Elsevier

World Neurosurgery

Volume 119, November 2018, Pages e395-e402
World Neurosurgery

Original Article
Hemodynamics in a Middle Cerebral Artery Aneurysm Before Its Growth and Fatal Rupture: Case Study and Review of the Literature

https://doi.org/10.1016/j.wneu.2018.07.174Get rights and content

Highlights

  • The ruptured right AchA aneurysm has much lower WSS and higher OSI than the unruptured left MCA aneurysm.

  • By comparing aneurysm growth region with WSS distribution, growth occurred in high WSS area.

  • The left MCA aneurysm grew in high WSS region and eventually rupture occurred in same region with low WSS.

Background

Hemodynamics plays an important role in the natural history of intracranial aneurysms. However, it is difficult to obtain longitudinal aneurysm image data. In this study, we had a rare chance to follow the process of growth and rupture of a middle cerebral artery (MCA) aneurysm. The aim of this study was to investigate the role of hemodynamics for growth and rupture in this particular aneurysm patient.

Methods

A 57-year-old woman presented with 2 unruptured MCA aneurysms and 1 ruptured anterior choroidal artery (AchA) aneurysm. The unruptured left MCA aneurysm grew in 7 months and ruptured at 11 months. The rupture region was confirmed during the clipping treatment. Computational fluid dynamic (CFD) simulations were conducted on the AchA and MCA aneurysms in 3 serial imaging procedures, and calculated hemodynamics was correlated with aneurysm growth and rupture.

Results

The ruptured right AchA aneurysm had much lower wall shear stress (WSS) and higher oscillatory shear index (OSI) than the unruptured left MCA aneurysm. Comparison of the aneurysm growth region with the WSS distribution showed that growth occurred in a high WSS area. During the progression of the MCA aneurysm, we observed that the high aneurysmal WSS region grew first and then the growing region changed into a low WSS level; eventually, rupture occurred in a low WSS area.

Conclusions

This case suggests that aneurysm rupture might be associated with low WSS and high OSI, whereas aneurysm growth may be related to high WSS in this particular individual MCA aneurysm patient.

Introduction

Intracranial aneurysms (IAs) are pathologic dilatations of the arterial walls, which affect approximately 2% to 3% of the general population.1, 2 Ruptured IAs cause subarachnoid hemorrhage, and the sequelae result in significant morbidity and mortality.3 Image-based computational fluid dynamics (CFD) can be a powerful tool for obtaining patient-specific hemodynamics in IAs to assess their growth and rupture risks.4, 5, 6, 7, 8 However, it is difficult to obtain longitudinal aneurysm image data to study the role of hemodynamics. Previous studies have focused on the hemodynamics analysis of cross-sectional data. Xiang et al.8 studied 38 ruptured and 81 unruptured cross-sectional aneurysm images and concluded that rupture was associated with low wall shear stress (WSS) and high oscillatory shear index (OSI). Through analyzing data from 210 cross-sectional aneurysm images, Cebral et al.6 demonstrated that rupture was associated with high maximum WSS. However, there are very few studies of the hemodynamics based on longitudinal aneurysm image data.9, 10, 11, 12

In this study, we followed the growth and rupture of a middle cerebral artery (MCA) aneurysm. The aim of this study was to investigate the role of hemodynamics in the aneurysm growth and rupture in this particular aneurysm patient.

Section snippets

Patient Information

A 57-year-old woman was sent to the emergency room with a sudden headache. Her diagnostic catheter angiography revealed 3 aneurysms, 1 ruptured anterior choroidal artery (AchA) aneurysm and 2 unruptured MCA aneurysm on the left and right carotids, respectively. The ruptured AchA aneurysm was confirmed by computed tomography, as shown in Figure 1. The sizes of the right AchA aneurysm, the right MCA aneurysm, and the left MCA aneurysm were 4.2 mm, 2.1 mm, and 6.3 mm, respectively. The ruptured

Hemodynamic Characteristics of 1 Ruptured Aneurysm and 1 Unruptured Aneurysm in the Same Patient

In the initial imaging, we compared hemodynamics of the ruptured AChA aneurysm in the right carotid (Figures 4A and 5A) and the unruptured MCA aneurysm in the left carotid side (Figures 4B and 5B). It is obvious that the ruptured right AChA aneurysm has much lower WSS and much higher OSI than the unruptured left MCA aneurysm (0.025 Pa vs. 9.7 Pa for sac-averaged WSS and 0.1137 vs. 0.009 for sac-averaged OSI for the right AchA aneurysm and the left MCA aneurysm, respectively) as summarized in

Discussion

Hemodynamics has been proved to play an important role in the natural history of IAs, including aneurysm formation, growth, and rupture.4, 5, 6, 7, 8 However, it is difficult to obtain prospective data to study the role of hemodynamics because currently most aneurysms are treated when aneurysm patients are examined in hospitals. The case of the patient described in this study is very rare. It has 3 unique characteristics: 1) in the initial imaging, we have images for both carotid artery sides

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    Conflict of interest statement: This work was supported by the National Natural Science Foundation of China (grant numbers: 81471167) and Jiangxi Province's Science and Technology Agency Support Program (No. 20161BBI90018).

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