Disseminated Herpes Zoster with Acute Encephalitis in an Elderly Man: A Case Report.

Introduction: Disseminated herpes zoster (HZ) is uncommon and typically occurs in immunocompromised populations, including patients with HIV/AIDS, transplantation recipients, and patients with autoimmune diseases. However, disseminated HZ may also occur in healthy patients. Many studies have found that its incidence is positively correlated with age, and the severity is also positively correlated with age. Central nervous system (CNS) complications during or following HZ are extremely rare. Encephalitis has been reported to affect only 0.1%-0.2% of HZ patients. The occurrence of disseminated HZ with acute encephalitis in immunocompetent patients is even less frequently reported. Case Presentation: An 85-year-old male presented with disseminated HZ and acute encephalopathy, later confirmed as varicella zoster virus (VZV) encephalitis via cerebrospinal fluid analysis and neuroimaging. Treatment with intravenous acyclovir and methylprednisolone led to gradual improvement in consciousness, and the skin lesions regressed, though dizziness persisted. Conclusion: Elderly patients with disseminated HZ should be closely monitored for potential neurological complications such as HZ encephalitis. Once clinical manifestations such as fever, headache, meningeal irritation, cranial nerve impairment, or even cognitive changes appear, the possibility of CNS infection should be suspected.