A1–A2 Fenestration Tube Technique for Clipping a Ruptured Anterior Communicating Artery Aneurysm

Abstract

A fenestration tube is a clipping reconstruction technique that allows the preservation of critical vessels in aneurysm surgery. A patient with a ruptured anterior communicating artery (ACoA) aneurysm with a posterior projection was admitted to our neurosurgery unit. A right dominant A1 with rotation of the A2 fork was observed on preoperative computed tomography angiography (CTA). During surgery, we observed that the recurrent artery of Heubner branched off the A2 just distal to the neck of the aneurysm. Successful clipping was achieved by building an “A1–A2 fenestration tube,” with preservation of the recurrent artery and of the ACoA perforators. Surgical nuances and the advantages of fenestration tubes are discussed.

Resumo

O tubo de fenestração é uma técnica de clipagem e reconstrução que permite a preservação de vasos críticos na cirurgia de aneurismas. Um paciente com um aneurisma da artéria comunicante anterior (ACoA) rompido com projeção posterior foi admitido em nosso serviço. A dominante direita A1 com rotação do garfo A2 foi observada na angiografia por tomografia computadorizada (ATC). Durante a cirurgia, a artéria recorrente foi observada ramificando-se a A2 apenas distal ao colo do aneurisma. Uma clipagem bem-sucedida foi alcançada criando um tubo de fenestração “A1–A2,” com preservação da artéria recorrente e dos perfurantes da ACoA. Nuances cirúrgicas e as vantagens dos tubos de fenestração são discutidas.

Keywords

intracranial aneurysm - anterior communicating artery - microsurgery

Palavras-chave

aneurisma intracraniano - artéria comunicante anterior - microcirurgia

Introduction

Stacking multiple fenestrated clips creates a fenestration tube.[1] This clipping technique allows reconstruction of complex aneurysms while preserving vascular structures. A critical aspect of anterior communicating artery (ACoA) aneurysm surgery is preservation of the multiple arteries and perforators that are related to the ACoA complex.[2] The recurrent artery of Heubner arises from the proximal A2 segment in most cases (58%), and its compromise or occlusion is associated with mediobasal striatum infarction and severe neurological deficits.[3] The surgeon must consider A1 dominance pattern,[4] projection of the dome of the aneurysm, ACoA angle,[5] and rotation of the A2 fork[6] when planning treatment strategy.[7] Aneurysms that project posteriorly with medial rotation of the dome of the aneurysm and of the A2 fork are a challenge because the neck of the aneurysm is hidden and perforators may be in the way of a potential clip.

Case

A 69–year-old patient was admitted to our center with subarachnoid hemorrhage (World Federation of Neurosurgical Societies [WFNS] scale of 1). A computed tomography angiography (CTA) revealed a 4.1mm × 9.5mm ruptured ACoA aneurysm with posterior projection, right A1 dominance and rotation of the ACoA complex, with medial shift of the dome of the aneurysm ([Fig. 1]). Surgical treatment was indicated.

Fig. 1 Preoperative computed tomography angiography.

Surgical Technique

Under general anesthesia, the patient was placed on a Mayfield skull clamp, with 20° of head extension and 30° of contralateral rotation. A pterional approach was performed from the right side, with interfascial dissection of the temporalis muscle. The orbital roof was flattened with a cutting burr, to increase the angle of view. Under the surgical microscope, initial arachnoidal dissection of the optic and carotid cisterns ([Fig. 2A]) allowed the exposure of the optic nerve and of the internal carotid artery. Blood clot cleansing with saline revealed the carotid bifurcation and ipsilateral A1. Following this artery, we identified the optic chiasm and ACoA complex ([Fig. 2B]). Lamina terminalis fenestration[8] and opening of Liliequist membrane allowed release of cerebrospinal fluid (CSF). Partial gyrus rectus resection[9] was necessary to expose the bilateral A2. The origin of the recurrent artery of Heubner was localized at the proximal A2. A retractor was placed under the medial frontal lobe with gentle traction. Transitory clipping of both A1 arteries (< 5 minutes of total ischemia time) was performed ([Fig. 2C]), and dissection of the aneurysm neck extended medially to the ipsilateral A1–A2 junction ([Fig. 2D]). Under direct visualization of the recurrent artery ([Fig. 2E]), a fenestration tube was completed with two 4 mm length Yaşargil aneurysm fenestrated clips (Aesculap AG & Co., Tuttlingen, Germany) over the A2, and two 6 mm length fenestrated clips over the A1 ([Fig. 2E]). Microdoppler sonography Mizuho Surgical Probe (Mizuho Inc., Tokyo, Japan) confirmed flow on both A2s, and absence of flow in the aneurysm sac.

Fig. 2 Surgical technique.

A postoperative cerebral angiography confirmed the exclusion of the aneurysm from circulation ([Fig. 3]), and patency of the arteries of the ACoA complex. The patient had a favorable outcome and was discharged with a Glasgow outcome scale of 5, three weeks after the surgery.

Fig. 3 Postoperative angiography.

Discussion

Drake was the first to introduce the use of fenestrated clips[10] in aneurysm surgery in 1969. By stacking multiple clips together, the surgeon can create a fenestration tube. This clipping technique allows treatment of complex aneurysms while preserving critical branches and perforators. In ACoA aneurysm surgery, traditional clipping with straight or curved clips may limit surgical exposure because the head of the clip and the artery to be protected are in the way of the line of sight of the surgeon; fenestrated clips are located instead “on top” of the artery, so the exposure is preserved, and less dissection of branches from the aneurysm is needed.[11] This way, fenestration tubes allow the surgeon the goal of aneurysm exclusion in a more precise and anatomical fashion. Another advantage of fenestration tubes is the increased closing force of multiple clips that allow treatment of giant atherosclerotic or calcified aneurysms,[12] but great care must be taken to avoid neck tears.

In our case, a right side approach was chosen because the right A1 was dominant. After exposure of the aneurysm, the recurrent artery of Heubner was observed branching just distal to the neck of the aneurysm, at the lateral side of the A2. Fenestrated clips were applied under direct visualization of the recurrent artery, distally from A2 to A1. There were no complications, and exclusion of the aneurysm was possible, maintaining patency in all vessels.

The disadvantages of this technique are the increased number of clips used, and increased clipping time (but less time required to dissect vessels). In cases in which parent artery or branch sacrifice is inevitable, bypass techniques[13] should be considered.

Overall, we believe that fenestration tube is a valuable technique in the surgeon’s armamentarium, and offers advantages over traditional clipping in ACoA aneurysm surgery.

Conclusion

The A1–A2 fenestration tube is a valuable clipping technique in ACoA aneurysm surgery.

Conflicts of Interests

The authors have no conflicts of interests to declare.

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