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Background: Anterior communicating artery (ACOM) aneurysms are among the most common aneurysms associated with aneurysmal subarachnoid hemorrhage (International Study of Unruptured Intracranial Aneurysms I (N Engl J Med 339:1725-1733, 1998), Wiebers (Lancet 362:103-110, 2003)). Surgical clipping of posterior-superiorly projecting ACOM aneurysms can be challenging, as the ipsilateral A2 can interfere with clip trajectory and ACOM perforating vessels obstructed from view. Intraluminal coils can further increase the difficulty of the procedure., Method: The relevant surgical anatomy with illustration is presented. A video detailing our technique on an illustrative case is provided., Conclusion: Surgical clipping of posterior-superiorly projecting ACOM aneurysms can require complex clip configurations. We describe the key steps of posterior-superiorly projecting ACOM aneurysm clipping through a lateral supraorbital craniotomy and fenestrated tandem clipping., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: The distal suboccipital segment of the occipital artery is commonly used as a donor vessel for aneurysms of the posterior circulation requiring revascularization techniques. Isolating this segment of vessel can be challenging due to its course in and out of the various layers of the suboccipital musculature., Methods: We describe the use of the proximal suboccipital segment of the occipital artery within the occipital groove at the lateral skull base as a donor segment for an interposition graft in revascularization surgery. We present a case detailing the use of this technique for treatment of a dissecting PICA aneurysm and photographs from cadaveric dissections demonstrating relevant anatomy., Results: Our patient is a 62-year-old man who presented with a high-grade subarachnoid hemorrhage from a proximal dissecting-type aneurysm of the posterior inferior cerebellar artery (PICA). Endovascular options were limited to coil sacrifice of the parent vessel, and thus the patient was taken for a far lateral craniotomy, trapping of the aneurysm, and revascularization of the PICA territory via a saphenous vein interposition graft sewn proximally and distally to the occipital artery within the occipital groove and a cortical segment of the affected PICA, respectively. Postoperative imaging demonstrated filling of the PICA territory via the graft, and the patient ultimately recovered from his subarachnoid hemorrhage., Conclusions: The use of the proximal suboccipital segment of the occipital artery is a viable option for a donor in posterior fossa revascularization surgery., (Copyright © 2023 Elsevier Inc. All rights reserved.)

We describe the technical nuances of in-situ bypass for treatment of a fusiform superior cerebellar artery (SCA) aneurysm via surgical trapping and a side-to-end in-situ bypass between duplicated SCAs. Our patient is a 40-year-old male who presented with an incidental aneurysm of the proximal right superior cerebellar artery (SCA). Formal angiography was performed that demonstrated a fusiform morphology of the aneurysm, as well as a duplicated SCA on that side. After extensive counseling, the patient elected to undergo surgical clip reconstruction with possible bypass. A large frontotemporal craniotomy was performed and a combined transsylvian-subtemporal approach to the ventral anterolateral brainstem was performed. After identifying the aneurysm, the tentorium was incised posterior to the insertion of the trochlear nerve to widen the operative field. An end-to-side anastomosis between the duplicated SCAs was performed, followed by trapping of the diseased arterial segment. The patient had an oculomotor nerve palsy post-operatively, however this resolved by his six-month follow-up. In-situ bypass is a viable technique for revascularizing the SCA territory during clip reconstruction of fusiform aneurysms. A duplicated SCA allows for an SCA to SCA bypass. Incising the tentorium can increase visualization of donor and recipient vessels and facilitate performance of the anastomosis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Aims: Intracranial aneurysms are treated with a variety of endovascular devices including coils, stents, and flow diverters. The mechanisms by which these devices result in aneurysm occlusion and subsequent healing have been the subject of significant research using various animal models. The murine Helsinki aneurysm model is a sidewall aneurysm created by the end-to-side anastomosis of a donor aortic graft onto the abdominal aorta of a recipient animal. The aim of this systematic review is to assess the efficacy of different endovascular devices for the treatment of the Helsinki model aneurysm., Methods: We performed a systematic review of Pubmed in accordance with PRISMA guidelines, yielding eight studies detailing the results of endovascular treatment of this preclinical aneurysm model. Studies were included if they provided rates of complete aneurysm occlusion after treatment., Results: In these studies, aneurysms were treated with coiling (n=81, 7 studies), stenting (n=67, 3 studies), stent-coiling (n=13, 1 study), and flow diversion (n=49, 2 studies). The results of each individual study are discussed with the goal of providing a measure of the relative efficacy of different endovascular devices for the treatment of this particular model aneurysm. We also pay special attention to insights into the mechanisms underlying aneurysm healing after different forms of endovascular therapy., Conclusion: The data presented here may be useful to investigators attempting to demonstrate superiority of novel endovascular devices relative to previous device iterations using this preclinical model., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: A significant proportion of patients with subarachnoid hemorrhage have a normal cerebral angiogram. Patients with angiographically negative subarachnoid hemorrhage (anSAH) with either perimesencephalic- (panSAH) or aneurysmal-pattern hemorrhage (aanSAH, also known as diffuse anSAH) have an excellent prognosis, but only if underlying vascular abnormalities are completely excluded. The rate of occult aneurysms in patients with aanSAH varies widely across studies. The purpose of this study was to quantify the value of repeat DSA in these patients., Methods: We reviewed the records of all patients initially diagnosed with aanSAH after a screening DSA at a single tertiary neurovascular referral center from January 2006-April 2018. Patients with panSAH and traumatic SAH were excluded. We also performed a systematic review and meta-analysis of positive second DSAs in previously published case series of patients with aanSAH who underwent two serial DSAs. For meta-analysis, PubMed Central, MEDLINE and Cochrane Library databases were searched for pertinent studies up to November 2019. The rate of aneurysm detection on repeat angiography was extracted from each study. Pooled rates for positive second angiogram were calculated as untransformed proportions in a binary random-effects model meta-analysis. Inter-study heterogeneity was calculated using an I 2 statistic., Results: Three of 27 patients (11.1%) with aanSAH and at least two DSAs were subsequently found to have a cerebral aneurysm in our institutional dataset. Twenty-six studies in our systematic review met inclusion criteria, and the pooled rate of positive second angiogram was 10.4% (95% CI 7.3%-13.5%, P < 0.001). Substantial inter-study heterogeneity was observed in the meta-analysis (I 2  = 61.7%, P < 0.001)., Conclusions: One in 10 patients with aanSAH has an occult ruptured aneurysm. A second-look DSA should be strongly considered in these cases., (© 2021. Springer Science+Business Media, LLC, part of Springer Nature and Neurocritical Care Society.)

