Diagnostic and therapeutic considerations for "mycotic" cerebral aneurysms: 2 case reports and review of the literature.

Objective: Cerebral aneurysms of an infectious etiology, so-called "mycotic" aneurysms, are rare neurovascular pathologies. Primary treatment may be targeted on the aneurysm, but care has to be driven by the underlying pathology to prevent an often fatal clinical course with a mortality rate reaching 90%. 2 case reports are presented, and the diagnostic and therapeutic issues outlined by reviewing the literature.

Case report: A 33-year-old female was admitted to our hospital with a sudden left-sided hemiparesis following a 3-week history of fever. An atypical intracerebral hemorrhage of the right parietal lobe due to a ruptured aneurysm of the distal middle cerebral artery (MCA) was diagnosed. Blood cultures containing Streptococcus sanguinus were the only finding for an infectious origin. Antibiotic therapy was started, followed by neurosurgical evacuation of the hematoma and clipping of the aneurysm. In a second case, endovascular coiling was the choice of treatment in a 38-year-old male presenting with a distal bifurcation aneurysm of the frontal MCA insular branch. An aortic valve replacement had been previously performed due to a congenital heart condition. The primary site of infection remained unclear and a 4-week course of broad-spectrum antibiotics was given intravenously.

Discussion: Cerebral aneurysms far distal to the usual sites of congenital aneurysms, organisms in blood chemistry, endocarditis, symptoms of infection, atypically located intracerebral hemorrhages, and young patients with immunodeficiency are strong factors for an infectious aneurysm. Cerebral angiography is mandatory to exclude aneurysms at other sites and early targeted antimicrobial treatment is crucial in these cases. Elimination of the aneurysm itself should be evaluated carefully because treating these aneurysms remains challenging compared to the ordinary group of cerebral aneurysms. Reconstructive procedures without sacrificing the parent artery often fail due to the fusiform and fragile aneurysm wall.

Conclusion: Cerebral aneurysms of an infectious origin often have a disastrous clinical course in which morbidity and mortality can be reduced by early diagnosis, appropriate antimicrobial therapy, and aneurysm elimination by an experienced team. Apart from the initial treatment, major attention should be focused on a thorough follow-up to confirm complete cure of the primary site of infection.