Brain imaging abnormalities in CNS virus infections.

Unlike bacterial and fungal meningitis in which imaging abnormalities are not specific for a particular agent, many virus infections of the CNS produce MRI abnormalities not seen by any other infectious agent. The changes caused by the specific virus can also be produced by noninfectious disorders. Imaging changes must always be evaluated in conjunction with the clinical symptoms, signs, and laboratory abnormalities, particularly the presence of a CSF pleocytosis. The purpose of this montage is to ensure that the clinician includes the specific virus in the differential diagnosis (figure).