Faculty Bibliography

SUMMARY:Does the world need another ICA classification scheme? We believe so. The purpose of proposed angiography-driven classification is to optimize description of the carotid artery from the endovascular perspective. A review of existing, predominantly surgically-driven classifications is performed, and a new scheme, based on the study of NYU aneurysm angiographic and cross-sectional databases is proposed. Seven segments - cervical, petrous, cavernous, paraophthlamic, posterior communicating, choroidal, and terminus - are named. This nomenclature recognizes intrinsic uncertainty in precise angiographic and cross-sectional localization of aneurysms adjacent to the dural rings, regarding all lesions distal to the cavernous segment as potentially intradural. Rather than subdividing various transitional, ophthalmic, and hypophyseal aneurysm subtypes, as necessitated by their varied surgical approaches and risks, the proposed classification emphasizes their common endovascular treatment features, while recognizing that many complex, trans-segmental, and fusiform aneurysms not readily classifiable into presently available, saccular aneurysm-driven schemes, are being increasingly addressed by endovascular means. We believe this classification may find utility in standardizing nomenclature for outcome tracking, treatment trials and physician communication.

Arteriovenous malformations of the brain are a considerable source of morbidity and mortality for patients who harbor them. Although our understanding of this disease has improved, it remains in evolution. Advances in our ability to treat these malformations and the modes by which we address them have also improved substantially. However, the variety of patient clinical and disease scenarios often leads us into challenging and complex management algorithms as we balance the risks of treatment against the natural history of the disease. The goal of this article is to provide a focused review of the natural history of cerebral arteriovenous malformations, to examine the role of stereotactic radiosurgery, to discuss the role of endovascular therapy as it relates to stereotactic radiosurgery, and to look toward future advances.

INTRODUCTION: Angioplasty and intracranial stenting (ICS) are both endovascular revascularization procedures that have emerged as treatment options for intracranial atherosclerotic disease (ICAD). Some believe angioplasty alone is better, while others believe stenting is better. This study examines recent trends in utilization and outcomes of angioplasty alone and ICS in the United States using a population-based cohort. METHODS: The National Inpatient Sample (NIS) database was queried for patients with ICAD who underwent angioplasty or ICS from 2005 to 2010. RESULTS: There were 1115 patients (angioplasty: n=495, ICS: n=620) with ICAD who underwent endovascular revascularization. Over time, the number of endovascular revascularization procedures increased. The percentage of symptomatic patients (p=0.015) as well as in the number of comorbidities of patients treated (p<0.001) also increased. Combined post-procedure stroke and death rates were 16% and 28.9% for angioplasty and ICS, respectively (p<0.001). A larger percentage of angioplasty patients presented symptomatically compared to those who underwent ICS (p<0.001). CONCLUSION: Angioplasty appears to be associated with higher rates of peri-procedural complications; however, that may represent patient selection bias. Further studies are needed to identify patients who would benefit from revascularization and to clarify the roles of angioplasty and ICS.

Aim: Embolization of cerebral and spinal neoplasms is performed for highly vascular tumors including hemangioblastomas, paragangliomas, juvenile nasopharyngeal angiofibromas, hemangiopericytomas, schwannomas, meningiomas, and selected metastases. While diagnostic angiography may contribute to clarify the tumoral arterial supply, superselective infusion of embolics may effectively obliterate the tumoral vascular bed. At present, determinants of safe and effective presurgical embolization remain under debate. Methods: We investigate and illustrate the endovascular technique, ideal timing, and effectiveness of presurgical embolization of cerebral and spinal tumors performed at the NYU Langone Medical Center. Results: Detailed diagnostic angiography is key to identify the arterial supply to the tumor, to consistently recognize dangerous external carotid-to-internal carotid anastomoses, and to detect the highly variable arterial supply to cranial nerves and neuronal structures. Meticulous technique is essential for performing safe and effective tumor embolization that causes tumor necrosis and facilitates subsequent resection by limiting intraoperative blood loss. Although general anesthesia precludes the use of provocative testing, it does improve patient comfort and enhances the accuracy of angiography by limiting motion artifact. Additionally, electrophysiology may provide an additional degree of safely when general anesthesia is used. Embolization may be best performed within a week prior to the scheduled surgery to allow for effective tumor necrosis while avoiding neovascularization. Embolic agents include a range of liquids, particulates, or coils. Selecting the most advantageous agent is performed in light of the desired degree of tumor penetration, the presence or possibility of a dangerous anastomosis, and the ability to navigate the microcatheter in a safe position for superselective infusion of embolics. Although the most effective embolization is obtained with small particles that penetrate the tumoral bed at the capillary level, these agents are also the most dangerous to use by putting cranial nerves and normal structures such as the retina and myelon at risk. Conclusion: In depth knowledge of anatomy, meticulous technique, and the proper choice of the embolic material determine the safety and effectiveness of preoperative tumor embolization that may contribute to surgical success.

