VZV encephalitis presentation not different from usual, viz fever, headache, altered consciousness, etc. But can be subacute onset.
The more common neuro manifestation of VZV in young children is post-infectious cerebellitis – usually mild and self limiting, child not unwell but risk of secondary
hydrocephalus in more severe cases.
There is also a well recognized association in childhood between VZV infection and stroke, usually presents after the rash has cleared – typically 3 months [London study, Miravet & Danchaivijitr 2007). Post-VZV thromboembolism also seen rarely eg lower limb DVT.
Encephalitis can present early, even before rash (which may
not be very obvious either). PCR for VZV DNA in the CSF is positive in around a third of patients; VZV specific IgG seen in 90% in CSF. Compare levels to serum as a way
of confirming CNS involvement.
Usually (not for cerebellitis), steroids given eg 60-80 mg of prednisolone daily for 3 to 5 days) is given (Gilden & Kleinschmidt-DeMasters 2000) esp where MRI evidence of vasculitis.
[encephalitis article, source?]