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.
