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

Dual fenestration of the A1 and azygos A2 segments of the anterior cerebral artery illustrated by Magnetic Resonance Imaging

PURPOSE

Fenestrations are probably the most common among the anomalies of intracranial arteries. They are known for their association with other vascular conditions, such as aneurysms and arterio-venous malformations. Anterior cerebral artery (ACA) in both A1 and A2 segments is subjected to many anomalies, including fenestrations, but they are rarer than hypoplasia and aplasia. The association of more than one anomaly has been described, but the presence of a dual fenestration in a single arterial segment has been anecdotally reported.

METHODS

A case of an incidentally discovered association of two ACA anomalies, i.e. dual fenestration in the A1 segment and azygos pattern in the A2 segment, is presented. Both anomalies were identified in a brain Magnetic Resonance Imaging (MRI) study with MR Angiography. The clinical indication for MRI was tinnitus. The other intracranial arteries were unremarkable (apart from duplicated posterior communicating arteries) and the brain parenchyma did not show abnormalities. No aneurysms were found.

CONCLUSIONS

The reported anomalies (the dual fenestration and the azygos A2 ACA) are located in the same arterial territory and potentially have a long-term effect on the local hemodynamics of the ACA facilitating the formation of aneurysms. Then, an imaging follow-up may be adviced.

Case Description: Infra-Optic Anterior Cerebral Artery in a Neonatal Doppler Ultrasound

There are few publications about the visualization of the circle of Willis and its variations using ultrasound. We hereby document the possibility of detecting a rare and clinically relevant variation of the circle of Willis, the infra-optic origin of the ACA, during routine cranial ultrasound in a preterm girl. Best visualization was with high resolution power doppler imaging, the diagnosis was MR confirmed near term. The importance of this diagnosis lies in the risk of aneurysm formation at an atypical location, information essential for proper management thereof. We suggest it is in a child's best interest to include a careful description of the circle of Willis when a sonographic or MR angio exam is performed for whatever reason.

Rare neurovascular variants that you probably have not seen before

BACKGROUND

Recognition of neurovascular variants is crucial for safe endovascular and neurosurgical interventions. We aim to review and highlight various uncommon neurovascular variants and anomalies with a discussion of their relevant embryology and pathology.

METHODS

A retrospective review of a prospectively maintained neurovascular database was performed to identify uncommon neurovascular variants and anomalies. A pictorial review of these neurovascular findings is provided along with relevant embryological development, clinical significance, and potential pathological associations.

RESULTS

A pictorial review of selected neurovascular variants and anomalies is presented. These entities, divided between intra- and extra-cranial findings, include infra-optic origin of the anterior cerebral artery, meningo-ophtalmic artery, duplicated posterior cerebral artery, duplicate middle cerebral artery (MCA), MCA fenestration, twig-like MCA, pure arterial malformation, corkscrew basilar artery, persistent hypoglossal artery, persistent trigeminal artery and its variants, direct branches from the common carotid and cervical internal carotid arteries (ICA) (ascending pharyngeal artery from the ICA, thyroidal arteries from the CCA/brachiocephalic, arteria thyroidea ima), and extra-cranial carotid fenestration. The angiographic findings of these entities are presented with relevant 3D reconstruction and multimodal cross-sectional imaging correlation when available.

CONCLUSIONS

This pictorial review highlights uncommon neurovascular variants and anomalies that neuroradiologists, interventionalists, and neurosurgeons should be aware of for accurate diagnosis and safe interventions.

Anatomical Variations and Anomalies of the Anterior Communicating Artery Complex

BACKGROUND

Intracranial arteries have a high rate of variation, but a clear schematic overview is lacking. In this pictorial review we classify and depict all variations and anomalies within the anterior communicating artery complex.

METHODS

PubMed was searched with the terms "Anterior Communicating Artery" AND "Variations" OR "Anomalies." Articles were selected based on their description of variants. Cross-referencing was used to broaden the range of variations. Surgical view during pterional craniotomy and transsylvian approach was used as a baseline for schematic drawings of the variations.

RESULTS

A total of 42 variants were identified, schematically drawn and classified into A1-A2 segment, anterior communicating artery, and the recurrent artery of Heubner.

CONCLUSIONS

The anterior communicating artery complex consists of the anterior cerebral artery, anterior communicating artery and the recurrent artery of Heubner. An overview of these variations may be helpful in distinguishing pathology from anatomical variations, assist neurosurgeons during clipping of cerebral aneurysms, and support interventional radiologists during endovascular treatments. This article summarizes the current knowledge of anatomical variations within the anterior communicating artery complex, their prevalence and clinical relevance. A total of 42 variants were identified and schematically depicted. We encourage all who diagnose, treat, and study the anterior communicating artery complex to use this overview for a uniform and better understanding of its anatomy.

Ruptured Fusiform Anterior Cerebral Artery Aneurysm in an Infant : Case Report and a Literature Review

Ruptured intracranial aneurysms in infants are rare and infantile fusiform anterior cerebral artery (ACA) aneurysms are much rarer. In this report, we described the case of a 7-month-old infant with a ruptured fusiform ACA aneurysm who presented with seizure and underwent endovascular treatment. The patient was initially in a coma and the neurologic condition did not improve after treatment. The clinical characteristics of the case and literature review were discussed.

Perforating and ophthalmic artery variants from the anterior cerebral artery: Two case reports

BACKGROUND

The diagnosis and therapy during surgery depend largely on a full account of anatomic characteristics. Apart from regular structures, the common, less common or even uncommon anatomic variations are critical for procedural planning. This is especially true during craniocerebral microsurgery, where small vascular variations can affect the final surgical results and patient prognosis.

CASE SUMMARY

Herein, two rare variations concerning the A1 (horizontal) segment of anterior cerebral artery (ACA1) were introduced. One enabled the communication between perforating branch of ACA1 and dural artery of anterior skull base, which was discovered during autopsy. The other was ophthalmic artery (OA) originating from ACA1, shown on digital angiography.

CONCLUSION

In this study, we found two rare anatomical variations. One was an abnormal OA originated from the anterior communicating artery. The other was a perforating branch of the A1 segment of the anterior cerebral artery, which communicated with meningeal vessels in the anterior skull base. This finding is of great significance for the treatment of anterior communicating artery aneurysm or in other anterior skull base surgery.