Giant Vertebrobasilar Fusiform Aneurysm Mass Effect Heralds Rapid in Situ Thrombosis and Ischemic Stroke in the Setting of Ulcerative Colitis.

Here we describe a case of brainstem infarction secondary to rapid thrombus formation in a giant vertebrobasilar fusiform aneurysm (GVBFA) that was preceded clinically by several months of headaches and dizziness initially attributable to mass effect. Less than a month after initial identification of the aneurysm, a large partially-occluding thrombus formed leading to infarction of the brainstem. Interestingly, this patient also had ulcerative colitis, which has been associated with acquired hypercoagulability. Balancing risk versus benefit in the management of GVBFA to prevent morbidity and mortality is very challenging; thus more information is needed to better stratify treatment options for patients, particularly those that may have an accelerating clinical course or co-morbidities that increase clotting risk.