Delayed Ischemic Stroke after Flow Diversion of Large Posterior Communicating Artery Aneurysm.

For securing large, giant, and wide-neck aneurysms, conventional coil embolization has substantial limitations, such as incomplete occlusion, recanalization, and a high recurrence rate. To overcome these limitations, a novel paradigm was suggested and, as a result, flow-diverting device was developed. The flow-diverting device is an innovative and effective technique to allow securing of large, giant, and wide-neck aneurysms. In numerous studies, the flow-diverting device has shown better outcomes than coil embolization. However, the flow-diverting device has also some risks, including rupture of aneurysm, intracerebral hemorrhage, and ischemic stroke. In addition, with more experience, unexpected complications are also reported.5)7) In the present case, we experienced a delayed ischemic stroke at 27 days after endovascular treatment. The patient had multiple aneurysms and, among them, we treated a large posterior communicating artery aneurysm using Pipeline™ Embolization Device. The patient was tolerable for 25 days, but then suddenly presented intermittent right hemiparesis. In the initial diffusion magnetic resonance imaging (MRI), there was no acute lesion; however, in the follow-up MRI, an acute ischemic stroke was found in the territory of anterior choroidal artery which was covered by Pipeline Embolization Device. We suspect that neo-intimal overgrowth or a tiny thrombus have led to this delayed complication. Through our case, we learned that the neurosurgeon should be aware of the possibility of delayed ischemic stroke after flow diversion, as well as, long-term close observation and follow-up angiography are necessary even in the event of no acute complications.