Deconstructive and reconstructive therapy - SLICE Next Frontiers 2023 - Marie-Claire SETTECHAU

Deconstructive and reconstructive therapy options for a giant saccular V4 aneurysm

The presented case is a 65-year-old female patient with two unexplained fainting episodes in the last week. The patient is a smoker and also has dyslipidemia and ischemic cardiomyopathy. Diagnostic workup showed a large saccular V4 segment aneurysm. The patient is in front of us, asking for help!

The first crucial step is determining whether this patient needs to be hospitalized due to the immediate risk of rupture. We are facing a giant aneurysm with a small neck at the V4 segment of the left vertebral artery. Considering the location of the aneurysm, related fainting attacks may suggest the instability of the aneurysm by moving and pressing the adjacent structures. Also, considering the patient's demographics and risk factors, we see that this aneurysm carries a high risk of rupture. So we better hospitalize this patient to make faster the preoperative evaluation to treat the patient in a shorter time.

Some clinical and morphological findings of an aneurysm -even in the patients who came to us by walking- should alert us to the imminent rupture. For example;

• Acute third cranial nerve palsy due mass effect of aneurysm

• Large-sized saccular aneurysms with small neck

• Aneurysms located in the posterior circulation

• Aneurysms that have irregular contours

The second crucial step is determining the best treatment strategy for this aneurysm. Two main endovascular treatment options for giant aneurysms are deconstructive and reconstructive techniques. The deconstructive approach sacrifices the parent artery (PAO) that contains the aneurysm. In contrast, the major reconstructive choices for this aneurysm are flow diversion alone (FD), primary coiling (PC), and stent-assisted coiling (SAC).

Reconstructive techniques should be the first strategies to evaluate because sacrificing an artery is not good, and as a rule, we should do everything to preserve the artery. FD alone is an option here, but FDs divert the flow, not the pressure. Conversely, stagnation of flow may increase the pressure in the aneurysm. With the combination of intra-aneurysmal thrombus formation and anti-aggregation therapy effect, FD alone might create delayed rupture risk [1]. 

Although SAC with FD or other types of stents might allow us to embolize the sac with coils, achieving complete embolization with only coils is usually impossible, as in the case presented. For that reason, it also has a risk of delayed rupture. Another reconstructive strategy is staged treatment to prevent delayed rupture. In the first stage, the aneurysmal sac is partially coiled, and a few weeks later, the aneurysm is also treated with FD in the second stage. The main concern of partial PC would be the occluding possibility of the parent artery.

Essential tips for applying a reconstructive strategy for this case:

• Intra-aneurysmal microcatheter looping technique or using an intermediate catheter might help to navigate the microcatheter distal to aneurysmal segment

• Definitely, catheterization and injection of both vertebral arteries are necessary to understand the anatomy during operation for managing this complex case

• Retrograde catheterization of the sac from the contralateral vertebral artery may allow using of a snare for navigating the microcatheter to the distal V4

• Due to acute curve of the artery, new devices like a catheter with a bendable tip "Bendit", and "Chikai black 14" microwire might help to catheterize the outlet of the aneurysm.

Although PAO is a viable option for unruptured complex giant aneurysms to achieve long-term complete occlusion rates, treatment-related morbidity for posterior circulation aneurysms is significantly higher than for anterior circulation aneurysms [2]. As also emphasized in the video, the V4 segment is a perforator-rich area, and losing multiple perforators with the parent artery might explain this difference. Besides that, ischemic complications are also common after PAO, especially when PICA is involved in the embolized segment [3].

Essential tips for applying a deconstructive strategy for this case:

• Status of PCOMs and location of PICA is crucial to evaluate before the procedure

• Distal segment of V4 should be embolized as well to prevent reversal of flow from the

basilar artery and contralateral vertebral artery

• Due to high antegrade flow, delivering the coils from a dual-lumen balloon catheter

enables to stop of the antegrade flow for safe coiling

• Deploying a stent from the aneurysm to the proximal parent artery might allow using the stent as a scaffold for safe segmental coiling

Further reading:

[1] K. Hou et al., “Delayed rupture of intracranial aneurysms after placement of intra-luminal flow diverter,” https://doi.org/10.1177/1971400920953299, vol. 33, no. 6, pp. 451–464, Aug. 2020, doi: 10.1177/1971400920953299.

[2] F. Cagnazzo et al., “Endovascular Treatment of Very Large and Giant Intracranial Aneurysms: Comparison between Reconstructive and Deconstructive Techniques-A Meta-Analysis,” AJNR Am J Neuroradiol, vol. 39, no. 5, pp. 852–858, May 2018, doi: 10.3174/AJNR.A5591.

[3] T. P. Madaelil et al., “Endovascular parent vessel sacrifice in ruptured dissecting vertebral and posterior inferior cerebellar artery aneurysms: clinical outcomes and review of the literature,” J Neurointerv Surg, vol. 8, no. 8, pp. 796–801, Aug. 2016, doi: 10.1136/NEURINTSURG-2015- 011732.