The patient was scanned with a CT scan (there was no MRI machine on site) and had a lumbar puncture after arriving at the emergency room. CSF analysis ,showed leukocytosis with 100% lymphocytes, elevated protein, normal glucose levels, negative gram stain, and viral PCR result revealing HSV-1.
The patient was admitted to the hospital and intravenous antiviral (Acyclovir) was started.

After a week had passed with no clinical improvement, an MRI was performed at a nearby facility. There were no additional complications found, and the same care continued with the previous working diagnosis. The patient recovered and was discharged after completing the antiviral course.

The leading non-epidemic and sporadic cause of viral fulminant encephalitis is the herpes simplex virus. Changes are typically detectable within 2-3 days of the onset of symptoms, making MRI the most sensitive radiological investigation. A typical MRI finding of herpes simplex encephalitis shows bilateral asymmetrical limbic system involvement, covering medial temporal lobes, insular cortices, infero-lateral frontal lobes, and cingulate gyri. Basal ganglia are usually spared.

Herpes simplex encephalitis is typically fatal in elderly patients, hence early diagnosis and the use of antivirals are crucial to a patient's prognosis.

Differential diagnoses like gliomatosis cerebri and infarcts in the MCA territory are taken into consideration.

However, observing preserved basal ganglia, a non-territorial pattern of damage, a clinical finding of a brief headache, and a behavioral shift aids in ruling out.