cloudy color of CSF in viral encephalitis?

[MudPhud20XX]

Firecracker says the CSF findings in viral encephalitis can be clear or cloudy color. I thought cloudy color was unique to bacterial meningitis, so what is causing the cloudy color in viral encephalitis?

The only thing that would be big enough to change the CSF opacity would be bacteria, so I am not sure what is causing the color change viral encephalitis.

Also, comparing between encephalitis (brain inflammation) vs meningitis (inflammation of meninges), virus usually is too small to get inside the brain via meninges whereas bacteria stays in meninges? Is this the case? What is the explanation that virus mostly causes encephalitis (brain inflammation) whereas bacteria mostly cause meningitis?

Many thanks in advance.

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[alicealicealice]

You still have lymphocytes (much bigger than bacteria) and elevated proteins which cause turbidity. Also you can get xanthochromia from hemorrhagic herpes encephalitis.

 

[MudPhud20XX]

You still have lymphocytes (much bigger than bacteria) and elevated proteins which cause turbidity. Also you can get xanthochromia from hemorrhagic herpes encephalitis.

Thank you alice!, could you also help me with the below questions too?

Also, comparing between encephalitis (brain inflammation) vs meningitis (inflammation of meninges), virus usually is too small to get inside the brain via meninges whereas bacteria stays in meninges? Is this the case? What is the explanation that virus mostly causes encephalitis (brain inflammation) whereas bacteria mostly cause meningitis?

 

[alicealicealice]

Actually, I believe the most common cause of meningitis overall is viral. It is known as aseptic meningitis that is a relatively mild illness that self resolves in an immunocompetent host. Coxsackie virus and other enteroviridiae are the most common causes I think, but HSV-2 can give you meningitis as well (different than the much more severe HSV-1 encephalitis).
As far as bacterial predilection for the meninges goes, I would guess it has to do with the route of infection, with hematogenous being the most common (there can also be continiguous spread). So it starts as meningieal inflammation, but bacterial meningitis makes you so sick that you present early in the course, and if left untreated the natural history would be to develop a (probably fatal) meningoencephalitis. Unlike most viral etiologies it would not resolve on its own. Presumably every encepahlitis is technically a meningoencephalitis, as the meningies overlying infected parenchyma would be inflamed, though the area of involvement may be limited (as with the temporal lobe prediliction of HSV-1)

 

[Phloston]

You still have lymphocytes (much bigger than bacteria) and elevated proteins which cause turbidity. Also you can get xanthochromia from hemorrhagic herpes encephalitis.

I'd say alice is on spot here. The only real thing you need to know relating to CSF and "color" for CNS viral disease is that HSV1/2 can cause haemorrhagic necrosis of the temporal lobes, leading to RBCs in the CSF.

If they ever mention RBCs in the CSF, your answer is going to be either subarachnoid haemorrhage or herpes infection.

They will typically suggest an infection + tell you there are RBCs in the CSF and then want you to answer "acyclovir."