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Published on: September 25, 2009
Association of middle cerebral artery aneurysms and variation of the A1 segment
Xiaohui Li1,2, Xi Yue2, Zhengyuan Xie2
1Department of Neurosurgery, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian, China.
Insights
Variations in the circle of Willis, specifically A1 segment dysplasia, are linked to middle cerebral artery aneurysms. A1 dysplasia is associated with smaller MCA diameters and larger aneurysm sizes, increasing rupture risk.
Area of Science:
- Neurology
- Vascular Surgery
- Radiology
Background:
- Blood flow disturbances from circle of Willis variations contribute to aneurysm formation.
- Fetal-type posterior cerebral artery (PCA) links to posterior communicating artery (PcoA) aneurysms.
- Anterior cerebral artery (ACA) variations correlate with anterior communicating artery (ACoA) aneurysms.
Purpose of the Study:
- To investigate the controversial relationship between circle of Willis variations and middle cerebral artery (MCA) aneurysms.
- To analyze anatomical variations of the circle of Willis in patients with and without MCA aneurysms.
Main Methods:
- Retrospective analysis of Computed Tomography Angiography (CTA) data from 269 aneurysm cases and 269 controls.
- Utilized 3D-Slicer software for artery diameter measurements and relationship analysis.
- Examined circle of Willis variations and MCA aneurysm correlation.
Main Results:
- A1 segment dysplasia was significantly more prevalent in the aneurysm group (P = 0.0125).
- MCA diameter was smaller in aneurysm patients (2.304 ± 0.5613 mm) vs. controls (2.611 ± 0.5500 mm, P = 0.001).
- A1 dysplasia correlated with smaller MCA diameter, larger aneurysm size, and increased occurrence/rupture risk.
Conclusions:
- Circle of Willis variations, particularly A1 dysplasia, impact MCA aneurysm occurrence and rupture.
- Altered blood flow, constricted parent artery diameter, and shifted flow impact contribute to MCA aneurysms.
- Ipsilateral A1 dysplasia is a significant factor in MCA aneurysm development and rupture.
Objective:
The disturbance of blood flow caused by variations in the circle of Willis is an important factor in the occurrence and development of aneurysms. Previous studies have confirmed that a fetal-type posterior cerebral artery(PCA) is closely related to posterior communicating artery (PcoA) aneurysms, while anatomical variations of the anterior cerebral artery (ACA) appear to correlate with the prevalence of aneurysms in the anterior communicating artery (ACoA). However, the relationship between variations in the circle of Willis and middle cerebral artery(MCA) aneurysms remains controversial.
Methods:
This study retrospectively analyzed the Computed Tomography Angiography (CTA) data of 269 cases of patients with intracranial aneurysms and 269 cases of patients without aneurysms at the Jiangmen Central Hospital from January 2012 to December 2023. The 3D-Slicer software was utilized to measure the artery diameter and investigate the relationship between anatomical variations of the circle of Willis and MCA aneurysm.
Results:
In the aneurysm group, there were 39 cases of A1 dysplasia on the affected side, compared to 20 cases in the control group, with a significantly higher prevalence in the aneurysm group (P = 0.0125). The average diameter of middle cerebral arteries was smaller in the aneurysm group (2.304 ± 0.5613 mm) than in the control group (2.611 ± 0.5500 mm), showing a significant difference (P = 0.001).In aneurysm patients, the MCA diameter on the affected side was smaller in the A1 dysplasia group (2.156 ± 0.5256mm) compared to the A1 normal development group (2.405 ± 0.5718mm, P = 0.0114). Additionally, the average maximum aneurysm diameter was larger in the A1 dysplasia group (6.958 ± 5.163mm) than in the A1 normal development group (5.483 ± 3.336mm, P = 0.03).The presence of ipsilateral A1 dysplasia had a statistically significant effect on the occurrence and rupture of MCA aneurysms.
Conclusions:
The variation in the circle of Willis may impact the occurrence and rupture of MCA aneurysms by altering blood flow distribution, constricting the diameter of the parent artery, and shifting the location of blood flow impact.
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