Demographic and anatomical comparison of ruptured and unruptured intracranial aneurysms: a case control study

Abstract

Background: Our understanding of the pathophysiology and management of intracranial aneurysms (IAs) continuously advances. This case-control study analyzed the demographics of patients with IAs and the morphological Digital Subtraction Angiography (DSA) characteristics of ruptured and unruptured IAs.

Methods: Two patient groups with saccular ruptured and unruptured IAs eligible for coiling were prospectively analyzed during a 3-year period. Patient groups were compared regarding gender, age, arterial vasculature side, anatomical location, diameter, preoperative DSA appearance, aneurysmal and anatomical Circle of Willis variations (CWV) co-existence.

Results: One hundred and three patients with ruptured and eighty-six patients with unruptured IAs were studied. Anterior communicating and internal carotid artery IAs were the dominant locations: 42.7 % and 23.3 % in ruptured and 29 % and 41.9 % in unruptured IAs, respectively. The female-to-male ratio was 1.78 in ruptured and 2.44 in unruptured IAs (p =0.317), while the rupture was more frequent in younger patients (p =0.034). Angiographically, smaller diameter (p =0.01), abnormal morphology (p =0.0001), and co-existence of CWV (p =0.016) were reported in ruptured IAs. Location at bifurcation/trifurcation (p =0.487) and the co-existence of additional or mirror IA did not differ significantly (p =0.879).

Conclusions: On DSA, ruptured and unruptured IAs differed in size, morphology, and co-existence of CWV; findings that may favor the treatment of specific unruptured IAs. However, a higher level of evidence is needed to include all these factors in the treatment decision process, provide patient-oriented treatment and reliably identify unruptured IAs at greater risk. HIPPOKRATIA 2021, 25 (3):100-107.

Keywords: Intracranial aneurysms; aneurysm morphology; aneurysm rupture; circle of Willis variations; digital subtraction angiography; endovascular treatment.

Figure 1. Bar plot of aneurysmal parent artery location. The X-axis presents the number of aneurysms at each parent artery location. The Y-axis shows the discrete number of parent arteries at each aneurysmal location. Ruptured aneurysms are represented in red color, whereas unruptured in gray. ICA: internal carotid artery, ACA: anterior carotid artery, aCOM: anterior communicating artery, MCA: middle cerebral artery, PCOM: posterior communicating artery, PICA: posterior inferior cerebellar artery, BA: basilar artery, VA: vertebral artery

Figure 2. Chart showing the correlation of parent artery location, number of aneurysms at the specific parent artery location, and the mean diameter. The size of the circle is analogous to the mean diameter of the aneurysms at the specific parent artery location. The mean diameter is shown on the left of each circle. Ruptured aneurysms are represented in red color, whereas unruptured in gray. ICA: internal carotid artery, ACA: anterior carotid artery, aCOM: anterior communicating artery, MCA: middle cerebral artery, PCOM: posterior communicating artery, PICA: posterior inferior cerebellar artery, BA: basilar artery, VA: vertebral artery.