What is the pathophysiology of infectious cerebral aneurysms?

Updated: Dec 06, 2018
  • Author: David S Liebeskind, MD, FAAN, FAHA, FANA; Chief Editor: Helmi L Lutsep, MD  more...
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Answer

Infectious aneurysms typically are situated in distal branches of the middle cerebral artery (MCA; 75-80% of cases), reflecting the embolic origin of these lesions. Cardioembolism of septic material complicates the course of 4% of patients with subacute bacterial endocarditis and may affect other patients with congenital heart disease and right-to-left shunts. Direct extension from lumen to adventitia of septic emboli containing Streptococcus viridans or Staphylococcus aureus (ie, the most common pathogens) may lead to degradation and aneurysm formation. Alternatively, diffuse infiltration from the periphery to the lumen may occur in the setting of meningitis, exemplified by aneurysms of the basal circulation associated with fungal infections. Infectious aneurysms are frequently multiple (20%) and have a greater propensity to bleed than other aneurysms.


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