Delayed coil migration following endovascular coiling of intracranial aneurysms: a systematic review and institutional case series.

PURPOSE: To systematically investigate delayed coil migration following endovascular coiling of intracranial aneurysms, augmented by two institutional cases. METHODS: A systematic review was conducted using MEDLINE, Embase, and Scopus from inception to June 27, 2025. Eligible cases involved coil migration after the index procedure; two institutional cases were added. Data were extracted using a standardized form and were analyzed descriptively. RESULTS: Thirty-two cases were identified: 30 from 17 prior studies and two institutional. Mean patient age was 54.9 years and 59.4% of aneurysms were ruptured. Mean aneurysm diameter was 5.2 mm and mean aspect ratio was 1.87, with half of those with a calculable aspect ratio below the 1.6 high-risk threshold. The anterior communicating artery was the most frequently affected location (28.1%). Detection ranged from less than 24 hours to more than 6 months post-procedure. Migrated coils most often lodged in the middle and anterior cerebral artery territories, and vessel occlusion occurred in 28.1%. Medical management of the migrated coil was the primary treatment (56.0%), and 11 of 14 medically managed patients (78.6%) were asymptomatic or had good recovery. Re-treatment was reported in 37.5% of cases, all with favorable outcomes at follow-up. CONCLUSION: Delayed coil migration predominantly affects small, broad-necked aneurysms in the anterior circulation. Medical management of the migrated coil yielded favorable outcomes in asymptomatic patients without vessel occlusion. Re-treatment in over one-third of cases had excellent outcomes. Early post-procedural imaging is recommended, and given the recanalization risk, long-term surveillance beyond standard post-coiling protocols may also be warranted.