Background: Open surgery has traditionally been preferred for the management of bifurcation middle cerebral artery (MCA) aneurysms. Flow diverting stents present a novel endovascular strategy for aneurysm treatment., Objective: To add to the limited literature describing the outcomes and complications in the use of flow diverters for the treatment of these complex aneurysms., Methods: This is a multicenter retrospective review of MCA bifurcation aneurysms undergoing flow diversion. We assessed post-treatment radiological outcomes and both thromboembolic and hemorrhagic complications., Results: We reviewed the outcomes of 54 aneurysms treated with flow diversion. Four (7.4%) of the aneurysms had a history of rupture (3 remote and 1 acute). Fourteen (25.9%) of the aneurysms already underwent either open surgery or coiling prior to flow diversion. A total of 36 out of the 45 aneurysms (80%) with available follow-up data had adequate aneurysm occlusion with a median follow-up time of 12 mo. There were no hemorrhagic complications but 16.7% (9/54) had thromboembolic complications., Conclusion: Flow diverting stents may be a viable option for the endovascular treatment of complex bifurcation MCA aneurysms. However, compared to published series on the open surgical treatment of this subset of aneurysms, flow diversion has inferior outcomes and are associated with a higher rate of complications., (© Congress of Neurological Surgeons 2021.)

Dr Thoralf Sundt III joined the department of neurosurgery at Mayo Clinic in 1969 and served as chairman from 1980 until his death in 1992. Dr Sundt was a pioneer in the field of cerebrovascular neurosurgery and among his many contributions to neurosurgical technology was the introduction of the Sundt clip graft (Codman, Raynham, Massachusetts), which was developed in partnership with Dr George Kees. This device is a vessel-encircling Teflon or Dacron graft loaded on a circular metallic spring initially designed to repair injuries to vessel walls during intracranial aneurysm surgery,1 which was not an uncommon complication resulting from the use of contemporary aneurysm clips.2 When used for this purpose, the clip graft has demonstrated both safety and efficacy in a modern series of surgical treatment of intracranial aneurysm.3 An additional application of the clip graft is the direct clipping of aneurysms, particularly side-wall aneurysms, though Dr Sundt recognized that the potential to occlude perforating arteries adjacent to the aneurysm neck would limit the general use of the clip graft for aneurysm clipping.2 In the following video, we present archival footage of Dr Sundt utilizing the Sundt clip graft during intracranial aneurysm surgery. The 3 cases are of the treatment of posterior communicating, middle cerebral, and anterior communicating artery aneurysms and depict the potential applications of the clip graft during aneurysm surgery. We also present footage of animal experiments Dr Sundt performed to validate the use of the clip graft. This footage likely represents some of the first microscopic neurosurgical recordings ever made. The patients consented to the procedure and to presentation of video recordings at the time of initial surgery. Image of Sundt at 0:11, Reproduced with permission from the American Association of Neurological Surgeons, 5550 Meadowbrook Dr, Rolling Meadows, IL 60008. Figures at 2:26 and 2:28, from Park PJ, Meyer FB, The Sundt clip graft, Neurosurgery, 2010;66(6 suppl operative):300-305, by permission of the Congress of Neurological Surgeons. Figure at 2:35, ©2009 Mayo, Clingman. Used with permission., (© Congress of Neurological Surgeons 2021.)

