Introduction to Brain Infections
Brain infections may manifest as follows:
Diffuse infection, resulting in encephalitis, sometimes affecting specific areas on the brain
Inflammation of the brain secondary to meningeal infections or parameningeal infections
Focal infection (eg, due to a brain abscess or to fungal or parasitic brain infections)
Slow virus infections, such as progressive multifocal leukoencephalopathy (caused by the JC virus) or subacute sclerosing panencephalitis (caused by the measles virus) also affect the brain; they are characterized by a long incubation and a prolonged course.
Certain noninfectious disorders can mimic encephalitis. An example is anti-NMDA (N-methyl-d-aspartate) receptor encephalitis, which involves an autoimmune attack on neuronal membrane proteins.
Multifocal brain involvement may also be a manifestation of acute diffuse disseminated encephalomyelitis (a postinfectious syndrome).