Acute Development and Rupture of a Basilar Tip Mycotic Aneurysm.

Infectious intracranial aneurysms (IIA) are rare but encountered when associated with rupture or detected on screening of high risk patients. The time course of the development of these aneurysms is unknown. Ultimately, the data published on mycotic aneurysms are in the form of case series, retrospective studies, with one recent systematic review, all of which have difficulty defining specifics regarding aneurysmal formation in these patients. We present a case that may help define the time frame of mycotic aneurysm growth. A patient with endocarditis, first identified to have a distal middle cerebral artery aneurysm treated with Onyx embolization, and an otherwise unremarkable cerebral angiogram experienced significant subarachnoid hemorrhage 5 days later. Within that short time frame on appropriate antibiotic therapy she developed and ruptured a basilar tip aneurysm, which was subsequently treated with coil embolization.