Intracranial hemorrhage

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(Class I)

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Infectious intracranial aneurysms are an etiology of ICH and subarachnoid hemorrhages that are unique to infective endocarditis. The prior terminology, mycotic aneurysm, is likely a misnomer, as the word “mycotic” implies only a fungal etiology. The preferred term is now infectious intracranial aneurysm.$^{39}$ Most commonly located in distal branches of middle cerebral artery territory,$^{40}$ infectious intracranial aneurysms develop when vegetations embolize into the intracranial arterial vasa vasorum.$^{26}$ The embolized bacteria then spread throughout the intima, with potential for invasion through the entire vessel wall.

Although infectious intracranial aneurysms rupture in only 2% to 4% of patients with infective endocarditis, these patients have a risk for mortality as high as 80%.$^{39,41}$ Unruptured aneurysms may be seen in up to 32% of patients with infective endocarditis, and though these may resolve with antibiotics, follow-up is important, since they continue to carry risk for future rupture.$^{28,42-44}$ Management is dependent on size and location. Management of some infectious intracranial aneurysms consists of open clipping or endovascular therapies such as acrylic glue or autologous clot injections.$^{26}$ Infectious intracranial aneurysms can be more challenging to manage compared to noninfectious intracranial aneurysms, since vascular walls can be extremely friable or fusiform. Recent literature has suggested that some small, stable, unruptured aneurysms may be managed medically with antimicrobial therapy only.$^{40}$