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BACKGROUND Complete surgical resection of arteriovenous malformations (AVMs), documented by postoperative angiography, is generally felt to represent cure, obviating the need for long-term follow-up imaging. Although AVM recurrence has been reported in the pediatric population, this phenomenon has only rarely been documented in adults. Recurrence after treatment solely with embolization, however, has been reported more frequently. Thus, patients undergoing multimodal therapy with surgery following preoperative embolization may also be at higher risk for recurrence. OBJECTIVE To determine if preoperative embolization contributes to recurrences of AVMs after complete surgical resection. METHODS A retrospective study of patients undergoing AVM resection was performed. Those with complete surgical AVM resection, confirmed by negative early postoperative cerebral angiography and with available follow-up angiographic imaging >6 months postoperatively were included. RESULTS Two hundred three patients underwent AVM resection between 1995 and 2012. Seventy-two patients met eligibility criteria. There were 3 recurrences (4%). Deep venous drainage and diffuse type of AVM nidus were significantly associated with recurrence. Although preoperative embolization did not reach statistical significance as an independent risk factor, radiographic data supported its role in every case, with the site of recurrence correlating with deep regions of nidus previously obliterated by embolization. CONCLUSION AVM recurrences in the adult population may have a multifactorial origin. Although deep venous drainage and diffuse nidus are clearly risk factors, preoperative embolization may also be a contributing factor with the potential for recurrence of unresected but embolized portions of the AVM. Follow-up angiography at 1 to 3 years appears to be warranted.

BACKGROUND Endovascular stenting is an effective treatment for patients with clinically significant cerebral venous sinus stenosis. Traditionally, stenting is indicated in elevated intravenous pressures on conventional venography; however, noninvasive monitoring is more desirable. Quantitative magnetic resonance angiography is an imaging modality that measures blood flow noninvasively. Established in the arterial system, applications to the venous sinuses have been limited. OBJECTIVE To examine quantitative magnetic resonance venography (qMRV) in the measurement of venous sinus flow in patients undergoing endovascular stenting and to identify a relationship with intravenous pressures. METHODS Five patients with intracranial hypertension secondary to venous sinus stenosis underwent cerebral venous stenting between 2009 and 2013 at a single institution. Preoperatively, venous sinus flow was determined by using qMRV, and intravenous pressure was measured during venography. After stenting, intravenous pressure, qMRV flow, and clinical outcomes were assessed and compared. RESULTS A mean prestenotic intravenous pressure of 45.2 mm Hg was recorded before stenting, which decreased to 27.4 mm Hg afterward (Wilcoxon signed rank test P = .04). Total jugular outflow on qMRV increased by 260.2 mL/min. Analysis of the change in intravenous pressure and qMRV flow identified a linear relationship (Pearson correlation r = 0.926). All patients displayed visual improvement at 6 weeks. CONCLUSION Venous outflow by qMRV increases after endovascular stenting and correlates with significantly improved intravenous pressures. These findings introduce qMRV as a potential adjunct to measure venous flow after stenting, and as a plausible tool in the selection and postoperative surveillance of the patient who has cerebral venous sinus stenosis.

BACKGROUND Carotid artery stenting is an endovascular treatment option for patients with extracranial carotid stenosis. However, intracranial blood flow changes following stenting have not been established. OBJECTIVE To determine the effects of stenting on intracranial blood flow. METHODS Records of patients who underwent stenting at our institution between 2004 and 2012 and had flow rates obtained pre- and poststenting by the use of quantitative magnetic resonance angiography were retrospectively reviewed. Percentage stenosis, stenosis length, and minimum vessel diameter were measured from cerebral angiography images. RESULTS Eighteen patients were included. Mean age was 65 years with 67% presenting with symptomatic stenosis. Degree of stenosis ranged from 60% to 90%. Internal carotid artery (ICA) mean flow improved significantly poststenting from 174.9 ± 83.6 mL/min to 250.7 ± 91.2 mL/min (P = .011). Ipsilateral middle cerebral artery (MCA) flow, however, was not significantly altered poststenting (107.8 ± 41.6 mL/min vs 114.3 ± 36.3 mL/min; P = .28). Univariate analysis revealed that improved minimum vessel diameter after stenting, but not percentage stenosis (P = .18) or stenosis length (P = .45), is significantly associated with increased ICA flow (P = .02). However, improved percentage stenosis, stenosis length, minimum vessel diameter, and ICA flow poststenting were not significantly associated with increased MCA flow (P = .64, .38, .13, .37, respectively). CONCLUSION ICA flow was compromised at baseline, improving 43% on average poststenting. Increased minimum vessel diameter was the factor most significantly associated with increased flow. Conversely, MCA flow was not significantly compromised at baseline nor altered after stenting, suggesting compensatory intracranial collateral supply prestenting that redistributes following ICA revascularization.

