Stents and Stent Mimickers in Endovascular Management of Wide-neck Intracranial Aneurysms

Abstract

Subarachnoid hemorrhage due to a ruptured cerebral aneurysm is a disastrous event accounting for approximately 5%-15% of all stroke cases and has a high mortality rate. One of the major goals in the management of these patients is to prevent rebleeding by securing the aneurysm either surgically or by endovascular means. Endovascular treatment is considered the first line of treatment for intracranial aneurysms; however, wide-neck aneurysms (WNAs) are specifically difficult to treat by endovascular means due to the difficulty in achieving a stable coil mass inside the aneurysm sac. To overcome this problem, assisted endovascular treatment techniques and devices have evolved over the years. Amongst these, stent-assisted coiling (SAC) techniques provide a scaffold for coil embolization. The concept of the stent-assisted technique inspired creative pioneers to invent new tools like the PulseRider (Pulsar Vascular, Inc. CA, USA) and the pCONUS (Phenox GmbH, Germany), which are a great help in managing wide-neck and bifurcation aneurysms. The concept of stent within stents and its related hemodynamic effect has led to the novel development of flow diverters for reconstructing the arterial wall and correcting the hemodynamic disturbances. In this article, we review the stents and stent-like devices currently in practice for the endovascular management of wide-neck and branch intracranial aneurysms.

Keywords: coiling; endovascular; endovascular coiling; flow diversion; stent assisted; stent-assisted coiling; wide neck aneurysm.

Figure 1. Balloon and stent-assisted coiling for anterior communicating artery aneurism (AcomA)

A: Balloon remodeling performed using a double lumen occlusion balloon (Eclipse 2L, Balt Extrusion, Montmorency, France) and coiling done using an Echelon 10 microcatheter (Microvention, CA, USA) with an Avigo 0.14 wire. Coiling of anterior communicating artery aneurysm with balloon protection. B: The balloon is deflated (thick arrow) to assess coil mass movement. A loop of coil (thin arrow) can be seen protruding into the parent vessel after balloon deflation. C: Non-subtracted image showing a 2.5 mm × 18 mm Leo Baby Stent (Balt Extrusion, Montmorency, France) deployed (marked by arrows) across the aneurysm neck compressing the prolapsed coil against the arterial wall maintaining vessel patency. D: Post coiling and stent placement angiogram shows exclusion of aneurysm and patent parent artery.

Figure 2. Y-stenting technique for the treatment of a wide-neck aneurysm located at the tip of the basilar artery

A-B: Vertebral angiogram showing a large lobulated irregular shaped basilar tip aneurysm with both P1 segments of the posterior cerebral artery (PCA) incorporated within the aneurysm sac. C-D: Arrows pointing to stents placed in bilateral P1 segments of PCAs. The Y-stenting was performed using an Enterprise stent (Codman Neuro, MA, USA) on the right and a Neuroform stent (Stryker, MI, USA) on the left. Catheterization of the aneurysm was performed through the struts of the stents (not shown). Good visualization of the Neuroform markers (arrow in C) is observed. E-F: Post embolization anterior-posterior (AP) and lateral (LAT) angiograms of the basilar artery show exclusion of remnant at the neck.

Figure 3. Waffle cone technique

Schematic diagram showing stent deployed in the aneurysm neck to provide support. The proximal part of the stent remains in the parent vessel, while coiling is performed through the flared distal end.

Figure 4. pCONus - a stent-mimicking, nitinol-based laser-cut device

Figure 5. The pCONus device for the treatment of an aneurysm of the anterior communicating artery (AcomA)

A: Anterior-posterior (AP) view of the left internal carotid artery (ICA) showing a saccular shaped wide-neck anterior communicating artery (AcomA) aneurysm. B-C: Oblique view of the left ICA showing pCONus in place within the aneurysm. Device markers can be seen as radiopaque dots marked by three circles. The extra-aneurysmal portion of the pCONus is not well visualized. D: Post coiling angiogram shows exclusion of the aneurysm.

Figure 6. The PulseRider

Modified from [24].

Figure 7. The barrel stent

Modified from [25].

Figure 8. The barrel stent

A: Oblique view of the left internal carotid artery (ICA) showing a wide-neck lobulated saccular aneurysm. B: Microcatheter in place (arrow). The tip of the microcatheter can be seen in the aneurysm sac as a black dot. C-D: The barrel stent is in place extending from the A1 to the A2 segment of the anterior communicating artery (AcomA) centered at the aneurysm neck. The stent is marked by circles in D. E: Immediate angiographic result showing exclusion of the aneurysm with the patent parent vessel. F: Six-month follow-up shows stable condition with no evidence of recurrence.

Figure 9. A flow diverter stent for the treatment of an anterior communicating artery (AcomA) aneurysm

A: Multiple intensity projection image of the left internal carotid artery (ICA) showing a wide-neck anterior communicating artery (AcomA) aneurysm (arrow). B: 3D angiographic image showing multiple fundal nipples, likely site of rupture in this aneurysm. C: Coiling performed as an emergency procedure to prevent rebleed. D: A seven-month follow-up angiogram shows persistent filling of the aneurysm at its neck (arrows). E-F: A flow diverter (SILK, Balt Extrusion, Montmorency, France) was placed extending from the A1 to the A2 segment of the AcomA across the aneurysm neck. The distal access wire is marked by the arrow head. Flow diverter - arrows in E and F. G: Reduced hemodynamic interchange between the aneurysm and the parent artery with optimal parent artery reconstruction as seen on the final angiogram.