Ruptured saccular aneurysm arising from fenestrated proximal anterior cerebral artery : case report and literature review

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.

Single-lane clipping technique for a ruptured aneurysm of A1 fenestration of the anterior cerebral artery: a case report and literature review

Fenestration of the A1 segment of the anterior cerebral artery is a rare vascular anomaly with a high risk of saccular aneurysm at the proximal end of the A1 fenestration. These aneurysms have a high risk of rupture. However, conventional surgical clipping can be technically challenging due to the anatomical characteristics. We report a case of A1 fenestration with a ruptured aneurysm wherein we successfully achieved complete obliteration of the aneurysm with a new "single-lane" clipping technique. A 64-year-old woman presented with a ruptured saccular A1 aneurysm at the proximal end of an A1 fenestration, resulting in subarachnoid hemorrhage. Microsurgical clipping was attempted; however, adequate exposure of the aneurysm could not be achieved. The recurrent artery of Heubner originated near the distal end of the lateral limb of the A1 fenestration. The lateral limb of the A1 fenestration had no perforating arteries, according to surgical examination. Thus, the aneurysm neck and lateral limb were concurrently obliterated using a nonfenestrated clip, preserving the medial limb of the A1 fenestration. The antegrade flow of the recurrent artery of Heubner was detected using the retrograde flow of the distal part of the lateral limb of the A1 fenestration during intraoperative indocyanine green video angiography. The postoperative course was uneventful without any evidence of ischemic stroke. For A1 aneurysms arising from the proximal end of the A1 fenestration, this technique may be a useful treatment option. Before using this technique, careful surgical exploration should be performed to assess the A1 perforating arteries.

Wire perforation of the missed tiny aneurysm originating from the fenestrated A1 segment during the endovascular approach

Vascular anomaly and aneurysmal formation of an anterior communicating artery (ACOM) complex has often been reported. Because of such a complicated relationship between the vascular structure and aneurysms, ACOM aneurysm is one of the most difficult aneurysms to treat among other common anterior circulation aneurysms. We herein report a case of wire perforation of a missed tiny aneurysm arising from the fenestrated A1 segment during the endovascular approach to ACOM aneurysm. Although the fenestration of A1 segment is a rare vascular anomaly, it is likely to accompany saccular type aneurysms in the vicinity of the vascular anomaly. Endovascular treatment for ACOM aneurysm requires more detailed evaluations of the accompanying vascular anomaly and hemodynamics around ACOM to avoid complications.

Microneurosurgical management of aneurysms of the A1 segment of the anterior cerebral artery: Anatomy and surgical technique

Background:

Aneurysms of the A1 segment of the anterior cerebral artery (ACA) are rare and have characteristics differentiating them from other intracranial aneurysms. Their microsurgical management is challenging and requires different strategies. In this article, we review the surgical anatomy of the A1 segment of the ACA with cadaveric dissections and describe the microsurgical management of complex A1 aneurysms with illustrative cases.

Methods:

A right pterional craniotomy and Sylvian dissection were performed on a formalin-fixed and silicone-injected cadaver head to depict the key anatomic structures and surgical corridors for microsurgical clipping of A1 segment aneurysms. The microneurosurgical management of ruptured and unruptured aneurysms of the A1 segment of the ACA is described with case illustrations.

Results:

The A1 segment of the ACA can be subdivided into proximal, middle, and distal subsegments, the former having abundant perforating branches. Both patients treated with microsurgical clipping had excellent and durable outcomes and postoperative cerebral angiograms showed complete aneurysm occlusion.

Conclusion:

Small A1 aneurysms may require early treatment as their rupture risk appears to be higher. A1 aneurysms are usually embedded in perforators, especially those arising from the proximal A1 subsegment, and require careful distal to proximal microdissection and strategic placement of the aneurysm clip blades. The approach, arachnoid dissection, and angles of attack are carefully planned after accounting for the aneurysm dome projection, precise location of the aneurysm neck and perforators, and the presence or absence of subarachnoid hemorrhage.

Microvascular Clipping of A1 Segment Aneurysms

Background

Aneurysms arising from the proximal segment (A1) of the anterior cerebral artery (ACA) are relatively rare. Because of their small size, abnormal location in relation to the parent artery and the risk of damage to the surrounding perforators, their surgical management is a big challenge. We present our experience with 7 patients of A1 segment aneurysms.

