The Association between Circle of Willis Patterns and Ruptured Aneurysm Sites
Keywords:
N/A, Subarachnoid hemorrhage; cerebral aneurysm; circle of Willis; atypical pattern; anterior communicating arteryAbstract
Background and Objectives: Intracranial aneurysmal rupture is the major cause of subarachnoid hemorrhage (SAH). Misdiagnosis of the ruptured sites may result in postoperative rebleeding and the patients may eventually die. The variation of circle of Willis (CW) patterns could increase wall shear stress, leading to aneurysm formation. Therefore, this study aimed to investigate the sites of aneurysms inside the CW in aneurysmal SAH patients and the association between the CW patterns and ruptured aneurysm sites.
Methods: This retrospective study was performed on the digital subtraction angiography (DSA) and 3D rotational angiography (3DRA) of patients with aneurysmal subarachnoid hemorrhage. The sites of aneurysms in the CW were assessed and the internal diameters of the component arteries were measured to classify the patterns of CW as the typical and the atypical patterns. Atypical patterns were divided into 3 subtypes: 1) atypical CW with transitional artery but without hypoplastic artery 2) atypical CW with hypoplastic artery and 3) atypical CW with aplastic artery.
Results: All 90 aneurysmal SAH patients enrolled in this study were 30% (27/90) males and 70% (63/90) females with the mean age of 55.93 ± 12.87 years. Atypical CW pattern was found as high as 95.96% of aneurysmal series with outnumbered hypoplastic subtype (54.44%). The highest incidence among the ruptured sites of all atypical subtypes appeared at the anterior communicating artery.
Conclusion: Most non-traumatic aneurysmal rupture in this study occurred within the CW and ACoA was the predominant aneurysm site. The prevalence of atypical pattern was very high among the aneurysmal SAH patients especially at ACoA, showing the association between the aberrant CW patterns and ruptured aneurysm sites.
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