Atypical Presentation of Varicella-Zoster Virus Encephalitis in an Elderly Immunocompetent Adult: Early Diagnosis and Positive Outcome Following Treatment.

Varicella encephalitis following herpes zoster ophthalmicus (HZO) is a rare but serious complication that can occur due to the reactivation of the varicella-zoster virus (VZV). HZO involves the ophthalmic division of the trigeminal nerve, typically presenting with a dermatomal rash, and can lead to various ocular complications. In some cases, this reactivation can extend to the central nervous system, resulting in encephalitis, which can lead to significant morbidity and mortality, particularly in immunocompromised or elderly individuals. This report describes a case of VZV encephalitis complicating HZO in an elderly immunocompetent male who presented with altered mental status following an initial presentation of HZO in the absence of a dermatomal rash, with a tentative diagnosis of an acute ischemic stroke. Early diagnostic confirmation was achieved through cerebrospinal fluid analysis and polymerase chain reaction, which identified VZV central nervous system infection. The patient was administered intravenous acyclovir, leading to complete neurological recovery. This case underscores the necessity of including VZV encephalitis in the differential diagnosis of acute encephalopathy, even when typical dermatological signs are absent. Furthermore, it emphasizes the critical role of prompt antiviral therapy in ensuring favorable clinical outcomes. Additionally, this case illustrates that VZV encephalitis can mimic stroke-like symptoms, highlighting the potential for misdiagnosis and the importance of considering infectious etiologies in such presentations.