Anterior communicating artery aneurysm associated with an infraoptic course of anterior cerebral artery and rare variant of the persistent trigeminal artery: A case report and literature review

The Infraoptic or Infrachiasmatic Course of the Anterior Cerebral Artery Emerging an Elongated Internal Carotid Artery

(1) Background: The normal A1 segment of the anterior cerebral artery (ACA) has a supraoptic course. The proximal infraoptic course of an A1 segment leaving the internal carotid artery (ICA) near the origin of the ophthalmic artery is a rare possibility. This study aimed to determine the prevalence and detailed anatomy of infraoptic A1 segments. (2) Methods: We retrospectively studied 145 computed tomography angiograms from 92 male and 53 female cases, with ages varying from 61 to 78 y.o. (3) Results: In 21/145 cases, infraoptic or infrachiasmatic horizontal-medial courses of A1 segments that emerged distally from the ICA were found. Distal infraoptic A1 segments were bilateral in 16/145 cases and unilateral in 3/145 cases. Infrachiasmatic A1 segments were found bilaterally in 2/145 male cases. All the infraoptic/infrachiasmatic A1 segments left long ICAs with low bifurcations. In 7/34 sides with distal infraoptic or infrachiasmatic A1 segments, supracarotid courses were present. In one female, the right A1 segment had an anterior supraclinoid, supracarotid and infraoptic course. In two female cases with a bilateral distal infraoptic A1, the segment was almost contacting the respective posterior cerebral artery. (4) Conclusions: In cases with dolicho(ectatic) ICAs, the A1 segments could have infraoptic and supracarotid courses the neurosurgeons should be aware of.

Embryology of the anterior communicating artery complex: implications on possible adult variants

The anterior cerebral artery (ACA) and the anterior communicating artery (AComA) are important arteries of the telencephalon and are prominent location for cerebral aneurysms. Their embryological development is closely linked, and explains the possible variants seen in adults. In this paper, we present details related to the development of these two arteries, focusing on some variants such as the infra-optic course of the ACA, the unpaired ACA, and the persistent primitive olfactory artery.

A Ruptured Anterior Communicating Artery Aneurysm with Infra-optic Course of the Anterior Cerebral Artery: A Case Report and a Short Review

Infra-optic course of the anterior cerebral artery (IOA) is rare and approximately 55 cases of this anomaly have been described. We present a case of a ruptured anterior communicating artery (ACoA) aneurysm arising at the junction between the left IOA and the bilateral A2 segments, at which the right A1 segment was absent. One of the recurrent arteries of Heubner branched off directly from the aneurysmal dome, and was obstructed at aneurysmal neck clipping via an anterior interhemispheric (AIH) approach. In this report, accompanied anatomical variations and surgical approaches for ACoA aneurysms with IOA are reviewed. An IOA is frequently associated with other vascular anomalies, and the origin of functionally important recurrent arteries of Heubner is also variable. Preoperative accurate evaluation of vessel structures and the maximal exposure at surgery are very important. Pterional approach from the ipsilesional side is reportedly to be safe, but interhemispheric approach is also suggested to be effective as to full exposure to recognize the perianeurysmal anatomical structures including potential vessel anomalies.

An MRI study of typical anatomical variants of the anterior communicating artery complex

PURPOSE

This magnetic resonance imaging study examined the most frequent anatomical variants of the anterior communicating artery (ACoA) complex of the cerebral arterial circle, and aimed to determine whether they were associated with ACoA complex aneurysm.

METHODS

The study enrolled 669 patients. Using three-dimensional time-of-flight magnetic resonance angiography, 617 patients were classified into the following groups based on the anatomical variation in the ACoA complex: no ACoA complex anomaly; ACoA complex aneurysm; and vascular anomaly distant from the cerebral arterial circle.

RESULTS

Of the 617 classified subjects, the classical anatomical description applied to 48.73% in the no ACoA complex anomaly group and 37.5% in the ACoA complex aneurysm group. One variant (left anterior cerebral artery segment A1 hypoplasia) was significantly more frequent in the ACoA complex aneurysm group. There was no sex difference in the prevalence of any variant.

CONCLUSIONS

Anatomical variants of the ACoA complex of the cerebral arterial circle were found in almost half of the subjects. One variant seemed to be associated with a higher likelihood of an aneurysm, but causality could not be inferred.

Infraoptic anterior cerebral artery or carotid-anterior cerebral artery anastomosis: A very rare embryological variation. Case series and review of literature

PURPOSE

An infraoptic course of the anterior cerebral artery (ACA) is a rare cerebrovascular variation that can be associated with anterior communicating artery aneurysm. The purpose of this study is: 1. Describe infraoptic ACA or Carotid-ACA anastomosis. 2. Discuss the embryology. 3. Demonstrate this rare variation on CT/MR angiography. 4. Discuss its clinical significance. 5. Understand the anatomy for appropriate management of associated vascular pathology (Anterior communicating aneurysm). 6.

LITERATURE REVIEW

METHODS

We describe 2 cases with CT/MR angiographic findings of this rare vascular variation along with review of embryology and literature.

RESULTS AND CONCLUSION

Generally, ACA arises from the internal carotid artery (ICA) terminus and runs medially superior to the optic nerves and communicates with contralateral ACA through the anterior communicating artery. An infraoptic course of the A1 segment of the ACA is associated with a low ICA bifurcation, usually located intradurally at or just above the level of the origin of the ophthalmic artery. Rarely, infraoptic origins of A1 are proximal or at the level of origin of the ophthalmic arteries and arise below the optic strut possibly extradurally. Abberant ACA course has been shown to be associated with aneurysms which needs prompt recognition, to allow optimum treatment planning (surgical/endovascular). Our first case has bilateral infraoptic ACA seen on CT angiography. The second case has ipsilateral (right) infraoptic ACA with associated anterior communicating artery aneurysm.

