Radiological classification of azygos anterior cerebral artery and evaluation of the accompanying vascular anomalies

Morphometric and Clinical Analysis of the Azygos Anterior Cerebral Artery: Insights From a Cadaveric Case Report Study

The azygos anterior cerebral artery (ACA) is an uncommon anatomical variation with important clinical implications. This study presents an in-depth morphometric analysis of a single brain specimen displaying this variant. The goal is to improve the understanding of its anatomical characteristics and its influence on cerebral vascular health. Through precise dissection and measurement, the study highlights the structural features of the azygos ACA and its potential role in clinical conditions, particularly in relation to aneurysm formation and associated risks. The brain specimen was sourced from the Laboratory of Microsurgical Anatomy of the Central Nervous System, Faculty of Medicine, National Autonomous University of Mexico (UNAM). The donor did not have a history of neurological disease or neurosurgical procedures, ensuring the integrity of the vascular structures for analysis. To facilitate analysis, red latex was injected into the specimen, which was then preserved in 10% formalin for two months. Morphometric assessments were carried out using a Mitutoyo Model CD-8" CX digital caliper with a resolution of 0.0005"/0.01mm, along with detailed photographic documentation. The study examined the brain of a 38-year-old male, which weighed 1,310 grams. Symmetry was observed in the A1 segments: the right A1 segment measured 11 mm in length and 3 mm in diameter, while the left A1 segment measured 10 mm in length and 2.4 mm in diameter. The anterior communicating artery (ACoA) was absent, and only a single A2 trunk was identified. This trunk had an initial diameter of 4 mm, which tapered to 3 mm over a length of 33 mm until it bifurcated. Common anatomical variations of the A1-ACoA complex include absence, bifurcation, hypoplasia, plexal arrangement, and fenestration. A thorough understanding of anterior cerebral circulation variants is essential for optimizing the treatment of vascular pathologies.

Middle Cerebral Artery Aneurysm and Distal Anterior Cerebral Artery (DACA) Aneurysms Related to Azygos and an Unusual Single Pericallosal Artery Variant: A Case Report

The authors describe the case of multiple rare distal anterior cerebral artery (DACA) aneurysms related to a middle cerebral artery (MCA) aneurysm, an azygos, and an undescribed anterior cerebral artery (ACA) anatomical variation. A 61-year-old woman in a severe clinical state was diagnosed with subarachnoid hemorrhage (SAH) secondary to a ruptured anterior A3 DACA aneurysm. The patient also had unruptured kissing superior A3 DACA aneurysms, an atherosclerotic DACA aneurysm between the anterior and superior DACA aneurysms, and an unruptured MCA left aneurysm. Two pericallosal anatomical variations were seen: an A2 azygos and a rare single post-bifurcation (callosomarginal artery) pericallosal artery. All aneurysms were clipped using a single-staged left craniotomy with interhemispheric, subfrontal, and transsylvian access. This study demonstrates a patient with rare anatomical ACA variants and multiple complex aneurysms treated in a single-stage craniotomy.

A Rare Case of Enlarged Dissecting Aneurysm Occurring One Year After Conservative Management of Azygos Anterior Cerebral Artery Dissection

Anterior cerebral artery (ACA) dissection is generally managed with conservative treatment, often resulting in a favorable prognosis. However, cases with delayed enlargement of dissecting aneurysms following conservative therapy are rare. We describe a 46-year-old male patient who presented with concurrent subarachnoid hemorrhage and cerebral infarction caused by ACA dissection. Initial digital subtraction angiography (DSA) revealed an azygos ACA, as well as dilation and stenosis in the A2 segment. Follow-up DSA on the sixth and fifteenth days detected dissecting aneurysms at the bifurcation of the left pericallosal artery and at the peripheral bifurcation of the middle internal frontal artery, with intervening stenosis. The patient recovered well without rebleeding after conservative management. However, one year later, magnetic resonance imaging (MRI) indicated an enlargement of the aneurysm. Simple coil embolization was performed, and a 6-month postoperative MRI confirmed the disappearance of the aneurysm. This case suggests that while conservative management of azygos ACA dissections can be effective, careful and long-term follow-up is crucial due to the potential for delayed aneurysm formation.

Anterior Interhemispheric Approach for the Surgical Treatment of Azygos Anterior Cerebral Artery Aneurysms: A Case Series

The azygos artery is an uncommon vascular variant of the anterior cerebral artery (ACA). This anomaly is associated in a high percentage with aneurysms. Management of azygos ACA aneurysms represents a surgical challenge. We present five patients who underwent microsurgical treatment for distal azygos ACA aneurysms with complex morphology. Four patients showed subarachnoid hemorrhage (SAH) and one complained of sentinel headache. Early preoperative digital subtraction angiography (DSA) or computerized tomography angiography (CTA) was performed. All patients were treated by surgical clipping via an anterior interhemispheric approach. During follow-up, all patients had a satisfactory outcome, with postoperative angiograms showing complete resolution of aneurysms.

Stenting-assisted embolization of a saccular aneurysm of the azygos anterior cerebral artery associated with fenestration at its beginning

Aneurysms of the azygos anterior cerebral artery (AACA) associated with fenestration are exceptional. We reported such a case. A 61-year-old woman presented with subarachnoid hemorrhage. Computed tomography angiography and digital subtraction angiography showed an aneurysm at the distal end of the AACA with a fenestration at its beginning. Stenting-assisted coiling of the aneurysm was performed. The postoperative recovery was uneventful. Follow-up DSA showed complete coiling of the aneurysm. By this case report and review of the literature, we found that the coexistence of the aneurysm and fenestration on the AACA was exceptional. Endovascular treatment of saccular AACA aneurysms is an appealing option.

Imaging markers of intracranial aneurysm development: A systematic review

BACKGROUND

Imaging markers of intracranial aneurysm (IA) development are not well established.

PURPOSE

To provide an overview of imaging markers of IA development.

METHODS

A systematic search of PubMed and Embase up to December 1st 2020 using predefined criteria. Thirty-six studies met our inclusion criteria. We performed a quantitative summary of the included studies.

RESULTS

We found converging evidence for A1 segment asymmetry as an anatomical marker of anterior communicating artery (Acom) aneurysm development, and moderate evidence for several other markers. No hemodynamic markers yielded converging or moderate evidence. There was large heterogeneity across studies, especially in the definitions of imaging markers and study outcomes used. Due to the poor methodological quality of many studies and unavailability of effect sizes or crude data to calculate effect sizes, a formal meta-analysis was not possible. Many studies had poor methodological quality and varied inmarkerdefinitions and outcome measuresused, which prevented us from performing a formal meta-analysis.

CONCLUSIONS

We only identified A1 segment asymmetry as an imaging marker of Acom aneurysm development with converging evidence. A meta-analysis was not possible due to the heterogeneity of marker definitions and outcomes used, and poor methodological quality of many studies. Future studies should use robust study designs and uniformly defined imaging markers and outcome measures.