Encephalitis

Inflammation of brain parenchyma, which can be:

Epidemiology and Risk Factors

Pathophysiology

Aetiology

Viral causes include:

  • HSV 1
    Classically temporal lobe involvement.
  • Arboviruses
  • Japanese encephalitis
  • Nipah virus
  • Hendra virus
  • Murray Valley
  • John Cunningham virus
    Classically immunosuppressed.
  • West Nile virus
    Most common cause of epidemic viral encephalitis.

Clinical Manifestations

Can be difficult to diagnose, with major symptoms resulting from infection of brain parenchyma:

  • Brain parenchyma
    • Speech disturbance
    • Seizures
    • Altered cognition

Certain causes result in particular presentations:

  • CMV
    • Ganglionitis
    • Polyradiculitis
  • John Cunningham virus
    • Progressive Multifocal Leucoencephalopathy
      Subacute:
      • Confusion
      • Weakness
      • Visual symptoms

Diagnostic Approach and DDx

Investigations

Bedside:

Laboratory:

Imaging:

  • MRI
    T2-weighted.

Other:

  • LP
    • PCR
  • EEG
    • Slow-wave activity
    • Epileptiform discharges
    • Extreme delta brush pattern
      Highly specific for NMDA-receptor encephalitis.

Management

Resuscitation:

ABC approach. Comment on team coordination and clinical priorities. Specific therapy:

  • Pharmacological
    • Antiviral
      Choice depends on nature of viral infection.
      • HSV encephalitis
        • Aciclovir 10mg/kg IV TDS for 14 days
        • Consider continuing until CSF is HSV DNA negative
      • CMV
        • Ganciclovir
        • Valganciclovir
  • Procedural
  • Physical

Supportive care:

Disposition:

Marginal and Ineffective Therapies

Anaesthetic Considerations

Complications

Prognosis

Varies depending on cause:

  • HSV
    • 20% treated
    • 70% untreated

Key Studies

References

  1. Bersten, A. D., & Handy, J. M. (2018). Oh’s Intensive Care Manual. Elsevier Gezondheidszorg.