Clinical presentation of HSE in children over 3 months and adults is typically is HSV-1, acute, or subacute, and generally has non-specific signs such as:
- Alteration of conscious (97%)
- CSF Pleocytosis (97%)
- Fever (90%),
- Personality Change (85%)
- Headache (81%)
- Vomiting (46%)
In newborns it typically presents 6-12 days after birth with general lethargy, poor feeding, and/or seizures and is HSV-2.
CSF should be taken immediately when HSE is suspected and sent for a PCR study. This is the gold standard and is sensitive 94-98% and specific 98-100%.
Lab studies are non-specific. Imaging (CT and MRI) and Electroencephalography abnormalities can take days to a week to appear on scans.
- CSF in patient with HSE will have elevated WBC, RBC, elevated protein, and normal glucose level with lymphocytic pleocytosis
- MRI findings if present would demonstrate temporal lobe lesions
- Electroencephalography (EEG) has characteristic periodic high-voltage spike wave activity emanating from the temporal lobes and slow wave complexes are highly suggestive of HSE.
IV acyclovir should be started immediately , before PCR results confirm, because its toxicity is rather low and HSE prognosis is poor untreated. In adults 10-15mg/kg q8h x14-21days, 3 months-12years 20mg/kg x10 days, neonates 30mg/kg/day.