J Korean Neurosurg Soc.  2022 Jul;65(4):531-538. 10.3340/jkns.2021.0283.

Could A1 Aplasia or Hypoplasia Affect the Morphology and Rupture Risk of Anterior Communicating Artery Aneurysm?

• Park SC
• Jung NY
• Park ES
• Kwon SC

• KMID: 2531622
• DOI: http://doi.org/10.3340/jkns.2021.0283

Abstract

Objective
: Anterior communicating artery (Acom) aneurysm is one of the most common intracranial aneurysms, constituting approximately 30–35% of all aneurysm formation in the brain. Anatomically, the H-complex (the anatomic morphology of both A1 to A2 segments) is thought to affects the nature of the Acom aneurysm due to its close relationship with the hemodynamics of the vessel. Therefore, we investigated the relative risk factors of aneurysmal rupture, especially focusing on H-complex morphology of the Acom.
Methods
: From January 2016 to December 2020, a total of 209 patients who underwent surgery, including clipping and coiling for Acom aneurysm in our institution were reviewed. There were 102 cases of ruptured aneurysm and 107 cases of unruptured aneurysm. The baseline morphology of aneurysms was investigated and the relationship between the H-complex and the clinical characteristics of patients with Acom aneurysms was assessed.
Results
: Of the 209 patients, 109 patients (52.1%) had symmetrical A1, 79 patients (37.8%) had unilateral hypoplastic A1, and 21 patients (10.0%) had aplastic A1. The hypoplastic A1 group and the aplastic A1 group were grouped together as unilateral dominancy of A1, and were compared with the symmetrical A1 group. There was no significant difference in demographic characteristics and radiological findings of Acom aneurysms between two groups. However, when dichotomizing the patients into ruptured cases and unruptured cases, unilateral dominance of the A1 segment was associated with aneurysmal rupture with statistical significance (p=0.011).
Conclusion
: These results suggest that the unilateral dominance of the A1 segment does not have a significant effect on the morphology of Acom aneurysms, but contributes to aneurysmal rupture. Thus, we can better understand the effects of hemodynamics on Acom aneurysm.

Keyword

Anterior cerebral artery; Intracranial aneurysm; Rupture; Subarachnoid hemorrhage; Hypoplasia

Figure

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  Fig. 1. Measurement methods for the morphology of aneurysm and H-complex variants in the study population. Symmetrical A1 is a case where both A1 arteries have no significant difference (A). In the case of hypoplastic A1, we defined it as A1 on one side with less than half of the diameter of the other side and less than 1 mm (B). Finally, aplastic A1 was defined as a case in which one side of the A1 was not visible on digital subtraction angiography (C).

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  Fig. 2. The method of measuring the size of aneurysms and each parameter used in this study. Neck width (n), dome width (d), height (h), the dome-to-neck ratio was calculated as d/n, the aspect ratio was calculated as h/n as described previously. Width of the A1 segment (w) was also measured.

Reference

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