Revision 11 for 'Septic-embolic encephalitis'

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Septic-embolic encephalitis

Septic-embolic encephalitis, also referred as septic-embolic brain abscess, corresponds to a focal or diffuse brain infection, ischemic and hemorrhagic damages following an infective thromboembolism from any part of the body 1. It is usually caused by bacterial infections from endocarditis. 


Septic-embolic encephalitis must be differentiated from sepsis-associated encephalopathy, which is a clinical syndrome related to a diffuse brain dysfunction in the context of sepsis and without overt CNS infection.


In most series CNS involvement during the course of infective endocarditis occurs in 20% to 40% of cases 2

Clinical presentation

Symptoms can vary from headache to unconsciousness, the most common are 1,3: fever, toxic encephalopathy (characterized by mental status changes and psychosis), meningism signs, headache and seizures.

Risk factors:
  • cardiac disease:
    • rheumatic cardiovascular disease
    • mitral valve prolapse
    • prosthetic cardiac valves
    • congenital heart disease 
  • drug addiction (intravenous drugs)
  • immunocompromised patients 
  • central venous catheter 
  • arteriovenous shunts  


In a context of an infectious site in the body, some etiological agents can get in the CNS carried by arterial blood. The most common explanations for this are 1-4

  • infections on heart left chambers (aortic and mitral valve endocarditis)
  • pulmonary infectious 
  • infections in other body sites that can get the arterial circulation by an arteriovenous shunt

There are three main pathogenic mechanism of brain damage 4:

  • occlusion of cerebral arteries by septic and thrombotic emboli (e.g. arising from heart valve vegetations): it can result in focal ischemia, cerebral hemorrhage, or both
  • meninges, brain, parenchyma, or vascular walls infection by septic emboli or bacteremia. Numerous microabscesses can be seen and occasionally they coalesce to form space-occupying macroabscesses.
  • toxic and immune mediated injury
  • Staphylococcus aureus (most common)
  • Streptococcus viridans
  • fungal infections 


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