HSV encephalitis most characteristically involves which brain region on imaging?

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

Answer: (B)

HSV encephalitis classically involves the temporal lobes on imaging, particularly the inferior and medial regions that form part of the limbic system. On MRI, this shows as T2/FLAIR hyperintensity with edema in the temporal lobes, often accompanied by diffusion restriction indicating cytotoxic edema and, at times, hemorrhagic necrosis seen on susceptibility-weighted imaging. The involvement is frequently unilateral or asymmetric, which helps distinguish it from other causes of encephalitis.

This regional pattern reflects the virus’s predilection for limbic structures, and it correlates with the typical clinical picture of fever, altered mental status, seizures, and possible aphasia if the dominant temporal lobe is affected. While other lobes can be involved in some cases, the temporal lobes are the most characteristic site, making them the key imaging region to anticipate in HSV encephalitis.