"Duplicated" or "multiple" cervical internal carotid and vertebral arteries from fenestration, duplication and vasa vasorum to segmental rete

Abstract

The appearance of multiple cervical arteries may be due to a variety of anatomic situations. Arterial fenestrations and duplications have different anatomic origins, with distinct appearances on angiography. They are associated with incomplete segmental development. The vasa vasorum of the internal carotid artery are rarely seen unless enlarged in pathological situations. They represent a peculiar segmental, in-situ, collateral circulation. Retes, on the other hand, correspond to a more complex reconstitution of an early segmental regression. Careful analysis of each of these features is required to choose the best appropriate terminology. The purpose of this paper is to report illustrative cases to enhance the distinctive features of each disposition.

Figure 1

Vertebral subtraction angiogram shows slit-like vertebral fenestration at the level of the third and fourth cervical spaces (arrows).

Figure 2

A) Right internal carotid injection lateral projection and B) MRA source image at the corresponding level show fenestration of the right cervical ICA. The two lumens shown on angiography (arrow) are seen to lie within the same vascular structure (double arrow).

Figure

3 3D vertebral angiogram shows duplication of the vertebral artery at the craniocervical junction. One of the vessels takes a subarachnoid course (double arrow), the other remaining extradural (arrow).

Figure 4

A) Axial T2 weighted MRI reveals large right-sided vagal tumour (arrows) supplied by artery shown on B) 3D angiography, arising from the proximal petrous segment of the ICA.

Figure 5

Left internal carotid subtraction angiogram A) lateral and B) frontal projections. There is segmental agenesis of the clinoid and terminal portions of the ICA with rete mirabile reconstitution of the distal flow.

Figure 6

A) Right ICA angiogram shows an enlarged fusion type of ACA at the anterior communicating artery complex (arrow), with associated infra-optic course of the right A1 segment. B) Right ICA angiogram shows an accessory MCA, often called the "duplicated" MCA, which corresponds to an enlarged Heubner artery sharing the cortical territory. C) Left VA angiogram shows a short left PcomA with early branching into P1 and P2, giving "pseudo-duplicated" appearance (arrow). D) Enlarged perforator anastomosis (arrow) at the proximal M1 segment shown on right ICA angiogram and E) similar disposition of perforator anastomosis at the basilar tip.

Figure 7

A) Common carotid angiogram shows carotid branch of the ascending pharyngeal artery within the carotid canal, anastomosing with the recurrent artery of the foramen lacerum (arrows). B) Schematic representation.