Flow-Driven Coil Migration in ACOM Aneurysm: Recanalization Case and Implications

Introduction Endovascular coil embolization has been effective for cerebral aneurysms since its inception; however, compared with surgical clipping, recanalization remains a concern after coiling. Significant recanalization often necessitates retreatment by re‐coiling or clipping. Established predictors include large/giant size, wide neck, ruptured status, and partial thrombosis. Migration or compaction of coils into intraluminal thrombus can further promote delayed recanalization. Purpose To present a case of recanalization of a partially thrombosed giant ACOM aneurysm after coiling. Methods Patient was encountered during routine clinical practice. Results A 64‐year‐old right‐handed man, heavy smoker and alcohol user with hypertension, presented with new‐onset generalized tonic‐clonic seizure. Brain MRI/MRA demonstrated a giant (3.5 × 2.4 × 3.0 cm) Anterior communicating (ACOM) artery aneurysm with substantial neck filling (17 × 8 × 6 mm) and partial thrombosis. The patient underwent stent‐assisted coil embolization of the aneurysm. At 6‐month follow‐up, diagnostic angiography revealed neck recanalization attributed to flow‐related coil migration into the partially thrombosed sac. He subsequently underwent additional embolization with a Pipeline Flex flow‐diverting stent. Conclusion Patients should be followed by a neurointerventional specialist after coiling to enable early detection of complications. Recanalization should be anticipated in giant, wide‐necked, ruptured, or partially thrombosed aneurysms. Complex intra‐aneurysmal flow and coil migration into mural thrombus can drive recurrence; in such settings, definitive flow diversion may be required at recurrence or considered in initial planning.