Neurology · Year 3 · from Neurology

Case 1: Herpes Simplex Encephalitis

Patient Demographics

  • Age: 34 years
  • Sex: Female
  • Occupation: Elementary school teacher

Chief Complaint

"She's been confused and had a seizure this morning."

History of Present Illness

The patient was brought to the emergency department by her husband after experiencing a generalized tonic-clonic seizure at home this morning. Over the past 4 days, she has had progressively worsening headache, fever (up to 39.2C), and fatigue. Two days ago, she began having difficulty finding words and seemed confused, not recognizing her own children. Yesterday, her husband noticed she was behaving strangely - "acting like a different person" with inappropriate comments and irritability. She had no prior history of seizures. No recent travel, no immunocompromising conditions.

Neurological Examination Findings

Vital Signs:

  • Temperature: 39.0C (102.2F)
  • HR: 102, BP: 138/85, RR: 18

Mental Status Examination:

  • GCS: 13 (E3V4M6)
  • Disoriented to time and place
  • Impaired attention - cannot recite months backward
  • Expressive aphasia - word-finding difficulty, paraphasic errors
  • Short-term memory severely impaired
  • Intermittent agitation and perseveration

Cranial Nerves:

  • Pupils 3mm, equal, reactive
  • Visual fields intact to confrontation
  • No facial asymmetry
  • Intact gag reflex

Motor Examination:

  • 5/5 strength bilateral upper and lower extremities
  • Normal tone

Sensory Examination:

  • Intact to light touch

Reflexes:

  • 2+ symmetric
  • Plantar responses flexor bilaterally

Coordination:

  • Unable to assess reliably due to encephalopathy

Key Clinical Features Suggesting HSV Encephalitis

  1. Acute/subacute encephalopathy with altered mental status
  2. Fever - present in most cases
  3. Seizures - common, especially with temporal lobe involvement
  4. Behavioral changes - personality change, psychiatric symptoms
  5. Aphasia - temporal lobe involvement
  6. Focal neurological findings - temporal lobe predilection

Neuro Workup

Laboratory Studies:

  • WBC: 12,500 (mild leukocytosis)
  • CMP: Normal
  • Coagulation: Normal

Lumbar Puncture:

  • Opening pressure: 22 cm H2O (mildly elevated)
  • WBC: 185 cells/uL (95% lymphocytes) - lymphocytic pleocytosis
  • RBC: 450 cells/uL - suggests hemorrhagic component
  • Protein: 85 mg/dL (elevated)
  • Glucose: 58 mg/dL (normal, serum glucose 95)
  • HSV PCR: POSITIVE for HSV-1 (results in 24-48 hours)
  • Gram stain: Negative
  • Bacterial culture: No growth

MRI Brain with Contrast:

  • T2/FLAIR hyperintensity in bilateral temporal lobes (left > right)
  • Involvement of insular cortex and orbitofrontal regions
  • Possible petechial hemorrhage on susceptibility-weighted imaging
  • No enhancement yet (early)
  • Characteristic finding: Medial temporal lobe involvement with relative sparing of basal ganglia

EEG:

  • Periodic lateralized epileptiform discharges (PLEDs) over left temporal region
  • Background slowing

Diagnosis

Herpes Simplex Virus Encephalitis (HSV-1)

Management

Immediate Treatment (started empirically before HSV PCR results):

  1. Intravenous Acyclovir 10 mg/kg every 8 hours
  • Started immediately upon clinical suspicion
  • Do NOT wait for PCR confirmation
  • Duration: 14-21 days
  • Renal dosing adjustment if needed
  1. Seizure prophylaxis/treatment:
  • Levetiracetam 1000 mg IV load, then 500 mg BID
  1. Supportive care:
  • ICU admission for monitoring
  • Fever control
  • IV fluids
  • Aspiration precautions

Monitoring:

  • Neurological checks every 2 hours
  • Repeat imaging if clinical deterioration
  • Monitor for increased intracranial pressure
  • Renal function monitoring (acyclovir nephrotoxicity)

Follow-up:

  • Repeat LP near end of treatment to document viral clearance (controversial)
  • MRI at completion of therapy
  • Neuropsychological evaluation for cognitive sequelae
  • Long-term seizure management if epilepsy develops

Prognosis:

  • Mortality with treatment: ~15-20%
  • Mortality without treatment: >70%
  • Common sequelae: Memory impairment (Kluver-Bucy syndrome if bilateral temporal), personality changes, seizures, aphasia
  • Early treatment significantly improves outcomes

Clinical Image

Image Description: MRI showing T2/FLAIR hyperintensity involving the temporal lobes bilaterally, characteristic of herpes simplex encephalitis. The medial temporal structures including hippocampus and insular cortex are preferentially affected.

Attribution: Image from Wikimedia Commons. Licensed under CC BY-SA 3.0. Source: https://commons.wikimedia.org/wiki/File:Herpes_simplex_encephalitis.jpg

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