A Review of Robotic Interventional Neuroradiology.

Robotic interventional neuroradiology is an emerging field with the potential to enhance patient safety, reduce occupational hazards, and expand systems of care. Endovascular robots allow the operator to precisely control guidewires and catheters from a lead-shielded cockpit located several feet (or potentially hundreds of miles) from the patient. This has opened up the possibility of expanding telestroke networks to patients without access to life-saving procedures such as stroke thrombectomy and cerebral aneurysm occlusion by highly-experienced physicians. The prototype machines, first developed in the early 2000s, have evolved into machines capable of a broad range of techniques, while incorporating newly automated maneuvers and safety algorithms. In recent years, preliminary clinical research has been published demonstrating the safety and feasibility of the technology in cerebral angiography and intracranial intervention. The next step is to conduct larger, multisite, prospective studies to assess generalizability and, ultimately, improve patient outcomes in neurovascular disease.

Interventional therapy for carotid artery disease using angioplasty and stenting with embolic protection.

Carotid artery angioplasty with stenting (CAS) has emerged as a viable alternative to endarterectomy for the treatment of occlusive vascular disease. Advances in endovascular techniques and the improvement of specialized stents have served to rapidly close the gap with the traditional gold standard surgery. Furthermore, the development of cerebral embolic protection devices has reduced the occurrence of distal embolization of atheromatous material during such interventions and has reduced periprocedural stroke rates considerably. Continued improvements in distal embolic protection have further improved the risk profile of CAS, and increased operator experience with these interventional procedures has also been shown to reduce periprocedural complication rates. Outcomes may continue to improve as more providers gain experience with the evolving endovascular device technology, and several prospective clinical trials are currently investigating the efficacy of CAS with embolization protection versus endarterectomy in different cohorts. This review will survey the background and current literature covering angioplasty and stenting for occlusive disease in the carotid arteries and discuss the current methods employed to prevent distal emboli during intervention.

Lesion stability characteristics outperform degree of stenosis in predicting outcomes following stenting for symptomatic intracranial atherosclerosis.

BACKGROUND: Intracranial atherosclerotic disease (ICAD) causes substantial morbidity and mortality. Treatment decisions have most commonly been driven by the degree of luminal stenosis. This study compares ICAD lesion stability features with percentage stenosis for associations with adverse outcomes following treatment with stents. MATERIALS AND METHODS: Retrospective analysis was performed of prospectively maintained procedure logs. Lesions were classified by symptom type as hypoperfusion, non-hypoperfusion, or indeterminate, and pretreatment asymptomatic intervals were noted. Hypoperfusion lesions and indeterminate or non-hypoperfusion lesions with ≥14 days of asymptomatic interval were classified as stable. Percentage stenosis was calculated and compared against these other symptom features for value in predicting technical complication, ischemic stroke, disability, or death at 90 days and 2 years using univariate and multivariate analysis. RESULTS: 130 lesions were treated in 124 patients. The only statistically significant percent stenosis finding was lesions with 60-99% stenosis were less likely to have technical complications. In univariate analysis, stroke at 2 years was less common with hypoperfusion and stable lesions. In multivariate analysis, only hypoperfusion status was associated with lower stroke rates at 2 years. CONCLUSIONS: Lesion stability features, particularly non-hypoperfusion symptomatology, outperform percentage stenosis in predicting outcomes following treatment of ICAD with stents. Further examination is needed to better classify the natural history of ICAD and more precisely classify lesion stability.

Stent angioplasty for cervical carotid artery stenosis in high-risk symptomatic NASCET-ineligible patients.

