CSF Sampling and Analysis Flashcards
What can be used to assess protein levels in CSF?
Urine dipstick
What restraint is needed for CSF collection?
General anaesthetic
Where to take a CSF sample?
The site from which the CSF is to be taken depends on the neuroanatomical localisation. As a general rule, collection should be performed from a site caudal to, or anatomically close to, the suspected lesion.
For the investigation of intracranial or cervical pathology; sample should be taken from?
cisterna magna (cerebellomedullary cistern, CM)
In lesions caudal to T3 where is CSF taken?
Lumbar collection
In cases of multifocal localisation, where is CSF collected?
Both sites
T or F
In dogs with thoracolumbar myelopathy, CSF collected from the CM cistern may not be representative of the underlying disease process.
True
What position should the patient be for CSF?
Lateral recumbency
What parameters need to be carefully monitor with a CSF?
Cardioresp
Why check the ET tube with CSF?
Check it does kink when neck flexed
Does the ET tube often need to be cuffed or uncuffed?
Uncuffed
What collection site is associated with a lower risk of blood contamination and often provides a larger volume of fluid for evaluation?
Cisterna magna
CSF collection usually follows advanced imaging in cases of intracranial pathology and should only be performed if there are no signs of?
Increaed ICP
When collected prior to the myelography, what should you do with the fluid why?
evaluated prior to injection of contrast, especially in cases where inflammatory disease is highly suspected.
When is CSF sampling contra indicated?
Signs or suspicion of a coagulopathy (e.g., thrombocytopaenia, Von Willebrand disease).
Signs suggestive of raised intracranial pressure either clinically (e.g., head pressing, anisocoria, reduced oculocephalic reflex) or on advance imaging.
Which breed would CSF sampling of the CM be contra indicated/or at least imaging taken first?
CKCS
French bulldog
Griffon Bruxellois
- Where chiari like malformation is common
CSF has low protein levels; what is the result of this on leukocytes?
Rapid deterioration
Within what time frame should a CSF sample be processed?
30-60 mins
How much fluid should be collected for CSF?
0.5ml should be enough; more will be needed if PCR etc
CSF Macroscopic evaluation. What is normal?
Clear
Why might CSF fluid be pink - red?
haemorrhage (either due to pathology or iatrogenic contamination)
Why might CSF be yellow xantochromic?
Old haemorrhage (>48 hours).
Why might CSF be yellow-green? (2)
secondary to purulent inflammation or neoplasia,
Why might CSF be grey-black?
melanin granules or melanocytes are present.
What does normal protein levels of CSF depend on? (3)
Species
Site
Method of measuring
Is protein higher in cisterna magna or lumbar collection? Why?
The protein level is generally higher if collection is performed from the lumbar site due to the cranial to caudal flow of CSF.
How to know if protein is elevated on urine dipstick?
++ or more, the CSF protein level is likely to be elevated (assuming the CSF is not blood contaminated).
If urine dip for protein is negative or trace; what dos this mean?
CSF likely normal
If CSF protein is + on urine dip; what does this mean?
ivocal and required quantification.
What tube to send CSF in to lab to quantify protein?
Plain
Normal CSF:
A) Erythrocytes?
B) WBC?
A) None
<5uL
What is an increased erthrocyte in CSF usually due to?
Contamination
Define pleocytosis
Increased WBC
How can CSF total cell count be performed manually?
counting chamber (eg., Malassez, Neubauer, or Fuchs Rosenthal)
To perform manural cell count of CSF; do you:
A) Stain?
B) Centrifuge?
A) No
B) No
Cytocentrifugation is often required to obtain a differential cell count and to..? Why is it done this way?
evaluate cell morphology in view of the usual low cellularity of the CSF,
What is used to centrifuge CSF?
Cytospin
Blood contamination may falsely increase(2)
protein level and cell count.
Define mild RBC contamination
(< 5000 RBC/uL).
If there is mild RBC contamination; how can you interpret the protein with a formula?
For every 1000 RBC, adjust protein down 1mg/dL.
If there is mild RBC contamination; how can you interpret the leukocytewith a formula?
For every 500 RBC, leucocyte count can be adjusted down by 1 WBC/uL.
An increased protein level with normal total cell count is called?
albumin-cytological dissociation
albumin-cytological dissociation; what can this be due to physiologically? (3)
An altered blood brain barrier (BBB) which allow protein from the blood circulation to enter the CNS
Increased production within the CNS,
Obstruction of flow
albumin-cytological dissociation; This is a non-specific finding and as such can be seen in. What are the possible underlying causes? (4)
compressive lesions,
neoplasia,
ischaemic Myelopathy
degenerative myelopathy amongst others.
eosinophilic pleocytosis is usually associated with what prognosis?
Poor
What count is extremely important in determining the most likely differential diagnoses, treatment, and in some cases prognosis ?
Differential cell count
Lymphocytis pleocytosis:
A) Protein level?
B) WBC level?
C) % lymphocytes?
A) Increased
B) >5 u/L
C) >50%
What can cause lymphocytic pleocytosis? (2, amongst others)
lymphoma,
Necrotizing non-suppurative meningoencephalitis
amongst others.
Mixed cell pleocytosis:
A) Protein level?
B) WBC level?
C) cells seen?
A) Increased
B) >5 uL
C) Mix of lymphocytes and mononuclear cells
What can cause mixed cell pleocytosis? (3, amongst others)
GME
Fungal
Protozoal dx
Amongst others
Neutrophillic pleocytosis:
A) Protein level?
B) WBC level?
C) What cells?
A) Increased
B) >5 uL
C) Neutrophils predominant
What can cause neutrophillic pleocytosis? (3)
Steroid responsive meningitis arteritis
Bacterial meningitis
Following myelography
Eosinophilic pleocytosis:
A) Protein level?
B) WBC level?
C) What cells?
A) Increased
B) >5 uL
C) eosinophils predominant
What can cause eosinophillic pleocytosis? (2)
Parasitic
Idiopathic
What cellular inclusions may be seen in CSF? (3)
lysosomal storage diseases
canine distemper virus inclusions;
abnormal lymphocytes in cases of lymphoma
What larvae may be seen in CSF?
Angiostrongylus spp.
What micro-organism may be seen in CSF?
Cryptococcus neoformans
CSF PCR can be performed in cases where an infectious aetiology is suspected.
What might be looked for in dogs? (3)
Canine distemper
Neospora
Toxoplasma
CSF PCR can be performed in cases where an infectious aetiology is suspected.
What might be looked for in cats? (2)
Toxoplasma
Coronavirus
Why is it important to run PCR on CSF?
In some cases, blood serology can be negative
If the history is consistent, culture of CSF can be performed, however, it is negative in more than ?% of the case
60%
What volume of CSF is needed for culture?
LARGE!
