Intracranial hemorrhagic events associated with flow diversion treatment: a retrospective analysis from a single academic institution.

Intracranial hemorrhages are highly concerning but underreported complications related to flow diversion (FD) treatment of intracranial aneurysms. Herein, we aimed to characterize these complications and the factors influencing their occurrence. We retrospectively reviewed patients treated with FD from 2013 to 2023 at a single U.S. institution, analyzing aneurysm characteristics, comorbidities, antiplatelet and anticoagulation use, and hemorrhage imaging features. Risk factors for intraparenchymal hemorrhages (IPHs) were assessed with univariate analysis. There were 622 patients harboring 788 aneurysms treated in 690 procedures during the study period. Within 7 months of follow-up, 15 intracranial hemorrhages were identified (2.2%): 2 acute subdural hematomas (SDH), 7 IPH, 1 intraventricular hemorrhage (IVH), and 5 subarachnoid hemorrhages (SAH), most of which presented within the first 24 h after initial treatment. Patients experiencing hemorrhages exhibited lower rates of functional independence (mRS ≤ 2) compared to those without hemorrhage (66.7% vs. 93.3%; p < 0.01). IPHs were slightly higher in patients receiving aspirin-ticagrelor (1.2%) compared to those on aspirin-clopidogrel (0.9%) or aspirin-prasugrel (0.0%). A univariate logistic regression model demonstrated an aneurysmal diameter ≥ 12 mm (OR = 8.98; 95% CI = 1.98-16.03) and aneurysms with prior treatment (OR = 7.20; 95% CI = 1.59-32.60) as factors influencing IPHs after treatment. The incidence of hemorrhage decreased over the time interval of study. Intracranial hemorrhages related to FD are rare but highly morbid complications. Treatments involving larger aneurysms and those with prior interventions are associated with a higher risk of IPHs.