CSF

• What is the clear, colorless body fluid found within the tissue surrounding the brain and spinal cord?

  Cerebrospinal fluid (CSF)
• What is the primary function of cerebrospinal fluid (CSF)?

  To supply nutrients to the nervous system and remove metabolic wastes
• How does CSF protect the brain and spinal cord?

  By producing a mechanical barrier that cushions them against trauma
• Where does CSF occupy in the central nervous system?

  In the subarachnoid space between the arachnoid and pia mater
• What are the three layers of the meninges?

  Dura mater, arachnoid mater, pia mater
• What is the function of the dura mater?

  It is the outer layer that lines the skull and vertebral canal
• What does the term "arachnoid" refer to in the context of the meninges?

  It refers to the spider web-like layer that lines the inner membrane
• What is the role of the pia mater?

  It is the thin membrane lining the surfaces of the brain and spinal cord
• What specialized cells produce cerebrospinal fluid (CSF)?

  Specialized ependymal cells in the choroid plexuses
• What is the rate of CSF production?

  20 mL per hour
• What is the total volume of CSF in adults and neonates?

  Adults: 90-150 mL; Neonates: 10-60 mL
• How is CSF reabsorbed to maintain normal values?

  It is reabsorbed back into the capillaries in the arachnoid granulations/villae
• What is the process of CSF production?

  It occurs via selective filtration under hydrostatic pressure and active transport secretion
• What is the blood-brain barrier?

  A tight-fitting structure of endothelial cells in the choroid plexuses that prevents molecule passage
• What is the primary function of the blood-brain barrier?

  To protect the brain from harmful chemicals and substances in the blood
• What happens when the blood-brain barrier is disrupted?

  WBC, proteins, and additional chemicals can enter the CSF
• What is CSF considered in relation to plasma?

  CSF is considered an ultrafiltrate of plasma
• What is a lumbar puncture used for?

  To collect cerebrospinal fluid (CSF)
• What are the normal intracranial pressure measurements?

  Normal: 5 to 15 mmHg; mild intracranial hypertension: 20 to 30 mmHg
• What precautions should be taken during a lumbar puncture?

  A careful technique is needed to prevent infection or neural tissue damage
• What fluid is collected during a lumbar puncture?

  Cerebrospinal fluid (CSF)
• What are the different tubes used for CSF collection and their purposes?

  • Tube 1: Chemistry/Serology (freezer temp.)
  • Tube 2: Microbiology (room temp.)
  • Tube 3: Hematology (refrigerated)
  • Tube 4: Microbiology/Serology
• What should be done if a single tube is collected during CSF analysis?

  The specimen should be sent first to microbiology, then hematology, and lastly to chemistry and serology
• What does crystal clear CSF indicate?

  Normal CSF appearance
• What does hazy or turbid CSF indicate?

  Increased WBC (>200 /uL), RBC (>400 /uL), lipids, and proteins
• What does xanthochromic CSF indicate?

  It is due to hemoglobin degradation products
• What does oily CSF indicate?

  Presence of radiographic contrast media
• What does clotted CSF indicate?

  Presence of protein and clotting factors, indicating a disrupted blood-brain barrier
• What does a pellicle in CSF indicate?

  It indicates tubercular meningitis
• What does bloody CSF indicate?

  Increased RBC (>6,000/uL) due to traumatic tap or intracranial hemorrhage
• What are the differences between a traumatic tap and intracranial hemorrhage in CSF analysis?

  • Traumatic Tap:
  • Distribution of blood in 3 tubes: Uneven
  • Clot Formation: +
  • Supernatant: Clear
  • Erythrophages: -
  • Intracranial Hemorrhage:
  • Distribution of blood in 3 tubes: Even
  • Clot Formation: -
  • Supernatant: Xanthochromic
  • Erythrophages: +
• Why should any cell count be performed immediately after CSF collection?

  WBC and RBC begin to lyse within 1 hour
• What is the normal WBC count in adults and neonates?

  Adults: 0-5 WBC/uL; Neonates: 0-30 WBC/uL
• What diluting fluid is used for WBC count in CSF analysis?

  3% acetic acid with methylene blue
• What is the appearance of CSF at different dilutions?

  Clear (undiluted), slightly hazy (1:10), hazy (1:20), slightly cloudy (1:100), cloudy/slightly bloody (1:200), bloody or turbid (1:10,000)
• Why is RBC count performed only in cases of traumatic tap?

  To correct for WBC count and total protein concentration
• What is the formula for correcting WBC count in the presence of RBC?

  WBC count/uL = # of cells counted x dilution / # of squares counted x depth
• What are the predominant cells in the CSF?

  Lymphocytes and monocytes
• What is pleocytosis?

  Increased number of normal cells in the CSF
• What type of cells are eosinophils associated with?

  Parasitic and fungal infections