L11: CSF Analysis (Beatty) Flashcards
Where should you collect CSF?**
DISTAL to lesion
-atlanto-occipital protein lower than lumbosacral protein
Fx of CSF
- mechanical protection
- metabolic: transport and excretion
4 part CSF analysis
1) physical features (color, clarity)
2) microprotein conc.
3) cell counts
4) microscopic exam
? –> Yellow/orange CSF
RBC breakdown (xanthochromia)
? –> red CSF
Hemorrhage
-EEE, herpesvirus
? –> grey/black CSF
Melanoma (uncommon)
At what WBC count does CSF become cloudy?
> 300-500 WBC/uL
Spectrophotometer is the only way to precisely measure CSF microprotein
(Albustix can estimate only)
Pleocytosis
Elevated WBCs (cell count) in CSF
- classified by predominant cell type
- usually a concurrent increase in protein conc. Is present
Normal WBC/uL
Normal RBC/uL in CSF
0
Normal % of cells in CSF
60-70% lymphs
30-40% large mononuclear phagocytes
Must concentrate CSF before evaluating
:)
Preservation of CSF
- send 2 aliquouts: 1 plain, one w/ hetastarch or serum
- plain used for protein
- serum or hetastarch used for cell counts/cytology
How to distinguish iatrogenic from pathologic blood contamination of CSF***
- absence of platelets: pathologic
- presence of platelets: iatrogenic
- increased protein and cell counts in both
Albuminocytologic dissociation in CSF means:
Increased protein concentration with NORMAL cell count
- seen with lesions that damage BBB, obstruct CSF flow, cause localized tissue damage/necrosis, cause inc. protein prod. In the CNS (infectious, neoplasia)
- can also be a non-specific finding
- don’t give steroids
- don’t know if albumin or globulins increased
Types of CSF abnormalities
- albuminocytologic dissociation
- inc. protein w/ normal cell count but increased neuts
- pleocytosis
- neoplastic
- other (myelin, infectious agents, etc. found)
What can cause CSF to have increased protein conc. W/ normal cell count BUT increased neuts (>25%)?
- early/mild inflammatory dz
- lesions NOT involving the meninges (IVDD, cervical stenotic myelopathy, spinal fx, severe seizure, CNS necrosis)
- blood contamination
- prior steroid or abx use*
Effect of steroids on WBCs
Down regulate adhesion molecules that neuts use to attach to endothelium (FYI)
2 pools of neuts
1) circulating
2) marginating (attached to endothelial cells)
Neutrophilic pleocytosis ddx
Always consider bacterial meningitis
Dogs:
- Steroid responsive meningitis-arteritis
- infectious etiology
- FCE
- chiari-malformation
Cats:
- infectious
- thiamine deficiency
Horses:
-EEE, WEE, VEE, bacterial
Others: contrast medium, CNS neoplasia
Ddx of lymphocytic pleocytosis
-viral meningitis most common
Dogs:
- usually immune mediated dz
- necrotizing meningoencephalitis
- infectious (rabies, distemper, toxo, coccidio)
Horses: WNV, EPM, Rabies, EHV, EEE, WEE, VEE
Young cats: feline polioencephalomyelitis
Can be lymphoma in any species
Ddx of mixed cell pleocytosis
Dogs:
- GME
- chronic SRMA
- infectious (fungal, protozoal)
Cats:
-chronic FIP
LA: listeriosis
Eosinophils don’t belong in a mixed cell pleocytosis; if they are present, it is automatically an eosinophilic pleocytosis
:)
Ddx for eosinophilic pleocytosis
- Eosinophilic steroid responsive meningitis (goldens)
- Infectious: parasites, protoza, algal
- CNS abscess in sheep
- P. Tenuis in alpacas
Cryptococcus in CSF of cat***
Causes mixed inflammatory population
When do you see myelin in CSF?
- demyelinating diseases (ie. Degenerative myelopathy in a GSD)
- iatrogenic if poke the spinal cord
Can see canine distemper inclusions on CSF
Diff quick best stain for it!
-lymphocytic plasmacytic inclusions
Can dx lymphoma on CSF if lymphoid population is lymphoblasts
Can’t call it if small cell lymphoma
Formation of CSF
- ultrafiltrate of plasma
- prod. mainly by choroid plexus
- moves caudally
- partially reabsorbed