We conducted a systematic review of the literature to evaluate the efficacy of various treatment modalities for intracranial aneurysms (IA) in patients with moyamoya disease (MMD) based on anatomical location of IA. A comprehensive review of studies documenting single cases or series of MMD patients with concomitant IA was conducted. Aneurysms were classified into two primary anatomical categories: those of the Circle of Willis (CoW) and those of peripheral "moyamoya" collateral vessels. Conservative, endovascular, and open surgical treatment modalities and their outcomes between each anatomical subgroup were descriptively compared. A total of 124 studies consisting of 275 patients with 313 IA were included. Of all IA, 59.6% were located on CoW vessels, 33.7% on peripheral vessels, and 6.7% in "other" locations. Of all CoW IA, 87.2% treated with endovascular techniques had no or minimal deficit at follow-up as compared with 56.7% of those treated with open surgery. Ninety-five percent of patients with peripheral aneurysms treated with endovascular therapy had no or minimal deficit, in contrast to open surgery (69.6%). Of peripheral IA treated conservatively with or without revascularization, 65.7% had spontaneous resolution as compared with 12.0% IA of the CoW. Our results support the use of endovascular techniques for direct treatment of both CoW and peripheral IA. Aneurysms of peripheral vessels respond well to indirect treatment through surgical revascularization as opposed to CoW aneurysms. The quality of evidence is limited due to heterogeneity of included studies and IA management in MMD patients should be considered in a case-specific manne.

Background: Flow diversion is a common endovascular treatment for cerebral aneurysms, but studies comparing different types of flow diverters are scarce., Objective: To perform a propensity score matched cohort study comparing the Pipeline Embolization Device (PED) and Flow Redirection Intraluminal Device (FRED) for posterior circulation aneurysms., Methods: Consecutive aneurysms of the posterior circulation treated at 25 neurovascular centers with either PED or FRED were collected. Propensity score matching was used to control for age, duration of follow-up imaging, adjunctive coiling, and aneurysm location, size, and morphology; previously ruptured aneurysms were excluded. The two devices were compared for the following outcomes: procedural complications, aneurysm occlusion, and functional outcome., Results: A total of 375 aneurysms of the posterior circulation were treated in 369 patients. The PED was used in 285 (77.2%) and FRED in 84 (22.8%) procedures. Aneurysms treated with the PED were more commonly fusiform and larger than those treated with FRED. To account for these important differences, propensity score matching was performed resulting in 33 PED and FRED unruptured aneurysm pairs. No differences were found in occlusion status and neurologic thromboembolic or hemorrhagic complications between the two devices. The proportion of patients with favorable functional outcome was higher with FRED (100% vs 87.9%, p=0.04)., Conclusion: Comparative analysis of PED and FRED for the treatment of unruptured posterior circulation aneurysms did not identify significant differences in aneurysm occlusion or neurologic complications. Variations in functional outcomes warrant additional investigations., Competing Interests: Competing interests: Ajith Thomas: DSMB SCENT trial by STRYKER. Funds paid to institution.Ramesh Grandhi: Consultant for Medtronic neurovascular, BALT neurovascular and Cerenovus.Christoph Griessenauer: Consultant for Stryker and received research funding from Medtronic.Naci Kocer: Consultant and proctoring agreement with MicroVention.Philipp Taussky:Reply: Consultant for Medtronic, Stryker, Cerenovus.Peter Kan: Consultant for Stryker, Medtronic, MicroVention, and Cerenovus.Vincent Tutino: Co-founder of Neurovascular Diagnostics, Inc.Monika Killer: Research grant from MicroVention/Terumo.Waleed Brinjikji: Microvention and Cerenovus consultant.Tom Marotta: Medtronic proctoring.Timo Krings: Consultant for Stryker, Medtronic, Penumbra, Cerenovus. stockholder in Marblehead Inc, royalties from Thieme.Clemens Schirmer: Research Support from Penumbra. Shareholder in Neurotechnology Investors.Giuseppe Lanzino: Consultant for Superior Medical Editing and Nested Knowledge.Christian Ulfert: Consulting fees from Johnson & Johnson.Charles Matouk: Consultant for Medtronic, Penumbra, Silk Road MedicalMarkus Mohlenbruch: Consultant for Medtronic, MicroVention, Stryker. Grants/grants pending: Balt (money paid to the institution), MicroVention (money paid to the institution). Payment for lectures includings service on speakers bureaus: Medtronic, MicroVention, and Stryker.Marshall Cress: Consulting for Cannon and Cerenovus.None related to this study and none are declared for the reminder of the authors., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The Pipeline Embolization Device (PED; Medtronic) has been used off-label for the treatment of challenging posterior circulation aneurysms. Data on this modality are primarily limited to small retrospective single-center series., Objective: To assess safety and efficacy of this treatment by establishing an international, multicenter collaboration., Methods: Consecutive posterior circulation aneurysms treated with the PED from 2012 to 2019 across 11 neurovascular centers were retrospectively reviewed. Baseline demographics, aneurysm and treatment characteristics, complications, occlusion status, and functional outcome were assessed., Results: There were 149 posterior circulation aneurysms treated with PED in 146 patients. A total of 24 (16.4%) patients presented with subarachnoid hemorrhage. Most aneurysms were dissecting/blister (36.2%) in morphology, followed by saccular (35.6%) and fusiform (28.2%). The most common locations were the vertebral (51.7%) and basilar arteries (22.8%). Complete or near-complete occlusion (>90%) was achieved in 90.9% of aneurysms at a median follow-up of 12 mo. Dissecting/blister aneurysms were most likely to occlude (P = .06). Symptomatic neurologic complications occurred in 9.4% of aneurysms, associated with larger size, ruptured presentation, presentations with brain stem compression, cranial nerve palsy, or stroke. Favorable functional outcome (modified Rankin Score 0-2) was achieved in 86.2% of patients. There were 6 fatalities of which 4 occurred in aneurysmal subarachnoid hemorrhage patients., Conclusion: This multicenter study shows that PED for the treatment of posterior circulation is preferentially used for the treatment of fusiform and dissecting/blister aneurysm morphologies. Despite the challenges presented by these less-common morphologies, flow diversion may be performed with a neurologic complication rate of about 10% and favorable long-term aneurysm occlusion rates., (Copyright © 2020 by the Congress of Neurological Surgeons.)

