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Background and Objectives: Deep brain stimulation (DBS) has developed into an effective therapy for several disease states including treatment-resistant Parkinson disease and medically intractable essential tremor, as well as segmental, generalized and cervical dystonia, and obsessive-compulsive disorder (OCD). Dystonia and OCD are approved with Humanitarian Device Exemption. In addition, DBS is also approved for the treatment of epilepsy in the anterior nucleus of the thalamus. Although overall considered an effective treatment for Parkinson disease and epilepsy, a number of specific factors determine the treatment success for DBS including careful patient selection, effective postoperative programming of DBS devices and accurate electrode placement. Furthermore, invasiveness of the procedure is a rate limiter for patient adoption. It is desired to explore a less invasive way to deliver DBS therapy., Methods: Here, we report for the first time the direct comparison of endovascular and parenchymal DBS in a triplicate ovine model using the anterior nucleus of the thalamus as the parenchymal target for refractory epilepsy., Results: Triplicate ovine studies show comparable sensing resolution and stimulation performance of endovascular DBS with parenchymal DBS., Conclusion: The results from this feasibility study opens up a new frontier for minimally invasive DBS therapy., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc on behalf of Congress of Neurological Surgeons.)

Introduction: Cervical stenosis (CS) is the pathologic narrowing of the central canal of the cervical spine. It is often incidentally discovered. It is unclear whether pre-existing CS can lead to worse outcomes and higher incidences of post-traumatic spinal cord injury (SCI)., Methods: We conducted a systematic review and meta-analysis of studies collected using keywords "cervical stenosis" AND ("trauma" OR "injury"). 381 articles were collected from Pubmed, Embase, and Cochrane, and 2,675 patients from 7 studies were included in the final analyses. Neo-bayesian statistics were used to estimate a number needed to treat (NNT)., Results: In a meta-analysis of studies with internal controls, patients with pre-existing CS are not at a higher risk of post-traumatic SCI (OR 2.73, 95% CI 0.78-9.50). However, CS patients have a greater incidence of SCI (0.41, 95%-CI 0.26-0.56) compared to patients without CS (0.18, 95%-CI 0.14-0.22). Patients with CS were also over-represented in the population of SCI patients (0.46, 95%-CI 0.27; 0.65). Using Neo-bayesian statistics, we estimate that 70 patients with CS must be treated to prevent one SCI. In patients who participate in higher risk physical activities, the NNT may be lower., Conclusions: Though patients with pre-existing CS do not have higher odds of SCI in studies with internal controls, we find that patients with CS do have higher incidences of SCI and are over-represented in the population of SCI patients. In select CS patients with active lifestyles, close follow-up and consideration of various treatment options may be indicated., (Copyright © 2024. Published by Elsevier Inc.)

Introduction: A scoring system to characterize the efficacy of middle meningeal artery (MMA) embolization is lacking and would help predict the likelihood of subdural hematoma resolution., Methods: We developed a simple angiographic classification system ranging from 0 to 3 for quantifying MMA Patency After Coil Embolization (PACE) based residual flow distal to the embolization. MMA embolizations using coils at our institution were used to validate the PACE score system using procedural angiograms. Follow-up CT scans following embolization were reviewed for acute blood products, and to characterize long-term resolution., Results: 60 patients were included in the study, with a total of 80 subdural hematomas with follow-up imaging that were available for analysis. 37 patients had a PACE score of 0, 18 had a PACE score of 1, 4 had a PACE score of 2, and 1 had a PACE score of 3. The presence of acute blood products was significantly lower in PACE 0 compared to PACE 1, 2, or 3. The cross-sectional area of the chronic subdural collections was statistically lower on follow-up CT scans after coil embolization., Conclusions: Coil embolization of the MMA may reduce the incidence of acute blood products after embolization and decrease the cross-sectional area of chronic subdural hematoma on long-term follow-up. Lower PACE scores may correlate with lower rates of acute blood products after the procedure and increased resolution of chronic subdural hematoma on follow-up. A larger cohort is required to characterize the superiority between the PACE scores., Competing Interests: Declaration of conflicting interestsDr Santiago-Dieppa is a consultant for Medtronic, Balt, and Stryker.

Laser interstitial thermal therapy (LITT) is a minimally invasive modality for addressing intracranial pathology. LITT is recognized as a primary therapeutic option for a range of intracranial pathologies, particularly in inaccessible lesions. In the present study, we systematically review the evidentiary base supporting contemporary applications of LITT. Three databases were queried according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify studies presenting primary data on contemporary applications of LITT. Studies were screened to determine eligibility according to predefined eligibility criteria. Thirty-nine studies featuring 1533 patients were included. Across all uses, including treatment of brain tumors, radiation necrosis (RN), mesial temporal lobe epilepsy (MTLE), epilepsy secondary to hypothalamic hamartomas, and cavernous malformations, LITT is safe and efficacious, especially in patients who are ineligible for or not amenable to craniotomy. LITT is particularly useful in treating recurrent brain metastases and glioblastomas, with an increased overall survival in the latter of up to 26 months. In the management of RN (pseudo-progression), studies show faster steroid cessation in patients treated with LITT compared to medical management while also pre-empting the need for open craniotomy and stereotactic biopsy in the workup of suspected recurrence. In MTLE, LITT offers comparable rates of seizure freedom and reduction compared to anterior temporal lobectomy with potentially improved neuropsychiatric outcomes. LITT is an advantageous option for treating brain tumors, RN, and MTLE, among other pathologies. Continued investigation in emerging LITT applications can help clinicians expand the use of magnetic resonance imaging-guided stereotactic laser ablation technology into the treatment of a broad spectrum of central nervous system pathologies., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: For rare neuro-endovascular cases in which transfemoral access is not feasible and the palmar circulation is insufficient for radial artery access, ulnar artery access may be considered., Materials and Methods: Mechanical thrombectomy via ulnar artery access was performed to preserve the dominant radial artery. The ulnar artery was serial dilated to 7-French with microdilator. Angiography was performed using a diagnostic catheter. The sheath was exchanged for a guide catheter, and a triaxial system was inserted. A mechanical thrombectomy was performed. The systematic literature review included all studies pertaining to techniques for ulnar artery access for neurointervention in the last 20 years (2003-2023) published in the PubMed, Web of Science, and Embase databases., Results: 67-year-old male developed left MCA syndrome in the setting of an infected abdominal aortic endograft. A transfemoral approach was ruled out due to concern for crossing the infected endograft. Allen test and ultrasound demonstrated that the right radial artery was of adequate size for access, but the ulnar artery was insufficient to support the palmar arch. Mechanical thrombectomy resulted in TICI 3 reperfusion. Systematic review of the literature yielded 2 case series and 1 case report of transulnar neurovascular procedures. Access site complications were rare and included 3 access site hematomas and 1 ulnar artery occlusion., Conclusion: We report our technique of serial dilation of the ulnar artery for neuroendovascular procedures and provide a systematic review of the literature for complication avoidance in ulnar artery access., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background and Objectives: Multiple preferences exist for embolic materials selection in middle meningeal artery embolization (MMAE) for chronic subdural hematoma with limited comparative literature data. Herein, we compare different embolic materials., Methods: Consecutive patients undergoing MMAE for chronic subdural hematoma at 14 North-American centers (2018-2023) were classified into 3 groups: (a) particles, (b) Onyx, (c) n-butyl cyanoacrylate (n-BCA). The end points were unplanned rescue surgery, radiographic success (≥50% reduction in hematoma thickness at last imaging "minimum of 2 weeks"), and major complications. Initial unmatched analysis compared the 3 groups; subsequent propensity score matching (PSM) compared particles vs liquid embolics (groups b and c combined). Additional subgroup PSM analyses compared particles vs Onyx, particles vs n-BCA, and Onyx vs n-BCA. All matched analyses controlled for age, sex, concurrent surgery, previous surgery, hematoma thickness, midline shift, pretreatment antithrombotics, and baseline modified Rankin Scale., Results: Eight hundred and seventy-two patients (median age 73 years, 72.9% males) underwent 1070 MMAE procedures. Onyx was most used (41.4%), then particles (40.3%) and n-BCA (15.5%). Surgical rescue rates were comparable between particles, Onyx, and n-BCA (9.8% vs 7% vs 11.7%, respectively, P = .14). Similarly, radiographic success (78.8% vs 79.3% vs 77.4%; P = .91) and major complications (2.4% vs 2.3% vs 2.5%; P = .83) were comparable. The PSM comparing particles vs liquid generated 128 matched pairs; general anesthesia and bilateral procedures were significantly higher in particles (37.8% vs 21.3%; P = .004 and 39.8% vs 27.3%; P = .034, respectively). No differences in surgical rescue, radiographic improvement, or major complications were noted ( P > .05). Concurrently, PSM comparing particles vs Onyx, particles vs n-BCA, and Onyx vs n-BCA, resulted in 112, 42, and 40 matched pairs, respectively, without differences in surgical rescue, radiographic success, or major complications ( P > .05)., Conclusion: We found no differences in radiological improvement, surgical rescue, or major complications between embolic materials in MMAE. Current randomized trials are exclusively using liquid embolics, and these data suggest that future trials involving particles are likely to produce similar outcomes., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Implementation of standardized protocols in neurooncology during the surgical resection of brain tumors is needed to advance the clinical treatment paradigms that use tissue for diagnosis, prognosis, bio-banking, and treatment. Currently recommendations on intraoperative tissue procurement only exist for diffuse gliomas but management of other brain tumor subtypes can also benefit from these protocols. Fresh tissue from surgical resection can now be used for intraoperative diagnostics and functional precision medicine assays. A multidisciplinary neuro-oncology perspective is critical to develop the best avenues for practical standardization. This perspective from the multidisciplinary Oncology Tissue Advisory Board (OTAB) discusses current advances, future directions, and the imperative of adopting standardized protocols for diverse brain tumor entities. There is a growing need for consistent operating room practices to enhance patient care, streamline research efforts, and optimize outcomes., Competing Interests: The authors, except WJS, are members of an advisory board sponsored by Nico Corporation. However, Nico Corporation was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication. CB is a consultant for Depuy-Synthes, Bionaut Labs, Haystack Oncology and Privo Technologies. CB is a co-founder of OrisDx and Belay Diagnostics. HB is a chairman of the Medical Advisory Board for Insightec. Insightec is developing focused ultrasound treatments for brain tumors. This arrangement has been reviewed and approved by the Johns Hopkins University in accordance with its conflict-of-interest policies. HB has consultation agreements with Insightec, Candel Therapeutics, Inc., Catalio Nexus Fund II, LLC, LikeMinds, Inc*, and Nurami Medical*, Intragel *includes equity or options. The remaining author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Rodriguez, Ahluwalia, Bettegowda, Brem, Carter, Chang, Das, Eberhart, Garzon-Muvdi, Hadjipanayis, Hawkins, Jacques, Khalessi, McDermott, Mikkelsen, Orr, Phillips, Rosenblum, Shelton, Solomon, von Deimling, Woodworth and Rutka.)

