Intracranial Aneurysms And Their Relationship To Circle Of Willis Variations: A Retrospective Analysis Of Patients In A University Hospital

Background: Cerebral aneurysms, their rupture and resultant neurological sequelae are a major cause of morbidity and mortality. Multiple studies have analyzed the etiology of cerebral aneurysms including hemodynamic and congenital factors. Since the arterial supply of the brain develops entirely from the third pharyngeal arch and the dorsal aorta, any insult to the developing vascular system increases the probability of development of variations, including aneurysms. Purpose: To identify the association of arterial variations with aneurysms. Methods: A total of 83 patients with 106 intracranial aneurysms diagnosed by cerebral angiography from January 2011 to July 2014 were analyzed for variations in the intracranial vasculature. The type and laterality of the vascular variants in relation to the aneurysms were also examined. Results: On evaluation of the aneurysms, 65 (61.3 %) had associated variations in the intracranial vasculature. Among these, 51 (78.5 %) had variations ipsilateral to the aneurysm. 90 (84.9%) were in the anterior circulation. 52 patients (62.7%) were female. Various vascular variations including hypoplasia of posterior communicating (P-Comm) artery (56.5 %), variant anterior cerebral (ACA) artery (17.39%), fetal type posterior cerebral (PCA) artery (21.7%), fenestration of vertebral artery (1.4%), superior cerebellar artery duplication (1.4%) and arteriovenous malformations were noted. Fetal type PCAs were significantly more common in patients with anterior communicating (A-comm) (p-value <0.0115) and P-Comm A aneurysms (p-value <0.0131). Also, variations of A1 segment of ACA were significantly more common in A-Comm aneurysms (p-value <0.0013). Conclusions: The distribution of aneurysms in the intracranial vasculature in our study is comparable to previous literature. Among the arterial variations we found that fetal type PCAs are significantly common among A-Comm and P-Comm aneurysms. Also, variations in the A1 segment of ACAs were commonly associated with A-Comm aneurysms. Although further conformation of these associations is required with a prospective randomized control trial, if established, screening for these variations could help in primary prevention and early treatment of these aneurysms.