Herpes Zoster Encephalitis in an Immunocompetent 8 year-old Girl

Background
Varicella Zoster virus (VZV) may be associated with neurologic complications in children, such as febrile convulsions, encephalitis, stroke or sinus thrombosis. Herpes Zoster (HZ) is a reactivation of VZV in a person with previous acute VZV infection or vaccinated with life attenuated vaccine. While in adults, HZ encephalitis is a recognised complication, it is rarely described in children.

Case Presentation Summary
We present a case of a VZV immune 8-year-old girl with a painful vesicular skin eruption in a C2-C4 distribution, progressive hemiplegia and hemi-sensory syndrome. CT showed an area of hypodensity in the contralateral thalamus. CSF analysis revealed a high lymphocyte count and MRI of brain and spine demostrated multiple lesions of T2 hyperintensity. She was treated with high dose acyclovir, steroids and intravenous immunoglobulin. She received intense physio- and occupational therapy. Within 2 weeks of initial presentation, she has regained over 75% of her function.

In view of the rash with a typical dermatomal distribution, multifocal MRI findings and time relationship between the rash and onset of neurologic signs, she was diagnosed with HZ encephalitis. CSF PCR testing for zoster was negative.

Learning Points/Discussion
In jurisdictions with universal varicella vaccination, decrease in the incidence of acute CNS complications in children is reported. However, mass introduction of VZV vaccine remains controversial, because of feared increase of the age and severity of primary varicella and of the incidence of Herpes Zoster. 
This is a rare presentation of HZ encephalitis in an immunocompetent child with a documented episode of primary varicella during infancy. We reviewed literature available on CNS complications of Herpes Zoster, their risk factors, diagnosis, management and outcomes in immunocompetent vaccinated and unvaccinated children.

HERPES ZOSTER ENCEPHALITIS IN AN IMMUNOCOMPETENT 8 YEAR-OLD GIRL WITH DOCUMENTED VARICELLA DURING INFANCY