Settings and Design

Tertiary care referral center.

Materials and Methods

Seven patients who were diagnosed with A1 aneurysms between 2009 and 2017 were included. Preoperative evaluation included Non-Contrast Computed Tomography (NCCT) head and angiography (Digital Subtraction Angiography with/without CT-Angiography). The clinicoradiological condition of the patients was graded as per World Federation of Neurological Surgeons (WFNS), Fisher and Hunt and Hess (H and H) Grading systems. A retrospective review of clinical features, radiological descriptions, surgical treatment, and outcomes was done.

Results

All patients underwent microneurosurgical clipping. All aneurysms were saccular, ranging in size from 4 to 14 mm and neck size varied from 2 to10 mm. Most aneurysms 5 (71.4%) had a posterior direction. Anatomical variations were noticed in 3 (42.8%) patients. Posteroinferiorly directed aneurysms were difficult to clip. As per Glasgow Outcome scale (GOS), 6 (85.7%) patients had a good outcome, whereas 1 (14.2%) had poor outcome. As per the modified Rankin Scale (mRS) too, 6 (85.7%) had a favorable outcome. There were no deaths.

Conclusion

A1 aneurysms are frequently associated with vascular anomalies and generally rupture when small. A1 aneurysms with a superior and anterior direction are relatively easy to clip whereas those directed postero-inferiorly are difficult. Close association with critical perforators also compounds the situation. Due to the rarity of A1 aneurysms, large series are few in literature.

Aneurysms of the Proximal (A1) Segment of the Anterior Cerebral Artery: A Clinical Analysis of 31 Cases

OBJECTIVE

This study aimed to investigate the characteristics of A1 aneurysms according to their locations and to compare their imaging appearances so as to identify factors associated with their rupture.

METHODS

We retrospectively reviewed the medical records of 31 patients harboring 32 A1 aneurysms diagnosed and treated between March 2009 and September 2018 at our institute.

RESULTS

Thirteen (41.9%) of the patients had vascular abnormalities, and multiple aneurysms were found in 13 (41.9%) patients. A total of 16 (53.3%) aneurysms were located on the proximal A1 segment, whereas the middle segments were affected in 7 (23.3%) and the distal segments in 7 (23.3%). Altogether, 93.8% of proximal A1 aneurysms projected posteriorly, 85.7% of middle aneurysms projected superiorly, and 85.7% of distal aneurysms projected inferiorly (P = 0.000). Four (33.3%) of the 12 total ruptured aneurysms were located on the distal A1 segment. Nine (69.2%) ruptured aneurysms were elongated or irregular in shape (P = 0.004). The aspect and height-width ratios of the ruptured aneurysms were higher than those of the unruptured aneurysms (P = 0.001, P = 0.018, respectively).

CONCLUSIONS

Most A1 aneurysms showed a directional predilection according to the location of the A1 segment. Additionally, A1 aneurysms with elongated or irregular shapes, high aspect or height-width ratios, and distal locations of the A1 segment showed high risks of rupture. Therefore, a thorough assessment of the characteristics of A1 aneurysms can enhance the selection of proper treatment strategies.

Aneurysms Arising From the Fenestrated Middle Cerebral Artery

Intracranial artery fenestration is segmental duplication of the lumen into 2 distinct channels and is known to have a low angiographical incidence of 0.3 to 0.9%. Intracranial artery fenestration is frequently associated with aneurysms, and aneurysms arising at the site of fenestrated middle cerebral artery (MCA) is extremely rare. To our best knowledge, there are only 10 such patients have been reported. Herein, the authors describe the 11th case of aneurysm arising from the fenestrated MCA. As the characteristics of fenestrated MCA aneurysms has not been well determined until now, these interesting patients are investigated and summarized.

Unilateral Fenestrated A1 Segment of Anterior Cerebral Artery Multiple Aneurysms: Case Reports and Literature Review

The fenestration of the cerebral arteries is infrequent anomaly mostly occurring in the posterior communicating artery, the vertebral artery, the basilar artery, and the middle cerebral artery.^[1] We report a case of unilateral A1 fenestration associated saccular aneurysm, focusing on its features of surgical treatment.

Radiographic and microsurgical characteristics of proximal (A1) segment aneurysms of the anterior cerebral artery

BACKGROUND

Proximal A1 segment aneurysms of the anterior cerebral artery (ACA) radiologically resemble internal carotid artery bifurcation (ICBIF) aneurysms because of their anatomical proximity. However, proximal A1 aneurysms exhibit distinguishing features, relative to ICBIF aneurysms. We report our experience of managing proximal A1 aneurysms, then compare them to ICBIF aneurysms.

