Associated Aneurysms in Infratentorial Arteriovenous Malformations: Role of Aneurysm Size and Comparison with Supratentorial Lesions.

BACKGROUND: The natural history and treatment of brain arteriovenous malformations (AVMs) is the object of ongoing debates and discussions. To capture the entirety of these complex lesions, associated vascular pathologies, such as associated aneurysms (AAs), have to be implemented in future risk stratification models, as they are believed to represent additional risk factors for intracranial hemorrhage. The present study aims to determine AA characteristics in posterior fossa AVMs and to compare with AAs accompanying supratentorial AVMs, with special focus on aneurysm size. METHODS: Patients with cerebral AVMs, treated in our department between 1990 and 2013, were analyzed retrospectively. Only patients with flow-related AAs of the feeding arteries were evaluated. Thus, patients harboring intranidal, venous or remote aneurysms were excluded. RESULTS: Of 485 patients with cerebral AVM, 76 patients harbored an AVM of the posterior fossa. Among those, 22 individuals exhibited a total of 35 AAs (n = 8 patients with multiple AAs). Most common location of AAs was the posterior inferior cerebellar artery (n = 20, 57%) and mean AA diameter was 7.9 mm (SD 5.5). In the subgroup of patients with a single AA, mean aneurysm size in posterior fossa AVMs was with 7.8 mm (SD 6.0; range 2-25 mm) significantly larger than the mean size of AAs with supratentorial AVMs (4.8 mm, SD 3.0; range 2-20 mm; p = 0.048). Intracranial hemorrhage was found in 18 of 22 patients (82%) with infratentorial AVMs, and of these, 11 patients suffered from aneurysm rupture. In 14 patients bearing a single AA, 8 (57%) had sustained hemorrhage from aneurysm rupture. The mean diameter of AAs was as supposed in the ruptured group with 9.8 mm (SD 6.9; range 4-25 mm) significantly larger than in the unruptured AA group exhibiting a mean of 5.0 mm (SD 3.3; range 2-10 mm; p = 0.038). Patients with posterior fossa AVMs and AAs were significantly older as compared to those patients with supratentorial lesions (57.1, SD 12.6 vs. 45.8 years, SD 15.9 years; p = 0.004), which was also evident in the subgroup of patients with single AAs (55.2, SD 11.7 vs. 45.8 years, SD 14.9 years; p = 0.038). CONCLUSIONS: AAs of posterior fossa AVMs are larger in diameter than aneurysms accompanying supratentorial AVMs. AA size influences risk for hemorrhage, which, together with the high number of hemorrhagic events in posterior fossa AVMs, justifies treating these pathologies. The higher age of patients with AVMs of the posterior fossa might be one reason for larger AAs in this cohort, when compared to patients with supratentorial AVMs and AAs.

An integrated, ontology-driven approach to constructing observational databases for research.

The electronic health record (EHR) contains a diverse set of clinical observations that are captured as part of routine care, but the incomplete, inconsistent, and sometimes incorrect nature of clinical data poses significant impediments for its secondary use in retrospective studies or comparative effectiveness research. In this work, we describe an ontology-driven approach for extracting and analyzing data from the patient record in a longitudinal and continuous manner. We demonstrate how the ontology helps enforce consistent data representation, integrates phenotypes generated through analyses of available clinical data sources, and facilitates subsequent studies to identify clinical predictors for an outcome of interest. Development and evaluation of our approach are described in the context of studying factors that influence intracranial aneurysm (ICA) growth and rupture. We report our experiences in capturing information on 78 individuals with a total of 120 aneurysms. Two example applications related to assessing the relationship between aneurysm size, growth, gene expression modules, and rupture are described. Our work highlights the challenges with respect to data quality, workflow, and analysis of data and its implications toward a learning health system paradigm.

Endovascular treatment of an intracranial aneurysm with a ruptured bleb.

