Endovascular coil occlusion of intracranial aneurysms assisted by a novel self-expandable nitinol microstent (neuroform)

Abstract

Endovascular treatment of wide neck intracranial aneurysms is technically difficult and leads to less favorable treatment results and long term outcome. We participated in a multicenter prospective study to evaluate the safety and performance of a new self-expandable nitinol micro stent (Neuroform) in stent assisted coil occlusion of wide neck intracranial aneurysms. Eighteen patients were enrolled in the study in a single center. The anatomy of the target aneurysm and the parent vessel, technical details of the procedure, device functionality, anatomic and clinical results were evaluated. All enrolled aneurysms were either wide necked or showed an unfavorable neck-to-fundus ratio. In 16 out of 18 patients the Neuroform device allowed stent assisted coil occlusion of the aneurysm. The occlusion rate was 95% in eight patients and 100% in eight patients. The two failures were both due to anatomic reasons. Flexibility of the stent, behavior during deployment and subsequent ability to retain coils within the aneurysmal sac were considered as good as or better than the properties of previous balloon expandable stents. No device-related adverse events were encountered. Procedure-related clinical complications occurred in seven patients but caused no severe permanent neurological deficit. The Neuroform neurovascular stenting system is a safe and effective adjunct for the stent-assisted coil occlusion of wide necked intracranial aneurysms. The major advantages of this device are its self-expanding property and very high flexibility which allows safe navigation, easy sizing, as well as accurate positioning of the stent while providing sufficient bridging of the aneurysm neck for subsequent coil placement.

Figure 1

Schematic drawing of the Neuroform stent device.

Figure 2

Wide-necked, incidental aneurysm of the left A1 segment (A). The aneurysm was bridged with a Neuroform stent and subsequently occluded with coils (B). The unsubtracted image (C) shows the position of the radio-opaque stent markers in the ICA bifurcation and in the A1 segment.

Figure 3

Wide-necked aneurysm of the right MCA bifurcation and a small aneurysm originating from the inferior division of the same vessel (A). Stent deployment from the M1 segment into the inferior division of the MCA and subsequent stent and TriSpan assisted coil occlusion of the MCA bifurcation aneurysm resulted in complete occlusion of the small M2 aneurysm and in subtotal occlusion of the MCA bifurcation aneurysm (B).

Figure 4

Cavernous aneurysm of the right ICA with recurrent filling due to coil packing six years after initial treatment (A). Stent deployment over the aneurysmal neck facilitated significantly the coil occlusion of the aneurysm. Complete occlusion of the aneurysm was possible despite the complex geometrical relationship between aneurysm and parent vessel. Prior endovascular treatments were restricted by the severe tortuosity of the proximal ICA. This vessel was straightened by coaxial placement of two self expanding Carotid Wallstents.