Complex foetal Pcom aneurysm - Ep.1/3

The Achilles' Heel of Flow Diverter Stents: Complex Fetal Posterior Communicating Artery

Aneurysm

This is a 57-year-old female patient who had an incidentally discovered bilobular-shaped Posterior communicating artery (Pom) aneurysm measuring 8-9 mm. The aneurysm is located at the origin of the Pcom, and the patient was verified to have a fetal Pcom.

Fetal Pcom: How can we prove it?

Do a vertebral run and observe the non-existent or very hypoplastic P1 segment.

Management:

For clipping, especially for larger fetal Pcom aneurysms, the relationship with the Anterior Choroidal Artery is critically important. Commonly, the sac/lobes of the aneurysm adhere to the anterior choroidal arteries. Microsurgically, this presents an additional risk to consider.

For an endovascular approach: Fetal Pcom aneurysms are one Achilles' heel of flow diverter (FD) stents due to increased inflow through the fetal Pcom, which prevents the endothelialization of the FDs, causing aneurysm to fill despite flow diversion. In their study of 49 Pcom aneurysms managed with FDs, Rinaldo et al. found that the presence of fetal Pcom variation significantly lowered the complete occlusion rate (43.7% vs. 81.8%). Additionally, the median time to occlusion was also significantly higher in the fetal Pcom group.' Baranoski et al., in their fetal Pcom aneurysm series, undersized the FD and compacted it on the neck of the aneurysm to increase the metal coverage of the neck. They achieved better results compared to previous studies, with a 75% (12 out of 16 complete or near-complete occlusion rate at the last follow-up.? Many FD series employ only a single standalone FD. Utilizing more than one FD might enhance flow diversion, potentially leading to complete occlusion of fetal Pcom aneurysms. Nevertheless, opinions among faculty vary regarding this approach: while it may not be cost-effective, there are also concerns about its safety.

The virtual FD treatment simulation for this aneurysm confirmed that the aneurysm is located on the external side of the curve, meaning there will be less metal coverage. Maneuvers like those described by Baranoski et al? may be necessary to increase the metal coverage on the side of the aneurysm, especially at the level of the neck. However, it should be considered that such manipulations can result in shortening the stent. This will affect the length of the device, and selecting an appropriate length device to cover the lesion should be taken into consideration.

What would be the faculty's treatment approach?

The majority of the faculty were in favor of coiling, whether with the assistance of a balloon or stent, followed by stent deployment after the coiling. The proximal landing zone of the stent varied among faculty members; some preferred extending the stent a few millimeters into the carotid artery, while others recommended ending the stent at the origin of the Pcom. Additionally, suggestions for the type of stent varied among the faculty, with preferences divided between braided and laser-cut stents.

Differently from the rest of the faculty, Pr. Berenstein favored Woven EndoBridge (WEB, Microvention) embolization followed by FD deployment to the carotid. Additionally, he suggested Nautilus (EndoStream Medical) device-assisted coiling as another option. Meanwhile, Pr. Cekirge advocated for  FD treatment.     

Demonstrated treatment approaches by faculty:

In Room B, the demonstrated treatment approach by Pr. Holtmanspötter involves balloon-assisted coiling followed by LVIS Evo (Micro Vention) stent deployment. The stent is deployed starting distal to the aneurysm, covers the neck of the aneurysm, and extends 1-2 mm into the carotid artery. Pr.

Holtmanspötter prefers to protrude the stent into the carotid artery, aiming to achieve better durability.

Treatment scoring by faculty

• Safety / Reproducibility / Durability / Artistic (elegance of the treatment): 7.98 out of 10

In Room A, the demonstrated treatment approach by Pr. Patankar involves Contour device (Crus Endovascular) implantation. Considering the bilobulated shape of the aneurysm, Pr. Patankar chose a 7 mm device in order to achieve better device positioning.

Treatment scoring by faculty

• Safety / Reproducibility / Durability / Artistic (elegance of the treatment): 7.77 out of 10

References

1- Rinaldo L, Brinjikji W, Cloft H, et al. Effect of Fetal Posterior Circulation on Efficacy of Flow Diversion for Treatment of Posterior Communicating Artery Aneurysms: A Multi-Institutional Study. World Neurosurg. 2019;127:1232-e1236. doi:10.1016/j.wneu.2019.04.112

2- Baranoski JF, Merrill S, Rutledge C, et al. Flow-Diversion for Complex Posterior Communicating Artery Aneurysms Associated With a Fetal Posterior Circulation. Stroke Vasc Interv Neurol. 2022;2:000134. Available from: https://doi.org/10.1161/SVIN.121.000134