Background: Hemorrhagic vascular lesions in the posterior cerebral circulation such as ruptured aneurysms and dissections can be challenging to treat. Flow diversion has become an important off-label option, but few studies have analyzed the safety of these devices in this setting. Using an international, multicenter cohort, we reviewed posterior circulation subarachnoid hemorrhage (SAH) patients treated with the Pipeline Embolization Device (PED) in the acute setting and assessed the incidence of Takotsubo cardiomyopathy (TCM)., Methods: Eleven neurovascular centers were queried to identify cases of posterior circulation aneurysms or dissections treated with the PED in the acute setting of SAH. Among those, 5 centers had cases that matched the inclusion criteria. The following variables were evaluated: demographics, the location and morphology of the aneurysm, the clinical presentation, the specific form of treatment, complications including the development of TCM, antiplatelet medication regimen, and follow-up time., Results: A total of 23 patients were treated with PED after posterior circulation SAH, and 13% of these developed TCM. The lesions were the result of hemorrhagic intracranial dissection (8 patients), ruptured pseudoaneurysm (3), ruptured saccular aneurysm (7), blister aneurysm (4), and fusiform aneurysm (1). Ninety-one percent of patients had complete or near-complete aneurysm occlusion on follow-up imaging. Five patients died in the perioperative period; 16/18 survivors had a favorable outcome., Conclusions: We describe an unexpectedly high incidence of TCM after the placement of PEDs in patients with posterior circulation SAH in our large case series. Further studies will be needed to elucidate possible causes., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Intracranial aneurysms (IA) are associated with moyamoya disease (MMD). There are no clinically tested treatment guidelines. Reporting of cases is vital to better understand the underlying pathophysiology and potential ethnic predispositions and improve patient selection for intervention., Methods: Records of all patients diagnosed with MMD with concomitant IA who presented to our institution were retrospectively reviewed. Data related to demographic, clinical, MMD characteristics, aneurysm characteristics, surgical intervention, and follow-up were collected from the records of each patient. Aneurysm location was categorized into circle of Willis (CoW) aneurysms (originating from the CoW or its major branches) and peripheral aneurysms (arising from choroidal or lenticulostriate arteries)., Results: Ten patients were found to have a total of 14 IA. All patients were white. Ten aneurysms (71%) were classified as CoW aneurysms and 4 (29%) were classified as peripheral. Seven of 10 CoW aneurysms (70%) were located in the anterior circulation, whereas 3 (30%) were located in the posterior circulation. Aneurysms of anterior and posterior circulations were most commonly treated with coil embolization, whereas peripheral artery aneurysms were most commonly treated with either cerebral revascularization alone or aneurysm excision., Conclusions: Revascularization surgery seems to be an effective method of indirectly treating IA in patients with MMD. Previous literature in addition to our series shows that endovascular embolization is safe and efficacious in treating IA of most locations in patients with MMD. The use of open microsurgery for direct aneurysm treatment in this population poses many challenges., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Introduction: Stent-assisted coiling (SAC) of intracranial aneurysms paved the way for endovascular coiling of wide-neck and bifurcation aneurysms, improving rates of aneurysm obliteration and recurrence. In this review, we provide a comprehensive review of the most recent advances related to stent-assisted coiling of intracranial aneurysm., Areas Covered: The authors have made an attempt to cover the inception, applications, and limitations of SAC of intracranial aneurysms. Special focus is given to 1) the current and recently introduced SAC techniques, 2) most recent advances in device technology, and 3) outcome data for the discussed techniques and devices. The authors also discuss the potential future direction of SAC., Expert Opinion: technical refinements in the field of SAC should continue to focus on device development and addressing the limitations of SAC, namely aneurysm recurrence and need of antiplatelet agents. Although the recurrence rate of SAC has not been shown to be inferior to flow diverters, the use of intrasaccular and intravascular flow diverters are likely to expand in the future at the expense of SAC.

Background: Ruptured large and partially thrombosed aneurysms are challenging lesions to treat successfully., Methods: We describe the surgical treatment of a large, ruptured partially thrombosed middle cerebral artery (MCA) aneurysm. Once the Sylvian fissure is dissected, temporary clips are placed, and the clot is evacuated with simple microsuction and ultrasonic aspiration. The aneurysm is then carefully clip reconstructed to avoid compromise of the parent vessels., Conclusion: In cases of surgical clipping of large, thrombosed aneurysms, it is important to be aware of a few, but critically important, pitfalls to ensure successful outcome.

