• Often contain phagocytized bacteria
• Increased early viral, fungal, tubercular, parasitic
• Vacuoles may be present
Copyright © 2014. F.A. Davis Company
Cellular ConstituentsCellular Constituents
Copyright © 2014. F.A. Davis Company
Nucleated RBCs (NRBC)Nucleated RBCs (NRBC)
• Seen with bone marrow contamination from tap in 1% of specimens
• Neutrophils with pyknotic nucleii may resemble NRBCs
• Capillary structures and epithelial cells from traumatic taps
Copyright © 2014. F.A. Davis Company
Cellular ConstituentsCellular Constituents
Copyright © 2014. F.A. Davis Company
Lymphocytes and MonocytesLymphocytes and Monocytes
• Lymphs and monos in viral, fungal, tubercular
• Reactive lymphocytes with viral
• Multiple sclerosis has 50 or fewer lymphocytes/μL, both normal and reactive
• Seen in HIV and AIDS
Copyright © 2014. F.A. Davis Company
EosinophilsEosinophils
• Parasitic and fungal infections– (primarily Coccidioides
immitis)
• Medications and shunts into the central nervous system
Copyright © 2014. F.A. Davis Company
MacrophagesMacrophages
• Purpose is to remove cellular and other debris
• May be seen after repeated taps
• Hemorrhage: enter CSF within 2 hours to phagocytize RBCs
• RBCs degraded to hematoidin crystals representing unconjugated bilirubin
Copyright © 2014. F.A. Davis Company
Macrophages Macrophages (cont’d)(cont’d)
Copyright © 2014. F.A. Davis Company
Nonclinically Significant CellsNonclinically Significant Cells
• Seen after diagnostic procedures• Choroidal cells• Epithelial lining of choroid
plexus, singular and in clumps, uniform cells
• Ependymal cells lining ventricles and neural canal; less defined cell membranes in clumps
• Spindle cells lining arachnoid seen in clumps
Copyright © 2014. F.A. Davis Company
• Leukemias– Lymphoblasts, monoblasts, and myeloblasts– Nucleoli may be more prominent than in blood
• Lymphomas– Dissemination from lymph organs– Cleaved nucleii and prominent nucleoli
Malignant Cells of Malignant Cells of Hematologic OriginHematologic Origin
Copyright © 2014. F.A. Davis Company
Malignant Cells of Malignant Cells of Hematologic Origin (cont'd)Hematologic Origin (cont'd)
Copyright © 2014. F.A. Davis Company
Malignant Cells of Malignant Cells of Hematologic Origin (cont'd)Hematologic Origin (cont'd)
Copyright © 2014. F.A. Davis Company
• Metastatic carcinoma cells– Lung, breast, renal,
gastrointestinal, and melanoma
– Fused cell walls, nuclear irregularities, and hyperchromatic nucleoli
• Primary tumors– Astrocytomas,
retinoblastomas, medulloblastomas
Malignant Cells of Malignant Cells of Nonhematologic OriginNonhematologic Origin
Copyright © 2014. F.A. Davis Company
• CSF formed by plasma filtration• Normal values differ from plasma because of
selectivity of blood-brain barrier• Abnormal values result
– Alterations in the permeability of the blood-brain barrier
– Increased production or metabolism by the neural cells in response to a pathologic condition
Chemistry TestsChemistry Tests
Copyright © 2014. F.A. Davis Company
• Total protein is the most common test– Normal 15 to 45 mg/dL (mg, not grams)
• Method dependent• Increased in infants and persons >40
– Albumin is predominant, prealbumin is second– Alpha globulins-haptoglobin and ceruloplasmin– Transferrin is major beta globulin– TAU, carbohydrate-deficient transferrin seen in CSF, not
in blood; used to identify CSF– IgG major gamma globulin
Cerebrospinal ProteinCerebrospinal Protein
Copyright © 2014. F.A. Davis Company
• Decreased protein levels = fluid leakage• Elevated levels = damage to blood-brain barrier,
IG production within CNS, decreased clearance, degeneration of neural tissue
• Meningitis/hemorrhage most common causes of increased damage to blood-brain barrier
• Find abnormal results on clear fluid with low cell counts from neurologic disorders
Clinical SignificanceClinical Significance
Copyright © 2014. F.A. Davis Company
Elevated Results• Meningitis• Hemorrhage• Primary CNS tumors• Multiple sclerosis• Guillain-Barré syndrome• Neurosyphilis• Polyneuritis• Myxedema• Cushing disease• Connective tissue disease• Polyneuritis• Diabetes• UremiaDecreased results• CSF leakage/trauma• Recent puncture• Rapid CSF production• Water intoxication* Reference values for protein are usually 15 to 45 mg/dL, but are method dependent, and higher values are found in infants and people older than 40 years.
