Encephalitis due to herpes zoster without rash in an immunocompetent 12-year-old girl: case report and review of the literature

Background Neurological complications due to reactivation of varicella-zoster virus (VZV) are very uncommon in immunocompetent patients. Generally a vesicular rash is present on one or more dermatomes, preceding or following the main manifestation. Few cases are reported in the international literature, but they concern mainly adult or elderly patients. Case presentation A 12-year-old girl was referred to our hospital for persisting headache, cough and rhinitis for six days. After first examination, diagnosis of anterior sinusitis was made by nasal endoscopy. The day after, the girl developed psychotic symptoms and altered mental status. Computed tomography (CT) scan was immediately performed but was unremarkable; lumbar puncture revealed leukocytosis with lymphocytic predominance and cerebrospinal fluid polymerase chain reaction (PCR) detected varicella-zoster virus DNA. The diagnosis of acute VZV encephalitis was made. The patient was promptly treated with acyclovir infused intravenously and her clinical conditions rapidly improved. Tests made did not show any condition of immunosuppression. Conclusions Although if rare, reactivation of VZV can occur in immunocompetent children and its complications can involve central nervous system. Among these complications, meningitis is more common, but cerebral parenchyma can also be involved leading to a severe medical condition that is defined meningoencephalitis. In rare cases vesicular rash may be absent; therefore high level of suspicion is required even in those patients in which suggestive clinical features are not present to guide the diagnosis. Intravenous acyclovir represents the treatment of choice to obtain a fast clinical response and to prevent the onset of late-term complications.