BACKGROUND: The optimal revascularization strategy for symptomatic adult moyamoya remains controversial. Whereas direct bypass offers immediate revascularization, indirect bypass can effectively induce collaterals over time. OBJECTIVE: Using angiography and quantitative magnetic resonance angiography, we examined the relative contributions of direct and indirect bypass in moyamoya patients after combined direct superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass and indirect encephaloduroarteriosynangiosis (EDAS). METHODS: A retrospective review of moyamoya patients undergoing combined STA-MCA bypass and EDAS was conducted, excluding pediatric patients and hemorrhagic presentation. Patients with quantitative magnetic resonance angiography measurements of the direct bypass immediately and > 6 months postoperatively were included. Angiographic follow-up, when available, was used to assess EDAS collaterals at similar time intervals. RESULTS: Of 16 hemispheres in 13 patients, 11 (69%) demonstrated a significant (> 50%) decline in direct bypass flow at > 6 months compared with baseline, averaging a drop from 99 ± 35 to12 ± 7 mL/min. Conversely, angiography in these hemispheres demonstrated prominent indirect collaterals, in concert with shrinkage of the STA graft. Decline in flow was apparent at a median of 9 months but was evident as early as 2 to 3 months. CONCLUSION: In this small cohort, a reciprocal relationship between direct STA bypass flow and indirect EDAS collaterals frequently occurred. This substantiates the notion that combined direct/indirect bypass can provide temporally complementary revascularization.

Background Subarachnoid hemorrhage cases with multiple cerebral aneurysms frequently demonstrate a hemorrhage pattern that does not definitively delineate the source aneurysm. In these cases, rupture site is ascertained from angiographic features of the aneurysm such as size, morphology, and location. Objective To examine the frequency with which such features lead to misidentification of the ruptured aneurysm. METHODS : Records of patients who underwent surgical clipping of a ruptured aneurysm at our institution between 2004 and 2014 and had multiple aneurysms were retrospectively reviewed. A blinded neuroendovascular surgeon provided the rupture source based on the initial head computed tomography scans and digital subtraction angiography images. Operative reports were then assessed to confirm or refute the imaging-based determination of the rupture source. Results One hundred fifty-one patients had multiple aneurysms. Seventy-one patients had definitive hemorrhage patterns on initial computed tomography scans and 80 patients had nondefinitive hemorrhage patterns. Thirteen (16.2%) of the cases with nondefinitive hemorrhage patterns had discordance between the imaging-based determination of the rupture source and intraoperative findings of the true ruptured aneurysm, yielding an imperfect positive predictive value of 83.8%. Of all multiple aneurysm cases with subarachnoid hemorrhage treated by surgical or endovascular means at our institution, 4.3% (13 of 303) were misidentified. Conclusion Morphological features cannot reliably be used to determine rupture site in cases with nondefinitive subarachnoid hemorrhage patterns. Microsurgical clipping, confirming obliteration of the ruptured lesion, may be preferentially indicated in these patients unless, alternatively, all lesions can be contemporaneously and safely treated with endovascular embolization.

Background Endovascular embolization is a desirable treatment option for complex posterior circulation aneurysms, particularly recurrent aneurysms or those in difficult-to-access surgical locations. However, endovascular access is occasionally prohibited by proximal vertebral artery (VA) occlusion or vessel tortuosity. One strategy in such instances involves creation of an extracranial bypass conduit to the distal VA. Objective To describe a novel strategy to allow for endovascular treatment of aneurysms at high risk for direct surgery. Methods Three cases of carotid-VA bypass performed to provide endovascular access to posterior circulation aneurysms were identified. The clinical indications, radiographic characteristics, operative technique, and outcomes were reviewed. Results Indications for bypass were previously clipped recurrent basilar tip aneurysm, previously coiled midbasilar aneurysm with compaction requiring stent placement, and distal intracranial VA aneurysm with iatrogenic vertebral dissection/occlusion after initial coil attempt. In all cases, routine endovascular access for primary or stent-assisted coiling was prohibited by VA tortuosity. Bypass with the use of interposition saphenous vein grafts was successfully performed to the C1-C2 region of the V2 segment without complications. The bypass was followed by successful endovascular treatment in all cases 2 to 6 weeks after surgery. In 1 patient, 2 recurrent treatments through the graft were subsequently performed for coil compaction. Conclusion Extracranial carotid-VA bypass can be a valuable tool in the management of complex posterior circulation aneurysms. It is a safe and efficacious technique providing a conduit for repeated access to the posterior circulation in patients with otherwise prohibitive vertebral anatomy.