OBJECTIVE: To study the features and approaches of endovascular treatment for intracranial aneurysms with a ruptured bleb. METHODS: This retrospective study was carried out from June 2007 to June 2009 in Jilin University, Jilin, China. Thirty patients with intracranial aneurysms with ruptured blebs were included. The aneurysms were diagnosed by digital subtraction angiography (DSA), and the endovascular treatment was planned according to the relationship between the aneurysm body and the ruptured bleb. The aneurysms were classified into 4 types (type I, II, III, IV) based on the size of the neck of the aneurysm connected with the parent artery, the size of the body of the aneurysm, and the size of the junction formed between the aneurysm and bleb. Endovascular treatment for each type of aneurysm was performed. RESULTS: Type IV aneurysms were the most difficult operation performed, easily resulting in rupture and bleeding during surgery, whereas embolization of a type III aneurysm was relatively simple. Type I and II aneurysms resulted in better prognosis. Statistical analysis showed that the outcome of the treatment of type I and II aneurysms was better than that in type III and IV aneurysms, the outcome of type I, II, and III was better than that in type IV. CONCLUSION: The outcome of the endovascular treatment of an intracranial aneurysm with a ruptured bleb was related to the aneurysm type. Treatment in a type-dependent manner is therefore recommended.

Outcome in poor grade subarachnoid hemorrhage patients treated with acute endovascular coiling of aneurysms and aggressive intensive care.

BACKGROUND: Patients with poor grade (World Federation of Neurosurgeons (WFNS) Grades 4 and 5) subarachnoid hemorrhage (SAH) were historically considered to have a poor neurological outcome and therefore not traditionally offered aggressive treatment. In recent years there has been increasing evidence that early aggressive treatment of this patient group can result in a good outcome. Aim of this study is to identify the outcome of patients with WFNS Grade-4 and -5 SAH treated acutely with endovascular detachable coil embolization (DCE) and aggressive neurocritical care within our institution. METHODS: We retrospectively reviewed the records of patients with SAH WFNS Grades 4 and 5 treated with DCE within 7 days of admission between 1st January 2004 and 1st January 2008. Data collected included age, sex, grade SAH, position/number of Aneurysms, coiling complications, time spent on the neurosurgical critical care unit (NCCU), and 6-month outcome assessed by Glasgow outcome scale (GOS). GOS was dichotomized into good outcome (good recovery/moderate disability) and poor outcome (severe disability, vegetative, dead). RESULTS: A total of 193 acute SAH patients were admitted and treated within this time period, of these, 47 patients were classified as poor grade and included: 70% were female and 30% were male. The mean age was 56 years (33-88 years range). A total of 56 aneurysms were noted at angiography, 52 aneurysms were coiled. Complications of SAH Vasospasm was noted in 18 patients (38%), cerebral infarction in 13 patients (28%), seizures in 7 patients (15%), hydrocephalus in 25 patients (53%). Complications of DCE occurred in 2 patients (4% of total) these were an aneurysmal rupture and a peri-procedure thrombosis. Incomplete coiling occurred in another 5 patients (10.6% of total) due to technical difficulties. The median length of stay on the NCCU was 12 days (1-52 days range). Of the 47 poor grade patients coiled, 25 (53%) had a good outcome (good recovery/moderate disability) and 22 (47%) had a poor outcome (severe disability, vegetative, dead) by the time of the 6-month follow-up. CONCLUSION: Potentially, more than half the patients with WFNS Grade-4 and -5 SAH who are treated aggressively with coil embolization in association with supportive neurocritical care can achieve a good quality neurological outcome. However, it should be anticipated that these patients will spend a significant period of time in neurocritical care.

Differential effects of chromosome 9p21 variation on subphenotypes of intracranial aneurysm: site distribution.

