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Infectious encephalitis: mimics and chameleons
  1. Michel Toledano1,
  2. Nicholas W S Davies2
  1. 1Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
  2. 2Department of Neurology, Chelsea and Westminster Hospital, London, UK
  1. Correspondence to Dr Nicholas W S Davies, Chelsea & Westminster Hospital, NHS Trust, London SW10 9NH, UK; nicholas.davies{at}


‘Query encephalitis’ is a common neurological consultation in hospitalised patients. Identifying the syndrome is only part of the puzzle. Although historically encephalitis has been almost synonymous with infection, we increasingly recognise parainfectious or postinfectious as well as other immune-mediated causes. We must also distinguish encephalitis from other causes of encephalopathy, including systemic infection, metabolic derangements, toxins, inherited metabolic disorders, hypoxia, trauma and vasculopathies. Here, we review the most important differential diagnoses (mimics) of patients presenting with an encephalitic syndrome and highlight some unusual presentations (chameleons) of infectious encephalitis.

  • encephalopathy
  • autoimmune encephalitis
  • cns infection
  • vasculitis

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  • Contributors MT and NWSD contributed equally to the drafting of this manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Obtained.

  • Provenance and peer review Commissioned. Externally peer reviewed by Tom Solomon, Liverpool, UK, and Mark Ellul, Liverpool, UK.

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