Background: The effect of age on risk of intracranial aneurysm rupture is not well understood. We investigated the clinical course of patients 65 years and older with conservatively managed unruptured intracranial aneurysms (UIA) and determined risk factors for rupture in this population., Methods: We reviewed prospectively collected data on baseline characteristics and long-term follow-up for patients aged 65 years and older with an UIA that were initially managed with observation. The association between patient and aneurysmal characteristics and risk of rupture was performed using a multivariate Cox proportional hazard regression model., Results: There were 214 patients (mean age: 74.7 years, SD: 6.0) included in our study. The median follow-up time was 3.7 years, with a cumulative follow-up time of 883.7 person-years. During the study period, seven patients (3.3%) received interventional treatment of their UIA and eight patients (3.7%) experienced aneurysmal subarachnoid hemorrhage, yielding an annual risk of rupture of 0.9%. All aneurysms that ruptured were at least 10 mm in size. Increasing patient age [unit relative risk (RR) 1.19, 95% CI: 1.07-1.36, P=0.002], larger aneurysmal size (unit RR 1.10, 95% CI: 1.02-1.17, P=0.021), and increasing PHASES Score (unit RR 1.62, 95% CI: 1.32-2.06, P<0.001) were associated with higher risk of rupture., Conclusions: Our data do not suggest that UIA in older patients carry a high risk of rupture. A conservative approach appears justified in these patients, with the exception of selected patients with larger aneurysms (>10 mm in diameter) and low risk of interventional procedure.

Objective: It is generally accepted that larger saccular intracranial aneurysms are at greater risk to rupture. We investigated whether aneurysm location influences the effect of aneurysm size on the propensity of rupture., Methods: We reviewed patient and aneurysm characteristics in a consecutive series of patients with unruptured and ruptured aneurysms presenting to our institution between 2006 and 2018. Differences between unruptured and ruptured aneurysms at different locations were subsequently investigated., Results: A total of 766 aneurysms in 568 patients were included, with 355 and 411 unruptured and ruptured aneurysms, respectively. There were significant differences in the distribution of aneurysm location between unruptured and ruptured aneurysms (P < 0.001). The most common locations of unruptured aneurysms were the middle cerebral artery (MCA) (27.6%) and paraclinoid internal carotid artery (ICA) (25.4%), whereas the most common locations of ruptured aneurysms were the anterior communicating artery (ACOM) (34.8%) and posterior communicating artery (17.8%). Ruptured aneurysms were larger than unruptured aneurysms at all locations except at the ACOM, where there was no difference in size between unruptured and ruptured aneurysms (5.4 vs. 5.8 mm, respectively; P = 0.40). Ruptured ACOM aneurysms were also smaller than ruptured aneurysms of the paraclinoid ICA (5.8 vs. 10.3 mm; P < 0.001), MCA (5.8 vs. 8.0 mm; P = 0.021), and basilar apex (5.8 vs. 10.5 mm; P < 0.001), respectively., Conclusions: We observed no difference in size between unruptured and ruptured ACOM aneurysms, possibly suggesting a greater susceptibility for ACOM aneurysms to rupture at smaller sizes., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background and Purpose: Previous studies have documented disparate access to cerebrovascular neurosurgery for patients of different racial and socioeconomic backgrounds. We further investigated the effect of race and insurance status on access to treatment of unruptured intracranial aneurysms (UIAs) and compared it with data on patients with aneurysmal subarachnoid hemorrhage (aSAH)., Methods: Through the use of a national database, admissions for clipping or coiling of an UIA and for aSAH were identified. Demographic characteristics of patients were characterized according to age, sex, race/ethnicity, and insurance status, and comparisons between patients admitted for treatment of an UIA versus aSAH were performed., Results: There were 10 545 admissions for clipping or coiling of an UIA and 33 166 admissions for aSAH between October 2014 and July 2018. White/non-Hispanic patients made up a greater proportion of patients presenting for treatment of an UIA than those presenting with aSAH (64.3% vs 48.2%; P<0.001), whereas black/Hispanic patients presented more frequently with aSAH than for treatment of an UIA (29.3% vs 26.1%; P=0.006). On multivariate linear regression analysis, the proportion of patients admitted for management of an UIA relative to those admitted for aSAH increased with the proportion of patients who were women (P<0.001) and decreased with the proportion of patients with a black/Hispanic background (P=0.010) and those insured with Medicaid or without insurance (P=0.003)., Conclusion: For patients with UIAs, racial, ethnic, and socioeconomic backgrounds appear to continue to influence access to treatment., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Congenital hypoplasia or absence of the A1 segment of the anterior cerebral artery (ACA) has been associated with increased incidence of berry aneurysms at the anterior communicating artery (Acom) complex. It is not known, however, whether this anatomic variant also predisposes patients to complications after aneurysmal subarachnoid hemorrhage., Methods: Patients were included for analysis if they presented to our institution for clipping or coiling of an Acom aneurysm between the years of 2001 and 2013. Patients were deemed to have cerebral infarction if a new hypodensity in a vascular distribution was visualized on CT imaging. The association between A1 segmental abnormalities and radiologic infarction was subsequently evaluated in a risk-adjusted manner using stepwise multivariable logistic regression analysis., Results: Of 145 patients who presented with aneurysmal subarachnoid hemorrhage after rupture of an Acom aneurysm, 31 (21.4%) had a hypoplastic or absent A1 segment. On univariate analysis, there was a trend toward an increased rate of radiologic infarction in patients with A1 segment abnormalities (OR=2.11, 95% CI: 0.93-4.79; P=0.0757). On multivariable analysis, a hypoplastic or absent A1 segment was significantly associated with an increased rate of radiologic infarction (OR=2.54, 95% CI: 1.02-6.43; P=0.0466)., Conclusions: Our results suggest that a hypoplastic or absent A1 segment is associated with cerebral infarction following subarachnoid hemorrhage from ruptured Acom aneurysms, indicating a potential need for heightened vigilance and a reduced threshold for therapeutic intervention in patients harboring this abnormality.