Objective: We sought to investigate how priming the tube between air versus air mixed with saline ex vivo influenced suction force. We examined how priming the tube influenced peak suction force and time to achieve peak suction force between both modalities., Methods: Using a Dwyer Instruments (Dwyer Instruments Inc., Michigan City, IN, USA), INC Digitial Pressure Gauge, we were able to connect a .072 inch aspiration catheter to a rotating hemostatic valve and to aspiration tubing. We recorded suction force measured in negative inches of Mercury (inHg) over 10 iterations between having the aspiration tube primed with air alone versus air mixed with saline. A test was used to compare results between both modalities., Results: Priming the tube with air alone compared to air mixed with saline was found to have an increased average max suction force (-28.60 versus -28.20 in HG, p<0.01). We also identified a logarithmic curve of suction force across time in which time to maximal suction force was more prompt with air compared with air mixed with saline (13.8 seconds versus 21.60 seconds, p<0.01)., Conclusions: Priming the tube with air compared to air mixed with saline suggests that not only is increased maximal suction force achieved, but also the time required to achieve maximal suction force is less. This data suggests against priming the aspiration tubing with saline and suggests that the first pass aspiration primed with air may have the greatest suction force.

Introduction: Pediatric intracranial aneurysms (IAs) are rare and have distinct clinical profiles compared to adult IAs. They differ in location, size, morphology, presentation, and treatment strategies. We present our experience with pediatric IAs over an 18-year period using surgical and endovascular treatments and review the literature to identify commonalities in epidemiology, treatment, and outcomes., Methods: We identified all patients < 20 years old who underwent treatment for IAs at our institution between 2005 and 2020. Medical records and imaging were examined for demographic, clinical, and operative data. A systematic review was performed to identify studies reporting primary outcomes of surgical and endovascular treatment of pediatric IAs. Demographic information, aneurysm characteristics, treatment strategies, and outcomes were collected., Results: Thirty-three patients underwent treatment for 37 aneurysms over 18 years. The mean age was 11.4 years, ranging from one month to 19 years. There were 21 males (63.6%) and 12 females (36.4%), yielding a male: female ratio of 1.75:1. Twenty-six (70.3%) aneurysms arose from the anterior circulation and 11 (29.7%) arose from the posterior circulation. Aneurysmal rupture occurred in 19 (57.5%) patients, of which 8 (24.2%) were categorized as Hunt-Hess grades IV or V. Aneurysm recurrence or rerupture occurred in five (15.2%) patients, and 5 patients (15.2%) died due to sequelae of their aneurysms. Twenty-one patients (63.6%) had a good outcome (modified Rankin Scale score 0-2) on last follow up. The systematic literature review yielded 48 studies which included 1,482 total aneurysms (611 with endovascular treatment; 656 treated surgically; 215 treated conservatively). Mean aneurysm recurrence rates in the literature were 12.7% and 3.9% for endovascular and surgical treatment, respectively., Conclusions: Our study provides data on the natural history and longitudinal outcomes for children treated for IAs at a single institution, in addition to our treatment strategies for various aneurysmal morphologies. Despite the high proportion of patients presenting with rupture, good functional outcomes can be achieved for most patients., (© 2024. The Author(s).)

Background: Arachnoid cysts are cerebrospinal fluid-filled spaces that are typically congenital and treated conservatively or with fenestration when symptomatic. Chronic subdural hematomas (cSDHs) can arise in the presence of arachnoid cysts due to fragile leptomeningeal vessels or veins within the cyst wall or cyst lumen, leading to bleeding and subsequent hematoma formation. Middle meningeal artery (MMA) embolization is regularly used for the treatment of cSDH as an alternative to craniotomy and evacuation., Observations: Here, the authors present the first known report of the simultaneous resolution of an arachnoid cyst and cSDH following MMA embolization in an adult. A 24-year-old male presented to the emergency department with 1 month of worsening headaches. Imaging revealed the presence of a cSDH and ipsilateral arachnoid cyst. The cSDH was treated with MMA embolization using coils exclusively. Follow-up imaging 4 months after embolization demonstrated simultaneous resolution of both the hematoma and the arachnoid cyst., Lessons: MMA embolization has been used for the treatment of cSDH. In cases in which the hematoma is related to an arachnoid cyst, MMA embolization can also lead to the concurrent resolution of both pathologies. https://thejns.org/doi/10.3171/CASE24192.

Middle meningeal artery embolization (MMAE) is emerging as a safe and effective standalone intervention for non-acute subdural hematomas (NASHs); however, the risk of hematoma recurrence after MMAE in coagulopathic patients is unclear. To characterize the impact of coagulopathy on treatment outcomes, we analyzed a multi-institutional database of patients who underwent standalone MMAE as treatment for NASH. We classified 537 patients who underwent MMAE as a standalone intervention between 2019 and 2023 by coagulopathy status. Coagulopathy was defined as use of anticoagulation/antiplatelet agents or pre-operative thrombocytopenia (platelets <100,000/μL). Demographics, pre-procedural characteristics, in-hospital course, and patient outcomes were collected. Thrombocytopenia, aspirin use, antiplatelet agent use, and anticoagulant use were assessed using univariate and multivariate analyses to identify any characteristics associated with the need for rescue surgical intervention, mortality, adverse events, and modified Rankin Scale score at 90-day follow-up. Propensity score-matched cohorts by coagulopathy status with matching covariates adjusting for risk factors implicated in surgical recurrence were evaluated by univariate and multivariate analyses. Minimal differences in pre-operative characteristics between patients with and those without coagulopathy were observed. On unmatched and matched analyses, patients with coagulopathy had higher rates of requiring subsequent surgery than those without (unmatched: 9.9% vs. 4.3%; matched: 12.6% vs. 4.6%; both p  < 0.05). On matched multivariable analysis, patients with coagulopathy had an increased odds ratio (OR) of requiring surgical rescue (OR 3.95; 95% confidence interval [CI] 1.68-9.30; p  < 0.01). Antiplatelet agent use (ticagrelor, prasugrel, or clopidogrel) was also predictive of surgical rescue (OR 4.38; 95% CI 1.51-12.72; p  = 0.01), and patients with thrombocytopenia had significantly increased odds of in-hospital mortality (OR 5.16; 95% CI 2.38-11.20; p  < 0.01). There were no differences in follow-up radiographic and other clinical outcomes in patients with and those without coagulopathy. Patients with coagulopathy undergoing standalone MMAE for treatment of NASH may have greater risk of requiring surgical rescue (particularly in patients using antiplatelet agents), and in-hospital mortality (in thrombocytopenic patients).

ARISE (Aneurysm/AVM/cSDH Roundtable Discussion With Industry and Stroke Experts) organized a one-and-a-half day meeting and workshop and brought together representatives from academia, industry, and government to discuss the most promising approaches to improve outcomes for patients with chronic subdural hematoma (cSDH). The emerging role of middle meningeal artery embolization in clinical practice and the design of current and potential future trials were the primary focuses of discussion. Existing evidence for imaging, indications, agents, and techniques was reviewed, and areas of priority for study and key questions surrounding the development of new and existing treatments for cSDH were identified. Multiple randomized, controlled trials have met their primary efficacy end points, providing high-level evidence that middle meningeal artery embolization is a potent adjunctive therapy to the standard (surgical and nonsurgical) management of neurologically stable cSDH patients in terms of reducing rates of disease recurrence. Pooled data analyses following the formal conclusion and publication of these trials will form a robust foundation upon which guidelines can be strengthened for cSDH treatment modalities and optimal patient selection, as well as delineate future lines of investigation., Competing Interests: Disclosures Dr Kan reports compensation from Imperative Care, Inc, for consultant services; compensation from MicroVention, Inc, for consultant services; grants from Siemens Medical Solutions USA, Inc, the National Institutes of Health, and the Joe Niekro Foundation; and stock holdings in Vena Medical. Dr Fiorella reports compensation from Johnson & Johnson Health Care Systems, Inc, for consultant services. Dr Lanzino reports compensation from the American Heart Association for consultant services. Dr Siddiqui reports stock options in Createch Medical, Inc; securities holdings in VICIS, Inc; employment by the Jacobs Institute; stock holdings in NextGen Biologics, Inc; stock options in Three Rivers Medical, Inc; compensation from W. L. Gore & Associates, Inc, for consultant services; securities holdings in SongBird Therapy; compensation from Johnson & Johnson Medical Devices & Diagnostics Group-Latin America, LLC, for consultant services; stock holdings in Neurotechnology Investors; and stock holdings in Truvic Medical, Inc. Dr Khalessi reports compensation from Proximie for consultant services and stock options in Asayena. Dr Colby reports compensation from Cerenovus, Medtronic, Stryker, Balt USA, LLC, Rapid Medical Ltd, and MicroVention, Inc, for consultant services. Dr Wakhloo received grants from Philips and compensation from Acotec for consultant services; disclosures provided by Dr Wakhloo in compliance with the American Heart Association’s annual Journal Editor Disclosure Questionnaire are available at https://www.ahajournals.org/editor-coi-disclosures. Dr Arthur reports compensation from Perfuze for consultant services. The Aneurysm/AVM/Chronic Subdural Hematoma Roundtable Discussion With Industry and Stroke Experts I roundtable discussion event was collectively sponsored by Imperative Care, Stryker, InNeuroCo, the Brain Aneurysm Foundation, Philips, Bendit, Kaneka Neurovascular, Fluid Biomed, Johnson and Johnson Cerenovus, Penumbra, MicroVention, RapidAI, Viz.ai, Siemens Healthineers, and Medtronic. The content and writing of this article were not sponsored by industry. The other authors report no conflicts.

