INTERVENTIONAL NEURORADIOLOGIC THERAPY FOR INTRACRANIAL VASCULAR PATHOLOGY
|This article has been reviewed by the NeuroWiki Editorial Board|
The treatment of vascular disease has undergone a revolution in the past decade. In the past, open surgical techniques were the only treatment modalities available for vascular pathology that resulted in ischemic and hemorrhagic neurological sequelae. Times have changed. Catheter-based treatment modalities have been developed that rival or surpass open surgical techniques for the treatment of these disease entities.
Cerebral revascularization for the treatment of acute ischemic stroke has become a reality within the past 5 years. Site-specific intraarterial (IA) delivery of thrombolytic agents has enabled recanalization of lesions in the anterior, middle, and posterior cerebral arteries. The application of mechanical techniques to disrupt clot have pushed vessel recanalization rates to 85% as a matter of routine. Hemorrhagic complications still diminish the effectiveness of these techniques, yet a reduction in thrombolytic dosing and increased use of mechanical techniques may drive the clinical utility of these techniques forward. The problem we face is not whether but how rapidly recanalization can be achieved – with better education of the public about stroke symptoms (“brain attack”) in order to reduce the time to treatment.
Extracranial and intracranial revascularization for atherosclerotic disease has led the vascular revolution for ischemic cerebrovascular disease. Preliminary results suggest that the use of stents for revascularization of the cervical carotid bifurcation will supplant carotid endarterectomy (CEA) in the future. Multiple clinical trails are underway to compare the efficacy of stent placement to that of CEA. These trials will provide Level 1 evidence within the next few years. Intracranial atherosclerotic disease is being discovered at an alarming rate by the use of noninvasive imaging techniques like magnetic resonance (MR) and computed tomographic (CT) angiography. The application of angioplasty and stent techniques is gaining acceptance. Balloons and stents initially designed for the coronary circulation are being modified for delivery into the tortuous anatomy of the cerebral circulation. As a result, the location and scope of intracranial lesions that can be treated is increasing. Due to the findings of initial trials that have shown high rates of in-stent restenosis, use of drug coatings that inhibit fibrous tissue formation within cerebral vessels after manipulation may pave the way for broad application of these techniques for cerebral ischemia.
The treatment and management of cerebrovascular disease changed dramatically in the decade of the 1990s. Results of the initial clinical trial of the Guglielmi detachable coil (GDC, Boston Scientific Target, Fremont, CA) in 1990 led the way for a lasting and irreversible change in methods for the treatment of ruptured and unruptured intracranial aneurysms worldwide. At some centers, coil occlusion has become first-line therapy for all aneurysms. Initially, only one platinum coil was available. Today, five companies offer products used for endovascular treatment of intracranial aneurysms. More recently, biological modification of the platinum coil platform has been approved by the United States Food and Drug Administration (FDA). Coils with polymer and hydrogel modifications may promote complete aneurysm occlusion by inducing scar formation across the aneurysm neck. Intravascular stents have been used to achieve successful reconstruction of the pathology in the parent vessel adjacent to the aneurysm. Liquid polymers have been delivered directly into aneurysms to provide atraumatic methods for complete aneurysm filling. Level 1 evidence indicative of the effectiveness of aneurysm coiling is being amassed from a comparison of endovascular and open surgical techniques. A paradigm shift for the treatment of ruptured and unruptured aneurysms is on the horizon.
The treatment of cerebral arteriovenous malformations (AVMs) has benefited from catheter-based technology. The use of particles and silk, thread, and muscle fragments as embolic agents has been replaced by liquid polymers and sclerosing agents. Advances in catheter technology have enabled access of distal AVM feeding vessels, thereby enabling safer delivery of these substances. New liquid embolic agents show great promise for complete occlusion of AVMs. The ultimate goal of complete, lasting occlusion of the AVM nidus without the need for adjunctive radiosurgery or resection has thus far not been achieved.
Reprinted with permission from Mohr JP, Choi DW, Grotta JC, Weir B, Wolf PA (eds): STROKE: PATHOPHYSIOLOGY, DIAGNOSIS, AND MANAGEMENT (4th edition), pp. 1475-1520 (chapter 78), Copyright Elsevier 2004. Permission has been granted to reproduce this material in online electronic format for non-exclusive world English rights.