Posterior communicating artery occlusion and recanalization through a fusiform aneurysm after flow diversion.

Occlusion of branch vessels is a known potential sequela of the treatment of intracranial aneurysms with flow diversion. We present a case of occlusion and distal reconstitution of the origin of the posterior communicating artery through a fusiform aneurysm of the internal carotid artery after flow diversion. A 56-year-old woman was incidentally found to have a large fusiform aneurysm of the posterior communicating segment of the internal carotid artery incorporating the origin of the posterior communicating artery. The aneurysm was treated with placement of a Pipeline flow diverter. Follow-up computed tomography angiogram at 7 months demonstrated no change in aneurysm filling. A follow-up digital subtraction angiogram at 12 months demonstrated occlusion of the native origin of the posterior communicating artery with distal reconstitution through two accessory channels through the aneurysm. The remainder of the aneurysm was thrombosed. The patient had not had any clinical symptoms during this event. The unorganized nature of the thrombus within aneurysms after flow diversion may allow accessory vascular channels to form in the event of occlusion of a side branch.