Stent-Assisted Embolization of Cerebral Aneurysms

D.V. Svistov, D.V. Kandyba, A.V. Savello

(Faculty and Clinic of Neurosurgery, Medicomilitary Academy, Saint Petersburg)

The study goal was to estimate the first experience of stent-assisted combined embolization of cerebral aneurysms.

Materials and Methods. There were 18 patients with cerebral aneurysms, operated in the Radiosurgical Department of the Clinic of Neurosurgery in June-December of 2004. Intravascular stents were used in 8 cases. Fusiform aneurysms of the basilar (1) and left vertebral (1) arteries were watched in 2 of them; 6 patients had wide-neck saccular aneurysms. Three cases had underwent subtotal embolization of aneurysms with MDS microcoils (BALT) before; it resulted in a growth of aneurysm (2) or dilation of a parent artery (1). Primary operations were performed in 3 patients. Aneurysms of the left ICA were present in 3 cases (an ophthalmic segment – 1, a supraclinoid segment - 2). Besides, there were aneurysms of the main trunk of the basilar artery (1), of the left posterior cerebral artery (1), bifurcation of the basilar artery (1). A neck size and a dome-neck ratio of a filled part of saccular aneurysms were as follows: bifurcation of the basilar artery – 12 mm/2:1, the basilar artery – 6 mm/1:1, ICA – 8 mm/0.6:1, ICA – 5 mm/1:1, ICA – 6 mm/1:1, PCA – 10 mm/2:1. Fusiform aneurysms had the following size (length/diameter in mm): the basilar artery – 45/12, the vertebral artery – 32/10. The difference between a method, used by us, and a conventional intervention lay in preliminary implantation of the LEO (BALT) or Neuroform2 (Boston Scientific) self-expanding stents into an aneurysm neck (5 cases); then a microcatheter was inserted into an aneurysm cavity via the stent cell and detachable microcoils were implanted (DCS – 2cases , Balt Pression – 2 cases, Matrix – 1 case). Implantation of a stent into a communicating segment of the posterior cerebral artery followed subtotal embolization of big aneurysm in 1 patient. In fusiform aneurysms a stent was introduced into a dilation area and stent-in-stent implantation was used with the purpose of isolating an arterial wall.

Results. Stent implantation in operations for fusiform aneurysms was successful in all cases. Aneurysm catheterization via a stent network did not cause considerable difficulties and had no effect on operation duration. Use of stents allowed to exclude aneurysm from blood flow in all patients. An effect was achieved during intervention in 3 cases. It was delayed in 2 patients (watched during control angiographic examination 24 hour after operation). It was caused by progressive thrombosing of aneurysm (1) or a parent artery (1). Stent presence permitted to embolize an aneurysm neck by coils, whose diameter was 2-3 times smaller, than a neck’s angiographic diameter. For example, aneurysm of the ICA ophthalmic segment with a neck of 6 mm was embolized by Matrix coils with a diameter of 2 mm.

In fusiform aneurysms we implanted two stents into a dilation area. We met with certain technical difficulties, while conducting a microcatheter and a microguide through an aneurysm cavity in primary catheterization and in repeated introduction of a microguide via a stent. In both cases it led to crumpling of the 1/4 of the stent’s proximal part, which had no impact on its patency.

Complications were watched in 3 patients, but they did not effect a favorable outcome (mRS=0-7 in all cases; mRS=2-1).

Conclusion. Use of special self-expanding stents makes it possible to perform reconstructive intravascular interventions for intracranial aneurysms with complicated anatomy. A high rate of thromboembolic complications in stent implantation determines necessity of preoperative use of thrombocyte aggregation inhibitors, total heparinization during operation, postoperative use of antiaggregants and low-molecular heparins.