Analysis of Multiple Intracranial Aneurysms with Different Outcomes in the Same Patient After Endovascular Treatment

Background

Aneurysm recanalization after coiling, with or without stent assistance, is a major issue in the endovascular management of intracranial aneurysms. Multiple intracranial aneurysms with different outcomes after endovascular treatment may represent a useful disease model in which patient-specific risk factors can be balanced to investigate possible features linked to aneurysm recanalization. In the present study, we evaluated the impact of aneurysm-specific, treatment-related, and hemodynamics-related factors on multiple aneurysms and to explore the reason why one aneurysm recanalized and the other did not.

Methods

Between 2010 and 2015, 763 multiple intracranial aneurysms in 326 patients were diagnosed by digital subtraction angiography. We retrospectively collected and analyzed 13 pairs of multiple aneurysms with different outcomes (recanalized or stable) in the same patient. Patient-specific models were constructed and analyzed by a computational fluid dynamics method. The virtual stent deployment method was used, and the coils were simulated by a porous medium model. Factors were evaluated for significance with respect to recanalization.

Results

Aneurysm size (P = 0.021), neck width (P = 0.027), ruptured aneurysms (P = 0.002), reduction ratio of averaged velocity (P = 0.008), and wall shear stress (P = 0.024) were significantly associated with aneurysm recanalization. By contrast, the aneurysm location, all of treatment-related factors (packing density, duration of follow-up, stent use, initial angiographic result) and the reduction ratio of averaged pressure were not significantly associated (P > 0.05).

Conclusions

Small aneurysm size and neck width, unruptured aneurysm, and perianeurysmal hemodynamics with marked reduction may be important factors associated with the midterm durability of aneurysm embolization.

Introduction

Endovascular treatment of intracranial aneurysms is an accepted alternative to microsurgical clipping, with lower morbidity and mortality rates.¹ However, the relatively higher rate of recanalization is a major issue for endovascular treatment.1, 2, 3, 4 The mechanisms that lead to aneurysm recanalization are complex and mainly affected by patient-related factors, aneurysm-specific factors, treatment-related factors, and hemodynamics-related factors.2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 However, not all studies controlled for patient-related factors (patient age, sex, smoking, drinking, hypertension, antiplatelet drugs), disregarding such factors as confounding factors for aneurysm recanalization, when comparing aneurysm-specific and/or treatment-related factors among different patients. More recently, to remove the confounding effect of patients' characteristics on aneurysm rupture risk, some studies introduced multiple intracranial aneurysms.22, 23 Similarly, analyses between recanalized and stable aneurysms in the same patient are of great value, as multiple aneurysms with different outcomes after the same initial treatment method, such as endovascular embolization, are extremely rare, and the findings may provide an important reference.

To our knowledge, this was the first study to evaluate aneurysm-specific, treatment-related, and hemodynamics-related factors associated with aneurysm recanalization of multiple intracranial aneurysms with strict inclusion criteria and to explore the reason why one aneurysm recanalized and the other did not. This study design is of great value because it eliminates the inherent confounding effects, and thus the results may be more valid.