BACKGROUND AND PURPOSE: Although the North American Symptomatic Carotid Endarterectomy Trial (NASCET) has shown carotid endarterectomy (CEA) to be protective compared with medical therapy alone, its stringent eligibility criteria excluded patients with severe medical, angiographic, and neurological risk factors. We sought to determine the safety and efficacy of stent angioplasty in this high-risk subset for whom the perioperative morbidity and mortality of surgery are elevated. METHODS: Twenty-eight consecutive symptomatic NASCET-ineligible patients (10 female; median age, 72.2 years) underwent microcatheter-based carotid stent angioplasty. Half of the patients had sustained a previous stroke. Classification of surgical risk by Sundt criteria yielded no patients in grade 1, 3 patients in grade 2 (10.7%), 8 in grade 3 (28.6%), and 17 (60.7%) in grade 4. Stratification of stroke risk for medical therapy according to the European Carotid Surgery Trial (ECST) 5-point score showed 8 patients with a score of 3 (28.6%), 12 with 4 (42.8%), and 8 with 5 (28.6%). Follow-up was obtained in all patients at a median of 14 months. RESULTS: The procedure was technically successful in all cases (100%), with immediate stenosis reduction from a mean of 80.3% to 2.7%. There were no periprocedural deaths, 1 major stroke (3.6%), no minor strokes, and 3 transient ischemic attacks (10.7%). In-hospital complications included 2 nonfatal myocardial infarctions, 1 case of acute renal failure, and 1 groin hematoma requiring transfusion. There were 5 deaths during the follow-up period, all beyond 30 days after the procedure: 3 from cardiac causes, 1 from lung cancer, and 1 following unrelated surgery. The patient with major stroke died at 7.8 months during rehabilitation. No surviving patients had further strokes, and all except 1 (95.5%) remained asymptomatic. Anatomic follow-up in 20 patients showed occlusion in 2 (10%) (1 symptomatic, 1 asymptomatic) and intimal hyperplasia in 3 asymptomatic patients (15%). CONCLUSIONS: The clinical results and sustained freedom from symptoms and stroke during the short available follow-up period suggest that stent angioplasty may be useful in the treatment of symptomatic cervical carotid stenosis in high-risk patients despite a notable incidence of restenosis.

Temporary endovascular balloon occlusion of the internal carotid artery with a nondetachable silicone balloon catheter: analysis of technique and cost.

BACKGROUND AND PURPOSE: Temporary balloon occlusion has become a routine and medically accepted technique for the management of patients with aneurysms or intracranial or head/neck tumors. We describe our experience using a nondetachable silicone balloon (NDSB) catheter in 103 endovascular temporary balloon occlusions of the internal carotid artery, with attention focused on technique, complications, and cost. METHODS: Between 1993 and 1998, 103 patients underwent preoperative temporary balloon occlusion testing with a 1.5-mm NDSB catheter. Clinical testing during endovascular blockade was combined with qualitative cerebral blood flow analysis using technetium-99m HMPAO SPECT. Cost-effective analysis was performed, emphasizing cost and complication rates in comparison with those in previously reported series in which multiple types of temporary balloon occlusion catheters were used, predominantly not of the NDSB type. RESULTS: No carotid artery injury or complication, including cerebral infarction due to NDSB use, was encountered. Despite the increased cost of the NDSB catheter system, cost-effective analysis showed up to 40% reduction in cost per quality adjusted life years. CONCLUSION: Temporary balloon occlusion using the NDSB catheter is safe and cost-effective, owing to the low rate of complications.

Endovascular management of extracranial carotid artery dissection achieved using stent angioplasty.

BACKGROUND AND PURPOSE: Dissection of the carotid artery can, in certain cases, lead to significant stenosis, occlusion, or pseudoaneurysm formation, with subsequent hemodynamic and embolic infarcts, despite anticoagulant therapy. We sought to determine the therapeutic value of stent-supported angioplasty retrospectively in this subset of patients who are poor candidates for medical therapy. METHODS: Five men and five women (age range, 37-83 years; mean age, 51.2 years) with dissection of the internal (n=9) and common (n=1) carotid artery were successfully treated with percutaneous endovascular balloon angioplasty and stent placement. The etiology was spontaneous in five, iatrogenic in three, and traumatic in two. Seven of the treated lesions were left-sided and three were right-sided. RESULTS: The treatment significantly improved dissection-related stenosis from 74+/-5.5% to 5.5+/-2.8%. Two occlusive dissections were successfully recanalized using microcatheter techniques during the acute phase. Multiple overlapping stents were needed in four patients to eliminate the inflow zone and false lumen and establish an angiographically smooth outline within the true lumen. There was one case of retroperitoneal hemorrhage, but there were no procedural transient ischemic attacks (TIAs), minor or major strokes, or deaths (0%). Clinical outcome at latest follow-up (16.5+/-1.9 months) showed significant improvements compared with pretreatment modified Rankin score (0.7+/-0.3 vs 1.8+/-0.44) and Barthel index (99.5+/-0.5 vs 80.5+/-8.9). One delayed stroke occurred in a treated patient with contralateral carotid occlusion following a hypotensive uterine hemorrhage at 8 months; the remaining nine patients have remained free of TIA or stroke. CONCLUSION: In select cases of carotid dissection associated with critical hemodynamic insufficiency or thromboembolic events that occur despite medical therapy, endovascular stent placement appears to be a safe and effective method of restoring vessel lumen integrity, with good clinical outcome.