Background and Objectives: The choice of anesthesia type (general anesthesia [GA] vs nongeneral anesthesia [non-GA]) in middle meningeal artery embolization (MMAE) procedures for chronic subdural hematomas (cSDH) differs between institutions and left to care team discretion given lack of standard guidelines. We compare the outcomes of GA vs non-GA in MMAE., Methods: Consecutive patients receiving MMAE for cSDH at 14 North American centers (2018-2023) were included. Clinical, cSDH characteristics, and technical/clinical outcomes were compared between the GA/non-GA groups. Using propensity score matching (PSM), patients were matched controlling for age, baseline modified Rankin Scale, concurrent/prior surgery, hematoma thickness/midline shift, and baseline antiplatelet/anticoagulation. The primary end points included surgical rescue and radiographic success rates (≥50% reduction in maximum hematoma thickness with minimum 2 weeks of imaging). Secondary end points included technical feasibility, procedural complications, and functional outcomes., Results: Seven hundred seventy-eight patients (median age 73 years, 73.2% male patients) underwent 956 MMAE procedures, 667 (70.4%) were non-GA and 280 were GA (29.6%). After running 1:3 PSM algorithm, this resulted in 153 and 296 in the GA and non-GA groups, respectively. There were no baseline/procedural differences between the groups except radial access more significantly used in the non-GA group (P = .001). There was no difference between the groups in procedural technical feasibility, complications rate, length of stay, surgical rescue rates, or favorable functional outcome at the last follow-up. Subsequent 1:1 sensitivity PSM retained the same results. Bilateral MMAE procedures were more performed under non-GA group (75.8% vs 67.2%; P = .01); no differences were noted in clinical/radiographic outcomes between bilateral vs unilateral MMAE, except for longer procedure duration in the bilateral group (median 73 minutes [IQR 48.3-100] vs 54 minutes [39-75]; P < .0001). Another PSM analysis comparing GA vs non-GA in patients undergoing stand-alone MMAE retained similar associations., Conclusion: We found no significant differences in radiological improvement/clinical outcomes between GA and non-GA for MMAE., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Background: Middle meningeal artery (MMA) embolization is an apparently efficacious minimally invasive treatment for nonacute subdural hematomas (NASHs), but how different embolisates affect outcomes remains unclear. Our objective was to compare radiographic and clinical outcomes after particle or liquid MMA embolization., Methods: Patients who had MMA embolization for NASH were retrospectively identified from a multi-institution database. The primary radiographic and clinical outcomes-50% NASH thickness reduction and need for surgical retreatment within 90 days, respectively-were compared for liquid and particle embolizations in patients treated 1) without surgical intervention (upfront), 2) after recurrence, or 3) with concomitant surgery (prophylactic)., Results: The upfront, recurrent, and prophylactic subgroups included 133, 59, and 16 patients, respectively. The primary radiographic outcome was observed in 61.8%, 61%, and 72.7% of particle-embolized patients and 61.3%, 55.6%, and 20% of liquid-embolized patients, respectively (p = 0.457, 0.819, 0.755). Hazard ratios comparing time to reach radiographic outcome in the particle and liquid groups or upfront, recurrent, andprophylactic timing were 1.31 (95% CI 0.78-2.18; p = 0.310), 1.09 (95% CI 0.52-2.27; p = 0.822), and 1.5 (95% CI 0.14-16.54; p = 0.74), respectively. The primary clinical outcome occurred in 8.0%, 2.4%, and 0% of patients who underwent particle embolization in the upfront, recurrent, and prophylactic groups, respectively, compared with 0%, 5.6%, and 0% who underwent liquid embolization (p = 0.197, 0.521, 1.00)., Conclusions: MMA embolization with particle and liquid embolisates appears to be equally effective in treatment of NASHs as determined by the percentage who reach, and the time to reach, 50% NASH thickness reduction and the incidence of surgical reintervention within 90 days., Competing Interests: Declaration of conflicting interestsHoward Riina is a consultant for Medtronic. Elad Levy has shares/ownership interest in NeXtGen Biologics, RAPID Medical, Claret Medical, Cognition Medical, Imperative Care, Rebound Therapeutics, StimMed, and Three Rivers Medical; has a patent for Bone Scalpel; receives honoraria for training and lectures from Medtronic, Penumbra, MicroVention, and Integra; is a consultant for Clarion, IRRAS AB, GLG Consulting, Guidepoint Global, Imperative Care, Medtronic, StimMed, Misionix, and Mosiac; is the Chief Medical Officer of Haniva Technology; is a national principal investigator for Medtronic; is on the steering committees of SWIFT Prime and SWIFT Direct trials; is the site PI for the CONFIDENCE study (MicroVention) and sub-PI for the STRATIS study (Medtronic); serves on the advisory board for Stryker (AIS Clinical Advisory Board), NeXtGen Biologics, MEDX, Cognition Medical; Endostream Medical, and IRRAS AB; and provides medical/legal opinions for medical legal review; and has leadership or fiduciary roles in CNS, ABNS, and UBNS. Alejandro Spiotta has research support from Penumbra, Stryker, Medtronic, and RapidAI and is a consultant for Penumbra, Stryker, Terumo, and RapidAI. Bradley Gross is a consultant for Medtronic and Medvision. Adita Pandey has stock in NextGen Biologics and FlexDex Surgical. Ricardo Hanel is a consultant for Medtronic, Stryker, Cerenovous, Microvention, Balt, Phenox, Rapid Medical, and Q'Apel; he is on advisory board for MiVI, eLum, Three Rivers, Shape Medical and Corindus; he has received unrestricted research grants from NIH, Interline Endowment, Microvention, Stryker, CNX; he is an investor/stockholder for InNeuroCo, Cerebrotech, eLum, Endostream, Three Rivers Medical Inc, Scientia, RisT, BlinkTBI, and Corindus. David Langer is a consultant of ORBEYE. Michael Levitt has grants from the National Institutes of Health, The Aneurysm and AVM Foundation, Congress of Neurological Surgeons Society of NeuroInterventional Surgery, is a consultant for Medtronic, has investigator-initiated unrestricted educational grants from Medtronic and Styker, is a shareholder of Proprio, Cerebrotech, Synchron, Hyperion Surgical, has equity interest in Fluid Biomed and Stereotaxis, is an advisor for Aeaean Advisers, and is on the Journal of NeuroInterventional Surgery editorial board. Philipp Taussky is a consultant for Avail Medsystems, Johnson & Johnson, Medtronic, and Stryker Neurovascular. Peter Kan is a consultant for Stryker Neurovascular, MicroVention, and Imperative Care. Ramesh Grandhi is a consultant for Balt Neurovascular, Cerenovus, Integra, and Medtronic Neurovascular.

Objective: Middle meningeal artery embolization (MMAe) has burgeoned as a treatment for chronic subdural hematoma (cSDH). This study evaluates the safety and short-term outcomes of MMAe patients relative to traditional treatment approaches., Methods: In this retrospective large database study, adult patients in the National Inpatient Sample from 2012-2019 with a diagnosis of cSDH were identified. Cost of admission, length of stay (LOS), discharge disposition, and complications were analyzed. Propensity score matching (PSM) was utilized., Results: A total of 123,350 patients with cSDH were identified: 63,450 without intervention, 59,435 surgery only, 295 MMAe only, and 170 surgery plus MMAe. On PSM analysis, MMAe did not increase the risk of inpatient complications or prolong the length of stay compared to conservative management (p>0.05); MMAe had higher cost ($31,170 vs. $10,768, p<0.001) than conservative management, and a lower rate of nonroutine discharge (53.8% vs. 64.3%, p=0.024). Compared to surgery, MMAe had shorter LOS (5 vs. 7 days, p<0.001), and lower rates of neurological complications (2.7% vs. 7.1%, p=0.029) and nonroutine discharge (53.8% vs. 71.7%, p<0.001). There was no significant difference in cost (p>0.05)., Conclusions: MMAe had similar LOS and decreased odds of adverse discharge with a modest cost increase compared to conservative management. There was no difference in inpatient complications. Compared to surgery, MMAe treatment was associated with decreased LOS and rates of neurological complications and nonroutine discharge. This nationwide analysis supports the safety of MMAe to treat cSDH.

