Delayed rupture of a large intracranial internal carotid artery aneurysm after flow diverter placement

Delayed rupture after flow diverter (FD) placement is a serious complication, and often it leads to death; however, the exact mechanism leading to the rupture remains unclear. Therefore, in this case, study, we report a case of delayed rupture after FD placement and discuss its causes. This study presents the case of a 69-year-old female with multiple aneurysms who underwent FD placement with coil embolization for a large intracranial internal carotid artery aneurysm. Postoperatively, the patient had no significant symptoms, and angiography and magnetic resonance imaging revealed decreased intra-aneurysmal blood flow. However, on the 3rd postoperative day, she developed a sudden disturbance of consciousness. Computed tomography revealed a massive subarachnoid hemorrhage, diagnosed as a delayed rupture. We decided to withhold therapy due to her serious condition. Previous studies have suggested that hemodynamic mechanisms can cause delayed aneurysm rupture. Based on the computational fluid dynamics (CFD) of the aneurysm, we suggest that an increase in intra-aneurysmal pressure after FD placement may have caused the delayed rupture. Preoperative CFD analysis may help evaluate the risk of delayed rupture for large aneurysms with a high inflow from the parent vessel.