Herpes simplex encephalitis

Case contributed by Dr Tamsir Rongpipi


History of fever and abnormal behavior.

Patient Data

Age: 30 years
Gender: Male



There is increase area of T2 and FLAIR hyperintensity in left temporal lobe extending into the insular cortex, posterior thalamus and in the posterior aspect of posterior occipital ventricle with mass effect, swollen gyri and effacement of its sulci. The involved areas show restricted diffusion but less intense compared to infarction. On contrast administration there is heterogenous enhancement of the affect area with leptomeningeal enhancement. No signal loss is seen in SWAN sequence.

Case Discussion

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.

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