Background: Flow diversion (FD) has emerged as an effective treatment modality for aneurysms of the posterior communicating artery (PCOM). Whether or not a fetal posterior circulation (FPC) affects PCOM aneurysm occlusion rates after FD remains undetermined., Methods: We performed a retrospective cohort study in which treatment outcomes for FD of PCOM aneurysms from multiple institutions were reviewed. The primary outcome of interest was complete aneurysm occlusion at last follow-up. The presence of a FPC, defined as a PCOM diameter larger than that of the P1 segment, was noted and its relationship to complete aneurysm occlusion was investigated using a Cox proportional hazards model., Results: There were 49 patients with 49 PCOM aneurysms treated with FD who met inclusion criteria for analysis. A FPC was present in 16 patients (32.7%). Complete aneurysm occlusion was observed in 34 patients (69.4%). Complete occlusion was less common for patients with a FPC (43.7% vs. 81.8%; P = 0.007). For patients with and without a FPC, median time to occlusion was 51 and 6 months, respectively (P = 0.002). Using a multivariable Cox proportional hazards model, a FPC was associated with reduced odds of complete occlusion on last follow-up (risk ratio 0.35, 95% confidence interval 0.14-0.89; P = 0.029)., Conclusions: Our results indicate reduced efficacy of FD for the treatment of PCOM aneurysms associated with a FPC. These findings may influence treatment selection for aneurysms at this location., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: Clinical trials forming the basis of current guidelines for the management of intracranial aneurysms have relied on patient-reported modified Rankin Scale (mRS) scores to assess functional outcome. The effect of patient demographics on perception of disability and, by extension, patient-reported mRS score, is not well understood., Methods: A consecutive series of patients with a previously treated or untreated unruptured intracranial aneurysm (UIA) prospectively underwent a structured interview with a trained nurse. At the conclusion of this interview, the patients were assigned an mRS score in accordance with their degree of disability. During the same visit, patients were also required to grade themselves on a paper sheet containing the mRS and corresponding information. Data on patient and aneurysm characteristics were also collected during the same visit. Agreement between patient- and nurse-reported mRS scores was assessed using Cohen's kappa coefficient. The effect of patient demographics on the frequency of higher patient- than nurse-reported mRS scores was assessed using the Pearson's chi-square and Fisher's exact tests., Results: A total of 209 patients with a UIA were included in the study, 38 of whom (18.2%) had undergone previous treatment. The majority of patients were female (161/209, 77.0%), and the mean age of the cohort was 60.2 years (SD 13.7 years). Agreement between patient- and nurse-reported mRS scores occurred in 72.7% of cases (95% CI 66.3%-78.3%), with a kappa coefficient of 0.58 (95% CI 0.49-0.67). Patients younger than 75 years were more likely to report a higher mRS score than the nurse (19.4% vs 3.4%, p = 0.034). Among female patients, those without a college degree were more likely to report a higher mRS score than the nurse (22.5% vs 9.5%, p = 0.035)., Conclusions: The results suggest that patient demographics may influence perception of disability. These findings should be considered when using patient-reported mRS scores to determine functional outcome.

OBJECTIVE The mechanism by which greater institutional case volume translates into improved outcomes after surgical clipping of unruptured intracranial aneurysms (UIAs) is not well established. The authors thus aimed to assess the effect of case volume on the rate of various types of complications after clipping of UIAs. METHODS Using information on the outcomes of inpatient admissions for surgical clipping of UIAs collected within a national database, the relationship of institutional case volume to the incidence of different types of complications after clipping was investigated. Complications were subdivided into different categories, which included all complications, ischemic stroke, intracerebral hemorrhage, medical complications, infectious complications, complications related to anesthesia, and wound complications. The relationship of case volume to different types of complications was assessed using linear regression analysis. The relationships between case volume and overall complication and stroke rates were fit with both linear and quadratic equations. The numerical cutoff for institutional case volume above and below which the authors found the greatest differences in mean overall complication and stroke rate was determined using classification and regression tree (CART) analysis. RESULTS Between October 2012 and September 2015, 125 health care institutions reported patient outcomes from a total of 6040 cases of clipping of UIAs. On linear regression analysis, increasing case volume was negatively correlated to both overall complications (r 2 = 0.046, p = 0.0234) and stroke (r 2 = 0.029, p = 0.0557) rate, although the relationship of case volume to the complication (r 2 = 0.092) and stroke (r 2 = 0.067) rate was better fit with a quadratic equation. On CART analysis, the cutoff for the case number that yielded the greatest difference in overall complications and stroke rate between higher- or lower-volume centers was 6 cases/year and 3 cases/year, respectively. CONCLUSIONS Although the authors confirm that increasing case volume is associated with reduced complications after clipping of UIAs, their results suggest that the relationship between case volume and complications is not necessarily linear. Moreover, these results indicate that the effect of case volume on outcome is most evident between very-low-volume centers relative to centers with a medium-to-high volume.