BACKGROUND AND PURPOSE: Recently, a genome-wide association study identified associations between single nucleotide polymorphisms on chromosome 9p21 and risk of harboring intracranial aneurysm (IA). Aneurysm characteristics or subphenotypes of IAs, such as history of subarachnoid hemorrhage, presence of multiple IAs and location of IAs, are clinically important. We investigated whether the association between 9p21 variation and risk of IA varied among these subphenotypes. METHODS: We conducted a case-control study of 981 cases and 699 controls in Japanese. Four single nucleotide polymorphisms tagging the 9p21 risk locus were genotyped. The OR and 95% CI were estimated using logistic regression analyses. RESULTS: Among the 4 single nucleotide polymorphisms, rs1333040 showed the strongest evidence of association with IA (P=1.5x10(-6); per allele OR, 1.43; 95% CI, 1.24-1.66). None of the patient characteristics (gender, age, smoking, and hypertension) was a significant confounder or effect modifier of the association. Subgroup analyses of IA subphenotypes showed that among the most common sites of IAs, the association was strongest for IAs of the posterior communicating artery (OR, 1.69; 95% CI, 1.26-2.26) and not significant for IAs in the anterior communicating artery (OR, 1.22; 95% CI, 0.96-1.57). When dichotomizing IA sites, the association was stronger for IAs of the posterior circulation-posterior communicating artery group (OR, 1.73; 95% CI, 1.32-2.26) vs the anterior circulation group (OR, 1.28; 95% CI, 1.07-1.53). Heterogeneity in these ORs was significant (P=0.032). The associations did not vary when stratifying by history of subarachnoid hemorrhage (OR, 1.42; 95% CI, 1.18-1.71 for ruptured IA; OR, 1.27; 95% CI, 1.00-1.62 for unruptured IA) or by multiplicity of IA (OR, 1.57; 95% CI, 1.21-2.03 for multiple IAs; OR, 1.36; 95% CI, 1.15-1.61 for single IA). CONCLUSIONS: Our results suggest that genetic influence on formation may vary between IA subphenotypes.

A Comparative Classification Analysis of Abdominal Aortic Aneurysms by Machine Learning Algorithms.

The objective of this work was to perform image-based classification of abdominal aortic aneurysms (AAA) based on their demographic, geometric, and biomechanical attributes. We retrospectively reviewed existing demographics and abdominal computed tomography angiography images of 100 asymptomatic and 50 symptomatic AAA patients who received an elective or emergent repair, respectively, within 1-6 months of their last follow up. An in-house script developed within the MATLAB computational platform was used to segment the clinical images, calculate 53 descriptors of AAA geometry, and generate volume meshes suitable for finite element analysis (FEA). Using a third party FEA solver, four biomechanical markers were calculated from the wall stress distributions. Eight machine learning algorithms (MLA) were used to develop classification models based on the discriminatory potential of the demographic, geometric, and biomechanical variables. The overall classification performance of the algorithms was assessed by the accuracy, area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and precision of their predictions. The generalized additive model (GAM) was found to have the highest accuracy (87%), AUC (89%), and sensitivity (78%), and the third highest specificity (92%), in classifying the individual AAA as either asymptomatic or symptomatic. The k-nearest neighbor classifier yielded the highest specificity (96%). GAM used seven markers (six geometric and one biomechanical) to develop the classifier. The maximum transverse dimension, the average wall thickness at the maximum diameter, and the spatially averaged wall stress were found to be the most influential markers in the classification analysis. A second classification analysis revealed that using maximum diameter alone results in a lower accuracy (79%) than using GAM with seven geometric and biomechanical markers. We infer from these results that biomechanical and geometric measures by themselves are not sufficient to discriminate adequately between population samples of asymptomatic and symptomatic AAA, whereas MLA offer a statistical approach to stratification of rupture risk by combining demographic, geometric, and biomechanical attributes of patient-specific AAA.

Republished: Competitive flow diversion of multiple P1 aneurysms: proposed classification.

We report the case of a patient with subarachnoid hemorrhage and three aneurysms arising from the posterior communicating artery (Pcomm)-P1 complex, treated with endovascular coiling and competitive flow diversion. The largest and likely ruptured Pcomm aneurysm was treated with traditional coiling. Two smaller potentially ruptured aneurysms arose from the distal right posterior cerebral artery (PCA) P1 segment. After a failed attempt to treat with conventional flow diversion across the PCA-P1 segment, the P1 aneurysms were successfully treated with competitive flow diversion distal to the PCA-P1 segment from Pcomm to the P2 segment. Over 12 months, competitive flow diversion redirected flow to the right PCA territory via the internal carotid artery-Pcomm-P2, reducing the size of the PCA-P1 segment and obliterating the P1 aneurysms. Competitive flow diversion treatment should be considered for aneurysms occurring at the circle of Willis when traditional methods are not feasible. Herein, we introduce a novel classification for competitive flow diversion treatment.

