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Patient case: Encephalitis

Patient case: Encephalitis

Discussion

A 32-year-old man is brought to the emergency department by his wife due to confusion, fever, and seizures. She reports that he developed a headache and mild fever three days ago, which worsened into drowsiness and difficulty speaking. This morning, he had a seizure at home and became unresponsive for a short period. He has no significant past medical history but recently recovered from a mild respiratory illness.

On examination, his temperature is 38.7°C (101.7°F), heart rate is 102 beats per minute, and he appears confused, unable to follow commands. Neurological assessment reveals neck stiffness and photophobia but no focal weakness. A CT scan of the brain shows no structural abnormalities, and a lumbar puncture reveals elevated white blood cells and proteins in the cerebrospinal fluid (CSF), with viral PCR confirming herpes simplex virus (HSV) encephalitis.

The patient is started on intravenous acyclovir and supportive care, including seizure management and close neurological monitoring. Over the next week, his mental status gradually improves, and he is discharged with a follow-up for cognitive rehabilitation.

Questions
1. What is the primary cause of encephalitis?

a) Bacterial infections

b) Viral infections

c) Fungal infections

d) Autoimmune disorders.

2.Which symptom strongly suggests encephalitis rather than meningitis?

a) Fever and neck stiffness

b) Seizures and altered mental status

c) Headache and photophobia

d) Nausea and vomiting

3.What is the most appropriate initial treatment for HSV encephalitis?

a) High-dose corticosteroids

b) Intravenous acyclovir

c) Oral antibiotics

d) Antipyretics and supportive care only

4.What diagnostic test is most useful in confirming HSV encephalitis?

a) Blood culture

b) Brain CT scan

c) CSF PCR for herpes simplex virus

d) EEG (electroencephalogram)

Reveal answers

Answers

1. Answer: b) Herpes simplex virus (HSV) encephalitis

The combination of fever, confusion, seizures, and CSF findings strongly suggests HSV encephalitis, which is one of the most common causes of viral encephalitis. Bacterial meningitis presents similarly but typically lacks seizures early in the course.

2. Answer: b) Seizures and altered mental status

While fever and neck stiffness are common in both meningitis and encephalitis, the presence of seizures and significant confusion strongly favors encephalitis, as it indicates brain parenchymal involvement.

3. Answer: b) Intravenous acyclovir

HSV encephalitis requires urgent treatment with IV acyclovir to reduce viral replication and prevent severe neurological damage. Delaying treatment increases the risk of long-term complications.

4. Answer: c) CSF PCR for herpes simplex virus

CSF PCR is the gold standard for diagnosing HSV encephalitis, as it detects the viral DNA directly. Brain CT may help rule out other causes, but it does not confirm the infection.