Cerebrospinal Fluid Analysis

Composition

Normal (and abnormal) CSF Composition
Property Normal Traumatic Tap Infection SAH Other
Colour Clear Bloodstained
  • Clear in viral infection
  • Turbid in bacterial infection
  • Fibrinous in fungal infection
 Bloodstained
Opening Pressure 5-20cmH2O
  • -/↑ In viral
  • ↑ In bacterial
RBC (count) Nil ↑ ↑/↑↑
WBC (count) 0-3 1 WCC:500 RBC
↑ In the setting of an EVD.
  • PMN leukocytosis (>500)
    Favours bacterial.
  • Lymphocytosis
    Favours viral, TB, fungal, or listeria.
  • Monocyte dominant (>100)
    Favours viral infection.
  • Mixed lymphocytosis\monocytosis
    GBS, status epilepticus.
  • Lymphocytosis and monocytosis can also occur in GBS and vasculitis
Protein (g/L) 0.18-0.45
  • ↑ (<1) In viral
  • ↑↑ (>1) In bacterial
  • -/↑ (0.1-0.5) in fungal
  • ↑ In vasculitis
  • ↑ In sarcoidosis
  • ↑ In GBS
  • ↑ In status epilepticus
  • Oligoclonal bands in MS
Glucose (mmol/L) 2.5-3.5
  • ↓ (<2.2) In bacterial
  • ↓ (<2.5) In fungal
  • ↓ Due to RBC metabolism
Glucose CSF:Serum (ratio) . 0.6
  • >0.6 In viral
  • <0.6 In bacterial
Other
  • CSF culture
  • LDH
    ↑ In bacterial.
  • Cryptococcal antigen
  • Bacterial antigen
  • Viral PCR
    • HSV
    • VZV
    • HZV
    • Enterovirus
    • Adenovirus
  • Antibodies
    • Anti-NMDA
    • Anti-AMPA
    • Anti-DPPX
    • Anti-LGI1
    • Anti-GABA B
    • Anti-IgLON5
    • Anti-neuronal
  • Xanthochromia
    Bilirubin in CSF.

Notes

Things to Request:

  • Microscopy
  • Gram stain
  • Culture
    Extended if considering listeria, cryptococcus.
  • Cytology and cell counts
    • Oligoclonal bands
  • Protein
  • Any other disease-specific tests
    • Viral PCR
    • Antigens
  • An ↑ CSF WCC is referred to as a pleocytosis
  • Xanthochromia classically occurs due to metabolism of lysed RBCs from a SAH, but can also occur if serum bilirubin >100μmol/:
  • Glucose CSF:serum ratio is inaccurate if serum BSL ⪆17mmol/L due to saturation of glucose transporters
  • β-2 transferrin is specific for CSF, and is used to confirm suspicion of CSF rhinorrhea or CSF otorrhea.
  • For health-care associated meningitis or ventriculitis, an ↑ WCC is only suggestive and culture is required for definitive inclusion or exclusion of the diagnosis

References

  1. Venkatesh, B., P. Scott, and M. Ziegenfuss. Cerebrospinal Fluid in Critical Illness. Critical Care and Resuscitation: Journal of the Australasian Academy of Critical Care Medicine 2, no. 1 (March 2000): 42–54.
  2. Bersten, A. D., & Handy, J. M. (2018). Oh’s Intensive Care Manual. Elsevier Gezondheidszorg.