BACKGROUND Heparin-induced thrombocytopenia type II (HIT II) correlates with a higher incidence of thromboembolic complications and unfavorable outcome. OBJECTIVE To examine the risk factors and outcomes for patients with HIT II with aneurysmal subarachnoid hemorrhage. METHODS Demographics, risk factors, treatments, and outcomes data of 600 aneurysmal subarachnoid hemorrhage patients admitted to the University of Illinois Medical Center in Chicago between June 2002 and July 2007 were retrospectively reviewed. Patients meeting the clinical criteria for HIT II were compared with those who did not develop thrombocytopenia. RESULTS Twenty-five patients (6%) met the clinical criteria for HIT II, and 396 (94%) did not develop thrombocytopenia. Both groups were the same with respect to age, Hunt-Hess score and Fisher grade on admission, medical conditions, and social risk factors. The HIT II patients had significantly more unfavorable outcomes (modified Rankin Scale score >3), deep vein thrombosis, stroke, pulmonary embolism, and death. Development of HIT II was strongly associated with symptomatic vasospasm (odds ratio, 5.7; 95% confidence interval, 2.5-13.1; P < .001) and number of angiographic procedures (odds ratio, 1.7; 95% confidence interval, 1.3-2.2; P < .001). Forward buildup selection modeling demonstrated the latter to be the strongest predictor for HIT II development (odds ratio, 2.3; 95% confidence interval, 1.7-3.2; P = .02). CONCLUSION Heparin-induced thrombocytopenia type II correlates with a worse outcome and higher risk of thromboembolic complications in aneurysmal subarachnoid hemorrhage patients. In addition, HIT II was strongly associated with the number of angiographic procedures performed during the same hospitalization.

OBJECTIVE The success of endovascular treatment of intracranial aneurysms with Guglielmi detachable coils (GDCs) is dependent on the long-term exclusion of the aneurysm from the circulation. We reviewed our experience with the long-term angiographic follow-up monitoring of aneurysms that had been treated with GDCs. METHODS All patients whose aneurysms had been treated with GDCs between January 1995 and August 1999 and who subsequently underwent follow-up angiography at 6 months or more were included in this study. We reviewed all of the angiographic findings, to determine the percentage of aneurysm occlusion on the initial angiograms and on the last available follow-up angiograms. The categories of aneurysm occlusion used were 100%, ≥95%, and less than 95% occlusion. RESULTS One hundred thirty patients with 141 aneurysms underwent 143 endovascular coiling procedures and subsequently underwent angiographic follow-up monitoring of 6 months or more. There were 102 female and 28 male patients. The mean angiographic follow-up period was 16.7 months (range, 6–62 mo). The initial rates of occlusion were 100% for 56 aneurysms (39%), ≥95% for 65 aneurysms (46%), and less than 95% for 22 aneurysms (15%). Recurrence of one aneurysm (1.8%) was observed. Of the 87 aneurysms that were incompletely occluded initially, there was progressive thrombosis in 40 (46%), stable neck remnants in 23 (26%), and enlargement of the residual neck in 24 (28%). The final occlusion rates, determined on the last available angiograms, were 100% for 88 aneurysms (61%), ≥95% for 31 aneurysms (22%), and less than 95% for 24 aneurysms (17%). No patient experienced repeat or new subarachnoid hemorrhage more than 6 months after the initial treatment. CONCLUSION Late angiographic follow-up monitoring of aneurysms that have been treated with GDCs demonstrates the durability of the treatment. Aneurysms with large residual neck remnants were subjected to further treatment, whereas aneurysms with small residual neck remnants remain under observation.

