Efficacy and current limitations of intravascular stents for intracranial internal carotid, vertebral, and basilar artery aneurysms

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Object. Results of previous in vitro and in vivo experimental studies have suggested that placement of a porous stent within the parent artery across the aneurysm neck may hemodynamically uncouple the aneurysm from the parent vessel, leading to thrombosis of the aneurysm. For complex wide-necked aneurysms, a stent may also aid packing of the aneurysm with Guglielmi detachable coils (GDCs) by acting as a rigid scaffold that prevents coil herniation into the parent vessel. Recently, improved stent system delivery technology has allowed access to the tortuous vascular segments of the intracranial system. The authors report here on the use of intracranial stents to treat aneurysms involving different segments of the internal carotid artery (ICA), the vertebral artery (VA), and the basilar artery (BA).

Methods. Ten patients with intracranial aneurysms located at ICA segments (one petrous, two cavernous, and three paraclinoid aneurysms), the VA proximal to the posterior inferior cerebellar artery origin (one aneurysm), or the BA trunk (three aneurysms) were treated since January 1998. In eight patients, stent placement across the aneurysm neck was followed (immediately in four patients and at a separate procedure in the remaining four) by coil placement in the aneurysm, accomplished via a microcatheter through the stent mesh. In two patients, wide-necked aneurysms (one partially thrombosed BA trunk aneurysm and one paraclinoid segment aneurysm) were treated solely by stent placement; coil placement may follow later if necessary.

No permanent periprocedural complications occurred and, at follow-up examination, no patient was found to have suffered symptoms referable to aneurysm growth or thromboembolic complications. Greater than 90% aneurysm occlusion was achieved in the eight patients treated by stent and coil placement as demonstrated on immediate postprocedural angiograms. Follow-up angiographic studies performed in six patients at least 3 months later (range 3–14 months) revealed only one incident of in-stent stenosis. In the four patients originally treated solely by stent placement, no evidence of aneurysm thrombosis was observed either immediately postprocedure or on follow-up angiographic studies performed 24 hours (two patients), 48 hours, and 3 months later, respectively.

Conclusions. A new generation of flexible stents can be used to treat complex aneurysms in difficult-to-access areas such as the proximal intracranial segments of the ICA, the VA, or the BA trunk. The stent allows tight coil packing even in the presence of a wide-necked, irregularly shaped aneurysm and may provide an endoluminal matrix for endothelial growth. Although convincing experimental evidence suggests that stent placement across the aneurysm neck may by itself promote intraluminal thrombosis, the role of this phenomenon in clinical practice may be limited at present by the high porosity of currently available stents.

Article Information

Address reprint requests to: L. Nelson Hopkins, M.D., Department of Neurosurgery, 3 Gates Circle, Buffalo, New York 14209–1194.

© AANS, except where prohibited by US copyright law.

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Figures

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    Case 1. Left: Digital subtraction angiogram, lateral projection, obtained 6 months after stent and coil placement in a pseudoaneurysm of the petrous portion of the ICA. There is evidence of coil compaction but no stenosis within the stented segment (arrows). Right: No changes are observed in the repeated follow-up angiographic study, lateral projection, 14 months after treatment.

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    Case 2. Upper Left: Digital subtraction angiogram, anteroposterior (AP) projection, revealing a giant aneurysm at the junction of the petrous and cavernous portions of the ICA. An intravascular balloon-expandable stent (AVE GFX coronary stent) mounted on its delivery system (arrows) is being navigated across the neck of the aneurysm. Upper Center: Plain x-ray film obtained after stent and coil placement in the aneurysm clearly showing that the coils are on each side of the stent (arrows) at the point at which the neck of the redundant aneurysm surrounds the parent vessel. The stent thus acts as a rigid endoluminal scaffold that allows for the relatively tight packing of this wide-necked, irregularly shaped aneurysm. Upper Right: Digital subtraction angiogram, oblique projection with right ICA injection, obtained after stent placement and GDC deployment, revealing a dense coil mass within the aneurysm. In this projection, it appears that the coil loops are herniating within the parent vessel (arrows). However, as shown in upper center, this effect is related to the presence of coils wrapping around the stent at the base of this irregularly shaped aneurysm. Lower Left and Right: Digital subtraction angiograms, lateral (lower left) and oblique (lower right) projections, demonstrating a stable coil mass and no evidence of in-stent stenosis 10 months later.

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    Case 4. Digital subtraction angiograms, right VA injection, AP view. A: Wide-necked pseudoaneurysm of the VA. The GDCs that had been placed 2 years earlier are compacted at the top of the dome. B: Following placement of an intravascular stent, the coils are detached within the aneurysm. C: The intravascular stent allows satisfactory packing of the aneurysm despite the wide neck and the irregular aneurysm geometry that are unfavorable to GDC treatment alone.

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    Case 4. Digital subtraction angiograms, right VA injection, AP view obtained at the 5-month follow-up examination. a: There is persistent aneurysm obliteration and mild-to-moderate instent stenosis, but good flow distal to the stenosed segment. b: Close-up view of image in a, demonstrating presence of stenosis (arrows) within the stented segment.

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    Case 5. Upper Left: Magnetic resonance T2-weighted image demonstrating a mass in the ventral pons with intraluminal flow voids consistent with an aneurysm. Upper Center and Upper Right: Digital subtraction angiograms, lateral (upper center) and AP (upper right) projections demonstrating a giant aneurysm arising from the BA trunk. Lower Left: Plain skull x-ray film, lateral view. An intravascular stent is in place (arrow). The stent allows tight packing of this giant irregularly shaped aneurysm. Lower Center: Coils fill the aneurysm on each side of the stent (arrows). Lower Right: Digital subtraction angiogram, right VA injection, lateral view. Final result after stent placement and deployment of 22 GDCs: satisfactory aneurysm obliteration and excellent distal flow with even filling of the anterior circulation.

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    Case 5. Five-month follow-up digital subtraction angiogram, lateral projection, demonstrating mild aneurysm recanalization with no evidence of aneurysm growth.

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    Case 7. Left: Digital subtraction angiogram, lateral projection with left common CA injection, revealing a wide-necked intracavernous aneurysm. Right: Plain skull x-ray film, lateral projection, demonstrating the presence of a coil mass. An intravascular stent (arrows) “adapts” to the natural curvature of the vessel.

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    Case 7. Rotational follow-up angiogram, left ICA injection, multiple projections (a–c) demonstrating persistent aneurysm obliteration and no evidence of in-stent stenosis 3 months posttreatment.

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