Azygos anterior cerebral artery shield masquerading as an aneurysm

Here, we describe a case of a woman suspected to have an anterior cerebral artery (ACA) aneurysm that was ultimately found to have an azygous ACA shield. This benign entity highlights the importance of thorough investigation with cerebral digital subtraction angiography (DSA). This 73-year-old female initially presented with dyspnea and dizziness. CT angiogram of the head suggested an incidental 5 mm ACA aneurysm. Subsequent DSA demonstrated a Type I azygos ACA supplied by the left A1 segment. Also noted was a focal dilatation of the azygos trunk as it gave rise to the bilateral pericallosal and callosomarginal arteries. Three-dimensional visualization demonstrated a benign dilatation secondary to the four vessels branching; no aneurysm was noted. Incidence of aneurysms at the distal dividing point of an azygos ACA ranges from 13% to 71%. However, careful anatomical examination is imperative as findings may be a benign dilatation for which case intervention is not indicated.

Azygos anterior cerebral artery associated with hypoplastic A1 fragment of right anterior cerebral artery

Anterior cerebral arteries are paired and supply the major portion of the medial surface of the brain. They are branches of the intracranial part of the internal carotid artery and form the anterior portion of the circle of Willis (CW) which is situated in the interpeduncular fossa. During routine dissection in the department of anatomy, All India Institute of Medical Sciences, Bibinagar, Hyderabad, a rare variation had been observed in the CW, azygos anterior cerebral artery associated with hypoplastic A1 fragment of the right anterior cerebral artery in a 63-year-old female cadaver. It is important to identify and study this kind of rare variation for surgeons, anatomists, and radiologists during dissection, surgical, radiological, and diagnostic interventions.

Endovascular treatment of a ruptured blister-like aneurysm at an azygos anterior cerebral artery: A case report and review of the literature

Background

Endovascular treatment for a ruptured blister-like aneurysm (BLA) has recently become a hopeful approach. BLAs are usually located on the dorsal wall of the internal carotid artery, whereas one located on the azygos anterior cerebral artery (ACA) is so rare, it has never been reported. We report a case of a ruptured BLA arising at the distal bifurcation of an azygos ACA treated by stent-assisted coil embolization.

Case Description

A 73-year-old woman presented with a disturbance of consciousness. Computed tomography showed diffuse subarachnoid hemorrhage, which was observed to be particularly dense in the interhemispheric fissure. Three-dimensional rotation angiography showed a tiny and conical bulge on the distal bifurcation of the azygos trunk. Follow-up digital subtraction angiography performed on day 4 showed enlargement of the aneurysm, and a BLA arising at the azygos bifurcation was diagnosed. Stent-assisted coiling (SAC) was performed using a low-profile visualized intraluminal support (LVIS) Jr. stent, which was implanted from the left pericallosal artery to the azygos trunk. Follow-up angiography showed that the aneurysm thrombosed gradually and reached complete occlusion 90 days after onset.

Conclusion

SAC for a BLA at the distal bifurcation of an azygos ACA might be an effective treatment option leading to early complete occlusion, but thrombus formation as an intraoperative complication should be noted in the BLA at the bifurcation or the peripheral artery, as in the present case.

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.

Microsurgical Clip Ligation of an Unruptured Azygos Bifurcation Aneurysm Indented by the Falx Cerebri: 3-Dimensional Operative Video

Dissecting pericallosal aneurysms from the falx cerebri is technically challenging, as one must release the adherent dome but minimize shearing injury, which could result in intraoperative rupture. We discuss a 51-yr-old woman with a history of hypertension and smoking who presented with severe headaches and was found to have a 6-mm unruptured, multilobulated pericallosal aneurysm abutting the falx, with anterior and superior projecting domes on either side. She also had an azygos anterior cerebral artery (ACA), a rare anatomic variant associated with pericallosal aneurysms, where both A1 segments form a single A2. After considering endovascular and open surgical techniques, we proceeded with clip ligation given her younger age, smoking history, daughter aneurysms seen on angiography, and azygos ACA. We positioned her supine with her head turned lateral, left side down to maximize gravitational retraction, mapped a bicoronal incision, and performed a small craniotomy, followed by an interhemispheric approach. Rather than cutting the falx around the dome, a described technique that risks blind vessel injury, we temporarily clipped inflow vessels to reduce the dome's turgor and sharply and bluntly dissected apart its attachments, which freed the aneurysm from beneath the falx and allowed visualization of associated vessels. Using suction to manipulate the dome, we then placed stacked, angled clips, and used a micro-Doppler to confirm brisk inflow and outflow. Postoperatively, she was neurologically intact, and her angiogram showed no residual aneurysm. Our 3-dimensional video demonstrates a safer, alternative approach to treating this rare aneurysm with its associated anatomical variant. Patient consented to her clinical presentation and microscope media being used for academic purposes.

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

PURPOSE

There is not a classification of azygos anterior cerebral artery (ACA) based on anatomical branching levels in the literature. In the present study, a classification of azygos ACA was made based on radiological imaging for a common terminology, and frequency, accompanying vascular anomalies and malformations were investigated.

METHODS

A total of 4913 cases who had brain CTA, MRA, contrast-enhanced MRI and DSA in January 2010-January 2020 period were screened for the study. Based on anatomical branching level, azygos ACAs were classified into four groups. Aneurysms, anomalies and malformations accompanying azygos ACA were identified. The associations of azygos ACA types with the presence of aneurysm or ACA A1 segment anomalies were investigated.

RESULTS

Azygos ACA was observed in 57 cases (29 male and 28 female) and frequency of azygos ACA was 1.16%. Average age of the cases with ACA was 56.19 ± 19.65 years. Forty-eight of the cases had type C azygos ACA, four cases type B, four cases type D and one case type A azygos ACA. A total of nine intracranial aneurysms were identified in seven of the cases (12.28%). Five of the aneurysms were located in MCA and four in distal ACA. Most common vascular anomalies accompanying azygos ACA were unilateral vertebral artery hypoplasia and ACA A1 segment hypoplasia. Azygos types did not have significant correlations with the presence of aneurysms or ACA A1 segmental anomalies (p = 0.683 and p = 0.949, respectively).

CONCLUSION

Azygos ACA is a rare variation, but it could be accompanied by aneurysms or other vascular anomalies.

Aneurysm of azygos anterior cerebral artery: A report of two cases

Aneurysms of azygos anterior cerebral artery (ACA) are rare with very few cases reported in medical literature. We report here two cases of aneurysm of azygos ACA among 105 patients with subarachnoid hemorrhage. The two aneurysms were successfully clipped by using the bifrontal basal interhemispheric approach.

Saccular aneurysm of the azygos anterior cerebral artery: three case reports

The azygos anterior cerebral artery, a rare anomaly in the circle of Willis in which only a single vessel supplies the medial aspects of both anterior cerebral hemispheres, is closely associated with saccular aneurysms. We present three cases of azygos anterior cerebral artery aneurysms among the 781 cerebral aneurysms surgically treated at our institution in an 11-year period. These three cases all involved elderly women who presented with subarachnoid hemorrhage. Conventional cerebral angiography and CT angiography revealed small saccular aneurysms at the distal ends of the azygos anterior cerebral arteries. These aneurysms were clipped successfully using a bifrontal interhemispheric approach. Hence, the pathogenesis of these particular aneurysms relating to hemodynamic change, associated anomalies, and surgical pitfalls is discussed with review of literature.