Please confirm topic selection

Are you sure you want to trigger topic in your Anconeus AI algorithm?

Please confirm action

You are done for today with this topic.

Would you like to start learning session with this topic items scheduled for future?

Updated: Dec 15 2020


  • A 46-year-old male is brought to the emergency department by his wife due to a seizure event. She reports that prior to the event, he complained of headache, fever, and nausea. She also reports her husband appeared confused. On exam, the patient cannot clearly answer questions. A CT of the head shows no evidence of a hemorrhage, or a space-occupying lesion. MRI of the brain is shown. A lumbar puncture is performed, and cerebral spinal fluid analysis shows a normal opening pressure, a lymphocytic pleocytosis, normal glucose, and elevated protein. PCR is positive for herpes simplex virus-1.
  • Brain parenchymal infection
    • abnormalities in brain functioning are expected
      • e.g., altered mental status, changes in personality, problems with speech and movement
      • this distinguishes encephalitis from meningitis
  • Typically caused by infection
    • viral (most cases)
      • herpes simplex virus (HSV)
        • most common cause
      • varicella virus (VZV)
      • epstein-barr virus (EBV)
      • measles, mumps, rubella
      • HIV
      • Japanese encephalitis virus
      • St. Louis encephalitis virus
      • West nile virus
    • bacterial
      • toxoplasmosis
    • noninfectious
      • acute disseminated encephalitis
  • There can be both an infection of the brain parenchyma and meninges
    • leading to a meningoencephalitis
  • Symptoms  
    • seizures
    • fever
    • headache
    • nausea
    • vomiting
  • Physical exam
    • altered mental status
    • personality changes
    • focal neurological deficits
      • cranial nerve palsies
      • hemiparesis.
    • meningsmus
      • only in pure encephalitis
  • CT scan of the head
    • performed first
    • rules-out space occupying lesions
    • normal CT does not rule-out encephalitis
    • MRI is the preferred imaging modality for HSV encephalitis
  • Lumbar puncture
    • perform after head imaging
    • cerebral spinal fluid analysis to determine etiology
      • HSV 
        • ↑ white blood cells
          • predominantly lymphocytes
        • ↑ red blood cells
          • grossly bloody tap
        • ↑ protein
          • elevated
        • normal glucose
    • PCR
      • most accurate for herpes encephalitis
    • culture
    • Gram stain
  • Brain biopsy
    • last resort
    • only if etiology is unknown
  • Intracranial malignancy
    • primary or metastatic
  • Medication side-effects
  • Paraneoplastic or autoimmune disease
    • anti-NMDA receptor encephalitis
  • Amoebic meningoencephalitis 
    • caused by Naegleria fowleri
    • amoeba are seen on CSF analysis 
  • Supportive
    • assess airway, breathing, and circulation (ABCs)
    • initiate seizure precautions
    • manage fever and pain
  • Treatment is then dependent on etiology
    • HSV encephalitis
      • initiate acyclovir immediately  
        • if renal impairment must give IV fluids to prevent crystalline nephropathy 
      • can be considered with VZV encephalitis
      • associated with a reduction in morbidity and mortality
      • foscarnet in acyclovir-resistant herpes
  • Serial monitoring of intracranial pressure
Prevention, Prognosis, and Complications
  • 50 - 75% mortality in untreated HSV encephalitis
  • < 1 or > 55 years old, immunocompromised is associated with poorer outcome
1 of 6
Private Note

Attach Treatment Poll
Treatment poll is required to gain more useful feedback from members.
Please enter Question Text
Please enter at least 2 unique options
Please enter at least 2 unique options
Please enter at least 2 unique options