Background and Objectives: Endovascular techniques have become the first-line treatment for carotid-cavernous fistulas (CCFs). Direct transorbital venous access may be used if anatomic constraints limit standard transarterial or transvenous access. We describe our institutional experience with the transorbital approach for Barrow Type A-D CCFs., Methods: Patients with CCFs undergoing transorbital endovascular treatment at our institution between 2017 and 2019 were retrospectively reviewed. Demographic, treatment, and outcome data were collected., Results: Eight patients met inclusion criteria, 4 female and 4 male patients. The mean age was 43 years, with 6 right-sided CCF and 2 left-sided CCFs. Symptoms were present for an average of 1.5 months before treatment. All patients presented with eye pain and subjective visual changes. Seven (87.5%) patients presented with proptosis, 6 (75%) patients had elevated intraocular pressure (IOP), and 3 (37.5%) patients had ophthalmoplegia. Six CCFs (75%) were spontaneous, and 2 CCFs (25%) were traumatic. Barrow types were A (n = 1), B (n = 1), C (n = 1), and D (n = 5). All patients underwent direct percutaneous transorbital embolization with coils followed by Onyx. Three patients had undergone prior transarterial and/or transvenous treatment. A radiographic cure was obtained in all patients after direct transorbital embolization. After CCF cure, cranial nerve palsies resolved in 66.7% of patients, visual acuity in the affected eye was improved or stable in 75% of patients, and IOP had normalized in 85.7% of patients. Proptosis improved in all patients, with complete resolution in 75%., Conclusion: Direct transorbital embolization is a safe and potentially curative treatment for all 4 Barrow types of CCFs., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Background Knowledge regarding predictors of clinical and radiographic failures of middle meningeal artery (MMA) embolization (MMAE) treatment for chronic subdural hematoma (CSDH) is limited. Purpose To identify predictors of MMAE treatment failure for CSDH. Materials and Methods In this retrospective study, consecutive patients who underwent MMAE for CSDH from February 2018 to April 2022 at 13 U.S. centers were included. Clinical failure was defined as hematoma reaccumulation and/or neurologic deterioration requiring rescue surgery. Radiographic failure was defined as a maximal hematoma thickness reduction less than 50% at last imaging (minimum 2 weeks of head CT follow-up). Multivariable logistic regression models were constructed to identify independent failure predictors, controlling for age, sex, concurrent surgical evacuation, midline shift, hematoma thickness, and pretreatment baseline antiplatelet and anticoagulation therapy. Results Overall, 530 patients (mean age, 71.9 years ± 12.8 [SD]; 386 men; 106 with bilateral lesions) underwent 636 MMAE procedures. At presentation, the median CSDH thickness was 15 mm and 31.3% (166 of 530) and 21.7% (115 of 530) of patients were receiving antiplatelet and anticoagulation medications, respectively. Clinical failure occurred in 36 of 530 patients (6.8%, over a median follow-up of 4.1 months) and radiographic failure occurred in 26.3% (137 of 522) of procedures. At multivariable analysis, independent predictors of clinical failure were pretreatment anticoagulation therapy (odds ratio [OR], 3.23; P = .007) and an MMA diameter less than 1.5 mm (OR, 2.52; P = .027), while liquid embolic agents were associated with nonfailure (OR, 0.32; P = .011). For radiographic failure, female sex (OR, 0.36; P = .001), concurrent surgical evacuation (OR, 0.43; P = .009), and a longer imaging follow-up time were associated with nonfailure. Conversely, MMA diameter less than 1.5 mm (OR, 1.7; P = .044), midline shift (OR, 1.1; P = .02), and superselective MMA catheterization (without targeting the main MMA trunk) (OR, 2; P = .029) were associated with radiographic failure. Sensitivity analyses retained these associations. Conclusion Multiple independent predictors of failure of MMAE treatment for chronic subdural hematomas were identified, with small diameter (<1.5 mm) being the only factor independently associated with both clinical and radiographic failures. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Chaudhary and Gemmete in this issue.

Background: By 2030, nonacute subdural hematomas (NASHs) will likely be the most common cranial neurosurgery pathology. Treatment with surgical evacuation may be necessary, but the recurrence rate after surgery is as high as 30%. Minimally invasive middle meningeal artery embolization (MMAE) during the perioperative period has been posited as an adjunctive treatment to decrease the potential for recurrence after surgical evacuation. We evaluated the safety and efficacy of concurrent MMAE in a multi-institutional cohort., Methods: Data from 145 patients (median age 73 years) with NASH who underwent surgical evacuation and MMAE in the perioperative period were retrospectively collected from 15 institutions. The primary outcome was the rate of recurrence requiring repeat surgical intervention. We collected clinical, treatment, and radiographic data at initial presentation, after evacuation, and at 90-day follow-up. Outcomes data were also collected., Results: Preoperatively, the median hematoma width was 18 mm, and subdural membranes were present on imaging in 87.3% of patients. At 90-day follow-up, median NASH width was 6 mm, and 51.4% of patients had at least a 50% decrease of NASH size on imaging. Eight percent of treated NASHs had recurrence that required additional surgical intervention. Of patients with a modified Rankin Scale score at last follow-up, 87.2% had the same or improved mRS score. The total all-cause mortality was 6.0%., Conclusion: This study provides evidence from a multi-institutional cohort that performing MMAE in the perioperative period as an adjunct to surgical evacuation is a safe and effective means to reduce recurrence in patients with NASHs.

Background and Purpose: Comprehensive stroke centers continually strive to narrow neurointerventional time metrics. Although process improvements have been put in place to streamline workflows, complex pathways, disparate imaging locations, and fragmented communications all highlight the need for continued improvement., Materials and Methods: This Quality Improvement Initiative (VISIION) was implemented to assess our transition to the Viz.ai platform for immediate image review and centralized communication and their effect on key performance indicators in our comprehensive stroke center. We compared periods before and following deployment. Sequential patients having undergone stroke thrombectomy were included. Both direct arriving large-vessel occlusion and Brain Emergency Management Initiative telemedicine transfer large-vessel occlusion cases were assessed as were subgroups of OnHours and OffHours. Text messaging thread counts were compared between time periods to assess communications. Mann-Whitney U and Student t tests were used., Results: Eighty-two neurointerventional cases were analyzed pre vs. post time periods: (DALVO-OnHours 7 versus 7, DALVO-OffHours 10 versus 5, BEMI-OnHours 13 versus 6, BEMI-OffHours 17 versus 17). DALVO-OffHours had a 39% door-to-groin reduction (157 versus 95 minutes, P = .009). DALVO-All showed a 32% reduction (127 versus 86 minutes, P = .006). BEMI-All improved 33% (42 versus 28 minutes, P = .036). Text messaging thread counts improved 30% (39 versus 27, P = .04)., Conclusions: There was an immediate improvement following Viz.ai implementation for both direct arriving and telemedicine transfer thrombectomy cases. In the greatest opportunity subset (direct arriving large-vessel occlusion-OffHours: direct arriving cases requiring team mobilization off-hours), we noted a 39% improvement. With Viz.ai, we noted that immediate access to images and streamlined communications improved door-to-groin time metrics for thrombectomy. These results have implications for future care processes and can be a model for centers striving to optimize workflow and improve thrombectomy timeliness., (© 2023 by American Journal of Neuroradiology.)

Background: Systematic use of neurosurgical training simulators across institutions is significantly hindered by logistical and financial constraints., Objective: To evaluate feasibility of large-scale implementation of an intraoperative catastrophe simulation, we introduced a highly portable and low-cost immersive neurosurgical simulator into a nationwide curriculum for neurosurgery residents, during years 2016 to 2019., Methods: The simulator was deployed at 9 Society of Neurological Surgeons junior resident courses and a Congress of Neurological Surgeons education course for a cohort of 526 residents. Heart rate was tracked to monitor physiological responses to simulated stress. Experiential survey data were collected to evaluate simulator fidelity and resident attitudes toward simulation., Results: Residents rated the simulator positively with a statistically significant increase in satisfaction over time accompanying refinements in the simulator model and clinical scenario. The simulated complications induced stress-related tachycardia in most participants (n = 249); however, a cohort of participants was identified that experienced significant bradycardia (n = 24) in response to simulated stress., Conclusion: Incorporation of immersive neurosurgical simulation into the US national curriculum is logistically feasible and cost-effective for neurosurgical learners. Participant surveys and physiological data suggest that the simulation model recreates the situational physiological stress experienced during practice in the live clinical environment. Simulation may provide an opportunity to identify trainees with maladaptive responses to operative stress who could benefit from additional simulated exposure to mitigate stress impacts on performance., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Purpose: The extent to which racial/ethnic brain tumour survival disparities vary by age is not very clear. In this study, we assess racial/ethnic brain tumour survival disparities overall by age group and type., Methods: Data were obtained from the Surveillance, Epidemiology, and End Results (SEER) 18 registries for US-based individuals diagnosed with a first primary malignant tumour from 2007 through 2016. Cox proportional hazards regression was used to compute adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs) for the association between race/ethnicity and brain tumour survival, stratified by age group and tumour type., Results: After adjusting for sex, socioeconomic status, insurance status, and tumour type, non-Hispanic (NH) Blacks (HR: 1.26; 95% CI: 1.02-1.55), NH Asian or Pacific Islanders (HR: 1.29; 95% CI: 1.01-1.66), and Hispanics (any race) (HR: 1.28; 95% CI: 1.09-1.51) all showed a survival disadvantage compared with NH Whites for the youngest age group studied (0-9 years). Furthermore, NH Blacks (HR: 0.88; 95% CI: 0.91-0.97), NH Asian or Pacific Islanders (HR: 0.84; 95% CI: 0.77-0.92), and Hispanics (any race) (HR: 0.91; 95% CI: 0.85-0.97) all showed a survival advantage compared with NH Whites for the 60-79 age group. Tests for interactions showed significant trends, indicating that racial/ethnic survival disparities disappear and even reverse for older age groups ( P  < 0.001). This reversal appears to be driven by poor glioblastoma survival among NH Whites ( P  < 0.001)., Conclusion: Disparities in brain tumour survival among minorities exist primarily among children and adolescents. NH White adults show worse survival than their minority counterparts, which is possibly driven by poor glioblastoma biology.