Ruptured carotid artery aneurysms of the ophthalmic (C6) segment: clinical and angiographic long term follow-up of a multidisciplinary management strategy.

BACKGROUND: The management of ruptured C6 aneurysms remains controversial. Detailed long-term outcome data are still lacking. Thus the present study provided a detailed long term follow-up for a multidisciplinary approach combining microsurgical clipping, endovascular embolisation and parent artery occlusion with/without bypass protection. METHODS: In our single centre analysis of 64 consecutive patients, indications for microsurgery were: superior aneurysm projection, giant/large or wide necked aneurysms and aneurysms at branching sites. Indications for embolisation were: narrow necks, neck calcification, close aneurysm relation to the clinoid process or adhesion to the distal dural ring, and aneurysm location in the concavity of the carotid siphon curve. RESULTS: 23 patients (35.9%) underwent microsurgery, 38 patients (59.4%) embolisation and three patients (4.7%) parent artery occlusion under bypass protection. Retreatment was required in 20.9% (surgery 8.7%, endovascular 31.6%). Procedure related transient complications occurred in 10.9% (surgery 13.0%, endovascular 10.5%). Procedure related permanent morbidities occurred in 6.3% (surgery 8.7%, endovascular 5.3%), including visual deficits in 4.7% (surgery 4.4%, endovascular 5.3%). One endovascular patient died. Angiographic follow-up (29.2 (SD 31.9) months) revealed total aneurysm occlusion in 94.4% of the surgical and 82.9% of the endovascular patients. Clinical follow-up (58.7 (SD 47.6) months) showed 73.4% of the population reaching Glasgow Outcome Scale 4-5, these data being equivalent to the International Subarachnoid Aneurysm Trial (ISAT) outcomes. CONCLUSIONS: Based on favourable neuroradiological and ophthalmological outcomes, microsurgery is recommended for superiorly projecting aneurysms, especially aneurysms involving the ophthalmic artery, and for giant/large or wide necked aneurysms. Based on stable aneurysm occlusion and excellent clinical outcomes, embolisation can be recommended for inferiorly/medially projecting small, narrow necked aneurysms.

The SAFARI Score to Assess the Risk of Convulsive Seizure During Admission for Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Seizure is a significant complication in patients under acute admission for aneurysmal SAH and could result in poor outcomes. Treatment strategies to optimize management will benefit from methods to better identify at-risk patients. OBJECTIVE: To develop and validate a risk score for convulsive seizure during acute admission for SAH. METHODS: A risk score was developed in 1500 patients from a single tertiary hospital and externally validated in 852 patients. Candidate predictors were identified by systematic review of the literature and were included in a backward stepwise logistic regression model with in-hospital seizure as a dependent variable. The risk score was assessed for discrimination using the area under the receiver operator characteristics curve (AUC) and for calibration using a goodness-of-fit test. RESULTS: The SAFARI score, based on 4 items (age ≥ 60 yr, seizure occurrence before hospitalization, ruptured aneurysm in the anterior circulation, and hydrocephalus requiring cerebrospinal fluid diversion), had AUC = 0.77, 95% confidence interval (CI): 0.73-0.82 in the development cohort. The validation cohort had AUC = 0.65, 95% CI 0.56-0.73. A calibrated increase in the risk of seizure was noted with increasing SAFARI score points. CONCLUSION: The SAFARI score is a simple tool that adequately stratified SAH patients according to their risk for seizure using a few readily derived predictor items. It may contribute to a more individualized management of seizure following SAH.

Proposed Parent Vessel Geometry Based Classification of Anterior Communicating Artery-Located Aneurysms.

