Varicella zoster virus encephalitis in a patient with disseminated herpes zoster: report and review of the literature.

Herpes zoster infection occurs owing to reactivation of varicella zoster virus and classically manifests as a vesicular eruption involving a single dermatome. Disseminated herpes zoster - defined as having greater than twenty vesicles outside the primary or adjacent dermatome - is uncommon and typically occurs in immunocompromised individuals. Central nervous system complications during or following a zoster outbreak are exceedingly rare. Encephalitis is reported to affect only 0.1-0.2% of patients and occurs more often in disseminated cases and in outbreaks involving those dermatomes in close proximity to the central nervous system. We present an elderly woman with disseminated herpes zoster and altered mental status who was subsequently diagnosed with varicella zoster virus encephalitis and describe the characteristics of patients with disseminated zoster who developed varicella zoster virus encephalitis.