Flow Diversion with Low-Profile Braided Stents for the Treatment of Very Small or Uncoilable Intracranial Aneurysms at or Distal to the Circle of Willis

BACKGROUND AND PURPOSE:The endovascular treatment of aneurysms located at or distal to the circle of Willis and not amenable to coiling remains a challenge. We report our experience with flow-diversion treatment using low-profile braided stents as a stent monotherapy procedure for treating distally located very small or uncoilable aneurysms.MATERIALS AND METHODS:We retrospectively reviewed our data bases to identify patients with aneurysms located at or distal to the circle of Willis who were treated with stent monotherapy using low-profile braided stents. The immediate and follow-up angiographic findings and clinical status of the patients were assessed.RESULTS:Twenty aneurysms in 19 patients were included in the study. The mean size of the aneurysms was 4.7 ± 2.4 mm. Patients were treated via telescopic implantation of 2 stents for 11 aneurysms; single-stent placement was used for the remaining aneurysms. The technical success rate was 95%. We observed a technical complication in 1 case (5.3%) and a late ischemic event in another (5.3%). The final angiographies during a mean follow-up of 14.7 months showed complete aneurysm occlusion in 73.7%. The complete occlusion rate of the aneurysms treated with telescopic stent placement was 81.8%. The modified Rankin scale scores of all patients at the last follow-up were between 0 and 2.CONCLUSIONS:Flow diversion with low-profile braided stents as a stent monotherapy procedure for very small or uncoilable intracranial aneurysms located at or beyond the circle of Willis is a promising, relatively safe, and durable endovascular procedure.

In the past decade, several self-expandable stents dedicated to intracranial use have been introduced to treat wide-neck and complex aneurysms previously not amenable to coiling.^1–4 Stents create a mechanical scaffold, which prevents coil protrusion into the parent artery. In addition to this mechanical scaffolding effect, the implantation of stents also produces hemodynamic and biologic effects in the parent arteries that promote aneurysm occlusion. Stent deployment across the orifice of an aneurysm redirects the blood flow in the parent artery to decrease hemodynamic stress, which facilitates thrombosis in the aneurysmal sac.⁵ Furthermore, stents induce neointimal proliferation in the parent artery, which eventually leads to healing of the aneurysm neck.⁶ The hemodynamic and biologic effects of stents promote the progressive occlusion of partially coiled aneurysms and impede their recanalization.On the basis of the hemodynamic and biologic effects of stents, flow-diversion treatment as a stent monotherapy procedure using conventional stents has been proposed for the endovascular treatment of intracranial aneurysms not amenable to coiling or alternative open surgical procedures.⁷ Flow diversion as a stent monotherapy procedure consists of the implantation of a self-expandable stent or stents across the neck of an aneurysm, without coiling the aneurysm sac. A limited number of previous case series reported the application of stent monotherapy with balloon-expandable or conventional self-expandable stents and focused on the treatment of aneurysms located proximal to the circle of Willis.^7–10Low-profile braided stents have been recently introduced to treat aneurysms located at small-sized, distal parent arteries. Low-profile intracranial stents can be deployed into arteries with diameters between 1.5 and 3.5 mm, and they can be delivered through microcatheters with an internal diameter of 0.0165 inches, which allows easier navigation in small-sized, delicate vessels.¹¹ In this report, we present our experience with flow-diversion treatment as a stent monotherapy procedure for treating very small or uncoilable intracranial aneurysms located at or beyond the circle of Willis using low-profile braided stents. In this retrospective study, we investigated the feasibility, efficacy, and midterm durability of the stent monotherapy procedure with LEO Baby stents (Balt, Montmorency, France).