A rare complication of flow diverter: delayed migration causing aneurysm expansion and brainstem compression.

Flow-diverting stents (FD) are admitted therapeutic devices for challenging aneurysms. Delayed migrations of FD remain exceptional, particularly with brainstem compression. We report a case of delayed migration of pipeline embolization device (PED) responsible of medulla oblongata compression due to expansion of posterior inferior cerebellar artery (PICA) aneurysm. This is the first report of brainstem compression due to delayed migration of FD. Among the seven previously reported cases of FD delayed migration, two led to death. Our case illustrates the importance of technical issues of stenting and the role of surgery facing the clinical emergency of vascular compression of lower brainstem. We wanted to warn neurosurgeons of this rare and delayed complication, which likely could become less exceptional with the increase of indications and utilizations of FD.