Endovascular treatment of cerebral artery aneurysms during pregnancy: report of three cases.

Historically, surgical management of cerebral aneurysms during pregnancy has been controversial. Debate originally focused on early versus late intervention, before or after delivery of the fetus. More recently, treatment has centered on rapid intervention. We describe the endovascular treatment of cerebral artery aneurysms with Guglielmi detachable coils in three pregnant women.

Endovascular stenting for carotid artery stenosis: preliminary experience using the shape-memory- alloy-recoverable-technology (SMART) stent.

We describe our initial clinical experience using the newly available self-expanding, Nitinol, shape-memory-, alloy-recoverable-technology (SMART) stent in treating carotid artery occlusive disease. Five stents were used in four carotid arteries in four consecutive patients with carotid stenosis of at least 70%. Technical success (<20% residual stenosis) was achieved in all cases. No procedural complications specifically related to use of the SMART stent were encountered. All patients remained symptom-free, with no evidence of transient ischemic attacks or new strokes during an average follow-up period of 6 months. Excellent performance of the SMART stent for the endovascular treatment of carotid artery stenosis has been shown based on our early experience. Validation with greater numbers and longer-term follow-up is required. The specific technical characteristics, potential advantages, and disadvantages of this stent are discussed and compared with other currently used carotid artery stents.

Primary stenting for high-grade basilar artery stenosis.

We report two patients with symptomatic high-grade stenosis of the basilar artery refractory to appropriate maximal medical therapy in whom endovascular stenting was performed successfully without preliminary balloon angioplasty. Excellent angiographic results were achieved and there were no procedural or periprocedural complications. The patients were asymptomatic and neurologically intact at a mean clinical follow-up of 6.5 months. Primary stenting of basilar artery stenosis may be an alternative to balloon angioplasty for patients with symptomatic lesions refractory to medical therapy or in whom anticoagulation is contraindicated.

Intraventricular contrast medium leakage during ethanol embolization of an arteriovenous malformation.

We report the unusual phenomenon of abrupt intraventricular contrast medium leakage from the choroid plexus occurring during ethanol embolization of a periventricular arteriovenous malformation. There was no evidence of any associated intraventricular hemorrhage to suggest that leakage arose from a vessel perforation, as was first suspected. Intraventricular contrast medium leakage has been reported previously in the setting of ependymitis, and it is likely that similar pathogenetic mechanisms apply in this case. To our knowledge, this is the first reported case of intraventricular contrast medium leakage occurring during an embolization procedure.

Cerebral hyperperfusion syndrome after percutaneous transluminal stenting of the craniocervical arteries.

