Cerebrospinal fluid (CSF)
OUTLINES: • CSF definition, functions and methods • of sampling • Indications and contraindications of CSF Sampling. • Examination of CSF. • Abnormalities in CSF examination.
[email protected] q The liquid surrounding q Physical support & protec on (shock absorber) the brain and spinal cord. q Provides controlled chemical environment q It flows in the (nutrient supply and waste removal) subarachnoid space q Intra and extra cerebral (Between arachnoid and pia transport ma er) (Neuroendocrine func on) CIRCULATION
ABSORPTION EXCRETION
• Formed at the choroid plexuses by the cells lining the ventricles. Excre on volume = • Rate of forma on: 500 ml/day occurs at the arachnoid villi produc on volume • Mechanism of forma on: à protrude through the dura to => constant CSF volume 1) Selec ve ultrafiltra on of plasma the venous sinuses of the brain. 2) Ac ve secre on by epithelial membranes. à bloodstream q CNS infec on Obtained by lumbar q Demyelina ng puncture diseases (At the interspace L3-4, or lower)1 q CNS Malignancy Using asep c techniques q Hemorrhage in CNS ⇒ Then, separated into 3 aliquots: ü For chemistry & serology ü For microbiology ü For cell count. Immediate analysis is required to avoid exposure to microbes q Bleeding diathesis CONTRAINDICATIONS Because it is a precious sample, (tendency) (lumbar puncture) OF LP preserving any remaining
sample is highly suggested. q Increased intracranial pressure q Infec on at site of needle inser on 1: Because spinal cord ends at L2
o Normal CSF is: 1) Colorless 2) Clear 3) Free of clots 4) Free of blood
CSF o If CSF is turbid => perform microscopic examina on.
1- Physical Usually due to leucocytes or may be due to micro-organisms examina on of
Blood & Hemoglobin pigments in CSF Due to: TRAUMATIC TAP Subarachnoid hemorrhage (SAH) u Bright red color Xanthochromia u RBCS decrease in number as Hemoglobin pigment breakdown the fluid is sampled. It indicates hemorrhage = RBCs lysis and metabolism if we exclude: previously occurred (2 hours earlier) 1) Prior trauma c tap 2) Hyperbilirubinemia (bilirubin > 20 mg/dL) Tests of interest: 1
o Glucose o Protein1: total and Specific e.g. Albumin, Immunoglobulin, others e.g. myelin basic protein CSF o Lactate
analysis of o Glutamine :(replaced by measuring plasma [ammonia] Biochemical
• Not clinically informative q Enters CSF via facilita ve ↑ CSF [glucose] • Provides only confirmation of hyperglycemia transporter (GLUT). q CSF [glucose] is ~ 2/3 that of PLASMA Which equals 50 - 80 mg/dl2 v In hypoglycemia: • Disorder in carrier-mediated transport => CSF glucose may be very low e.g. TB meningitis, sarcoidosis v • Active metabolism of glucose by cells In hyperglycemia: ↓CSF [glucose] or organisms e.g: => CSF glucose is raised. (hypoglycorrhachia): acute purulent, amebic, & fungal meningitis q Analysis should be done Immediately or preserve the • Increased metabolism by the CNS specimen with an glycoly c e.g. by CNS neoplasm e.g. fluoride ion. 1. The most reliable diagnos cally and accessible analy cally 2. A plasma sample must be obtained 2-4 hours before CSF sample N.B. In viral meningi s, CSF [glucose] is usually normal q ↑ CSF [total protein]: q Must be compared to the serum [protein] q Proteins, mostly albumin are found in the CSF (0.15-0.45 g/L) q Source of CSF proteins: Lysis of 80% from plasma by ultrafiltra on (Albumin mainly) contaminant blood 20% from intrathecal synthesis (Immunoglobulin mainly) (traumatic tap)
Useful Obstruction nonspecific ↑ permeability of the epithelial Like in: indicator of membrane due • Tumors pathological to: • Abscess states: • Bacterial or fungal infec on • Cerebral hemorrhage
↑ production by CNS tissue in:
• Multiple sclerosis (MS) • Subacute Sclerosing Panencephalitis (SSPE) q q CSF IgG can arise from: Albumin is produced solely in the liver ü plasma cells within CSF q Its presence in CSF must occur through BBB ü the blood through BBB CSF Albumin (mg/dL) CSF serum albumin index: q ↑CSF [IgG] without concomitant ↑ in CSF [Alb] suggests = Serum Albumin (g/dL) If < 9 = intact BBB local production of IgG like in: * ü mul ple sclerosis (MS) ü subacute sclerosing panencephali s (SPEE) CSF IgG/Serum IgG CSF IgG index: = CSF serum Albumin index Normally: < 0.7 * What to do if ↑ CSF [protein] was detected?
