Herpes simplex encephalitis is the most common cause of fatal sporadic necrotizing viral encephalitis. In adults and older children, HSE commonly involves temporal and frontal lobes and is caused by Type 1 herpes simplex virus (HSV). In neonates, it is commonly caused by Type 2 HSV, being acquired during delivery and there is diffuse brain involvement.

Differential diagnoses to be considered are infarcts and status epilepticus. Status epileptics present unilaterally and typically involves mainly the cortex and postictal edema is more widespread and predominantly affects the entire hemispheric cortex.

In this patient PCR for HSV in CSF was positive.