Comparison of coiling followed by staged-flow diversion and flow diversion-assisted coiling for intracranial very large and giant aneurysms of the internal carotid artery.

To compare the clinical and imaging efficacy of flow diversion-assisted coiling (FD-assisted coiling) and coiling followed by staged-flow diversion (staged-FD) in the treatment of very large and giant intracranial aneurysms of the internal carotid artery. Between April 2015 and June 2024, 60 patients with very large and giant (≥ 20 mm in diameter) saccular intracranial aneurysms of the internal carotid artery were retrospectively analyzed at a single institution. Patients were classified into two groups: the FD-assisted coiling group (n = 45) and the staged-FD group (n = 15). Immediate occlusion rates, perioperative complication rates, and clinical and imaging follow-up results were compared between the two groups. Aneurysm occlusion was determined using the O'Kelly-Marotta (OKM) grading system. The rate of complete or subtotal immediate postoperative occlusion was significantly higher in the staged-FD group compared to the FD-assisted coiling group [60% (9/15) vs. 26.7% (12/45), p = 0.019]. The complication rate was significantly lower in the staged-FD group compared to the FD-assisted coiling group[0% (0/15) vs. 31.1% (14/45), p = 0.034]. On postoperative day 190 (172.3, 204.3), 45 patients in both groups underwent mid-term DSA. In the FD-assisted coiling group, 54.8% (17/31) had OKM D. In the staged-FD group, 63.6% (7/11) had OKM D. The median time interval between the first-stage coiled embolization and the second-stage FD placement was 40 (15,69) days. For very large and giant saccular intracranial aneurysms of the internal carotid artery, coiling followed by staged-FD achieves higher rates of complete or subtotal embolization in the immediate postoperative period and has a lower complication rate compared to single-stage FD-assisted coiling.