Objective To determine the angiographically proven rate and persistence of occlusion of intracranial aneurysms after surgical clipping as reported in the literature. This should establish a basis for comparing surgery with new endovascular methods of treatment. Methods We reviewed the literature published during the period from 1979 through 1999, dividing the articles into two groups. The first group of articles reported patients undergoing surgical treatment with immediate postoperative angiography. The second group of articles documented symptomatic recurrence or regrowth of aneurysms that were surgically treated previously. The data from these articles are presented for analysis. Results During the period 1979 to 1999, six series of patients undergoing surgical treatment of aneurysms with immediate postoperative angiography were reported. These reported series comprised a total of 1,397 patients, of whom 1,370 underwent postoperative angiography demonstrating 1,569 clipped aneurysms. Residual filling was found in 82 aneurysms (5.2%) on postoperative angiography. Of the 1,370 patients, only 124 patients with 169 aneurysms were reported to have had any long-term angiographic follow-up. The second group consisted of 226 patients representing six reported groups of patients, who either presented up to 24 years after aneurysm clipping with recurrent symptoms of hemorrhage or mass effect, or had important findings on intraoperative and postoperative angiograms. Conclusion The lack of information regarding both the frequency of residual filling or regrowth and long-term angiographic follow-up of patients with surgically treated aneurysms makes meaningful comparison between surgical treatments and new treatment methods for intracranial aneurysms difficult or impossible. Detailed analysis with high-quality angiography should be performed to determine the success of surgical treatment.

Objective We present our initial experience with Guglielmi detachable coils (GDCs). The aim of this study was to determine the criteria for aneurysms, ruptured or unruptured, that are suitable for this technique. The importance of aneurysm geometry and its impact on the final results are discussed. Methods A retrospective analysis of 329 patients with 339 cerebral aneurysms that were treated at the University of Illinois Hospital at Chicago from May 1994 to June 1997 was conducted. One hundred eighty-five patients were treated surgically, and 144 were selected for treatment using GDCs. Of the 144 patients selected for GDC treatment, 55 patients with 55 aneurysms were admitted during the acute phase of subarachnoid hemorrhage and 89 patients with 97 aneurysms had nonruptured aneurysms or were treated after clinical recovery of previously ruptured aneurysms. All procedures were performed with the patients under general anesthesia and with systemic heparinization using live simultaneous biplane roadmapping, with the exception of the first four patients. These patients were treated before the installation of the biplane system. The percentage of aneurysm occlusion was determined at the end of each procedure. Follow-up angiography was scheduled to be performed at 6 months, 1 year, and 2 years after treatment. Patient selection For the initial 25 patients (Group 1), selection for coiling was restricted to nonsurgical candidates or patients in whom coiling was thought to be the best treatment choice, based on medical condition and location of the aneurysm. The geometry of the aneurysm was not considered to be an important factor in the selection for coiling. The remaining patients (Group 2) were selected for coiling based on aneurysm geometry, as determined by pretherapeutic angiography. Aneurysms that were considered to be favorable for coiling included those that had a dome-to-neck ratio of at least 2 and an absolute neck diameter less than 5 mm. Results The initial 25 patients (Group 1) were treated from May 1994 to February 1995. There were high morbidity and mortality rates, with 56% of the treated aneurysms occluded at 6 months. The remaining patients (Group 2) consisted of 119 patients with 123 aneurysms. There was no mortality directly related to the coiling procedure, and permanent morbidity was limited to 1.0%. Three patients (2.5%) developed transient neurological deficits secondary to the procedure, and seven patients (5.8%) experienced periprocedural complications that did not result in neurological sequelae. The morphological results were strongly correlated to the geometry of the aneurysms, with a complete occlusion rate of 72% among the acutely ruptured aneurysms and 80% among the nonacute aneurysms, when patients were selected for treatment based on the geometry of the aneurysms and the dome-to-neck ratio was at least 2. The occlusion rate dropped to 53% when selection was not based on aneurysm geometry and the dome-to-neck ratio was less than 2. A summary of the morphological outcomes for the Group 2 patients shows that 86% of the aneurysms that initially underwent coiling using GDCs were completely occluded (78% by coils alone, 3.0% in conjunction with surgery, and 5.0% with parent artery occlusion). Residual small neck remnants were present in 11% of the Group 2 aneurysms (3.0% were scheduled for surgical treatment of residual neck remnant growths not amenable to further endovascular treatment, and 8% were scheduled for initial 6-mo follow-up examinations). Death resulting from unrelated causes before initial follow-up occurred in 3.0% of the patients. Conclusion These preliminary results suggest that using GDCs is a safe technique resulting in low morbidity and mortality rates for the treatment of intracranial aneurysms in appropriately selected patients. The percentage of complete aneurysm occlusion is related to the density of coil packing, which is strongly dependent on the geometry of the aneurysm. Optim

