Rare neurovascular variants that you probably have not seen before

Abstract

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.

Keywords: Neurovascular variants; angiography; arterial variants; neurointervention; variant anatomy.

Figure 1.

Angiogram of the right internal carotid artery and axial CT angiogram demonstrating an infra-optic anterior cerebral artery (red) arising from the anterior genu of the ICA (blue). A posterior communicating artery (blue) is noted arising from its expected location of the supraclinoid ICA.

Figure 2.

A. Angiogram of the right common carotid artery demonstrating no ophthalmic artery from the ICA (blue). The OphA (red) originates from the MMA (green). This is better seen in the selective angiogram of the external carotid artery (C). The choroidal artery blush (black arrow on C) is noted from the selective external carotid artery injection.

Figure 3.

Angiogram of the right ICA in the lateral projection demonstrating a true fetal PCA, or “duplicated PCA” (red and green).

Figure 4.

(a) angiogram in the anteroposterior projection showing the ICA (blue) giving rise to the left ACA (red) and the two left MCA branches (superior division in green and inferior division in yellow). (b) A 3D reconstruction of the angiogram.

Figure 5.

Anteroposterior and 3D reconstruction of an angiogram showing a right MCA fenestration.

Figure 6.

Angiogram in oblique orientation demonstrating the plexiform vessels constituting a left T-MCA with delay filling of the MCA territory compared to the ACA territory.

Figure 7.

Angiogram of the vertebral artery with 3D volume rendering reconstruction demonstrating a PAM of the distal basilar artery with coiled and tortuous basilar tip involving the PCA and SCA branches.

Figure 8.

Angiogram of the vertebral artery with 3D volume rendering reconstruction demonstrating tortuosity with many distal angular turns of the basilar artery consisting with CBA. This patient presented with multiple intracranial anterior circulation aneurysms.

Figure 9.

(a) lateral angiogram of the ICA (blue) showing a PTA (red) anastomosing the ICA to the basilar artery. Coil-embolized aneurysms can be seen in the posterior and anterior communicating arteries. (b) Lateral angiogram of the ICA (blue) showing a PTA variant contributing to the anterior inferior cerebellar territory as cerebellar artery (red).

Figure 10.

Lateral common carotid angiogram and 3D angiogram demonstrating a PHA (blue) persistent anastomosis between the ICA (green) and the BA. The external carotid artery is noted in red.

Figure 11.

An axial CT scan showing a right-sided aberrant ICA (highlighted in red) protruding in the tympanic fossa. The left ICA is highlighted in blue for comparison.

Figure 12.

Right ICA angiogram demonstrating the pharyngeal branch of the ascending pharyngeal artery (red) branching off the ICA (blue).

Figure 13.

Angiogram demonstrating superior thyroidal artery (red) arising from the CCA (blue) proximal to the carotid bifurcation.

Figure 14.

Angiogram of the brachiocephalic artery demonstrating a thyroid ima artery arising from the proximal brachiocephalic trunk.