ABSTRACT
Most viral infections of the central nervous system (CNS) are severe and have a high morbidity and mortality unless appropriate specific antiviral therapy is available, and is administered before brain damage has occurred. Fortunately, the CNS appears to be relatively protected from viral infections. Many of the viruses which do affect the CNS are common causes of systemic infection, such as herpes viruses and enteroviruses, and involvement of the CNS is relatively uncommon. When it does occur it is a medical emergency which requires rapid diagnosis and treatment in order to avoid irreversible brain damage. The diagnosis may be achieved by identification of viral DNA in the cerebrospinal fluid (CSF) by using polymerase chain reaction (PCR) analysis. Serological studies, identifying the antibodies generated by the host response to the virus in samples of serum and CSF, are also important. In the past, brain biopsy played an important role in the diagnosis of viral infections of the CNS, but this is now rarely performed and pathologists will more often encounter viral infections at autopsy. If a post mortem examination is to be performed on a patient with a suspected viral infection then liaison with the virologist is essential to ensure that appropriate samples are obtained. Fresh brain tissue, sampled bearing in mind the anatomical targets of the different viruses, is important, together with specimens of CSF and serum.
