Treatment strategy and follow-up evaluation for an unruptured anterior communicating artery aneurysm associated with pseudo-occlusion of the internal carotid artery using computational fluid dynamics simulations.

Basic research on cerebral aneurysms using computational fluid dynamics (CFD) simulations has recently progressed. We describe a clinical case with the use of CFD simulations. A 76-year-old woman had an unruptured anterior communicating artery aneurysm associated with pseudo-occlusion of the internal carotid artery (ICA). Pre-operative CFD simulations demonstrated that carotid artery stenting (CAS) would decrease hemodynamic stress on the aneurysm and might reduce the risk of aneurysm rupture. We performed CAS, and did not surgically treat the aneurysm because of her advanced age. A 7-month follow-up angiogram showed no change in the aneurysm size. We performed CFD simulations using the patient-specific flow waveforms at the bilateral ICAs before and 7 months after CAS. Maximum time-averaged wall shear stress of the aneurysm decreased from 8.3 Pa to 4.4 Pa. The pressure loss coefficient of the aneurysm, a proposed hemodynamic value for rupture risk, increased from 1.83 to 2.75. These findings indicated that CAS might reduce the rupture risk of the aneurysm according to previous reports on CFD studies. The aneurysm remains unruptured for 14 months from the CAS. This is the first report to attempt to reduce the rupture risk of an unruptured aneurysm with flow alteration based on CFD simulations.