METHODS

Among 2191 aneurysms treated between 2000 and 2016 in a single institution, we retrospectively reviewed 100 cases categorized as ICBIF or A1 aneurysms. We included aneurysms originating from the ICBIF and ACA, proximal to the anterior communicating artery (A1 segment) and divided them into two groups: proximal A1 (n = 32) and ICBIF (n = 50). If any portion of the aneurysm involved the ICBIF, it was classified as ICBIF. Aneurysms wholly located in the A1 segment were classified as proximal A1. Patient factors and angiographic factors were evaluated and compared.

RESULTS

The proximal A1 group exhibited differences in aneurysm size (p = 0.013), posterior aneurysm direction (p = 0.001), and A1 perforators as incorporating vessels (p = 0.001). The proximal A1 group tended to rupture more frequently when the aneurysm was smaller (p = 0.046). One case of morbidity occurred in the proximal A1 group.

CONCLUSION

Compared to ICBIF aneurysms, proximal A1 aneurysms were smaller and directed posteriorly, with incorporating perforators. Because of these characteristics, it may be difficult to perform clipping with 360° view in microsurgical field. Therefore, when planning to treat proximal A1 aneurysms, different treatment strategies may be necessary, relative to those used for ICBIF aneurysms.

Unruptured Saccular Aneurysm Arising from the Fenestrated A1 Segment of the Anterior Cerebral Artery: Report of 2 Cases

Some cases of aneurysms originating from the fenestrated A1 segment of the anterior cerebral artery (ACA) have been reported, but the pitfalls of the surgical procedure have not been well determined. We herein report 2 cases of a saccular aneurysm arising from the fenestrated A1 segment. Case 1 was a 72-year-old man incidentally diagnosed with an unruptured left ACA aneurysm on magnetic resonance imaging (MRI). Cerebral angiography revealed a saccular aneurysm arising from the proximal end of the left A1 segment. He underwent surgical clipping via the left pterional approach. The aneurysm originated from the proximal bifurcation of the fenestrated left A1 segment. A fenestrated ring clip was applied to obliterate the aneurysmal neck and one small fenestrated trunk, preserving the other fenestrated trunk and perforators around the fenestration. Case 2 was a 73-year-old man incidentally diagnosed with an unruptured ACA aneurysm on MRI. Cerebral angiography revealed a saccular aneurysm arising from the proximal end of the fenestrated left A1 segment. He underwent surgical clipping via the interhemispheric approach. The aneurysm originated from the proximal bifurcation of the fenestrated left A1 segment. A fenestrated ring clip was applied to obliterate the aneurysmal neck and one hypoplastic fenestrated trunk, preserving the other fenestrated trunk and perforators around the aneurysm. Detailed intraoperative evaluations of the anatomical structure and hemodynamics around the fenestration are important. The intentional obliteration of a fenestrated trunk and application of fenestrated clips need to be considered in difficult cases in order to expose the aneurysmal neck.

Management of Proximal Anterior Cerebral Artery Aneurysms: Anatomical Variations and Technical Nuances

OBJECTIVE

The proximal segment of the anterior cerebral artery (A1) is among the most uncommon locations for occurrence of an intracranial aneurysm. These aneurysms may be missed if small or misinterpreted when they are near the internal cerebral artery bifurcation or Anterior Communicating Artery region. The association with congenital vascular anomalies and multiplicity makes them unique.

METHODS

Seventeen A1 aneurysms were diagnosed in sixteen patients between January 2000 and October 2014 in our institution. A retrospective review of the clinical, radiological, and management (microsurgical and endovascular) details of these patients was conducted.

RESULTS

The incidence of A1 aneurysm was 1.71% of all patients harboring aneurysms and 1.19% of all aneurysms. Half of these patients exhibited subarachnoid hemorrhage. Fourteen aneurysms underwent microsurgical or endovascular intervention. All patients recovered well, except for one patient who died in the postoperative period.

CONCLUSIONS

A1 aneurysms are rare, with wide anatomic variations. In this article, we discuss those variations in detail with illustrative cases and pictures. We also discussed the microsurgical and endovascular strategies to encounter them highlighting the technical challenges.