Anterior Communicating Artery Aneurysms: Anatomical Considerations and Microsurgical Strategies

Abstract

Anterior communicating artery aneurysms account for 23-40% of ruptured intracranial aneurysms and 12-15% of unruptured aneurysms and are the most common intracranial ruptured or unruptured aneurysms. Because they have relatively complex anatomical structures and anatomical variations and are adjacent to important blood vessels and structures, in the process of microsurgical exposure of an Anterior communicating artery aneurysm, attention should be paid not only to the anatomical characteristics of the aneurysm itself but also to the adjacent important blood vessels and perforating arteries; therefore, both surgical clipping and endovascular embolization are serious challenges for neurosurgeons. No matter which treatment is chosen, it is necessary to determine the structure of the Anterior communicating artery and its perforating arteries as well as whether there is a fenestration deformity of the Anterior communicating artery and the relationship between bilateral A1-A2 before surgery. The shape and size of the aneurysm itself and its location relative to adjacent blood vessels also need to be considered to better complete the procedure, and this is especially true for microsurgical clipping. Clarifying the anatomy before surgery is helpful for better selecting the surgical approach and surgical side, which could affect the intraoperative exposure of the aneurysm and adjacent arteries, the surgical difficulty, the resection rate, and the postoperative complications. Therefore, starting with Anterior communicating artery aneurysms and their adjacent structures and variations, this paper reviews the latest progress in surgical treatment based on anatomic specificity as well as the most recent clinical studies.

Keywords: AcoA aneurysm; anatomical; clipping; coiling; microsurgical strategies; surgical strategy.

Figure 1

Several common AcoAs. (A,B). Right A1 hypoplasia; (C) Duplicated AcoAs; (D) Right A1 segment fenestration; (E) AcoA fenestration deformity; (F) Absence of the AcoA. (1) AcoA; (2) A2 segment of the ACA; (3) A1 segment of the ACA; (4) MCA; (5) ICA; (6) Basilar artery; (7) recurrent artery of Heubner.

Figure 2

The relationship between the AcoA and bilateral A1. Different cases showed different relationships and locations for AcoA and bilateral A1.

Figure 3

Common types of the recurrent artery of Heubner. (A) 2-branch recurrent artery (4 in Figure); (B) 3-branch recurrent artery (4 in Figure); (C) 4-branch recurrent artery (4 in Figure). (1) ICA; (2) Optic chiasma; (3) A1 segment of the ACA; (4) recurrent artery of Heubner. (5) AcoA; (6) A2 segment of the ACA; (7) Median callosal artery; (8) Frontopolar artery.

Figure 4

Relationship between the AcoA and perforating branch vessels (start from the posterior, superior, and inferior wall). (A) (1) Right A1 segment; (2) AcoA; (3) Right A2 segment; (4) Left A2 segment; (5) Median callosal artery; (6) Left A1 segment; (7/8) Left recurrent artery; (9) Frontopolar artery; (10) Perforating artery of the hypothalamus. (B) (1) Left internal carotid artery; (2) Left middle cerebral artery; (3) Left A1 segment; (4) Optic chiasm; (5) AcoA; (6/7/8) Left 3 recurrent arteries; (9) Subcallosal artery; (10) Left A2 segment; (11) Right medial frontobasal artery; (12) Right recurrent artery; (13) Right A2 segment; (14) Hypothalamic branches.

Figure 5

Supraorbital lateral-longitudinal fissure approach to the AcoA. (A) Midline and scalp incision; (B) To identify key holes and identify bone windows; (C) Exposing the beginning of the A1 segment of the anterior cerebral artery at the lateral orbit; (D) Exposing the whole process of the A1 segment of the anterior cerebral artery; (E) Separating the longitudinal fissure and exposing the A1 segment of the anterior cerebral artery; (F) Exposing the anterior communicating artery complex; (G) Exposing the beginning of the A1 segment of the anterior cerebral artery at the lateral orbit during a real surgery; (H) Exposing the whole process of the A1 segment of the anterior cerebral artery during a real surgery; (I) Raising the frontal lobe next to the midline, exposing and separating the olfactory bundle. (1) key hole; (2) temporalis muscle; (3) superior temporal line; (4) superficial temporal artery; (5) temporal lobe; (6) MCA; (7) beginning of the A1 segment of the ACA; (8) ICA; (9) oculomotor nerve; (10) optic nerve; (11) optic chiasma; (12) A1 segment of the ACA; (13) base of the frontal lobe; (14) anterior cistern of the optic chiasma; (15) recurrent artery; (16) A2 segment of the AcoA; (17) cerebral falx; (18) medial frontal lobe; (19) gyri rectus; (20) olfactory bundle; (21) anterior cranial fossa; (22) AcoA.

Figure 6

Longitudinal fissure pterion surgical approach. A patient with ruptured multiple intracranial aneurysms and hemorrhage (Hunt-Hess grade IV). (A) CTA revealed a left posterior communicating artery aneurysm and an AcoA aneurysm. Lateral view showed a posteriorly projecting AcoA aneurysm and the left A2 posterior to the right A2 (indicated by the red arrow). The left longitudinal fissure pterional approach was selected for surgery. (B) Surgical incision and patient positioning. (C) Postoperative three-dimensional CT reconstruction indicated the size and location of the surgical bone window. (D) Postoperative CTA revealed complete clipping of the AcoA aneurysm and the left posterior communicating artery aneurysm, with no remnants and good vessel protection.

Figure 7

Selection of the operative side based on the anteroposterior relationship of the bilateral A2. (A) DSA after spontaneous subarachnoid hemorrhage showed superiorly projecting microanterior communicating aneurysms, the left A2 located anterior to the right A2, and the left side as the closed side; the right side should be selected as the operative side; (B) CTA examination after spontaneous subarachnoid hemorrhage showed a superiorly projecting AcoA aneurysm, the left A2 posterior to the right A2, and the left side as the open side; the left side should be selected as the operative side.