M AUBF: CSF ANALYSIS

• CSF is a major fluid of the body.
• CSF provides physicians with a tool by which to evaluate the central nervous system (CNS).
• CSF Function:

  • supply nutrients to the nervous tissue
  • remove metabolic wastes
  • produce a mechanical barrier to cushion the brain and spinal cord against trauma
• Brain and spinal cord are lined with MENINGES
• Dura mater - Lines the skull and vertebral canal
• Arachnoid - filamentous; spider like
• Pia mater - thin membrane lining the surfaces of the brain and spinal cord
• CSF is produced in the choroid plexuses of the two lumbar ventricles and the third and fourth ventricles
• In adults, approximately 20 mL of fluid is produced every hour.
• To maintain a volume of 90 to 150 mL in adults and 10 to 60 mL in neonates, the circulating fluid is reabsorbed back into the blood capillaries in the arachnoid granulations/villae at a rate equal to its production.
• The fluid flows through the subarachnoid space located between the arachnoid and pia mater
• tight-fitting structure of the endothelial cells in the choroid plexuses is termed the blood–brain barrier
• The choroid plexuses are capillary networks that form the CSF from plasma by mechanisms of selective filtration under hydrostatic pressure and active transport secretion
• The procedure for obtaining CSF is known as a LUMBAR PUNCTURE
• Contraindication to performing lumbar puncture is the presence of infection at the puncture site
• 10–20 mL of CSF is slowly removed into three or four sterile tubes that are numbered sequentially
• If only one tube can be collected, it must be tested first by microbiology.
• All diluents should be checked biweekly for contamination
• The speed of the cytocentrifuge should be checked monthly with a tachometer
• If nondisposable counting chambers are used, they must be soaked in a bactericidal solution for at least 15 minutes then thoroughly rinsed with water and cleaned with isopropyl alcohol after each use.
• Cell count: Specimens that contain up to 200 WBCs or 400 RBCs/μl may appear clear
• Utilizes standard Neubauer calculation formula used for blood cell counts
• Cell Count: WBCs - 0-5/μL
• WBC Count: 3% glacial HAc - lyse RBC
• WBC Count: Methylene blue - added to diluting fluid to stain (differentiate neutrophils and mononuclear cells)
• WBCs are counted in the four corner squares and center square on both sides of the hemocytometer and the number is multiplied by the dilution factor to obtain the number of WBCs per microliter.
• Differential count performed on a Wright stained smear
• Differential count specimen should be concentrated prior to the preparation of the smear
• Differential count: sedimentation, filtration, centrifugation, and cytocentrifugation
• Differential count: Cytocentrifuge/ routine centrifuge for 5-10 mins
• Differential count: 100 cells - report in percentage. If <100 cells counted - report only the numbers of the cell types seen
• NONPATHOLOGICALLY SIGNIFICANT CELLS: CHOROIDAL CELLS, EPENDYMAL CELLS, SPINDLE SHAPED CELLS
• MALIGNANT CELLS: HEMATOLOGIC

  • LYMPHOBLAST
  • MYELOBLAST
  • MONOBLAST
  • LYMPHOMA CELLS
• MALIGNANT CELLS: NONHEMATOLOGIC

  • ASTROCYTOMA
  • RETINOBLASTOMA
  • MEDULLOBLASTOMA
• Choroidal cells are from the epithelial lining of the choroid plexus.
• Ependymal cells are from the lining of the ventricles and neural canal. They have less defined cell membranes and are frequently seen in clusters. Nucleoli are often present
• Spindle-shaped cells represent lining cells from the arachnoid. They are usually seen in clusters and may be seen with systemic malignancies
• CSF PROTEINS: Normal Value

  • Adults: 15 to 45 mg/dL
  • Infants: 150 mg/dL
  • Immaure: 500 mg/dL
• CSF PROTEINS: Increased In

  • Damage to BBB (Meningitis, Hemorrhage)
  • Production of Igs in CNS (Multiple Sclerosis)
• CSF PROTEINS: Decreased In

  • CSF Leakage