The evolution of intracranial aneurysm treatment techniques and future directions.

Treatment techniques and management guidelines for intracranial aneurysms (IAs) have been continually developing and this rapid development has altered treatment decision-making for clinicians. IAs are treated in one of two ways: surgical treatments such as microsurgical clipping with or without bypass techniques, and endovascular methods such as coiling, balloon- or stent-assisted coiling, or intravascular flow diversion and intrasaccular flow disruption. In certain cases, a single approach may be inadequate in completely resolving the IA and successful treatment requires a combination of microsurgical and endovascular techniques, such as in complex aneurysms. The treatment option should be considered based on factors such as age; past medical history; comorbidities; patient preference; aneurysm characteristics such as location, morphology, and size; and finally the operator's experience. The purpose of this review is to provide practicing neurosurgeons with a summary of the techniques available, and to aid decision-making by highlighting ideal or less ideal cases for a given technique. Next, we illustrate the evolution of techniques to overcome the shortfalls of preceding techniques. At the outset, we emphasize that this decision-making process is dynamic and will be directed by current best scientific evidence, and future technological advances.

Clinical Outcomes of Transplanted Modified Bone Marrow-Derived Mesenchymal Stem Cells in Stroke: A Phase 1/2a Study.

BACKGROUND AND PURPOSE: Preclinical data suggest that cell-based therapies have the potential to improve stroke outcomes. METHODS: Eighteen patients with stable, chronic stroke were enrolled in a 2-year, open-label, single-arm study to evaluate the safety and clinical outcomes of surgical transplantation of modified bone marrow-derived mesenchymal stem cells (SB623). RESULTS: All patients in the safety population (N=18) experienced at least 1 treatment-emergent adverse event. Six patients experienced 6 serious treatment-emergent adverse events; 2 were probably or definitely related to surgical procedure; none were related to cell treatment. All serious treatment-emergent adverse events resolved without sequelae. There were no dose-limiting toxicities or deaths. Sixteen patients completed 12 months of follow-up at the time of this analysis. Significant improvement from baseline (mean) was reported for: (1) European Stroke Scale: mean increase 6.88 (95% confidence interval, 3.5-10.3; P<0.001), (2) National Institutes of Health Stroke Scale: mean decrease 2.00 (95% confidence interval, -2.7 to -1.3; P<0.001), (3) Fugl-Meyer total score: mean increase 19.20 (95% confidence interval, 11.4-27.0; P<0.001), and (4) Fugl-Meyer motor function total score: mean increase 11.40 (95% confidence interval, 4.6-18.2; P<0.001). No changes were observed in modified Rankin Scale. The area of magnetic resonance T2 fluid-attenuated inversion recovery signal change in the ipsilateral cortex 1 week after implantation significantly correlated with clinical improvement at 12 months (P<0.001 for European Stroke Scale). CONCLUSIONS: In this interim report, SB623 cells were safe and associated with improvement in clinical outcome end points at 12 months. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01287936.

Early Hypoalbuminemia is an Independent Predictor of Mortality in Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Hypoalbuminemia has been identified as a predictor of morbidity and mortality in critically ill patients. There is very little data on the significance and the prognostic value of hypoalbuminemia in patients with aneurysmal subarachnoid hemorrhage (aSAH). This study analyzed the impact of hypoalbuminemia on patient presentation, complications, and outcomes. METHODS: Records of patients admitted with aSAH were examined. Data on baseline characteristics, prevalence of delayed cerebral ischemia, and discharge outcomes were collected. Multivariable logistic regression analysis was performed to assess for associations. RESULTS: One-hundred and forty-two patients comprised the study cohort (mean age 54.6 ± 13.4), among which 45 (31.5 %) presented with hypoalbuminemia. No difference in baseline characteristics was noted between patients with hypoalbuminemia and those with normal serum albumin. The overall hospital mortality rate was significantly higher in patients with hypoalbuminemia, compared to those with normal albumin (28.9 % vs. 11.3 %; p = 0.04). Hypoalbuminemia was neither associated with delayed cerebral ischemia nor disability at discharge, but independently associated with in-hospital death (odds ratio: 4.26, 95 % confidence interval: 1.09-16.68; p = 0.04). CONCLUSION: In patients with aSAH, early hypoalbuminemia is an independent predictor of hospital mortality but not disability at discharge.

The role of intra-arterial chemotherapy as an adjuvant treatment for glioblastoma.

Glioblastoma multiforme (GBM) is an aggressive tumor with poor survival outcomes and limited treatment options. We conducted a literature review to compare the survival outcomes of intra-arterial (IA) and intravenous (IV) chemotherapy delivery for GBM. Nine studies of IA chemotherapy infusion with 301 total patients met our criteria for inclusion and three studies contained IV treatment groups for comparison (n = 230 for IA, n = 71 for IV). The studies were grouped by either using newly diagnosed or recurrent GBM patients. In the newly diagnosed group, IV chemotherapy produced a statistically higher median overall survival (MOS; 16.3 months) compared with IA treatment (14.02 months). However, the total number of adverse events in IA chemotherapy was 1.08 per patient whereas for IV it was higher at 1.54 events per patient. Our recurrent GBM group includes only patients treated with IA chemotherapy which resulted in an average MOS of 10.84 months. This group had 2.7 adverse events per patient but no IV group is available for comparison. Historically, the survival of patients with recurrent GBM ranges from 3 to 9 months (Gil-Gil et al. Bevacizumab for the treatment of glioblastoma. Clin Med Insights Oncol 2013;7:123-35). For this reason, we believe IA chemotherapy to be a viable methodology in recurrent GBM patients to prolong survival at the risk of procedure-related complications and in newly diagnosed patients with the benefit of decreased complications.

