- In most cases with acute viral (memingo-) encephalitis, the histological picture is non-specific.
- There is a perivascular lymphocytic infiltration, sometimes mixed with leukocytes – perivascular inflammatory ‘cuffing’ .
- In gray substance are found areas of necroses. Around them are formed microglial proliferations (nodules).
- Sometimes, in rabies for example, the viral target is the ganglion cell, with phagocytosis of its fragments – neurophagia.
- In severe cases brain tissue shows necrotic vasculitis and focal hemorrhages.