Axial FLAIR Sequence MRI of Brain. Abnormality in medial temporal lobe is highlighted.
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HSV Encephalitis (Herpes Simplex Encephalitis - Type 1)
Patient Case
This patient had 3 weeks of confusion, manifesting with disorientation, impaired cognition and subtly strange behavior with NO major change in level of consciousness, motor, coordination, gait deficits, and no oculobulbar manifestations (NO dysarthria, ocular abnormalities, or dysphagia).
The diagnosis is: Herpes simplex type 1 encephalitis
- Herpes encephalitis manifests with a limbic encephalitis (medial temporal inflammation) and pathologic findings of Cowdry, Type A intranuclear inclusions in neurons and glia.
Case Specifics
- In this case, MRI abnormalities are prominent in the medial temporal lobe, hippocampal formation, and insular cortex.
- Note, however, that the patient had been symptomatic for 3 weeks. The MRI may be normal early in the disease course.
- In this case, CSF shows a mild pleocytosis (increase in WBCs) with a predominance of lymphocytes, normal glucose, and mild elevation of protein. HSV-1 PCR is positive.
- However, CSF pleocytosis can be neutrophilic early in the time-course of disease, there can be in increase in RBCs, and protein elevation can be much higher than in this case.
Treatment
- Acyclovir IV, typically for 14 to 21 days (although some clinicians use an even shorter course of acycvlovir)