OBJECTIVE: Cerebral hyperperfusion syndrome is a recognized complication of carotid endarterectomy, with a reported incidence of 0.3 to 1.2%. The incidence of cerebral hyperperfusion after endovascular revascularization procedures of the craniocervical arteries remains unknown. We evaluated the incidence of cerebral hyperperfusion syndrome in our endovascular revascularization series. To our knowledge, there are no previous studies evaluating the incidence of hyperperfusion syndrome after percutaneous transluminal angioplasty/stenting. METHODS: Between March 1996 and February 2000, 140 patients underwent percutaneous transluminal angioplasty/stenting of the craniocervical arteries at our institution. In all patients, selective bilateral arteriography of the carotid and vertebral arteries was performed to document the sites of craniocervical stenosis and collateral blood flow and the results of the endovascular revascularization procedure. We then reviewed all pertinent medical records, arteriographic films, and sectional imaging studies to determine the incidence of cerebral hyperperfusion in this series. RESULTS: Seven patients (5.0%) developed clinical or radiological manifestations of cerebral hyperperfusion. In the target group, percutaneous transluminal stenting achieved a 90 to 100% reduction in stenotic lesions (mean stenosis, 91%) of the carotid (n = 5) and vertebral (n = 2) arteries. All seven patients remained neurologically stable immediately after treatment. There was delayed development of clinical and radiographic findings, suggestive of cerebral hyperperfusion. Six patients showed evidence of ipsilateral hemispheric edema, including two patients who developed intracranial hemorrhage (one parenchymal, one parenchymal and subarachnoid) documented by computed tomographic brain scans. Symptoms resolved within 72 hours in the four patients without hemorrhage. The two patients with hemorrhage recovered during a more protracted period (range, 3 wk to 6 mo). There were no long-term sequelae or deaths during a cumulative follow-up of 84 months (mean follow-up, 12 mo). CONCLUSION: Hyperperfusion syndrome is an uncommon but potentially serious complication of extracranial and intracranial angioplasty and stenting procedures. The clinical manifestations are similar to hyperperfusion syndrome after carotid endarterectomy; however, the prevalence may be greater in the high-risk cohort commonly referred for endovascular treatment. Our findings suggest that patients undergoing endovascular stenting procedures should be closely monitored for evidence of hyperperfusion, with careful monitoring of blood pressure, heart rate, and anticoagulation. Further research is needed to confirm that cerebral hyperperfusion is the pathogenesis of this condition.

Stent-supported coil embolization: the treatment of fusiform and wide-neck aneurysms and pseudoaneurysms.

OBJECTIVE: We describe a consecutive series of patients treated with endovascular stent-supported coil embolization for symptomatic or enlarging wide-neck and fusiform aneurysms and pseudoaneurysms of the carotid and vertebrobasilar arteries. METHODS: Seven stent-supported coil embolization procedures were performed for seven aneurysms in seven consecutive patients. There were five pseudoaneurysms, one dissecting aneurysm, and one berry aneurysm. Four aneurysms were located in the carotid artery, and three were located in the vertebrobasilar system. Three aneurysms were intracranial. Four patients were symptomatic, and three had angiographic evidence of increasing aneurysm size. RESULTS: Technical success was achieved in six (86%) of seven patients. Entanglement of a coil with the stent struts necessitated partial coil delivery into the parent artery in one patient, but there were no neurological or other adverse sequelae. The 30-day rate of periprocedural stroke or mortality was 0%. At a mean clinical follow-up of 14.5 months, neurological status was at baseline or better in all patients. To date, all treated patients remain clinically asymptomatic with oral administration of aspirin only. CONCLUSION: Stent-supported coil embolization represents an emerging therapeutic alternative to surgery for the treatment of symptomatic or enlarging wide-neck and fusiform aneurysms and pseudoaneurysms of the cervical and vertebrobasilar arteries, which are not amenable to conventional unsupported coil embolization. Experience with greater numbers of patients and long-term follow-up are required to further validate this technique.

Balloon-assist technique for endovascular coil embolization of geometrically difficult intracranial aneurysms.