BACKGROUND AND OBJECTIVES: The present study is focused on correlation of parent vessels and neck diameters with anterior communicating artery (AComA) aneurysmal depth and growth direction. The study principally aims to suggest a new classification of AComA-located aneurysms based on the physical characteristics of parent vessels. METHODS: A retrospective analysis was performed of 155 patients with ruptured AComA-located aneurysms. The percentage of difference between both A1 arteries was measured on computed tomography angiography images and neck locations were determined. Accordingly, AComA-located aneurysms were classified into 2 groups. In both groups, A1 and A2 arteries and neck size diameters were measured and their relation with aneurysmal depth was studied. The aspect ratio was calculated. RESULTS: Eleven patients in which the aneurysm neck originates from the AComA proper with almost equal A1s were classified as the true AComA aneurysm group whereas 144 patients in whom the aneurysm neck originates at the dominant A1 bifurcation into the AComA and A2 with the average difference between both A1s of about 84.44% were classified as the dominant A1-bifurcation group. There is significant correlation between aneurysmal depth and neck diameter in both groups (P ≤ 0.05, P < 0.001). The aspect ratio was calculated as equal to 1.166. CONCLUSIONS: The dominant A1 bifurcation type is the most common type of AComA-located aneurysm. The present classification provides clinical value in understanding how AComA aneurysms grow and behave. It helps to understand the geometry of multilobulated aneurysms such as ruptured blebs locations during treatment procedures respecting the direction of the dominant A1 axis in group II. Multiple anatomic variations of this complex AComA area can clarify future subtypes of these 2 groups. Thus, further investigation of more patients is needed.

Basilar artery perforator aneurysms (BAPAs): review of the literature and classification.

Basilar artery perforator aneurysms (BAPAs) are an uncommon subtype of perforating artery aneurysms, with only 18 published cases since their initial description in 1996 by Ghogawala et al To date, there are only seven published cases of ruptured BAPAs treated using endovascular techniques. Given the rarity of these aneurysms, the natural history and ideal approach to treatment has not been established. We describe a new endovascular approach to treating these aneurysms using staged telescoping stents, summarize all published cases of BAPAs, and present a unique classification system to enable future papers to standardize descriptions.

Reconsidering the logic of World Federation of Neurosurgical Societies grading in patients with severe subarachnoid hemorrhage.

OBJECTIVE: Current data show a favorable outcome in up to 50% of patients with World Federation of Neurosurgical Societies (WFNS) Grade V subarachnoid hemorrhage (SAH) and a rather poor prediction of worst cases. Thus, the usefulness of the current WFNS grading system for identifying the worst scenarios for clinical studies and for making treatment decisions is limited. One reason for this lack of differentiation is the use of "negative" or "silent" diagnostic signs as part of the WFNS Grade V definition. The authors therefore reevaluated the WFNS scale by using "positive" clinical signs and the logic of the Glasgow Coma Scale as a progressive herniation score. METHODS: The authors performed a retrospective analysis of 182 patients with SAH who had poor grades on the WFNS scale. Patients were graded according to the original WFNS scale and additionally according to a modified classification, the WFNS herniation (hWFNS) scale (Grade IV, no clinical signs of herniation; Grade V, clinical signs of herniation). The prediction of poor outcome was compared between these two grading systems. RESULTS: The positive predictive values of Grade V for poor outcome were 74.3% (OR 3.79, 95% CI 1.94-7.54) for WFNS Grade V and 85.7% (OR 8.27, 95% CI 3.78-19.47) for hWFNS Grade V. With respect to mortality, the positive predictive values were 68.3% (OR 3.9, 95% CI 2.01-7.69) for WFNS Grade V and 77.9% (OR 6.22, 95% CI 3.07-13.14) for hWFNS Grade V. CONCLUSIONS: Limiting WFNS Grade V to the positive clinical signs of the Glasgow Coma Scale such as flexion, extension, and pupillary abnormalities instead of including "no motor response" increases the prediction of mortality and poor outcome in patients with severe SAH.

Validation of the Modified Raymond-Roy classification for intracranial aneurysms treated with coil embolization.

