Herpesviruses cause various acute, subacute, and chronic disorders of the central (CNS) and peripheral (PNS) nervous systems in adults and children. Both immunocompetent and immunocompromised individuals may be affected.
Zoster (
shingles), a result of reactivation of varicella zoster virus (VZV), is the most frequent neurologic complication. Other neurological complications include
encephalitis produced by type I herpes simplex virus (HSV-1), and less frequently HSV-2, as well as by VZV and cytomegalovirus (CMV). Acute
meningitis is seen with VZV and HSV-2, and benign recurrent
meningitis with HSV-2. Combinations of
meningitis/
encephalitis and
myelitis/
radiculitis are associated with Epstein Barr Virus (EBV);
myelitis with VZV, CMV, EBV, and HSV-2; and ventriculitis/
encephalitis with VZV and CMV. Brainstem
encephalitis due to HSV and VZV, and polymyeloradiculitis due to CMV are well documented. HHV-6 produces childhood
exanthem subitum (roseola) and
febrile convulsions. Immunocompetent and immunocompromised hosts manifest different incidences and patterns of
herpesvirus infections. For example,
stroke due to VZV-mediated large vessel disease (
herpes zoster ophthalmicus) occurs predominantly in immunocompetent hosts, while small vessel disease (leukoencephalitis) and ventriculitis develop almost exclusively in immunocompromised patients. EBV-associated primary CNS
lymphomas also are restricted to immunosuppressed individuals. Recent large CSF PCR studies have shown that VZV, EBV, and CMV more frequently produce
meningitis,
encephalitis, or
encephalopathy in immunocompetent hosts than was formerly realized. We review
herpesvirus infections of the nervous system and illustrate the expanding spectrum of disease by including examples of a 75-year-old male on
steroid treatment for chronic
lung disease with fatal HSV-2
meningitis and an 81-year-old male with
myasthenia gravis, long-term
azathioprine use, and an EBV-associated primary CNS
lymphoma.