Question:medium
A 25 year old person presents with acute onset of fever and focal seizures. MRI scan shows hyperintensity in the temporal lobe and frontal lobe with enhancement. The most likely diagnosis is:
A 25 year old person presents with acute onset of fever and focal seizures. MRI scan shows hyperintensity in the temporal lobe and frontal lobe with enhancement. The most likely diagnosis is:
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Temporal lobe hyperintensity with fever and seizures equals HSV.
Updated On: Jun 24, 2026
- Meningococcal meningitis
- Herpes simplex encephalitis
- Japanese encephalitis
- Tuberculous meningitis
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The Correct Option is B
Solution and Explanation
The combination to anchor on is fever with focal seizures and an MRI lighting up the temporal lobes. That picture is almost a signature.
First, separate encephalitis from meningitis. Seizures and focal signs mean the inflammation is in the brain tissue itself, so we are dealing with an encephalitis. Pure meningitis tends to give headache, neck stiffness and photophobia without focal cortical irritation.
Next, let the imaging localise the culprit. Herpes simplex virus, mainly type 1, travels along the trigeminal or olfactory routes and settles in the limbic structures of the medial temporal and inferior frontal lobes. On MRI this shows up as $temporal + frontal$ hyperintensity, frequently with swelling, petechial hemorrhage and contrast enhancement, exactly as written.
Why this matters clinically: HSV encephalitis is the leading sporadic, potentially lethal viral encephalitis, and prompt intravenous acyclovir sharply cuts mortality, so the diagnosis cannot wait.
The alternatives sit elsewhere. Japanese encephalitis prefers the thalami and basal ganglia. Meningococcal disease gives meningism plus a purpuric rash. Tuberculous meningitis enhances the basal cisterns and causes hydrocephalus. None mimics the temporal lobe pattern.
\[\boxed{\text{Herpes simplex encephalitis}}\]
First, separate encephalitis from meningitis. Seizures and focal signs mean the inflammation is in the brain tissue itself, so we are dealing with an encephalitis. Pure meningitis tends to give headache, neck stiffness and photophobia without focal cortical irritation.
Next, let the imaging localise the culprit. Herpes simplex virus, mainly type 1, travels along the trigeminal or olfactory routes and settles in the limbic structures of the medial temporal and inferior frontal lobes. On MRI this shows up as $temporal + frontal$ hyperintensity, frequently with swelling, petechial hemorrhage and contrast enhancement, exactly as written.
Why this matters clinically: HSV encephalitis is the leading sporadic, potentially lethal viral encephalitis, and prompt intravenous acyclovir sharply cuts mortality, so the diagnosis cannot wait.
The alternatives sit elsewhere. Japanese encephalitis prefers the thalami and basal ganglia. Meningococcal disease gives meningism plus a purpuric rash. Tuberculous meningitis enhances the basal cisterns and causes hydrocephalus. None mimics the temporal lobe pattern.
\[\boxed{\text{Herpes simplex encephalitis}}\]
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