Objective: Anatomic variations of the anterior communicating artery (ACOM) complex have been shown to influence ACOM aneurysm morphology. It is not known whether these variations predispose unruptured ACOM aneurysms to grow over time., Methods: We retrospectively reviewed the course of patients with untreated, unruptured ACOM aneurysms monitored with serial imaging at our institution. The primary outcome of interest was aneurysm growth. Predictors of aneurysm growth were determined using a Cox proportional hazards model., Results: There were 81 patients with an unruptured ACOM aneurysm who were included in our study. Growth occurred in 9 (11.1%) patients, yielding a yearly growth rate of 2.8%. Aneurysms that grew were larger on initial detection than were those that remained stable in size (8.3 mm vs. 6.2 mm; P = 0.031). The ratio of the diameter of A1 segments was greater in patients with aneurysms that grew (2.1 vs. 1.4; P = 0.003), as was the frequency of patients with an A1 ratio >2.3 (25.0% vs. 6.6%; P = 0.023). Among aneurysms that grew, location at the A1-A2 junction was more common than origination solely from the ACOM (88.9% vs. 11.1%). When follow-up time was adjusted for, increasing aneurysm size (unit relative risk [RR] 1.25, 95% confidence interval [CI] 1.06-1.45; P = 0.011) and location at the A1-A2 junction (RR 6.15, 95% CI 1.12-114.49; P = 0.035) were significant predictors of aneurysm growth., Conclusions: We identify several anatomic characteristics that may be associated with increased risk of ACOM aneurysm growth. These data could influence management strategies of unruptured ACOM aneurysms., (Copyright © 2017 Elsevier Inc. All rights reserved.)

OBJECTIVE Hypoplasia of the A 1 segment of the anterior cerebral artery is frequently observed in patients with anterior communicating artery (ACoA) aneurysms. The effect of this anatomical variant on ACoA aneurysm morphology is not well understood. METHODS Digital subtraction angiography images were reviewed for 204 patients presenting to the authors' institution with either a ruptured or an unruptured ACoA aneurysm. The ratio of the width of the larger A 1 segment to the smaller A 1 segment was calculated. Patients with an A 1 ratio greater than 2 were categorized as having A 1 segment hypoplasia. The relationship of A 1 segment hypoplasia to both patient and aneurysm characteristics was then assessed. RESULTS Of 204 patients that presented with an ACoA aneurysm, 34 (16.7%) were found to have a hypoplastic A 1 . Patients with A 1 segment hypoplasia were less likely to have a history of smoking (44.1% vs 62.9%, p = 0.0410). ACoA aneurysms occurring in the setting of a hypoplastic A 1 were also found to have a larger maximum diameter (mean 7.7 vs 6.0 mm, p = 0.0084). When considered as a continuous variable, increasing A 1 ratio was associated with decreasing aneurysm dome-to-neck ratio (p = 0.0289). There was no significant difference in the prevalence of A 1 segment hypoplasia between ruptured and unruptured aneurysms (18.9% vs 10.7%; p = 0.1605). CONCLUSIONS Our results suggest that a hypoplastic A 1 may affect the morphology of ACoA aneurysms. In addition, the relative lack of traditional risk factors for aneurysm formation in patients with A 1 segment hypoplasia argues for the importance of hemodynamic factors in the formation of ACoA aneurysms in this anatomical setting.