BACKGROUND: The Raymond-Roy Occlusion Classification (RROC) qualitatively assesses intracranial aneurysm occlusion following endovascular coil embolization. The Modified Raymond-Roy Classification (MRRC) was developed as a refinement of this classification scheme, and dichotomizes RROC III occlusions into IIIa (opacification within the interstices of the coil mass) and IIIb (opacification between the coil mass and aneurysm wall) closures. METHODS: To demonstrate in an external cohort the predictive accuracy of the MRRC, the records of 326 patients with 345 intracranial aneurysms treated with endovascular coil embolization from January 2007 to December 2013 were retrospectively analyzed. RESULTS: Within this cohort, 84 (24.3%) and 83 aneurysms (24.1%) had MRRC IIIa and IIIb closures, respectively, during initial coil embolization. Progression to complete occlusion was more likely with IIIa than IIIb closures (53.6% vs 19.2%, p≤0.01), while recanalization was more likely with IIIb than IIIa closures (65.1% vs 27.4%, p<0.01). Kaplan-Meier estimates demonstrated a significant difference in the test of equality for progression to complete occlusion (p=0.02) and recurrence (p<0.01) between class IIIa and IIIb distributions. For the entire cohort, male gender (p<0.01), ruptured aneurysm (p=0.04), intraluminal thrombus (p<0.01), and MRRC IIIb closure (p<0.01) were identified as predictors of recanalization. For aneurysms with an initial RROC III occlusion, MRRC IIIa closure was found to be an independent predictor of progression to complete occlusion (p=0.02). CONCLUSIONS: This study confirms that the MRRC enhances the predictive accuracy of the RROC.

Performance of language tasks in patients with ruptured aneurysm of the left hemisphere worses in the post-surgical evaluation.

OBJECTIVE: To assess the language and verbal fluency performance in aneurismal SAH pre- and post-surgery in patients caused by an aneurysm of the anterior communicating artery (AcomA), left middle cerebral artery (L-MCA) and left posterior comunicating artery (L-PcomA). METHODS: Assessment in 79 patients with SAH, on two occasions: pre- and post surgical treatment. They were divided into three groups by the aneurysms' location. RESULTS: Deterioration is detected in the performance of all patients during the post-surgical period; L-MCA aneurysm patients displayed a reduction in verbal naming and fluency; L-PcomA patients deteriorated in the written language and fluency tasks. CONCLUSION: After the surgical procedure the patients decreased in various language tasks and these differences in performance being directly related to the location of the aneurysm.

Characterization of cerebral aneurysms for assessing risk of rupture by using patient-specific computational hemodynamics models.

BACKGROUND AND PURPOSE: Hemodynamic factors are thought to play an important role in the initiation, growth, and rupture of cerebral aneurysms. This report describes a pilot clinical study of the association between intra-aneurysmal hemodynamic characteristics from computational fluid dynamic models and the rupture of cerebral aneurysms. METHODS: A total of 62 patient-specific models of cerebral aneurysms were constructed from 3D angiography images. Computational fluid dynamics simulations were performed under pulsatile flow conditions measured on a normal subject. The aneurysms were classified into different categories, depending on the complexity and stability of the flow pattern, the location and size of the flow impingement region, and the size of the inflow jet. The 62 models consisted of 25 ruptured and 34 unruptured aneurysms and 3 cases with unknown histories of hemorrhage. The hemodynamic features were analyzed for associations with history of rupture. RESULTS: A large variety of flow patterns was observed: 72% of ruptured aneurysms had complex or unstable flow patterns, 80% had small impingement regions, and 76% had small jet sizes. By contrast, unruptured aneurysms accounted for 73%, 82%, and 75% of aneurysms with simple stable flow patterns, large impingement regions, and large jet sizes, respectively. Aneurysms with small impingement sizes were 6.3 times more likely to have experienced rupture than those with large impingement sizes (P = .01). CONCLUSIONS: Image-based patient-specific numeric models can be constructed in an efficient manner that allows clinical studies of intra-aneurysmal hemodynamics. A simple flow characterization system was proposed, and interesting trends in the association between hemodynamic features and aneurysmal rupture were found. Simple stable patterns, large impingement regions, and jet sizes were more commonly seen with unruptured aneurysms. By contrast, ruptured aneurysms were more likely to have disturbed flow patterns, small impingement regions, and narrow jets.