[Combination of infraoptic anterior cerebral artery with an aneurysm of the ACA-AcomA complex. Case study and literature review]

The infraoptic anterior cerebral artery (ACA) is an abnormal vessel that usually is a bifurcation of the intradural part of the internal carotid artery (ICA) or near the site of discharge of the ophthalmic artery, which passes under the ipsilateral optic nerve and penetrates between the optic nerves into the prechiasm cistern, reaching the ACA-AcomA complex. The infra-optic ACA is an extremely rare anomaly, but it may be of great clinical significance in surgery of the arteries of the anterior sections of the Willis circle. The article describes the case of a combination of infra-optical ACA with an aneurysm of the ACA-AcomA complex. This observation is of interest both from the viewpoint of the rarity of the considered pathology and the associated increased risk of the formation of intracranial aneurysms.

Surgical Significance of Infra-Optic Course of A1 Segment of Anterior Cerebral Artery: Report of Two Cases

Anatomic variations of the anterior cerebral artery-anterior communicating artery complex (ACA-AComA) are common. An infra-optic course of the A1-ACA is extremely rare, and recognition of this variant is very important in planning surgery for ACA-AComA complex aneurysms. We present two cases of spontaneous subarachnoid hemorrhage due to ruptured AComA aneurysms with unilateral infra-optic course of the A1-ACA. In both the cases, the preoperative catheter angiography revealed low bifurcation with a horizontal course of internal carotid artery. In our first case, the finding was rather unexpected; however, in our second case, we could anticipate an infra-optic course of A1-ACA. Preoperative recognition of this anomaly helps in achieving proximal vascular control with ease and confidence. It also enhances surgical safety of aneurysm clipping, by avoiding unnecessary dissection elsewhere. This emphasizes the importance of careful preoperative angiographic evaluation. In the presence of this anomaly, one should always search for other associated vascular anomalies.

Persistent Primitive Trigeminal Artery Associated With Anterior Communicating Artery Aneurysm and Hypoplastic Vertebral Artery

The persistent trigeminal artery is one of the presegmental arteries in the embryonic period; in some rare cases, it is associated with cerebral aneurysm but as a cause of subarachnoid hemorrhage (SAH) has not been described in the literature. We report a patient who presented a Fisher IV SAH associated with a ruptured intracranial aneurysm. The performed cerebral angiography demonstrated the presence of aneurysm in the anterior communicating artery associated to hypoplastic vertebral artery on the same side. We considered those finding coincidental. The coexistence of saccular aneurysm with anatomical variations in the intracranial vasculature is briefly discussed. It was managed by endovascular embolization. The patient returned to normal activities.

Carotid-Anterior Cerebral Artery Anastomosis Associated with Paraclinoid Aneurysm and Ophthalmic Artery Originating From Middle Meningeal Artery: Case Report and Consideration of Terminology

BACKGROUND

We summarized 63 cases of anterior cerebral artery (ACA) anomaly with an infraoptic course reported in the literature including abstracts written in English. All cases were reported individually, with a maximum of 3 cases. This report describes our findings in another case and opinions regarding the terminology.

CASE DESCRIPTION

A 78-year-old woman presented with subarachnoid hemorrhage. A carotid angiogram showed a right paraclinoid aneurysm with an anomaly of the ACA. The right ACA originated from the internal carotid artery at the level of the ophthalmic segment intradurally with an infraoptic course. The right ophthalmic artery originated from the ipsilateral middle meningeal artery. We performed an emergent endovascular coil embolization with balloon assistance, and the patient recovered well.

CONCLUSIONS

Use of the terminology "infraoptic course of the ACA" versus "carotid-ACA anastomosis" was discussed. Based on the literature reports, at least one third of the cases have a normal-positioned ACA rather than the infraoptic ACA. Also, based on embryogenesis, it is thought that the infraoptic ACA is not a misplaced A1 segment, but rather persistence of an embryologic vessel. Therefore, based on the literature and embryology, we prefer the term "carotid-ACA anastomosis" rather than "infraoptic ACA." However, as a morphologic and positional description, the term "infraoptic ACA" has value. To the best of our knowledge, the present case of a carotid-ACA anastomosis associated with a paraclinoid aneurysm and ophthalmic artery originating from the middle meningeal artery is the first to appear in the literature.

Dissecting Aneurysm at the Proximal Segment of the Anterior Cerebral Artery Associated with Infraoptic Course Anterior Cerebral Artery

A 48-year-old man presented a subarachnoid hemorrhage caused by a rupture of a dissecting aneurysm at the proximal segment (A1 segment) of the right anterior cerebral artery (ACA). He also had an anomalous artery named infraoptic course ACA and an agenesis of the contralateral ACA A1 segment. Balloon occlusion test at the bifurcation of the right internal carotid artery demonstrated that the distal segments of the bilateral ACAs were perfused through the infraoptic course ACA. Therefore, we surgically trapped the A1 segment including the aneurysm. The patient got discharged without any neurological deficit. Natural course of ACA dissecting aneurysms is unclear because of rarity of the disease and treatment strategy is still controversial. Most of the dissecting aneurysms in the A1 segment are surgically treated, because they often present with massive hemorrhage and poor prognosis. In the present case, the contralateral A1 segment was absent but trapping of the dissecting aneurysm could be achieved without vascular reconstruction (e.g., bypass surgery) because of the presence of the infraoptic course ACA.