Objective: Electric scooters (e-scooters) are an increasingly popular form of transportation, but their use has also resulted in increased incidence of traumatic brain injury (TBI). Previous reports have predominantly described mild TBI with limited attention to other injury patterns. Our objective was to evaluate the impact of e-scooter use on rates of severe TBI., Methods: We performed a multicenter retrospective case review of patients who presented with severe TBI (Glasgow Coma Scale score 3-8) related to e-scooter use and undertook a systematic literature review to identify other reports of severe TBI related to e-scooter use., Results: Of the 19 patients (mean age, 38 ± 16 years; 73.7% male) included in the case series, 13 (68.4%) experienced a fall and 6 (31.6%) were involved in a collision. Various cerebral injury patterns, associated craniofacial fractures, and cervical spine injuries were also seen. Twelve patients (63.2%) underwent intracranial pressure monitor placement and 6 (31.6%) underwent a decompressive hemicraniectomy. Most patients (n = 12; 63.2%) were discharged to acute rehabilitation, with a median modified Rankin Scale score of 2 at 4.9 ± 7.7 months follow-up (52.6% had a good outcome of modified Rankin Scale score ≤2), but 4 patients died of primary injuries. The systematic review identified 18 studies with 77,069 patients between 2019 and 2021, with 37 patients who required intensive care and 6 patients who had neurosurgical intervention., Conclusions: Severe TBI after e-scooter use is associated with high morbidity and is likely underdiagnosed in the literature. Awareness and public policies may be helpful to reduce the impact of injury., (Published by Elsevier Inc.)

Objective  Mobilization of cranial nerve III (CNIII) at its dural entry site is commonly described to avoid damage from stretching during approaches to the parasellar, infrachiasmatic, posterior clinoid, and cavernous sinus regions. The histologic relationships of CNIII as it traverses the dura, and the associated surgical implications are nonetheless poorly described. We herein assess the histology of the CNIII-dura interface as it relates to surgical mobilization of the nerve. Methods  A fronto-orbitozygomatic temporopolar approach was performed on six adult cadaveric specimens. The CNIII-dural entry site was resected and histologically processed. The nerve-tissue planes were assessed by a neuropathologist. Results  Histologic analysis demonstrated that CNIII remained separate from the dura within the oculomotor cistern (porous oculomotorius up to the oculomotor foramen). Fusion of the epineurium of CNIII and the connective tissue of the dura was seen at the level of the foramen, with no clear histologic plane identified between these structures. Conclusion  CNIII may be directly mobilized within the oculomotor cistern, while dissections of CNIII distal to the oculomotor foramen should maintain a thin layer of connective tissue on the nerve., Competing Interests: Conflict of Interest None declared., (Thieme. All rights reserved.)

Objective: Traditional and extended transnasal transsphenoidal approaches provide direct access to a variety of anterior skull base pathologies. Despite increased utilization of transnasal approaches in children, anatomic studies on pediatric skull base maturation are limited. We herein perform a surgically relevant morphometric analysis of the sella and parasellar regions during pediatric maturation., Methods: Measurements of sellar length (SL), sellar depth (SDp), sellar diameter (SDm), interclinoid distance (ID), intercavernous distance (ICD), and the presence of sphenoid sinus pneumatization (SSP), and sphenoid sinus type (SST) were made on thin-cut CT scans from 60 patients (evenly grouped by ages 0-3, 4-7, 8-11 12-15, 16-18, and >18 years) for analysis. Data were analyzed by sex and age groups using t-tests and linear regression., Results: Sella and parasellar parameters did not differ by sex. SL steadily increased from 8.5 ± 1.2 mm to 11.5 ± 1.6 mm throughout development. SDp and SDm increased from 6.0 ± 0.9 mm to 9.3 ± 1.4 mm and 9.0 ± 1.6 mm to 14.4 ± 1.8 mm during maturation, with significant interval growth from ages 16-18 to adult (p < 0.01). ID displayed significant growth from ages 0-3 to 4-7 (18.0 ± 2.4 mm to 20.7 ± 1.9 mm; p = 0.002) and ICD from ages 0-3 to 8-11 (12.0 ± 1.8 mm to 13.5 ± 2.1 mm; p < 0.001), without further significant interval growth. SSP was not seen in patients < 3, but was 100% by ages 8-11. SSTs progressed from conchal/presellar (60% at ages 4-7) to sellar/postsellar (80% at adulthood)., Conclusion: The sella and parasellar regions have varied growth patterns with development. Knowledge of the expected maturation of key anterior skull base structures may augment surgical planning in younger patients., (Copyright © 2022. Published by Elsevier B.V.)

The use of artificial intelligence (AI) and robotics in endovascular neurosurgery promises to transform neurovascular care. We present a review of the recently published neurosurgical literature on artificial intelligence and robotics in endovascular neurosurgery to provide insights into the current advances and applications of this technology. The PubMed database was searched for "neurosurgery" OR "endovascular" OR "interventional" AND "robotics" OR "artificial intelligence" between January 2016 and August 2021. A total of 1296 articles were identified, and after applying the inclusion and exclusion criteria, 38 manuscripts were selected for review and analysis. These manuscripts were divided into four categories: 1) robotics and AI for the diagnosis of cerebrovascular pathology, 2) robotics and AI for the treatment of cerebrovascular pathology, 3) robotics and AI for training in neuroendovascular procedures, and 4) robotics and AI for clinical outcome optimization. The 38 articles presented include 23 articles on AI-based diagnosis of cerebrovascular disease, 10 articles on AI-based treatment of cerebrovascular disease, two articles on AI-based training techniques for neuroendovascular procedures, and three articles reporting AI prediction models of clinical outcomes in vascular disorders of the brain. Innovation with robotics and AI focus on diagnostic efficiency, optimizing treatment and interventional procedures, improving physician procedural performance, and predicting clinical outcomes with the use of artificial intelligence and robotics. Experimental studies with robotic systems have demonstrated safety and efficacy in treating cerebrovascular disorders, and novel microcatheterization techniques may permit access to deeper brain regions. Other studies show that pre-procedural simulations increase overall physician performance. Artificial intelligence also shows superiority over existing statistical tools in predicting clinical outcomes. The recent advances and current usage of robotics and AI in the endovascular neurosurgery field suggest that the collaboration between physicians and machines has a bright future for the improvement of patient care. The aim of this work is to equip the medical readership, in particular the neurosurgical specialty, with tools to better understand and apply findings from research on artificial intelligence and robotics in endovascular neurosurgery., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Bravo et al.)

Anatomic knowledge of the internal auditory canal (IAC) and surrounding structures is a prerequisite for performing skull base approaches to the IAC. We herein perform a morphometric analysis of the IAC and surgically relevant aspects of the posterior petrous bone during pediatric maturation, a region well-studied in adults but not children. Measurements of IAC length (IAC-L), porus (IAC-D) and midpoint (IAC-DM) diameter, and distance from the porus to the common crus (CC; P-CC) and posterior petrosal surface (PPS) to the posterior semicircular canal (PSC; PPS-PSC) were made on thin-cut axial CT scans from 60 patients (grouped by ages 0-3, 4-7, 8-11 12-15, 16-18, and > 18 years). IAC-L increased 27.5% from 8.7 ± 1.1 at age 0-3 to 11.1 ± 1.1 mm at adulthood (p = 0.001), with the majority of growth occurring by ages 8-11. IAC-D (p = 0.52) and IAC-DM (p = 0.167) did not significantly change from ages 0-3 to adult. P-CC increased 31.1% from 7.7 ± 1.5 at age 0-3 to 10.1 ± 1.5 mm at adulthood (p = 0.019). PPS-PSC increased 160% from 1.5 ± 0.7 at age 0-3 to 3.9 ± 1.2 mm at adulthood (p < 0.001). The majority of growth in P-CC and PPS-PSC occurred by ages 12-15. Knowledge of these patterns may facilitate safe exposure of the IAC in children., (© 2022. The Author(s).)

Objective: The middle fossa transpetrosal approach to the petroclival and posterior cavernous sinus regions includes removal of the anterior petrous apex (APA), an area well studied in adults but not in children. To this end, the authors performed a morphometric analysis of the APA region during pediatric maturation., Methods: Measurements of the distance from the clivus to the internal auditory canal (IAC; C-IAC), the distance of the petrous segment of the internal carotid artery (petrous carotid; PC) to the mesial petrous bone (MPB; PC-MPB), the distance of the PC to the mesial petrous apex (MPA; PC-MPA), and the IAC depth from the middle fossa floor (IAC-D) were made on thin-cut CT scans from 60 patients (distributed across ages 0-3, 4-7, 8-11, 12-15, 16-18, and > 18 years). The APA volume was calculated as a cylinder using C-IAC (length) and PC-MPB (diameter). APA pneumatization was noted. Data were analyzed by laterality, sex, and age., Results: APA parameters did not differ by laterality or sex. APA pneumatization was seen on 20 of 60 scans (33.3%) in patients ≥ 4 years. The majority of the APA region growth occurred by ages 8-11 years, with PC-MPA and PC-MPB increasing 15.9% (from 9.4 to 10.9 mm, p = 0.08) and 23.5% (from 8.9 to 11.0 mm, p < 0.01) between ages 0-3 and 8-11 years, and C-IAC increasing 20.7% (from 13.0 to 15.7 mm, p < 0.01) between ages 0-3 and 4-7 years. APA volume increased 79.6% from ages 0-3 to 8-11 years (from 834.3 to 1499.2 mm3, p < 0.01). None of these parameters displayed further significant growth. Finally, IAC-D increased 51.1% (from 4.3 to 6.5 mm, p < 0.01) between ages 0-3 and adult, without significant differences between successive age groups., Conclusions: APA development is largely complete by the ages of 8-11 years. Knowledge of APA growth patterns may aid approach selection and APA removal in pediatric patients.