A proposed parent vessel geometry-based categorization of saccular intracranial aneurysms: computational flow dynamics analysis of the risk factors for lesion rupture.

OBJECT: The authors created a simple, broadly applicable classification of saccular intracranial aneurysms into three categories: sidewall (SW), sidewall with branching vessel (SWBV), and endwall (EW) according to the angiographically documented patterns of their parent arteries. Using computational flow dynamics analysis (CFDA) of simple models representing the three aneurysm categories, the authors analyzed geometry-related risk factors such as neck width, parent artery curvature, and angulation of the branching vessels. METHODS: The authors performed CFDAs of 68 aneurysmal geometric formations documented on angiograms that had been obtained in patients with 45 ruptured and 23 unruptured lesions. In successfully studied CFDA cases, the wall shear stress, blood velocity, and pressure maps were examined and correlated with aneurysm rupture points. Statistical analysis of the cases involving aneurysm rupture revealed a statistically significant correlation between aneurysm depth and both neck size (p < 0.0001) and caliber of draining arteries (p < 0.0001). Wider-necked aneurysms or those with wider-caliber draining vessels were found to be high-flow lesions that tended to rupture at larger sizes. Smaller-necked aneurysms or those with smaller-caliber draining vessels were found to be low-flow lesions that tended to rupture at smaller sizes. The incidence of ruptured aneurysms with an aspect ratio (depth/neck) exceeding 1.6 was 100% in the SW and SWBV categories, whereas the incidence was only 28.75% for the EW aneurysms. CONCLUSIONS: The application of standardized categories enables the comparison of results for various aneurysms' geometric formations, thus assisting in their management. The proposed classification system may provide a promising means of understanding the natural history of saccular intracranial aneurysms.

Staged bilateral vertebral artery occlusion for ruptured dissecting aneurysms of the basilar artery: a report of 2 cases.

BACKGROUND: Dissecting aneurysm of the basillary artery BA is rare. Although mortality rate is high, management remains controversial. We report 2 cases of dissecting aneurysm of the BA presenting with subarachnoid hemorrhage (SAH), both of which were successfully treated using staged occlusion of bilateral vertebral arteries (VAs). CASE DESCRIPTION: A 64-year-old man and a 34-year-old woman presented with SAH associated with ruptured dissecting aneurysm of the BA. After endovascular occlusion of a single VA, blood flow in the dissected lumen was reduced. However, one aneurysm rebled and the bleb of the other did not change. Vertebral arteries were also occluded using endovascular techniques at 4 and 2 weeks after initial treatment, respectively. On the second intervention, stump pressure ratios of VAs intended for occlusion were 62.5% and 50.6%, respectively. The patients tolerated temporary occlusion of bilateral VAs well. Subsequent permanent occlusion of bilateral VAs resulted in no neurological complication. Complete obliteration of the aneurysmal lumen was demonstrated on magnetic resonance angiography performed 72 and 5 months later, respectively. CONCLUSION: Staged bilateral VA occlusion might be the last recourse to prevent further hemorrhage from BA dissecting aneurysm. The technique can be safely applied when the stump pressure ratio is 50.6% or greater and when the patient tolerates temporary occlusion, which suggests the existence of sufficient collateral flow from the anterior circulation.

ISAT and ISUIA: the impact on informed consent.

The International Subarachnoid Aneurysm Trial (ISAT) was a multicenter randomized trial that compared the safety and efficacy of endovascular coil treatment versus surgical clipping for the treatment of ruptured brain aneurysms. To be eligible for enrollment in the ISAT trial, each patient had to be deemed equally suitable for either coiling or clipping. The investigators used the term "clinical equipoise" to describe this balance. This study more than any other has set the playing field for the future of interventional radiology/endovascular neurosurgery politics.