What is the main finding (both gross and microscopic) in bacterial meningitis?
pus formation - both neutrophils and gross pus
the pus tends to collect more aorund the cerebral veins
Why is the location of the pus important clinically?
Helps to figure out the organism:
TB, HIB, and Crypto tend to coat the base of the brain while Strep tends to be more on the surface
What is the concern when the pus starts to organize and become fibrous?
the concern is that it will block CSF reabsorption and lead to a communicating hydrocephalus
True or false, it is common to have a negative gram stain (no organisms) in a bacterial meningitis.
Where do you usually ses neutrophils under histology in bacterial meningitis?
in the subarachnoid space, but can enter the vessles or vessel walls or sometimes even into the parenchyma itself
What is it called when the neutrophils proliferate in the vessles? In the parenchyma?
vessel = phlebitis
pharenchyma = cerebritis
What is the main worry with phlebitis?
They can pack the vessels so tightly that they act as a thrombus and cut off blood supply
What protein gets laid down when the prurulent exudate begins to organize?
In what way do the symptoms of a TB meningitis differ from than of a typical bacterial meningitis?
Comes on in a more chronic fashion, not acute - will be ongoing for weeks
Nonspecific CNS symptoms
Difficult to diagnose
WHat will a TB meningitis look like on gross pathology?
- exudate on the basal side - can obliterate the cisterna magna and encase the cranial nerves
- Tuberculomas form in severe cases
- may be able to see the granulomas without microscopy - will look like small white granules
What will a TB meningitis look like on histology?
- infiltate of mononuclear cells!!! NOT PMNs!!!
- acid fast will often be positive
What is the concern with the granulomas int he CNS?
if there are too many, they can block and fill arteries as an obliterative endarteritis, which will impede blood flow to the brain
What do granulomas look like under high mag?
Caseous debri in the center and palisading layers of histiocytes and lymphocytes on the periphery
What will a vriral meningitis look like on gross an microscopid pathology?
Pretty normal in most cases
on gross, maybe slightly swollen
on microscopic, maybe some lymphocytic infiltrate of the meninges