Clinical Significance of Elevated Clinical Significance of Elevated Protein ValuesProtein Values
Copyright © 2014. F.A. Davis Company
• Turbidity • Automated instrumentation available
– Nephelometry
MethodologyMethodology
Copyright © 2014. F.A. Davis Company
• Comparisons between serum and CSF levels of albumin and IgG
• CSF/serum albumin index– Blood-brain barrier integrity
• CSF IgG index• Comparison of the CSF/serum albumin index with
the CSF/serum IgG index• Values for CSF albumin and globulin adapted for
automated instruments
Protein FractionsProtein Fractions
Copyright © 2014. F.A. Davis Company
IgG index = CSF IgG (mg/dL)/serum IgG (g/dL)
CSF albumin (mg/dL)/serum albumin (g/dL)
• Values >0.70 indicate IgG production within the CNS
Protein Fractions Protein Fractions (cont’d)(cont’d)
Copyright © 2014. F.A. Davis Company
• Detection of oligoclonal bands– Represent inflammation within the CNS– Located in the gamma region of the protein
electrophoresis– Simultaneous serum electrophoresis must be
performed
Electrophoresis and Electrophoresis and Immunophoretic TechniquesImmunophoretic Techniques
Copyright © 2014. F.A. Davis Company
• Multiple sclerosis (MS) = no bands in serum, bands in CSF
• Leukemia, lymphoma, viral, HIV: bands in both• Primary purpose for MS, compare also to IgG
index• Encephalitis, neurosyphilis, Guillain-Barré, and
neoplasms may give same pattern • Consider symptoms
Electrophoresis and Immunophoretic Electrophoresis and Immunophoretic Techniques (cont'd)Techniques (cont'd)
Copyright © 2014. F.A. Davis Company
• Presence in CSF indicates demyelination of myelin sheath around axons of neurons
• Monitors the course of multiple sclerosis• Effectiveness of treatment• Immunoassay procedures available
Myelin Basic Protein Myelin Basic Protein
Copyright © 2014. F.A. Davis Company
• Selective transport across blood-brain barrier• Approximately 60% to 70% plasma glucose
– Plasma = 100 mg/dL; CSF = 65 mg/dL– Draw blood 2 hours before spinal tap
• Significance– Values that are decreased relative to plasma values– Elevated CSF glucose values are always a result of
plasma elevations
CSF GlucoseCSF Glucose
Copyright © 2014. F.A. Davis Company
• Markedly decreased with increased neutrophils in bacterial meningitis
• Tubercular meningitis decreased with increased lymphocytes
• Viral/fungal meningitis, normal glucose and increased lymphocytes
CSF GlucoseCSF GlucoseClinical SignificanceClinical Significance
Copyright © 2014. F.A. Davis Company
• Diagnosis and management of meningitis– Bacterial, TB and fungal levels >25 mg/dL – Viral <25 mg/dL
• More reliable than CSF glucose• Levels remain elevated until treatment becomes
effective, then fall rapidly• Can result from any condition that decreases
oxygen flow to the tissues– Monitor severe head injuries
CSF LactateCSF Lactate
Copyright © 2014. F.A. Davis Company
• Produced by brain cells from ammonia and α-ketoglutarate to remove toxic ammonia
• Indirect test for the presence of excess ammonia in the CSF
• Normal: 8 to 18 mg/dL– Elevated in liver disease– Elevated in children with Reye syndrome– Disturbance of consciousness when glutamine levels are more
than 35 mg/dL • More reliable than direct CSF ammonia
CSF GlutamineCSF Glutamine
Copyright © 2014. F.A. Davis Company
• Gram stain and cultures must be performed on sediment from centrifuged CSF; cytocentrifuge helps Gram stains
• Blood cultures also must be drawn• Difficult to interpret Gram stains, few organisms and
often debris• Organisms: S. pneumocystis<<AU: Should this be
Streptococcus pneumocystis or pneumoniae?>>, Haemophilus influenza, Escherichia coli, Neisseria meningitidis, Listeria monocytogenes, S. agalactiae
Microbiology TestsMicrobiology Tests
Copyright © 2014. F.A. Davis Company
• Cultures also plated on chocolate agar• TB smears very important because of growth time delay• Latex agglutination tests are available for
– Group B streptococcus, Haemophilus influenzae, S. pneumocystis<<AU: Should this be Streptococcus pneumocystis or pneumoniae?>>, Neisseria meningitidis, and Escherichia coli
• Gram stain is the best for detection• Compare with hematology and chemistry results
Microbiology Tests Microbiology Tests (cont’d)(cont’d)
Copyright © 2014. F.A. Davis Company
• Naegleria fowleri– Found in ponds, lakes, and
some pools– Enters nasal passages and
migrates to the brain– Motile amoeba seen in wet
preps, nonmotile in cytospin preps
– Elongated with tapered posterior
ParasitesParasites
Copyright © 2014. F.A. Davis Company
• Primary test is for neurosyphilis, third stage• Performed less now that people have been treated
early with penicillin• Detect active cases within the CNS• The Venereal Disease Research Laboratories (VDRL)
produces the recommended test for specificity• Should be accompanied by a positive serum
Fluorescent Treponemal Antibody Absorption (FTA-ABS)<<AU: defined FTA-ABS: ok?>>
Serologic TestingSerologic Testing
top related