Herpes simplex encephalitis commonly involves which brain region, which may show abnormalities on MRI?

• A. Frontal lobes
• B. Parietal lobes
• C. Temporal lobes
• D. Occipital lobes

Answer: (C)

Herpes simplex encephalitis classically targets the temporal lobes, especially the medial and inferior portions such as the hippocampus and amygdala. This limbic system predilection explains why patients often present with rapid changes in behavior, memory disturbances, and focal neurological deficits. On MRI, you typically see edema and sometimes hemorrhagic necrosis in one or both temporal lobes, which is a characteristic pattern helping to distinguish HSV encephalitis from other encephalitides. While other brain regions can be involved, the temporal lobes are the sites most commonly affected and most diagnostic on imaging. Prompt recognition is important because treatment with intravenous acyclovir should be started urgently, even before confirmatory testing.