Intravascular stents for intracranial internal carotid and vertebral artery aneurysms: preliminary clinical experience
Results of previous in vitro and in vivo experimental studies have suggested that the 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 the 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 the intracranial stenting of aneurysms involving different segments of the internal carotid artery (ICA) and the vertebral artery (VA). Four patients with intracranial aneurysms located at the petrous, cavernous, and paraclinoid segments of the ICA and at the VA proximal to the origin of the posterior inferior cerebellar artery, respectively, were treated since January 1998. In three of these patients, stent placement across the aneurysm neck was followed by GDC placement, accomplished via a microcatheter through stent mesh. In one patient, the aneurysm was treated solely by stenting. No periprocedural complications were observed, and at follow up, no patient was found to have suffered symptoms referable to aneurysm growth or thromboembolic complications. More than 90% occlusion of the aneurysm was achieved in the three cases treated by stenting and GDC placement. One of these patients underwent 6-month follow-up angiography that did not reveal any in-stent stenosis. In the case treated solely by stent placement, no evidence of aneurysm thrombosis was observed either immediately postprocedure or on follow-up angiography performed 24 hours later. A new generation of flexible stents can be used to treat intracranial aneurysms in difficult-to-access areas such as the proximal intracranial segments of the ICA or the VA. 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.