**Abstract**

Varicella-zoster virus (VZV) causes a diverse spectrum of neurologic complications: aseptic meningitis, encephalitis, cerebral infarction associated with granulomatous vasculitis, myelitis, and cranial polyneuropathy. These VZV-associated central nervous system (CNS) diseases usually result from reactivation of latent infection in immunosuppressive conditions, such as old age, diabetes mellitus, cancer, human immunodeficiency virus (HIV) infection, and the use of immunosuppressive drugs. However, they also occur in immunocompetent subjects. Since VZV antigen or DNA is often detected in the cerebrospinal fluid of these patients, it is thought that reactivated VZV reaches the central nervous system by direct spread from latently infected sensory ganglia. Analysis of cerebrospinal fluid by PCR is important for the diagnosis of VZV-associated CNS diseases particularly in the absence of exanthema/herpes zoster. Clinicians should be aware of the neurologic complications of VZV infection, because early acyclovir therapy is necessary for these disorders.

**Keywords:** varicella-zoster virus (VZV), neurologic infections, central nervous system (CNS), encephalitis, meningitis

#### **1. Introduction**

The clinical manifestations of varicella-zoster virus (VZV) infections of the central nervous system (CNS) include aseptic meningitis, encephalitis, cerebral infarction associated with granulomatous vasculitis, myelitis, and multiple cranial neuropathies (**Figure 1**) [1–4]. In these patients, viral antigens or DNA are often detected in the cerebrospinal fluid (CSF) or the sites of pathology. Thus, those neurological disorders reflect reactivation of latent VZV in the trigeminal ganglia and dorsal root ganglion, with subsequent spread of the infection into the CNS [1]. In addition, the incidence of CNS complications caused by VZV is more likely higher in elderly individuals; those with underlying diseases, such as malignant tumors and HIV; and those who are immunosuppressed due to the use of steroids or immunosuppressive drugs [5–8]. However, it can also affect healthy individuals; therefore, these CNS VZV infections may be suspected even in patients without underlying diseases. Among CNS infections caused by VZV, diseases other than meningitis are rare; however, clinicians should be aware of the various clinical features of CNS infections caused by VZV to start early and accurate antivirus drugs for treatment.

**Figure 1.** *Neurological complications associated with VZV reactivation.*