The operative exoscope is a novel tool that combines the benefits of surgical microscopes and endoscopes to yield excellent magnification and illumination while maintaining a comparatively small footprint and superior ergonomic features. Until recently, current exoscopes have been limited by 2-dimensional viewing; however, recently a 3-dimensional (3D), high-definition (4K-HD) exoscope has been developed (Sony-Olympus, Tokyo, Japan). 1 Our group had previously described the first in-human experiences with this novel tool including microsurgical clipping of intracranial aneurysms. We have highlighted the benefits of the exoscope, which include providing an immersive experience for surgeons and trainees, as well as superior ergonomics as compared with traditional microsurgery. 2 To date, exoscopic 3D high-definition indocyanine green (ICG) video angiography (ICG-VA) has not been described. ICG-VA, now a mainstay of vascular microsurgery, uses intravenously injected dye to visualize intravascular fluorescence in real time to assess the patency of arteries and assess clip occlusion of aneurysms. 3 , 4 The ability to safely couple this tool with the novel exoscope has the potential to advance cerebrovascular microsurgery. Here, we present a case of a 11-year-old male with Alagille syndrome, pancytopenia, and peripheral pulmonary stenosis found to have a 12 × 13 × 7 mm distal left M1 aneurysm arising from the inferior M1/M2 junction. The patient was neurologically intact without evidence of rupture. In order to prevent catastrophic rupture, the decision was made to treat the lesion. Due to the patients underlying medical conditions including baseline coagulopathy, surgical management was felt to be superior to an endovascular reconstruction, which would require long-term antiplatelet therapy. Thus the patient underwent a left-sided pterional craniotomy with exoscopic 3D ICG-VA. As demonstrated in Video 1, ICG-VA was performed before definitive clip placement in order to understand flow dynamics with particular emphasis on understanding the middle cerebral artery outflow. Postoperatively, the patient remained at his neurologic baseline and subsequent imaging demonstrated complete obliteration of the aneurysm without any neck remnant. The patient continues to follow and remains asymptomatic and neurologically intact without radiographic evidence of residual or recurrence., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Although mechanical thrombectomy has become the standard of care for large-vessel occlusion, the role of conscious sedation versus general anesthesia (GA) with intubation during thrombectomy remains controversial. Aphasia may increase patient agitation or apparent uncooperativeness/confusion and thereby lead to higher use of GA. The purpose of this study was to identify risk factors for GA and determine if the side of vessel occlusion potentially impacts GA rates., Materials and Methods: Patients who underwent mechanical thrombectomy of the middle cerebral artery (MCA) for acute ischemic stroke at our institution between April 2014 and July 2017 were retrospectively reviewed. Patient characteristics, procedural factors, and outcomes were assessed using multivariate regression analyses. Mediation analysis was utilized to investigate whether aphasia lies on the causal pathway between left-sided MCA stroke and GA., Results: Overall, 112 patients were included: 62 with left-sided and 50 with right-sided MCA occlusion. Patients with left-sided MCA occlusion presented with aphasia significantly more often those with right-sided occlusion (90.3% vs. 32.0%; P<0.001). GA rates were significantly higher for patients with left-sided compared with right-sided MCA occlusion (45.2% vs. 20.0%; P=0.028). Aphasia mediated 91.3% of the effect of MCA stroke laterality on GA (P=0.02). GA was associated with increased door-to-groin-puncture time (106.4% increase; 95% confidence interval, 24.1%-243.4%; P=0.006) and adverse discharge outcome (odds ratio, 1.04; 95% confidence interval, 1.01-1.07; P=0.019)., Conclusions: Patients who had a stroke with left-sided MCA occlusion are more likely to undergo GA for mechanical thrombectomy than those with right-sided MCA occlusion. Aphasia may mediate this effect and understanding this relationship may decrease GA rates through modification of management protocols, potentially leading to improved clinical outcomes. Our study suggests that GA should preferentially be considered for the subset of patients with acute ischemic stroke undergoing mechanical thrombectomy for left-sided MCA occlusion., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The institution-wide response of the University of California San Diego Health system to the 2019 novel coronavirus disease (COVID-19) pandemic was founded on rapid development of in-house testing capacity, optimization of personal protective equipment usage, expansion of intensive care unit capacity, development of analytic dashboards for monitoring of institutional status, and implementation of an operating room (OR) triage plan that postponed nonessential/elective procedures. We analyzed the impact of this triage plan on the only academic neurosurgery center in San Diego County, California, USA., Methods: We conducted a de-identified retrospective review of all operative cases and procedures performed by the Department of Neurosurgery from November 24, 2019, through July 6, 2020, a 226-day period. Statistical analysis involved 2-sample z tests assessing daily case totals over the 113-day periods before and after implementation of the OR triage plan on March 16, 2020., Results: The neurosurgical service performed 1429 surgical and interventional radiologic procedures over the study period. There was no statistically significant difference in mean number of daily total cases in the pre-versus post-OR triage plan periods (6.9 vs. 5.8 mean daily cases; 1-tail P = 0.050, 2-tail P = 0.101), a trend reflected by nearly every category of neurosurgical cases., Conclusions: During the COVID-19 pandemic, the University of California San Diego Department of Neurosurgery maintained an operative volume that was only modestly diminished and continued to meet the essential neurosurgical needs of a large population. Lessons from our experience can guide other departments as they triage neurosurgical cases to meet community needs., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: Compared to adult AVMs, there is a paucity of data on the microsurgical treatment of pediatric AVMs. We report our institutional experience with pediatric AVMs treated by microsurgical resection with or without endovascular embolization and radiation therapy., Methods: We retrospectively reviewed all patients ≤ 18 years of age with cerebral AVMs that underwent microsurgical resection at Rady Children's Hospital 2002-2019., Results: Eighty-nine patients met inclusion criteria. The mean age was 10.3 ± 5.0 years, and 56% of patients were male. In total, 72 (81%) patients presented with rupture. Patients with unruptured AVMs presented with headache (n = 5, 29.4%), seizure (n = 9, 52.9%), or incidental finding (n = 3, 17.7%). The mean presenting mRS was 2.8 ± 1.8. AVM location was lobar in 78%, cerebellar/brainstem in 15%, and deep supratentorial in 8%. Spetzler-Martin grade was I in 28%, II in 45%, III in 20%, IV in 6%, and V in 1%. Preoperative embolization was utilized in 38% of patients and more frequently in unruptured than ruptured AVMs (62% vs. 32%, p = 0.022). Radiographic obliteration was achieved in 76/89 (85.4%) patients. Complications occurred in 7 (8%) patients. Annualized rates of delayed rebleeding and recurrence were 1.2% and 0.9%, respectively. The mean follow-up was 2.8 ± 3.1 years. A good neurological outcome (mRS score ≤ 2) was obtained in 80.9% of patients at last follow-up and was improved relative to presentation for 75% of patients., Conclusions: Our case series demonstrates high rates of radiographic obliteration and relatively low incidence of neurologic complications of treatment or AVM recurrence.

Objective: Moyamoya disease (MMD) is a vasculopathy of the internal carotid arteries with ischemic and hemorrhagic sequelae. Surgical revascularization confers upfront peri-procedural risk and costs in exchange for long-term protective benefit against hemorrhagic disease. The authors present a cost-effectiveness analysis (CEA) of surgical versus non-surgical management of MMD., Methods: A Markov Model was used to simulate a 41-year-old suffering a transient ischemic attack (TIA) secondary to MMD and now faced with operative versus nonoperative treatment options. Health utilities, costs, and outcome probabilities were obtained from the CEA registry and the published literature. The primary outcome was incremental cost-effectiveness ratio which compared the quality adjusted life years (QALYs) and costs of surgical and nonsurgical treatments. Base-case, one-way sensitivity, two-way sensitivity, and probabilistic sensitivity analyses were performed with a willingness to pay threshold of $50,000., Results: The base case model yielded 3.81 QALYs with a cost of $99,500 for surgery, and 3.76 QALYs with a cost of $106,500 for nonsurgical management. One-way sensitivity analysis demonstrated the greatest sensitivity in assumptions to cost of surgery and cost of admission for hemorrhagic stroke, and probabilities of stroke with no surgery, stroke after surgery, poor surgical outcome, and death after surgery. Probabilistic sensitivity analyses demonstrated that surgical revascularization was the cost-effective strategy in over 87.4% of simulations., Conclusions: Considering both direct and indirect costs and the postoperative QALY, surgery is considerably more cost-effective than non-surgical management for adults with MMD.

Background: Removal of the anterior clinoid process (ACP) can expand anterior skull base surgical corridors. ACP development and anatomical variations are poorly defined in children., Objective: To perform a morphometric analysis of the ACP during pediatric maturation., Methods: Measurements of ACP base thickness (ACP-BT), midpoint thickness (ACP-MT), length (ACP-L), length from optic strut to ACP tip (ACP-OS), pneumatization (ACP-pneumo), and the presence of an ossified carotico-clinoid ligament (OCCL) or interclinoid ligament (OIL) were made from high-resolution computed-tomography scans from 60 patients (ages 0-3, 4-7, 8-11 12-15, 16-18, and >18 yr). Data were analyzed by laterality, sex, and age groups using t-tests and linear regression., Results: There were no significant differences in ACP parameters by laterality or sex, and no significant growth in ACP-BT or ACP-MT during development. From ages 0-3 yr to adult, mean ACP-L increased 49%, from 7.7 to 11.5 mm. The majority of ACP-L growth occurred in 2 phases between ages 0-3 to 8-11 and ages 16-18 to adult. Conversely, ACP-OS was stable from ages 0-3 to 8-11 but increased by 63% between ages 8-11 to adult. Variations in ACP morphology (OCCL/OIL/ACP-pneumo) were found in 15% (9/60) of scans. OCCL and OIL occurred in patients as young as 3 yrs, whereas ACP-pneumo was not seen in patients younger than 11 yrs., Conclusion: The ACP demonstrates stable thickness and a complex triphasic elongation and remodeling pattern with development, the understanding of which may facilitate removal in patients <12. Clinically relevant ACP anatomic variations can occur at any age., (Copyright © 2020 by the Congress of Neurological Surgeons.)

