Neuropathology of viral infections

Advancements in diagnostic methods, particularly polymerase chain reaction (PCR)-based testing of cerebrospinal fluid for viral nucleic acids, have diminished the role of neuropathologic examination in the diagnosis of viral infections of the central nervous system (CNS). Nevertheless, neuropathologic examination of CNS tissue remains important in the diagnosis of atypical viral encephalitides and in the exclusion of non-infectious etiologies. In addition to routine hematoxylin and eosin stains on tissue sections, the neuropathologist may utilize immunohistochemistry, in situ hybridization, electron microscopy, and PCR-based testing of the tissue specimen. In this review, we cover the general pathologic features of viral infections of the CNS as well as the specific features of CNS infections caused by poliovirus, herpes simplex virus, varicella-zoster virus, Epstein-Barr virus, cytomegalovirus, rabies virus, West Nile virus, Eastern equine encephalitis virus, measles virus, JC virus, human immunodeficiency virus, and human T lymphotropic virus type 1.