Carotid-anterior cerebral artery (ACA) anastomosis associated with azygos ACA and ophthalmic artery arising from the middle meningeal artery: a case report

Carotid-anterior cerebral artery anastomosis with an anteromedial course variant diagnosed by magnetic resonance angiography

PURPOSE

To describe a case of right carotid-anterior cerebral artery (ACA) anastomosis with a unique course in the proximal segment.

METHODS

A 78-year-old woman with a history of right carotid endarterectomy 2 years prior underwent cranial magnetic resonance (MR) imaging (MRI) and magnetic resonance angiography (MRA) of the head and neck regions separately using a 3.0-Tesla scanner. MRA was performed using a standard 3-dimensional time-of-flight technique.

RESULTS

MRA of the intracranial region revealed no pathological lesions. However, a large artery arose from the ophthalmic segment of the right ICA, took an anteromedial course and after making a hairpin turn, continued to the bilateral A2 segments of the ACA. Bilateral A1 segments of the ACA were absent. MRA source images and oblique sagittal reformatted images showed that the anomalous artery was running inferior to the right optic nerve, indicative of carotid-ACA anastomosis or an infraoptic course of the ACA. As some patients have an ipsilateral normal A1 segment, the latter name seems to be inadequate.

CONCLUSION

We encountered a case of right carotid-ACA anastomosis in which the proximal segment had a unique course, ran anteromedially, and made a hairpin turn. This type has not been reported in the relevant English-language literature. Usually, this variation takes a medial course and ascends between the bilateral optic nerves. Careful observation of MRA images, including their source images, is required for the correct diagnosis of this rare variation.

Left anterior cerebral artery arising from a right internal carotid artery: a rare case of carotid-anterior cerebral artery anastomosis

Carotid-anterior cerebral artery anastomosis (carotid-ACA anastomosis) is described as infrequent vascular connections between the pre-ophthalmic segment of the internal carotid artery (ICA) and the A1 segment of the anterior cerebral artery (ACA). The embryological origin of these variant is still unclear and they are often associated to other vascular anomalies of the circle of Willis, as well as to the presence of aneurysms. Carotid-ACA anastomosis is often right-sided although left and bilateral cases have also been described. We report a rare case by MR angiography of a carotid-ACA anastomosis in which the abnormal vessel arises from the right ICA and takes an infraoptic course to join the A2 segment of the contralateral ACA, making this vascular anomaly function as a 'left ACA with an origin at the right ICA'. The A1 segment of the left ACA is absent and both A2 segments of the ACAs present fenestration. To our knowledge, no similar cases have been reported in English literature so far.

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.

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.