Exploring potential association between flow instability and rupture in patients with matched-pairs of ruptured-unruptured intracranial aneurysms.

BACKGROUND: Patients with multiple intracranial aneurysms present a great challenge to the neurosurgeon, particularly when presenting with subarachnoid hemorrhage. Misjudgment may result in disastrous postoperative rebleeding from the untreated but true-ruptured lesion. METHODS: In this study, computational fluid dynamic simulations of two matched-pairs of ruptured-unruptured cerebral aneurysms were performed to investigate the potential association between flow instability and aneurysm rupture. Two pairs of cerebral aneurysms from two patients were located in the middle cerebral artery and the anterior communicating artery respectively. RESULTS: Our results demonstrated highly disturbed states of the blood flows in the ruptured aneurysms of the two patients with multiple aneurysms, which are characterized by remarked velocity and wall shear stress (WSS) fluctuations at late systole. The ruptured aneurysms exhibit obviously temporal intra-cycle WSS fluctuations rather than the unruptured aneurysms of the same patient. Cycle-to-cycle fluctuations are further observed in the ruptured aneurysms when the flow turns to decelerate. CONCLUSIONS: The obvious differences observed between matched-pairs of ruptured-unruptured aneurysms imply that flow instability may be a potential source correlating to aneurysm rupture.