Q 1.31. Anatomy and Physiology of Cerebrospinal Fluid (CSF). CSF Syndromes.

1. Cerebrospinal Fluid (CSF):

    • CSF is a clear, colorless plasma-like fluid that bathes the central nervous system (CNS), including the brain and spinal cord.
    • It circulates through a system of cavities within the CNS:
      • Ventricles: These are interconnected spaces within the brain.
      • Subarachnoid space: The space between the arachnoid and pia mater layers of the meninges.
      • Central canal of the spinal cord.
    • The majority of CSF is secreted by specialized tissue called the choroid plexus, located in the lateral, third, and fourth ventricles.
    • CSF serves several essential functions:
      • Cushioning: It protects the brain and spinal cord from mechanical forces.
      • Immunological protection: Basic defense for the CNS.
      • Waste removal: Clears metabolic waste products.
      • Transport of neuromodulators and neurotransmitters.
      • Clinical diagnosis: CSF samples obtained via lumbar puncture aid in diagnosis.


2. Choroid Plexus:

    • The choroid plexus is responsible for CSF production.
    • It is found in the walls of the lateral ventricles and the roofs of the third and fourth ventricles.
    • Structural components of a choroid plexus villus:
      • Modified ependymal cells (choroid cells): These cells secrete CSF into the ventricles.
      • Pia mater layer (tela choroidea).
      • Fenestrated capillaries beneath the pia mater.
    • Choroid cells actively secrete CSF by taking up various chemicals from the underlying blood vessels.


3. Circulation of CSF:

    • CSF flows through the following path:
      • Lateral ventricle → third ventricle → fourth ventricle → central canal of spinal cord → subarachnoid space.
    • Arachnoid granulations and glymphatics are involved in CSF absorption.


4. Clinical Syndromes Involving CSF:

  • Protein-Cell Dissociation refers to an abnormal finding in the CSF where the protein concentration is elevated, but the cell count (pleocytosis) remains normal.
      • Clinical Significance:
        • This dissociation is often seen in chronic inflammatory conditions affecting the central nervous system (CNS).
        • Examples include neurosyphilissubacute sclerosing panencephalitis (SSPE), and some cases of multiple sclerosis (MS).
        • In these conditions, the immune response leads to increased protein production without a significant increase in white blood cells (WBCs) in the CSF.
      • Diagnostic Clues:
        • When encountering protein-cell dissociation, consider the patient’s clinical history, neurological symptoms, and other laboratory findings.
        • Additional tests (such as serological tests for syphilis or oligoclonal band analysis) may help confirm the underlying cause.
  • Cell-Protein Dissociation: refers to an abnormal finding in the CSF where the cell count (pleocytosis) is elevated, but the protein concentration remains normal.
          • Clinical Significance:
            • This dissociation is typically observed in viral infections affecting the CNS.
            • Examples include viral encephalitisaseptic meningitis, and certain herpes simplex virus (HSV) infections.
            • In these cases, the immune response leads to an influx of inflammatory cells (lymphocytes) into the CSF without a significant increase in total protein.
          • Diagnostic Clues:
            • Consider the patient’s symptoms (fever, headache, altered mental status), recent infections, and CSF cell count.
            • PCR testing for specific viruses (e.g., HSV, enteroviruses) can help confirm the diagnosis.
  • Hydrocephalus: Abnormal accumulation of CSF due to impaired flow or absorption.
  • Meningitis: Inflammation of the meninges affecting CSF composition.
  • Subarachnoid hemorrhage: Bleeding into the subarachnoid space.
  • Normal Pressure Hydrocephalus (NPH): Characterized by enlarged ventricles and normal CSF pressure.
  • CSF leaks: Abnormal communication between CSF and external environment.



1 kenhub.com

2 link.springer.com

3 academia.edu

4 link.springer.com

5 uptodate.com

Verified by Dr. Petya Stefanova