Stratified Outpatient Management and Radiological Follow-Up After Endovascular Treatment for Unruptured Intracranial Aneurysms

IntroductionThis study aimed to evaluate post-procedural clinical courses and radiological outcomes after endovascular treatment for unruptured intracranial aneurysms using a multi-institutional dataset and explore a preliminary, risk-stratified outpatient follow-up framework. Materials and methodsWe retrospectively reviewed 79 endovascular treatment cases across 77 patients for unruptured intracranial aneurysms between 2018 and 2025 at Soseikai General Hospital (Kyoto, Japan) and affiliated institutions.Outpatient visit timing/content, adverse events, and follow-up MRI findings were analyzed. ResultsTreatment modalities included coil embolization (65 cases: 57 non-stent and eight stent-assisted) and flow diverter (FD) placement (14 cases).Regarding coil-treated cases, stent-assisted coiling required more frequent post-procedural antiplatelet therapy (APT) and close monitoring than non-stent coiling, whereas non-stent coiling without post-discharge APT was associated with no early hemorrhagic events.Seven patients required unscheduled visits before the first scheduled appointment.In the coil embolization cases, unscheduled visits were related to an access site complication (n = 1), cerebral ischemic symptoms (n = 1), and headache and dizziness (n = 1) in the non-stent coiling group; headache (n = 1) was reported in the stent-assisted coiling group.In the FD group, patients presented with intracranial hemorrhage (n = 1), worsened visual function (n = 1), and headache (n = 1).At the first scheduled visit (n = 72; mean: 34.6 ± 17.5 days, median: 33.0 days), clinical management primarily focused on APT adjustment.One patient treated with an FD required emergency readmission during this visit due to exacerbation of mass effect.When evaluated according to postoperative antithrombotic status, within three months post-procedure, any hemorrhagic events occurred in 13.6% of the discharge APT group (n = 59), whereas none occurred in the non-APT group (n = 20), although ischemic symptoms occurred in 10.0% (two of 20 cases).While initial follow-up MRI (n = 66; mean: 90.2 ± 33.0 days, median: 96.0 days) showed no radiological evidence of aneurysm recurrence, it detected suspected foreign-body granulomas (two cases) and moderate parent artery stenosis (one case).The second MRI (n = 57; mean: 317.1 ± 110.0 days, median: 305.0 days) revealed delayed recurrence in 3.5% (two of 57 cases).Over the entire follow-up, no rupture occurred; recurrence was observed in three cases (5.1% of 59 cases with long-term follow-up MRI), and one case (1.7%; 1/59) required retreatment, corresponding to 3.8% (3/79) and 1.3% (1/79) of the total cohort. ConclusionsPost-procedural management may be stratified according to treatment modality and post-discharge APT.While patients treated with FDs or stent-assisted coil embolization require intensive clinical monitoring to detect early complications, our findings suggest that the initial scheduled outpatient visit and MRI might be safely deferred until approximately three months after treatment in carefully selected low-risk patients undergoing non-stent coil embolization without post-discharge APT.Individualized early visits may still be offered to address patient anxiety.This risk-stratified approach represents a preliminary framework for optimizing outpatient follow-up schedules.