Internally Peer Reviewed When left untreated, meningitis of any etiology, but particularly with the pyogenic and granulomatous forms, may lead to widespread destruction of the brain as shown here . In this case, there is marked hydrocephalus with little remaining cortex. The only normal appearing structures are the basal ganglia and thalamus. Consequently, hydrocephalus develops due to blockage of CSF outflow at the level of the aqueduct of Sylvius or the basal cisterns.
Cortical destruction results from both involvement of penetrating vessels and pressure atrophy.
The white matter is often intensely gliotic. This photomicrograph shows the rare instance in which ependymitis is the primary pathologic process. Ependymitis is evidenced by periventricular congestion and hemorrhage. Also, note the virtual absence of a meningeal reaction. Cases of primary ependymitis are usually associated with septicemia.