Objective: The effect of patient age on the likelihood of recurrence of ruptured aneurysms after endovascular coil embolization is not well understood. Our aim was to compare the incidence of aneurysmal recurrence after coiling between young and old patients., Methods: We performed a retrospective cohort study on patients presenting to our institution with a ruptured intracranial aneurysm treated with endovascular coiling. Aneurysm recurrence was defined as a Modified Raymond Roy Classification (MRRC) grade of 3A or 3B performed on first follow-up angiography. Patients were dichotomized into young and old patient groups, with patients 65 years and older categorized as older adults. The relationship between patient age and the likelihood of aneurysm recurrence was then investigated using multivariate logistic regression analysis., Results: There were 156 patients who met our inclusion criteria for analysis, 37 (23.7%) of whom were greater than or equal to 65 years of age. Elderly patients were less likely to experience aneurysm recurrence (27.0% vs. 42.9%, respectively; P = 0.085) or to undergo aneurysm retreatment (18.9% vs. 37.0%, respectively; P = 0.041). On multivariate analysis, after adjusting for smoking status, aneurysmal size, coil-embolization ratio, and MRRC grade at time of treatment, elderly age was independently associated with a reduced risk of aneurysm recurrence (odds ratio, 0.33; 95% confidence interval, 0.11-0.92; P = 0.034)., Conclusions: Our results suggest that elderly age may confer a reduced risk of aneurysmal recurrence after endovascular coiling, providing further evidence that coiling should be considered a first-line therapy in elderly patients with a ruptured aneurysm., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The effect of age on patient outcomes after rupture of the anterior communicating artery (Acom) aneurysms is not well-defined. We performed a retrospective cohort study of patients presenting to our institution with a ruptured Acom aneurysm between 2003 and 2012. Patients were divided into two groups on the basis of age at presentation, with patients 65years and older categorized as the elderly group. The effect of elderly age on patient outcomes was then evaluated using multivariate logistic regression analysis. There were 147 patients presenting with a ruptured Acom aneurysm. Of these, 41 (27.9%) were 65years or older. Patients in the elderly group were more likely to be female (68.3% vs. 40.6%, p=0.0026), and less likely to be active smokers (22.0% vs. 60.4%, p<0.0001) or to abuse alcohol (7.3% vs. 21.7%, p=0.0404). Elderly patients were more likely to have a history of hypertension (70.7% vs. 52.8%, p=0.0487) and coronary artery disease (19.5% vs. 2.8%, p=0.0006). Elderly patients were more likely to require a ventriculostomy (61.0% vs. 37.7%, p=0.0109) and ultimately to require permanent cerebrospinal fluid diversion (36.6% vs. 17.0%, p=0.0106). On adjusted analysis, age 65 years or older was associated with a greater likelihood of poor outcome at last follow-up within 1year of aneurysmal subarachnoid hemorrhage (odds ratio=3.76, 95% confidence interval: 1.30-11.78, p=0.0144). Our results suggest that elderly age is an independent risk factor for poor functional outcome after rupture of an Acom aneurysm., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Introduction: Large-scale studies examining the incidence and predictors of perioperative complications after surgical clipping of unruptured intracranial aneurysms (UIA) using nationally representative prospectively collected data are lacking in the literature., Methods: Using the American College of Surgeons' National Surgical Quality Improvement Program (ACS-NSQIP) dataset, we conducted a retrospective analysis of the complications experienced by patients that underwent surgical management of a UIA between the years of 2007 and 2013. The primary outcomes of interest were mortality within the 30-day perioperative period and adverse discharge disposition to a location other than home. Predictors of morbidity and mortality were elucidated using multivariable logistic regression analyses controlling for available patient demographic, comorbidity, and operative characteristics., Results: 662 patients were identified in the ACS-NSQIP dataset for operative management of an unruptured aneurysm. The observed rates of 30-day mortality and adverse discharge disposition were 2.27% and 19.47%, respectively. A hundred and eight (16.31%) patients developed at least one major complication. On multivariable analysis, death within 30days was significantly associated with increased operative time (OR 1.005 per minute, 95% CI 1.002-1.008) and chronic preoperative corticosteroid use (OR 28.4, 95% CI 1.68-480.42), whereas major complication development was associated with increased operative time (OR 1.004 per minute, 95% CI 1.002-1.006), age (OR 1.017 per year, 95% CI 1-1.034), preoperative dependency (OR 3.3, 95% CI 1.16-9.40) and diabetes mellitus (OR 2.89, 95% CI 1.45-5.75). Lastly, increasing age (OR 1.017 per year, 95% CI 1-1.034) as well as ASA Class 3 (OR 1.73, 95% CI 1.08-2.77) and 4 (OR 2.28, 95% CI 1.1-4.72) were independent predictors of discharge to a location other than home., Conclusion: Our study yields morbidity and mortality benchmarks for UIA surgery in a representative, national surgical registry. It will hopefully aid in recognizing those patients at greater risk for postoperative complications following surgical management, leading to appropriate changes in treatment strategies for this selected group of patients., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Objective: A large national surgical registry was used to establish national benchmarks and associated predictors of major neurologic complications (i.e., coma and stroke) after surgical clipping of unruptured intracranial aneurysms., Methods: The American College of Surgeons National Surgical Quality Improvement Program data set between 2007 and 2013 was used for this retrospective cohort analysis. Demographic, comorbidity, and operative characteristics associated with the development of a major neurologic complication (i.e., coma or stroke) were elucidated using a backward selection stepwise logistic regression analysis. This model was subsequently used to fit a predictive score for major neurologic complications., Results: Inclusion criteria were met by 662 patients. Of these patients, 57 (8.61%) developed a major neurologic complication (i.e., coma or stroke) within the 30-day postoperative period. On multivariable analysis, operative time (log odds 0.004 per minute; 95% confidence interval [CI], 0.002-0.007), age (log odds 0.05 per year; 95% CI, 0.02-0.08), history of chronic obstructive pulmonary disease (log odds 1.26; 95% CI, 0.43-2.08), and diabetes (log odds 1.15; 95% CI, 0.38-1.91) were associated with an increased odds of major neurologic complications. When patients were categorized according to quartile of a predictive score generated from the multivariable analysis, rates of major neurologic complications were 1.8%, 4.3%, 6.7%, and 21.2%., Conclusions: Using a large, national multi-institutional cohort, this study established representative national benchmarks and a predictive scoring system for major neurologic complications following operative management of unruptured intracranial aneurysms. The model may assist with risk stratification and tailoring of decision making in surgical candidates., (Copyright © 2016 Elsevier Inc. All rights reserved.)