Background: Middle meningeal artery (MMA) embolization has emerged as a promising treatment for chronic subdural hematoma (cSDH)., Objective: To determine the safety and efficacy of MMA embolization., Methods: Consecutive patients who underwent MMA embolization for cSDH (primary treatment or recurrence after conventional surgery) at 15 centers were included. Clinical details and follow-up were collected prospectively. Primary clinical and radiographic outcomes were the proportion of patients requiring additional surgical treatment within 90 d after index treatment and proportion with > 50% cSDH thickness reduction on follow-up computed tomography imaging within 90 d. National Institute of Health Stroke Scale and modified Rankin Scale were also clinical outcomes., Results: A total of 138 patients were included (mean age: 69.8, 29% female). A total of 15 patients underwent bilateral interventions for 154 total embolizations (66.7% primary treatment). At presentation, 30.4% and 23.9% of patients were on antiplatelet and anticoagulation therapy, respectively. Median admission cSDH thickness was 14 mm. A total of 46.1% of embolizations were performed under general anesthesia, and 97.4% of procedures were successfully completed. A total of 70.2% of embolizations used particles, and 25.3% used liquid embolics with no significant outcome difference between embolization materials (P > .05). On last follow-up (mean 94.9 d), median cSDH thickness was 4 mm (71% median thickness reduction). A total of 70.8% of patients had >50% improvement on imaging (31.9% improved clinically), and 9 patients (6.5%) required further cSDH treatment. There were 16 complications with 9 (6.5%) because of continued hematoma expansion. Mortality rate was 4.4%, mostly unrelated to the index procedure but because of underlying comorbidities., Conclusion: MMA embolization may provide a safe and efficacious minimally invasive alternative to conventional surgical techniques., (Copyright © 2020 by the Congress of Neurological Surgeons.)

Objective: The incidence of already common chronic subdural hematomas (CSDHs) and other nonacute subdural hematomas (NASHs) in the elderly is expected to rise as the population ages over the coming decades. Surgical management is associated with recurrence and exposes elderly patients to perioperative and operative risks. Middle meningeal artery (MMA) embolization offers the potential for a minimally invasive, less morbid treatment in this age group. The clinical and radiographic outcomes after MMA embolization treatment for NASHs have not been adequately described in elderly patients. In this paper, the authors describe the clinical and radiographic outcomes after 151 cases of MMA embolization for NASHs among 121 elderly patients., Methods: In a retrospective review of a prospectively maintained database across 15 US academic centers, the authors identified patients aged ≥ 65 years who underwent MMA embolization for the treatment of NASHs between November 2017 and February 2020. Patient demographics, comorbidities, clinical and radiographic factors, treatment factors, and clinical outcomes were abstracted. Subgroup analysis was performed comparing elderly (age 65-79 years) and advanced elderly (age > 80 years) patients., Results: MMA embolization was successfully performed in 98% of NASHs (in 148 of 151 cases) in 121 patients. Seventy elderly patients underwent 87 embolization procedures, and 51 advanced elderly patients underwent 64 embolization procedures. Elderly and advanced elderly patients had similar rates of embolization for upfront (46% vs 61%), recurrent (39% vs 33%), and prophylactic (i.e., with concomitant surgical intervention; 15% vs 6%) NASH treatment. Transfemoral access was used in most patients, and the procedure time was approximately 1 hour in both groups. Particle embolization with supplemental coils was most common, used in 51% (44/87) and 44% (28/64) of attempts for the elderly and advanced elderly groups, respectively. NASH thickness decreased significantly from initial thickness to 6 weeks, with additional decrease in thickness observed in both groups at 90 days. At longest follow-up, the treated NASHs had stabilized or improved in 91% and 98% of the elderly and advanced elderly groups, respectively, with > 50% improvement seen in > 60% of patients for each group. Surgical rescue was necessary in 4.6% and 7.8% of cases, and the overall mortality was 8.6% and 3.9% for elderly and advanced elderly patients, respectively., Conclusions: MMA embolization can be used safely and effectively as an alternative or adjunctive minimally invasive treatment for NASHs in elderly and advanced elderly patients.

Simulation-based training has become common practice across medical specialties, especially for learning complex skills performed in high-risk environments. In the field of endovascular neurosurgery, the demand for consequence- and risk-free learning environments led to the development of simulation devices valuable for medical trainees. The goal of this protocol is to provide instructive guidelines for the use of an endovascular neurosurgery simulator in an academic setting. The simulator provides trainees with the opportunity to receive realistic feedback on their knowledge of anatomy, as well as haptic feedback indicative of their success in handling the catheter-based systems without negative consequences. The utility of this specific protocol in relation to other neuroendovascular training modalities is also discussed.

Objective: Although stroke guidelines recommend antiplatelets be started 24 hours after tissue plasminogen activator (tPA), select mechanical thrombectomy (MT) patients with luminal irregularities or underlying intracranial atherosclerotic disease may benefit from earlier antiplatelet administration., Methods: We explore the safety of early (<24 hours) post-tPA antiplatelet use by retrospectively reviewing patients who underwent MT and stent placement for acute ischemic stroke from June 2015 to April 2018 at our institution., Results: Six patients met inclusion criteria. Median presenting and pre-operative National Institutes of Health Stroke Scale scores were 14 (Interquartile Range [IQR] 5.5-17.3) and 16 (IQR 13.7-18.7), respectively. Five patients received standard intravenous (IV) tPA and one patient received intra-arterial tPA. Median time from symptom onset to IV tPA was 120 min (IQR 78-204 min). Median time between tPA and antiplatelet administration was 4.9 hours (IQR 3.0-6.7 hours). Clots were successfully removed from the internal carotid artery (ICA) or middle cerebral artery (MCA) in 5 patients, the anterior cerebral artery (ACA) in one patient, and the vertebrobasilar junction in one patient. All patients underwent MT before stenting and achieved thrombolysis in cerebral infarction 2B recanalization. Stents were placed in the ICA (n=4), common carotid artery (n=1), and basilar artery (n=1). The median time from stroke onset to endovascular access was 185 min (IQR 136-417 min). No patients experienced symptomatic post-procedure intracranial hemorrhage (ICH). Median modified Rankin Scale score on discharge was 3.5., Conclusions: Antiplatelets within 24 hours of tPA did not result in symptomatic ICH in this series. The safety and efficacy of early antiplatelet administration after tPA in select patients following mechanical thrombectomy warrants further study., Competing Interests: Disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper., (Copyright © 2020 by KSCVS and KoNES.)

Background: The "Volume Pledge" aims to centralize carotid artery stenting (CAS) to hospitals and surgeons performing ≥10 and ≥5 procedures annually, respectively., Objective: To compare outcomes after CAS between hospitals and surgeons meeting or not meeting the Volume Pledge thresholds., Methods: We queried the Nationwide Inpatient Sample for CAS admissions. Hospitals and surgeons were categorized as low volume and high volume (HV) based on the Volume Pledge. Multivariable hierarchical regression models were used to examine the impact of hospital volume (2005-2011) and surgeon volume (2005-2009) on perioperative outcomes., Results: Between 2005 and 2011, 22 215 patients were identified. Most patients underwent CAS by HV hospitals (86.4%). No differences in poor outcome (composite endpoint of in-hospital mortality, postoperative neurological or cardiac complications) were observed by hospital volume but HV hospitals did decrease the likelihood of other complications, nonroutine discharge, and prolonged hospitalization. From 2005 to 2009, 9454 CAS admissions were associated with physician identifiers. Most patients received CAS by HV surgeons (79.2%). On multivariable analysis, hospital volume was not associated with improved outcomes but HV surgeons decreased odds of poor outcome (odds ratio [OR] 0.76, 95% confidence interval [CI] 0.59-0.97; P = .028), complications (OR 0.56, 95% CI 0.46-0.71, P < .001), nonroutine discharge (OR 0.70, 95% CI 0.57-0.87; P = .001), and prolonged hospitalization (OR 0.52, 95% 0.44-0.61, P < .001)., Conclusion: Most patients receive CAS by hospitals and providers meeting the Volume Pledge threshold for CAS. Surgeons but not hospitals who met the policy's volume standards were associated with superior outcomes across all measured outcomes., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Background: The development of infections such as urinary tract infections (UTIs) or pneumonia after a traumatic subdural hematoma (tSDH) can worsen patient outcomes and increase healthcare costs. We herein identify clinical parameters that influence the risk of infections after tSDH., Methods: This single-institution retrospective cohort study examined the incidence and risk factors for UTI and pneumonia among tSDH patients from 1990 to 2015. Multivariate logistic regression assessed the impact of various demographic and clinical variables on these outcomes., Results: 3024 patients with tSDHs were identified (73.1% male); Of those, 208 (6.9%) experienced a UTI and 434 (14.4%) experienced pneumonia. Of the 559 patients (18.5%) who underwent a craniotomy and/or craniectomy for evacuation of a tSDH, 62 (11.1%) experienced a UTI and 222 (39.7%) experienced pneumonia. Risk factors for both pneumonia and UTI included length of stay (LOS) ≥7 days (odds ratio [OR] = 6.0, P < 0.001; OR = 11.2, P < 0.001), intensive care unit LOS ≥7 days (OR = 8.1, P < 0.001; OR = 1.7, P = 0.012), and mechanical ventilation ≥14 days (OR = 3.4, P < 0.001; OR = 1.8, P = 0.007). Craniotomy/craniectomy increased the risk of pneumonia (OR = 1.4, P = 0.019) but not UTI. Glasgow Coma Scale (GCS) ≥13 was associated with a decreased pneumonia risk (OR = 0.5, P = 0.003), and male gender (OR = 0.5, P < 0.001) and age <60 (OR = 0.6, P < 0.001) were associated with a decreased UTI risk., Conclusions: Patients with prolonged hospitalizations and/or intensive care unit stays were more likely to experience UTIs and pneumonia. Male gender and younger age were protective against UTI, and higher GCS was protective against pneumonia. These data may aid the identification and treatment of at-risk populations after admission for a tSDH., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: The far-lateral and extreme-lateral infrajugular transcondylar-transtubercular exposure (ELITE) and extreme-lateral transcondylar transodontoid (ELTO) approaches provide access to lesions of the foramen magnum, inferolateral to mid-clivus, and ventral pons and medulla. A subset of pathologies in this region require manipulation of the vertebral artery (VA)-dural interface. Although a cuff of dura is commonly left on the VA to avoid vessel injury during these approaches, there are varying descriptions of the degree of VA-dural separation that is safely achievable. In this paper the authors provide a detailed histological analysis of the VA-dural junction to guide microsurgical technique for posterolateral skull base approaches., Methods: An ELITE approach was performed on 6 preserved adult cadaveric specimens. The VA-dural entry site was resected, processed for histological analysis, and qualitatively assessed by a neuropathologist., Results: Histological analysis demonstrated a clear delineation between the intima and media of the VA in all specimens. No clear plane was identified between the connective tissue of the dura and the connective tissue of the VA adventitia., Conclusions: The VA forms a contiguous plane with the connective tissue of the dura at its dural entry site. When performing posterolateral skull base approaches requiring manipulation of the VA-dural interface, maintenance of a dural cuff on the VA is critical to minimize the risk of vascular injury.

