HSV encephalitis

Case contributed by Marta Mazuque Mancilla
Diagnosis almost certain


Car accident. Psychomotor agitation. Temporal and spatial disorientation.

Patient Data

Age: 50 years
Gender: Male

Left temporal hypodensity with left insular effacement. Slight local mass effect over the left lateral ventricle.


Left temporobasal, hippocampal, and insular cortical thickening, with associated T2/FLAIR hyperintensity, less prominent in the ipsilateral thalamus. DWI hyperintensity in the affected region, without convincing restricted diffusion.

No contrast enhancement or hemorrhagic lesions seen.

The left temporal lesion caused a slight mass effect, with compression of the left lateral ventricle.

Case Discussion

This patient came to the hospital as a trauma patient from a car accident. The accident was due to his disturbed consciousness. The initial differential diagnosis was herpetic encephalitis or traumatic temporal parenchymal contusion. To investigate the lesion, MRI was performed.

MRI image was highly suggestive of the diagnosis and treatment was started. The diagnosis of herpetic encephalitis was later confirmed with a positive PCR for herpes simplex virus (HSV) on CSF testing. 

Mortality from HSV encephalitis is high, so starting the treatment early with antiviral drugs is necessary without waiting for a definitive diagnosis.

The patient was treated with acyclovir and symptoms were almost resolved.

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