BACKGROUND: Extracranial-intracranial (EC-IC) bypass and intracranial stenting (ICS) are both revascularization procedures that have emerged as treatment options for intracranial atherosclerotic disease (ICAD). This study describes and compares recent trends in utilization and outcomes of intracranial revascularization procedures in the United States using a population-based cohort. It also investigates the association of ICS and EC-IC bypass with periprocedural morbidity and mortality, unfavorable discharge status, length of stay (LOS), and total hospital charges. METHODS: The National Inpatient Sample (NIS) was queried for patients with ICAD who underwent EC-IC bypass or ICS during the years 2004-2010. Patient characteristics, demographics, perioperative complications, outcomes, and discharge data were collected. RESULTS: There were 627 patients who underwent ICS and 249 patients who underwent EC-IC bypass. Patients who underwent ICS were significantly older (P < 0.001) with more comorbidities (P = 0.027) than those who underwent EC-IC bypass. Patients who underwent EC-IC bypass experienced higher rates of postprocedure stroke (P = 0.014), but those who underwent ICS experienced higher rates of death (P = 0.006). Among asymptomatic patients, the rates of postprocedure stroke (P = 0.341) and death (P = 0.887) were similar between patients who underwent ICS and those who underwent EC-IC bypass. Among symptomatic patients, however, there was a higher rate of postprocedure stroke in patients who underwent EC-IC bypass (P < 0.001) and a higher rate of death among patients who underwent ICS (P = 0.015). CONCLUSION: The ideal management of patients with ICAD cannot yet be defined. Although much data from randomized and prospective trials on revascularization have been collected, many questions remain unanswered. There still remain cohorts of patients, specifically patients who have failed aggressive medical management, where not enough evidence is available to dictate decision-making. In order to further elucidate the safety and efficacy of these intracranial revascularization procedures, further clinical trials are needed.

We present flow-based results from the early stage design cycle, based on computational modeling, of a prototype flow-diverter device, known as the 'Sphere', intended to treat bifurcation aneurysms of the cerebral vasculature. The device is available in a range of diameters and geometries and is constructed from a single loop of NITINOL(R) wire. The 'Sphere' reduces aneurysm inflow by means of a high-density, patterned, elliptical surface that partially occludes the aneurysm neck. The device is secured in the healthy parent vessel by two armatures in the shape of open loops, resulting in negligible disruption of parent or daughter vessel flow. The device is virtually deployed in six anatomically accurate bifurcation aneurysms: three located at the Basilar tip and three located at the terminus bifurcation of the Internal Carotid artery (at the meeting of the middle cerebral and anterior cerebral arteries). Both steady state and transient flow simulations reveal that the device presents with a range of aneurysm inflow reductions, with mean flow reductions falling in the range of 30.6-71.8% across the different geometries. A significant difference is noted between steady state and transient simulations in one geometry, where a zone of flow recirculation is not captured in the steady state simulation. Across all six aneurysms, the device reduces the WSS magnitude within the aneurysm sac, resulting in a hemodynamic environment closer to that of a healthy vessel. We conclude from extensive CFD analysis that the 'Sphere' device offers very significant levels of flow reduction in a number of anatomically accurate aneurysm sizes and locations, with many advantages compared to current clinical cylindrical flow-diverter designs. Analysis of the device's mechanical properties and deployability will follow in future publications.

OBJECTIVE: To evaluate the efficacy of combining an endonasal endoscopic skull-base approach and repair with a transcranial orbitozygomatic approach for spheno-orbital meningiomas (SOMs). METHODS: Three patients with recurrent SOMs underwent combined orbitozygomatic and endonasal endoscopic surgery. In two patients both procedures were done in one operation and in one patient the endonasal surgery was done 2.5 months after the craniotomy. Extent of resection, complications, morbidity, and mortality were evaluated. RESULTS: Gross total resection was achieved in one patient and near total resection in the other two patients with tumor left in the cavernous sinus and parapharyngeal space. Two patients suffered cranial neuropathy from the transcranial surgery and the other developed a pseudomeningocele. There were no complications from the endonasal surgery. Patients having combined single setting cranionasal surgery were discharged on day 6 and 8, whereas the patient having only the endonasal component on a later date was discharged on day 2. CONCLUSIONS: A combined cranionasal approach involving transcranial orbitozygomatic and endonasal endoscopic approaches is an effective two-stage surgery for resecting SOMs invading into the sinuses and paranasal compartments. The ability to perform a multilayer closure involving a vascularized nasoseptal flap additionally decreases the risk of postoperative cerebrospinal fluid leak.

BACKGROUND: The balloon-assisted coil embolization (BACE) technique represents an effective tool for the treatment of complex wide-necked intracranial aneurysms; however, its safety is a matter of debate. This study presents the authors' institutional experience regarding the safety of the BACE technique. METHODS: 428 consecutive patients with 491 intracranial aneurysms (274 acutely ruptured and 217 unruptured) treated with conventional coil embolization (CCE) or with BACE were retrospectively reviewed. All procedure-related adverse events were reported, regardless of clinical outcome. Thromboembolic events, intraprocedural aneurysm ruptures, device-related complications, morbidity and mortality were compared between the CCE and BACE groups. RESULTS: The total rate of procedural and periprocedural adverse events was 9.6% (47/491 embolizations). Thromboembolic events, intraprocedural aneurysmal rupture and device-related complications occurred in 2.4%, 3.9% and 3.3% of procedures, respectively. The risk of thromboembolic events and device-related problems was similar between the CCE and BACE groups. A trend towards a higher risk of intraprocedural aneurysm rupture was observed in the BACE group (not statistically significant). The total cumulative morbidity and mortality for both groups was 2.6% (11/428 patients) and there was no statistically significant difference in the morbidity, mortality and cumulative morbidity and mortality rates between the two groups. CONCLUSION: In this series of patients with acutely ruptured and unruptured aneurysms, the BACE technique allowed treatment of aneurysms with unfavorable anatomic characteristics without increasing the incidence of procedural complications.