Completeness of Circle of Willis in asymptomatic and symptomatic extracranial carotid disease

Abstract

Introduction. This research has been aimed at determining whether incomplete Circle of Willis in patients with significant extracranial carotid stenosis is associated with a higher incidence of neurological symptomatology and/or ischemic cerebral lesions. Material and Methods. The research was conducted as a prospective study which comprised 211 patients who underwent surgical treatment of extracranial carotid disease at the Department of Vascular Surgery in Novi Sad and 102 patients in the control group. Each patient underwent preoperative magnetic resonance imaging and magnetic resonance angiography with visualization of cerebral parenchyma, extracranial and intracranial cerebral circulation. Assessment of Circle of Willis morphology was performed by 3D time-of-flight magnetic resonance angiogram sequence analysis. The patients were divided into two groups: group I - the patients with complete Circle of Willis and group II - the patients with incomplete Circle of Willis i.e. with the disruption of anterior and/or ipsilateral posterior circulation - regarding the side of significant carotid stenosis. Results. Out of 211 patients who were operated during a two-year period, 133 had the complete Circle of Willis, while 78 patients had the incomplete Circle of Willis. Out of 111 patients with symptomatic carotid disease or silent cerebral infarction, 52.5% (58) had the complete Circle of Willis and 47.5% (53) had the incomplete Circle of Willis. It was shown to be statistically different (P = 0.0146) in relation with the asymptomatic group of patients (100), where the frequency of the complete Circle of Willis was 75% (75) while the insufficiency of anterior or ipsilateral posterior collateralization was found in 25% (25). In the control group there were significantly fewer cases of developed collateral flow and the complete Circle of Willis (41%) compared to the operated patients with extracranial carotid stenosis (63%) (P = 0.0003). Conclusion. Incompleteness of Circle of Willis is associated with more frequent occurrence of neurological symptomatology or ischemic lesions of brain parenchyma in operated patients with significant extracranial carotid stenosis. The control group without extracranial carotid stenosis had less developed collaterals of Circle of Willis compared to extracranial carotid patients.