OBJECTIVE: The balloon-assist or neck-remodeling technique is an adjunctive method devised for the endovascular coil embolization of aneurysms characterized by a wide neck or unfavorable geometric features. Since its initial description, there have been few data to corroborate its utility, efficacy, and safety in aneurysm embolization. METHODS: Twenty patients (19 female patients and 1 male patient) with 22 aneurysms (19 unruptured aneurysms and 3 ruptured aneurysms) underwent balloon-assisted coil embolization. The balloon-assist technique was performed in the same treatment session after conventional coil embolization had failed in 55% of cases (12 of 22 cases) and was the primary treatment in 45% of cases. The majority of aneurysms were located in the supraclinoid carotid artery (13 paraophthalmic and 3 superior hypophyseal aneurysms). The mean angiographic measurements included a fundus of 8.7 +/- 3.7 mm, a neck of 5.3 +/- 2.2 mm, and a comparatively unfavorable fundus/neck ratio of 1.33 +/- 0.23. RESULTS: Technical success was achieved in 77% of cases (17 of 22). The rate of aneurysm obliteration at the end of the procedures was 97 +/- 3.8%. Angiographic follow-up data (mean follow-up period, 10.3 mo) obtained for 89% of the treated aneurysms (15 of 17) confirmed stable mean occlusion of 97.8 +/- 3.8%. Technical complications included two cases of asymptomatic distal vessel thromboembolism, which resolved angiographically within 24 hours, and one case of intraprocedural rupture of an arteriovenous malformation-related feeder artery aneurysm, which resulted in no neurological deficits and required no further treatment (transient complication rate, 13.6%; 3 of 22 cases). There were no deaths and no procedure-related 30-day or permanent morbidity. CONCLUSION: The balloon-assist method of coil embolization is characterized by promising intermediate-term angiographic and clinical outcomes and acceptable morbidity and mortality rates. Although this adjunctive method requires the use of an additional microcatheter and consequently involves a higher level of technical complexity, it extends the range of aneurysms that can be successfully treated with electrolytically detachable coils via an endovascular approach.

Tandem intracranial stent deployment for treatment of an iatrogenic, flow-limiting, basilar artery dissection: technical case report.

OBJECTIVE AND IMPORTANCE: Intimal dissection constitutes one of the complications associated with angioplasty of intracranial vessels. We present a case of iatrogenic dissection of the entire basilar artery, which was induced by angioplasty and stenting of symptomatic, focal, intracranial vertebral artery stenosis, and its successful treatment with tandem deployment of a downstream stent. CLINICAL PRESENTATION: A 61-year-old, hypertensive, renal transplant recipient presented with orthostatic vertebrobasilar insufficiency that was refractory to medical management, including anticoagulation therapy. Angiography revealed an occluded right vertebral artery and focal, high-grade, left intracranial vertebral artery stenosis. Magnetic resonance imaging showed multiple posterior fossa infarctions. The left intracranial vertebral artery stenosis was successfully treated with primary stent deployment and balloon angioplasty, with symptom resolution. On postprocedure Day 2, the patient noted worsening right hemiparesis. INTERVENTION: Subsequent angiography revealed a flow-limiting, windsock-type, basilar artery dissection beginning at the distal end of the left vertebral artery stent and extending to the origin of the left posterior cerebral artery. A tandem stent was navigated intracranially and deployed past the first one, successfully sealing the dissection inflow zone and reconstituting normal flow to the top of the basilar artery. A clinical follow-up examination at 3 months revealed no further orthostatic symptoms and only mild residual right-sided weakness. CONCLUSION: This is the first description of iatrogenic stent-induced dissection of the entire basilar artery that was successfully treated by inflow zone control via tandem intracranial stent deployment.

Patient presentation, angiographic features, and treatment of strangulation-induced bilateral dissection of the cervical internal carotid artery. Report of three cases.

Domestic violence leading to strangulation by an abusive spouse can cause carotid artery dissection. This phenomenon is rare and has been described in only three previous instances. The authors present their management strategies in three additional cases. Three young women aged 24 to 43 years were victims of manual strangulation committed by their spouses 3 months to 1 year before presentation. Two of the patients suffered delayed cerebral infarctions before presentation and angiography demonstrated focal, mirror-image severe residual stenoses in the high-cervical internal carotid artery (ICA), which were characteristic of a healed chronic dissection; there was no evidence of fibromuscular dysplasia. One of these patients underwent unilateral percutaneous angioplasty with stent placement, and the other underwent bilateral percutaneous angioplasty. Both patients have recovered from their strokes and remain clinically stable at 8 and 20 months posttreatment, respectively. The third patient presented with bilateral ischemic frontal watershed infarctions resulting from an occluded left ICA and a severely narrowed right ICA. Given the extent of the established infarctions, this case was managed with a long-term regimen of anticoagulation medications, and the patient remains neurologically impaired. These cases illustrate the susceptibility of the manually compressed ICA to traumatic injury as a result of domestic violence. They identify bilateral symmetrical ICA dissection as a consistent finding and the real danger of delayed stroke as a consequence of strangulation. Endovascular therapy in which percutaneous angioplasty and/or stent placement are used can be useful in treating residual focal stenoses to improve cerebral perfusion and to lower the risk of embolic or ischemic stroke.

