Question 28.4

Last updated 15/08/2022 - 05:00
 Topic: Neurology and Neurosurgery
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A 27-year-old patient with a prolonged ICU stay following a subarachnoid haemorrhage has developed fever with an altered consciousness level.

The CSF specimen result below was taken from the external ventricular drain.

Parameter

Patient Value

Adult Normal Range

Red Blood Cells

1946 x 106/L*

0 – 5

Neutrophils

198 x 106/L*

0 – 5

Mononuclear cells

74 x 106/L

a)    List your treatment decisions to be made based on the CSF.    (10% marks)

b)    Explain your rationale for the above.    (10% marks)
 

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College answer

Not available.

Discussion

The question that needs to be answered about the CSF is:

  • is this just the decomposition of the clot in the ventricles causing aseptic ventriculitis, or
  • is everything just inflamed from the irritant effects of the EVD being in situ for so long, or
  • is this bacterial ventriculitis, and the EVD is infected?

For CSF following SAH, analysis is challenging because there is usually enough blood in the CSF to confuse everything, and the process of clot dissolution brings out the neutrophils and macrophages, producing leukocytosis. Annoyingly, the patient can also be febrile purely from the blood in the CSF, leaking inflammatory chemicals into the delicate sensory filaments of the hypothalamic thermostat. 

So, what to do with this result? Pfausler et al (2004), reviewing the literature and their own retrospective case series, concluded that there were "no specific CSF features that distinguish in the early diagnosis of ventriculitis after SAH"  and suggested that everyone should just give antibiotics anyway, because nosocomial bacterial ventriculitis has a very high morbidity and mortality. These can then be ceased two or three days later, when the CSF culture comes back negative. 

Thus, one possible approach is:

a) 

  • Keep the EVD in situ
  • Culture the CSF
  • Commence IV antibiotics for the empirical treatment of ventriculitis
  • Cease IV antibiotics if nothing grows from the CSF over 72 hrs
  • If something grows, remove the EVD

b)

  • The rationale for this aggressive approach is that a small fraction of patients with SAH will go on to develop nosocomial bacterial ventriculitis, and for these patients the outcomes are much worse (16% mortality, 20% persistent vegetative state, as per Panic et al, 2022)
  • Perhaps 25% of patients with SAH and EVDs will develop fevers, and they will all have similar infected-looking CSF microscopy, but the majority will not have a genuine infection

References

Hoogmoed, J., et al. "Clinical and laboratory characteristics for the diagnosis of bacterial ventriculitis after aneurysmal subarachnoid hemorrhage." Neurocritical care 26.3 (2017): 362-370.

Pfausler, B., et al. "Cell index–a new parameter for the early diagnosis of ventriculostomy (external ventricular drainage)-related ventriculitis in patients with intraventricular hemorrhage?." Acta neurochirurgica 146.5 (2004): 477-481.

Beer, Ronny, Bettina Pfausler, and Erich Schmutzhard. "Management of nosocomial external ventricular drain-related ventriculomeningitis." Neurocritical care 10.3 (2009): 363-367.

Beer, R., et al. "Nosocomial ventriculitis and meningitis in neurocritical care patients." Journal of neurology 255.11 (2008): 1617-1624.

Panic, Hana, et al. "Etiology and Outcomes of Healthcare-Associated Meningitis and Ventriculitis—A Single Center Cohort Study." Infectious Disease Reports 14.3 (2022): 420-427.

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