The use of balloons in the field of neurosurgery is currently an essential part of our clinical practice. The field has evolved over the last 40 years since Serbinenko used balloons to test the feasibility of occluding cervical vessels for intracranial pathologies. Since that time, indications have expanded to include sacrificing cervical and intracranial vessels with detachable balloons, supporting the coil mass in wide-necked aneurysms (balloon remodeling technique), and performing intracranial and cervical angioplasty for atherosclerotic disease, as well as an adjunct to treat arteriovenous malformations. With the rapid expansion of endovascular technologies, it appears that the indications and uses for balloons will continue to expand. In this article, we review the history of balloons, the initial applications, the types of balloons available, and the current applications available for endovascular neurosurgeons.

OBJECTIVE : To demonstrate that nidus embolization of brain arteriovenous malformations (AVMs) with Histoacryl (B. Braun, Melsungen, Germany) is effective and yields low morbidity and mortality rates. METHODS : We present a retrospective analysis of 54 brain AVMs treated at the University of Illinois at Chicago from April 1994 to December 1995. Treatment modalities included embolization in all cases and then surgical resection or radiosurgery. INSTRUMENTATION : The nidus was reached with the combined use of a Magic microcatheter (Balt, Montmorency, France) and a Terumo 0.010-inch guidewire. TECHNIQUE : Embolization was performed only when the tip of the microcatheter was wedged into the nidus of the AVMs with no reflux of contrast proximally. The embolization was performed using simultaneous biplane roadmapping with the patient under general anesthesia without Amytal testing. RESULTS : Twenty-six of 54 patients are still waiting for more radical treatment. Two deaths and two minor and one severe permanent neurological deficit occurred. Three patients were cured with embolization alone ; 11 patients were cured after surgical resection. Three patients underwent radiosurgery, with one cure after 1 year. CONCLUSION : Nidus embolization with Histoacryl is an effective technique that permits complete cure of a large number of brain AVMs, with or without surgical resection and/or radiosurgery.

BACKGROUND: Onyx HD-500 is a liquid embolic used to treat intracranial aneurysms. OBJECTIVE: To determine the incidence of parent vessel stenosis and the management strategy for these patients. METHODS: Medical records of patients treated with Onyx HD-500 between 2008 and 2011 were retrospectively reviewed. Clinical and radiographic evaluations were assessed. Quantitative magnetic resonance angiography and NOVA (VasSol, Chicago, Illinois) images were reviewed for patients in whom these examinations were acquired. RESULTS: Seventeen patients underwent treatment of unruptured internal carotid artery aneurysms. Three patients (17.6%) developed visual symptoms after the procedure: 2 permanent and 1 transient. Four patients (23.5%) developed delayed internal carotid artery stenosis at the 6- to 8-month follow-up angiography, despite a standard antiplatelet regimen with confirmed sensitivities to aspirin and clopidogrel. Quantitative magnetic resonance angiography was obtained in all patients with stenosis to guide treatment. One patient progressed to complete but asymptomatic internal carotid artery occlusion. The second and third patients had asymptomatic stenosis of 40% and 70%, respectively, both of which resolved on follow-up angiography. The fourth patient developed critical stenosis distal to the aneurysm neck. Quantitative magnetic resonance angiography demonstrated adequate flow in the first 3 patients and decreased flow in the fourth patient, necessitating angioplasty and stenting. Prolonged dual antiplatelet regimens were continued in 2 of the 4 patients, 1 with progression of stenosis and 1 with improvement of stenosis. CONCLUSION: We observed a higher rate of parent vessel steno-occlusive progression after aneurysm embolization with Onyx HD-500 than reported in the literature, despite overall low morbidity. Quantitative vessel flow imaging was useful in subsequent medical management and decision making to perform therapeutic angioplasty/stenting to preserve flow.

OBJECTIVE: To document the influence of the treatment modality (early surgery versus early endovascular treatment) on measures of cerebral vasospasm in a nonrandomized series of 156 patients treated within 72 hours of aneurysmal subarachnoid hemorrhage. METHODS: The following parameters were prospectively collected in a computerized data base and retrospectively analyzed for association with vasospasm-related ischemic infarctions: 1) Hunt and Hess (HH H&H Grades I-Iv, P = 0.96).

The cavernous sinus in 3 of a series of 147 fast-flow direct carotid-cavernous fistulae was best reached through the vertebral artery. All three patients were anatomically cured without morbidity.