Background and Importance: Flow diversion for the treatment of aneurysm-induced hemifacial spasm (HFS) has not been previously described., Clinical Presentation: The authors present the case of a 60-yr-old woman who presented with 1 yr of progressive left HFS secondary to a vertebral artery aneurysm compressing the root entry zone of cranial nerve VII. The patient's aneurysm was successfully treated with a flow diverting stent., Conclusion: In the immediate postoperative period, the patient had near complete resolution of her HFS symptoms. At her 6-mo follow-up the patient had no angiographic filling of the aneurysm and her HFS symptoms had completely resolved., (Copyright © 2018 by the Congress of Neurological Surgeons.)

Large vessel occlusions (LVOs), variably defined as blockages of the proximal intracranial anterior and posterior circulation, account for approximately 24% to 46% of acute ischemic strokes. Commonly refractory to intravenous tissue plasminogen activator (tPA), LVOs place large cerebral territories at ischemic risk and cause high rates of morbidity and mortality without further treatment. Over the past few years, an abundance of high-quality data has demonstrated the efficacy of endovascular thrombectomy for improving clinical outcomes in patients with LVOs, transforming the treatment algorithm for affected patients. In this review, we discuss the epidemiology, pathophysiology, natural history, and clinical presentation of LVOs as a framework for understanding the recent clinical strides of the endovascular era., (© Congress of Neurological Surgeons 2019.)

Objective: Lesions of the foramen magnum, inferolateral-to-midclival areas, and ventral pons and medulla are often treated using a far-lateral or extreme-lateral infrajugular transcondylar-transtubercular exposure (ELITE) approach. The development and surgical relevance of critical posterior skull base bony structures encountered during these approaches, including the occipital condyle (OC), hypoglossal canal (HGC), and jugular tubercle (JT), are nonetheless poorly defined in the pediatric population., Methods: Measurements from high-resolution CT scans were made of the relevant posterior skull base anatomy (HGC depth from posterior edge of the OC, OC and JT dimensions) from 60 patients (evenly distributed among ages 0-3, 4-7, 8-11, 12-15, 16-18, and > 18 years), and compared between laterality, sex, and age groups by using t-tests and linear regression., Results: There were no significant differences in posterior skull base parameters by laterality, and HGC depth and JT size did not differ by sex. The OC area was significantly larger in males versus females (174.3 vs 152.2 mm2; p = 0.01). From ages 0-3 years to adult, the mean HGC depth increased 27% (from 9.0 to 11.4 mm) and the OC area increased 52% (from 121.4 to 184.0 mm2). The majority of growth for these parameters occurred between the 0-3 year and 4-7 year age groups. Conversely, JT volume increased nearly 3-fold (281%) from 97.4 to 370.9 mm3 from ages 0-3 years to adult, with two periods of substantial growth seen between the 0-3 to 4-7 year and the 12-15 to 16-18 year age groups. Overall, JT growth during pediatric development was significantly greater than increases in HGC depth and OC area (p < 0.05). JT volume remained < 65% of adult size up to age 16., Conclusions: When considering a far-lateral or ELITE approach in pediatric patients, standard OC drilling is likely to be needed due to the relative stability of OC and HGC anatomy during development. The JT significantly increases in size with development, yet is only likely to need to be drilled in older children (> 16 years) and adults.

Background: Acute ischemic stroke (AIS) remains a significant source of morbidity and mortality worldwide. Multiple recent randomized clinical trials for AIS patients presenting with large vessel occlusion have demonstrated radical improvement in outcomes with mechanical thrombectomy (MT), which is now recognized as the new standard of care for patients presenting up to 24 hr., Objective: To provide a perspective on training and credentialing requirements for practitioners in this field., Methods: Relevant articles were systematically searched and analyzed. Standards for Reporting Qualitative Research guidelines were utilized., Results: : The Committee for Advanced Subspecialty Training (CAST) brings together the principal specialties of Radiology, Neurology, and Neurosurgery. Their training standards document the most recent consensus on training for neuroendovascular surgery (NES) and include the endovascular treatment of AIS as a part of the field of NES. This unified consensus represents a significant landmark in the evolution of stroke therapy. Presently, training at most centers follows an apprenticeship type model. Simulation methods and objective performance metrics have not been widely incorporated. Maintenance of proficiency has not been conclusively addressed reflecting the overall developing nature of the field., Conclusion: The evolution of the standard of care interventional therapy for large vessel AIS utilizing MT raises concerns regarding work force needs, training standards, competency, and credentialing requirements for practitioners. The CAST framework represents the most modern and flexible approach for both individuals and training programs. Methods based on objective performance metrics utilizing simulation as primary vehicle may be the logical next steps in the evolution of NES., (Copyright © 2019 by the Congress of Neurological Surgeons.)

In 2005, the American Stroke Association published recommendations for the establishment of stroke systems of care and in 2013 expanded on them with a statement on interactions within stroke systems of care. The aim of this policy statement is to provide a comprehensive review of the scientific evidence evaluating stroke systems of care to date and to update the American Stroke Association recommendations on the basis of improvements in stroke systems of care. Over the past decade, stroke systems of care have seen vast improvements in endovascular therapy, neurocritical care, and stroke center certification, in addition to the advent of innovations, such as telestroke and mobile stroke units, in the context of significant changes in the organization of healthcare policy in the United States. This statement provides an update to prior publications to help guide policymakers and public healthcare agencies in continually updating their stroke systems of care in light of these changes. This statement and its recommendations span primordial and primary prevention, acute stroke recognition and activation of emergency medical services, triage to appropriate facilities, designation of and treatment at stroke centers, secondary prevention at hospital discharge, and rehabilitation and recovery.

Objective: Women have been shown to have a higher risk of cerebral aneurysm formation, growth, and rupture than men. The authors present a review of the recently published neurosurgical literature that studies the role of pregnancy and female sex steroids, to provide a conceptual framework with which to understand the various risk factors associated with cerebral aneurysms in women at different stages in their lives., Methods: The PubMed database was searched for "("intracranial" OR "cerebral") AND "aneurysm" AND ("pregnancy" OR "estrogen" OR "progesterone")" between January 1980 and February 2019. A total of 392 articles were initially identified, and after applying inclusion and exclusion criteria, 20 papers were selected for review and analysis. These papers were then divided into two categories: 1) epidemiological studies about the formation, growth, rupture, and management of cerebral aneurysms in pregnancy; and 2) investigations on female sex steroids and cerebral aneurysms (animal studies and epidemiological studies)., Results: The 20 articles presented in this study include 7 epidemiological articles on pregnancy and cerebral aneurysms, 3 articles reporting case series of cerebral aneurysms treated by endovascular therapies in pregnancy, 3 epidemiological articles reporting the relationship between female sex steroids and cerebral aneurysms through retrospective case-control studies, and 7 experimental studies using animal and/or cell models to understand the relationship between female sex steroids and cerebral aneurysms. The studies in this review report similar risk of aneurysm rupture in pregnant women compared to the general population. Most ruptured aneurysms in pregnancy occur during the 3rd trimester, and most pregnant women who present with cerebral aneurysm have caesarean section deliveries. Endovascular treatment of cerebral aneurysms in pregnancy is shown to provide a new and safe form of therapy for these cases. Epidemiological studies of postmenopausal women show that estrogen hormone therapy and later age at menopause are associated with a lower risk of cerebral aneurysm than in matched controls. Experimental studies in animal models corroborate this epidemiological finding; estrogen deficiency causes endothelial dysfunction and inflammation, which may predispose to the formation and rupture of cerebral aneurysms, while exogenous estrogen treatment in this population may lower this risk., Conclusions: The aim of this work is to equip the neurosurgical and obstetrical/gynecological readership with the tools to better understand, critique, and apply findings from research on sex differences in cerebral aneurysms.