=> Perform electrophore c separa on (CSF electrophoresis) the following differen al diagnosis is suspected: q MS If mul ple banding (oligoclonal q SSPE bands) of the γ-globulin is detected q Inflammatory diseases * Just for demonstra on albumin albumin
β1 prealbumin prealbumin β1 α1 β2 α2 β2 γ α2 α1 o CSF [Calcium], [Potassium] & [Phosphates] are lower than their levels in the blood. o CSF [Chloride] & [Magnesium] are higher than their levels in the blood
CSF o Abnormal CSF [Chloride] o marked ↓↓ in acute bacterial meningi s
Components of o slight ↓ in viral meningi s & brain tumors Other Chemical
Appearance Clear ,Colorless
Lymphocytes <5/mm3
Polymorphs Nil
pH 7.4
Total Volume 100 - 150 ml
Daily Secre on 450 - 500 ml
Specific Gravity 1.006 - 1.007
Protein 0.15 – 0.45 g/L
Glucose 50 - 80 mg/dL (2.8-4.2 mmol/L) (>50% plasma level)
Chloride 115 - 130 mmol /L
Calcium 1.0 - 1.40 mmol/L
Phosphorus 0.4 - 0.7 mmol/L 1: No need to memorize Magnesium 1.2 - 1.5 mmol/L them. References rates Potassium 2.6 - 3.0 mmol/L will be given in the exam Parameter Condi on
Bacterial Meningi s Tuberculous Meningi s Viral Meningi s (pyogenic) Appearance O en turbid O en fibrin web Usually clear
Predominant cell Polymorphs Mononuclear Mononuclear Cell count/mm3 90-1000+ 10-1000 50-1000
Bacteria In smear & culture O en none in smear None seen or cultured Protein (0.15-0.45 g/L) >1.5 (↑ ↑) 1-5 (↑ ↑) <1 (Normal)
Glucose (2.8-4.2 mmol/L) <1/2 plasma (↓ ↓) <1/2 plasma (↓ ↓) >1/2 plasma (Normal or slightly ↓) Chlorides (115 - 130 mmol/l) ↓ ↓ ↓ ↓ Normal or ↓
Otorrhea: leakage of CSF from the ear Rhinorrhea: leakage of CSF into the nose Q: How to iden fy it as CSF? =>Measure β-transferrin (a protein unique to the CSF) 1) CSF sampling is contraindicated in which ONE of the following ? 6) A CSF sample was taken from a 55-years old female for her annual check up, A- CSF infections the biochemistry lab noted the presence of oligoclonal band of of γ-globulin B- Vertigo In electrophoresis, this CAN indicate which ONE of the following: C- Increased intracranial pressure A- SSPE D- Immunocompromised patients B- Hemorrhage 2) While sampling CSF from a patient, the nurse noticed that a bright red C-Tumors color of blood has appeared and it was decreasing in color as he continue D- Autoimmune diseases sampling. This hemorrhage is most-likely due to: 7) Which ONE of the following components is present in higher levels in CSF A- Traumatic tap. than in the blood B- Subarachnoid hemorrhage. A- Ca C- Infection at site of needle insertion. B-Zn D- The sample is normal. C- Phosphate 3) Increased CSF (GLUCOSE) is a confirmation of : D- Cl A- Diabetes mellitus 8) The following schedule illustrate the result of some parameters of CSF B- Not clinically informative sample. C- Presence of micro organisms in CSF Parameter Result Reference rate D- Hypoglycemia Appearance Fibrin web clear 4) CSF (GLUCOSE) in a patient with viral meningitis is expected to be : A- Very high Predominant cell Mononuclear -- B- Very low Protein 4 g/dl 0.15-0.45 g/L C- Normal D- Depend on the cause. Bacteria None appear in smear None 5) Abnormal CSF total protein can be an indicator of which of the following pathological states Based on the results shown above, the most-likely diagnosis is: A- Tumors A-Bacterial meningitis B- MS B- Viral meningitis C- Bacterial or fungal infection C- Tuberculous meningitis
D- Hemorrhage D- SSPE E- All of them Answers: 1) C 2) A 3) B 4)C 5) E 6)A 7) D 8) C If you have any ques ons or comments, don’t hesitate to contact us
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Done by: Mohammed Alnafisah Sara Aldokhyl Ahmed alqahtani