Evolving treatment paradigms of cerebral aneurysm stasis in flow diversion.

Introduction: Flow diversion is an effective first-line treatment for intracranial aneurysms; however, the rate of incomplete occlusion is not insignificant. Data in neuroendovascular literature is limited regarding the implications of persistent incomplete occlusion despite flow diversion.

Methods: We conducted a retrospective analysis of a prospectively maintained database and identified 125 consecutive patients with treatment naïve intracranial aneurysms who underwent flow diversion with the PED from April 2014 - November 2022. Patients were divided into 3 groups based on the duration of stasis: venous, capillary, and no stasis. Comparative and multivariate analyses were performed between the three groups.

Results: At latest follow-up, complete occlusion occurred in 69.6 % and 82.4 % showed progression of occlusion. Retreatment was required in 2.4 %. There was no significant difference in retreatment (p = 0.667), complete occlusion (p = 0.774) or progression of occlusion (p = 0.848) at latest follow up. No patients experienced subarachnoid hemorrhage post-treatment. On multivariate analysis, hypertension was a negative predictor for complete occlusion (p = 0.006) and progression of occlusion (p = 0.017), while duration of stasis was noncontributory. The mean latest follow up was 12.55 months.

Conclusion: Flow diversion is a safe and effective first line treatment for intracranial aneurysms with a relatively low complication rate. Hypertension was a negative predictor of complete occlusion and progression of occlusion, while the degree of occlusion post-flow diversion may not be predictive of future rupture risk and the Raymond Roy Occlusion classification may not apply. The degree of stasis after initial treatment was not predictive of future occlusion, retreatment, nor aneurysm rupture risk. However, stasis degree may be worth additional analysis given this studies sample size, lack of long-term follow-up, and the lack of predictive factors in current literature to guide post-flow diversion management.