Acute distal migration of a flow diverting stent

The introduction of flow diverting stents, particularly for treatment of petrous to supraclinoid internal carotid artery aneurysms, has greatly impacted endovascular treatment of intracranial aneurysms. Despite their high efficacy, complications, such as ischemic events, distal hemorrhage, or problems with stent deployment, remain a significant concern. We present the first reported case of acute distal migration of a Pipeline Embolization Device (PED). A 24-year old female underwent elective placement of a PED for treatment of a left paraclinoid internal carotid artery aneurysm. Despite an uneventful intra-operative course, adequate stent placement and a normal neurologic examination immediately after placement, she demonstrated right hemiparesis shortly thereafter. Repeat angiography revealed acute distal migration of the PED and an occlusive thrombus. Thought to be secondary to chronic in-stent thrombosis, distal migration has been previously described in a delayed fashion over weeks to months. However, to our knowledge, this is the first reported case of distal flow diverter migration in an acute setting immediately following the procedure.