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

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 ane urysms, a stent may also aid packing of the aneurysm with Guglielmi detacha ble coils (GDCs) by acting as a rigid scaffold that prevents coil herniatio n into the parent vessel. Recently, improved stent system delivery technolo gy 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 proxim al to the posterior inferior cerebellar artery origin (one aneurysm), or th e BA trunk (three aneurysms) were treated since January 1998. In eight pati ents, stent placement across the aneurysm neck was followed (immediately in four patients and at a separate procedure in the remaining four) by coil p lacement in the aneurysm, accomplished via a microcatheter through the sten t mesh. In two patients, wide-necked aneurysms (one partially thrombosed BA trunk aneurysm and one paraclinoid segment aneurysm) were treated solely b y stent placement; coil placement may follow later if necessary. No permanent periprocedural complications occurred and, at follow-up examin ation, no patient was found to have suffered symptoms referable to aneurysm growth or thromboembolic complications. Greater than 90% aneurysm occlusio n was achieved in the eight patients treated by stent and coil placement as demonstrated on immediate postprocedural angiograms. Follow-up angiographi c studies performed in six patients st least 3 months later (range 3-14 mon ths) revealed only one incident of in-stent stenosis. In the four patients originally treated solely by stent placement, no evidence of aneurysm throm bosis was observed either immediately postprocedure or on follow-up angiogr aphic studies performed 24 hours (two patients), 48 hours, and 3 months Int er, respectively. Conclusions. A new generation of flexible stents can be used to treat compl ex 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 far endothelial growth. Although conv incing experimental evidence suggests that stent placement across the aneur ysm neck may by itself promote intraluminal thrombosis, the role of this ph enomenon in clinical practice may be limited at present by the high porosit y of currently available stents.