Repeat Flow Diversion for Retreatment of Incompletely Occluded Large Complex Symptomatic Cerebral Aneurysms: A Retrospective Case Series

BACKGROUND AND OBJECTIVES: Data regarding radiographic occlusion rates after repeat flow diversion after initial placement of a flow diverter (FD) in large intracranial aneurysms are limited. We report clinical and angiographic outcomes on 7 patients who required retreatment with overlapping FDs after initial flow diversion for large intracranial aneurysms. METHODS: We performed a retrospective review of a prospectively maintained database of cerebrovascular procedures performed at our institution from 2017 to 2021. We identified patients who underwent retreatment with overlapping FDs for large (>10 mm) cerebral aneurysms after initial flow diversion. At last angiographic follow-up, occlusion grade was evaluated using the O'Kelly-Marotta (OKM) grading scale. RESULTS: Seven patients (median age 57 years) with cerebral aneurysms requiring retreatment were identified. The most common aneurysm location was the ophthalmic internal carotid artery (n = 3) and basilar trunk (n = 3). There were 4 fusiform and 3 saccular aneurysms. The median aneurysm width was 18 mm; the median neck size for saccular aneurysms was 7 mm; and the median dome-to-neck ratio was 2.8. The median time to retreatment was 9 months, usually due to symptomatic mass effect. After retreatment, the median clinical follow-up was 36 months, MRI/magnetic resonance angiography follow-up was 15 months, and digital subtraction angiography follow-up was 14 months. Aneurysm occlusion at last angiographic follow-up was graded as OKM A (total filling, n = 1), B (subtotal filling, n = 2), C (early neck remnant, n = 3), and D (no filling, n = 0). All patients with symptomatic improvement were OKM C, whereas patients with worsened symptom burden were OKM A or B. Two patients required further open surgical management for definitive management of the aneurysm remnant. CONCLUSION: Although most patients demonstrated a decrease in aneurysm remnant size, many had high-grade persistent filling (OKM grades A or B) in this subset of mostly large fusiform aneurysms. Larger studies with longer follow-up are warranted to optimize treatment strategies for atypical aneurysm remnants after repeat flow diversion.