Endovascular treatment of a ruptured dual aperture cavernous aneurysm.

The authors describe the diagnosis and endovascular management of a multiaperture, ruptured cavernous internal carotid artery aneurysm causing a carotid cavernous fistula (CCF) using both transarterial and transvenous techniques. Although uncommon, recognition of the imaging characteristics of such a lesion will aide in successful management and improve treatment outcome. To the authors' knowledge, CCF due to a ruptured cavernous aneurysm with multiple shunts has not been previously reported.

Dural arteriovenous fistula associated with prothrombin gene mutation.

An association between dural arteriovenous fistula and cerebral sinus thrombosis is reported. It is clear in several cases that thrombosis precedes the development of the fistula while it is unclear that it occurs in every case. The authors report a case of a woman with sinus thrombosis and presence of prothrombin gene mutation who subsequently developed a large dural arteriovenous fistula. Various possible factors involved in the pathogenesis of a dural fistula are discussed, with emphasis on underlying thrombophilia and oral contraceptive use in this patient.

Endovascular treatment of noncarotid extracranial cerebrovascular disease.

The last two decades have witnessed a growing application of endovascular techniques for the treatment of atherosclerotic disease of the extracranial vertebral arteries, subclavian arteries, and brachiocephalic artery. Beginning with simple balloon angioplasty, these minimally invasive techniques have now progressed to the use of stent-supported angioplasty. Stent-supported angioplasty is currently providing a therapeutic alternative to traditional methods of open surgery for revascularization of these vessels and increasing the therapeutic options available for patients who have failed maximal medical therapy. Additionally, endovascular techniques are also being used successfully to treat a variety of nonatherosclerotic diseases affecting the noncarotid extacranial arteries, such as inflammatory, radiation, and anastomotic-graft strictures; acute intimal dissection; traumatic and spontaneous arteriovenous fistulas; and aneurysms or pseudoaneurysms. Continued innovation and refinement of endovascular devices and techniques will inevitably improve technical success rates, reduce procedure-related complications, and broaden the endovascular therapeutic spectrum for extracranial cerebrovascular disease.

Carotid artery cavernous fistulas.

The treatment of carotid cavernous fistulas has undergone a fundamental transformation during the preceding 30 years. Endovascular techniques have not only largely replaced surgical management of this disease, but have also resulted in substantially lower rates of procedure-associated morbidity and mortality. Percutaneous transarterial occlusion of direct cavernous carotid fistulas with preservation of the carotid artery using detachable balloons is now considered the current preferred therapeutic objective. Concurrent progress in percutaneous transvenous embolization techniques and materials has led to more effective and better-tailored therapies for indirect (dural) carotid cavernous fistulas. The current understanding of the clinicopathologic mechanisms associated with carotid cavernous fistulas and the endovascular therapies used in the contemporary management of this condition are reviewed.

Treatment of dural arteriovenous malformations and fistulas.

Dural arteriovenous fistulas (DAVFs) or malformations consist of pathological vascular channels located within the substance of the dura mater and usually involve the walls of a dural sinus or adjacent cortical vein. DAVFs can affect a variety of cerebral venous structures and can present at various clinical stages. Although some fistulas can spontaneously thrombose, the clinical course usually involves progression from venous sinus pressurization to occlusion and retrograde cortical venous drainage. The spectrum of clinical presentation ranges from an irritating pulse-synchronous bruit to a disabling neurologic ischemic deficit or life-threatening intracranial hemorrhage from venous hypertension. The authors present their clinical experience in the radiographic diagnosis and endovascular treatment of these potentially dangerous lesions.