Blood Flow Into Basilar Tip Aneurysms

Endovascular coil embolization is an established treatment for intracranial aneurysms. The efficacy of coil embolization has been proven for the prevention of rebleeding in the acute phase of aneurysmal subarachnoid hemorrhage. Endovascular coil embolization is occasionally preferred in the management of unruptured intracranial aneurysms because it is less invasive than surgical clipping. However, the longterm risk and durability of coil embolization are unknown. The frequencies of aneurysm rests or recurrences are higher after coil embolization than that after surgical clipping. Recent studies have revealed that recanalization after coil embolization occurs not only in the short term (typically within 1 year) but also in the long term (after several years). Repeated angiographic examinations or treatments because of the recanalization of coiled aneurysms result in a significant reduction in patient quality of life. Several risk factors for recanalization after coil embolization have been proposed: ruptured aneurysms, large size, wide neck, posterior circulation, and small embolization volume rate. These risk factors were identified on the basis of statistical analyses of certain cohorts. However, causal relationships based on pathophysiology or biomechanics remain unclear. We speculated that hemodynamic forces cause the recanalization of coiled aneurysms. Recent advances in computational fluid dynamics (CFD) have enabled us to evaluate the hemodynamics of intracranial aneurysms with increasing reliability and accuracy. Using state-of-the-art techniques, several studies have reported the influence of blood flow on the results of coil embolization for intracranial aneurysms. In this study, we investigated the hemodynamics of basilar tip aneurysms with special attention to the volume of blood flow into aneurysms through the neck. In addition, we examined the correlation between the configuration of the parent arteries and the proportion of blood flow entering into the aneurysms.