Concurrent Middle Cerebral Artery and Basilar Artery Occlusions Treated With Mechanical Thrombectomy in a Patient With Active COVID-19 Infection.

We report a rare case of acute ischemic stroke from concurrent large vessel occlusions (LVOs) and subsequent successful mechanical thrombectomy revascularization in a patient with active coronavirus disease 2019 (COVID-19) pneumonia. A 59-year-old woman presented to the emergency department after one week of intermittent chest pain, dyspnea, and diarrhea found to have COVID-19 pneumonia. On hospital day three, the patient developed acute altered mental status and hemiparesis with a National Institutes of Health Stroke Scale (NIHSS) of 22. CT with angiography demonstrated concurrent occlusions of the basilar artery and the M1 segment of the right middle cerebral artery (MCA) without intracranial hemorrhage. The patient was taken for urgent mechanical thrombectomy of the basilar artery, followed by the MCA, both of which were successful (thrombolysis in cerebral infarction (TICI) 3 and 2B) and timely. Despite early revascularization, the patient did not improve clinically with absent brainstem reflexes and a full MCA territorial infarct on imaging. This case describes a rare stroke syndrome of concurrent LVOs with rapid infarct progression despite timely revascularization. This example illustrates a severe cerebrovascular complication of active COVID-19 infection and the importance of vigilance regarding stroke prevention and neurological examination monitoring.

The neurosurgery research & education foundation-young neurosurgeons committee webinar series: Providing education and inspiration during the COVID-19 pandemic.

OBJECTIVE: During the COVID-19 pandemic, the American Association of Neurological Surgeons (AANS) Young Neurosurgeons Committee (YNC) and Neurosurgery Research & Education Foundation (NREF) launched the YNC-NREF Webinar Series to provide young and aspiring neurosurgeons with timely information, education, and inspiration in the absence of in-person programming. DESIGN: Five 90-minute Zoom webinars were evaluated, each including 1-2 keynote speakers, a panel discussion, and an audience question-and-answer section. Topics included overviews of neurosurgery, the match, subspecialties, and inspirational career stories. Optional pre- and post-webinar surveys with 11-point Likert-type scores were distributed to attendees. We compared groups using chi-squared and Kruskal-Willis tests, and perceptions pre- and post-webinar using Mann-Whitney tests. SETTING: The webinars were live using Zoom, and the recordings were published on NREF's YouTube channel. PARTICIPANTS: The webinar series targeted young neurosurgeons. The first five episodes had a particular focus on medical students and undergraduates. RESULTS: A total of 673 unique participants attended the webinar series; 257 (38%) and 78 (11%) attendees completed the pre- and post-webinar survey, respectively. Respondents had high baseline interest in neurosurgery and were motivated to learn about the match and training in the US, understand neurosurgeons' day-to-day lives, and ask questions. There were significant differences in perceptions between USMSs, IMSs, and undergraduate students. The webinar improved attendees' knowledge about neurosurgical specialties, the match, and US neurosurgery training. CONCLUSIONS: The YNC and NREF effectively engaged a large, diverse audience through an online webinar series, building a foundation for future virtual programming by organized neurosurgery. ACGME competencies.

Development of a rabbit human glioblastoma model for testing of endovascular selective intra-arterial infusion (ESIA) of novel stem cell-based therapeutics.

BACKGROUND: Endovascular selective intra-arterial (ESIA) infusion of cellular oncotherapeutics is a rapidly evolving strategy for treating glioblastoma. Evaluation of ESIA infusion requires a unique animal model. Our goal was to create a rabbit human GBM model to test IA infusions of cellular therapies and to test its usefulness by employing clinical-grade microcatheters and infusion methods to deliver mesenchymal stem cells loaded with an oncolytic adenovirus, Delta-24-RGD (MSC-D24). METHODS: Rabbits were immunosuppressed with mycophenolate mofetil, dexamethasone, and tacrolimus. They underwent stereotactic xenoimplantation of human GBM cell lines (U87, MDA-GSC-17, and MDA-GSC-8-11) into the right frontal lobe. Tumor formation was confirmed on magnetic resonance imaging, histologic, and immunohistochemistry analysis. Selective microcatheter infusion of MSC-D24 was performed via the ipsilateral internal carotid artery to assess model utility and the efficacy and safety of this approach. RESULTS: Twenty-five rabbits were implanted (18 with U87, 2 MDA-GSC-17, and 5 MDA-GSC-8-11). Tumors formed in 68% of rabbits (77.8% for U87, 50.0% for MDA-GSC-17, and 40.0% for MDA-GSC-8-11). On MRI, the tumors were hyperintense on T2-weighted image with variable enhancement (evidence of blood brain barrier breakdown). Histologically, tumors showed phenotypic traits of human GBM including varying levels of vascularity. ESIA infusion into the distal internal carotid artery of 2 ml of MSCs-D24 (107 cells) was safe in the model. Examination of post infusion specimens documented that MSCs-D24 homed to the implanted tumor at 24 hours. CONCLUSIONS: The intracranial immunosuppressed rabbit human GBM model allows testing of ESIA infusion of novel therapeutics (eg, MSC-D24) in a clinically relevant fashion.

Assessing opportunities for formal exposure to clinical neurosurgery within United States allopathic medical education curricula.

OBJECTIVE: The objective of this study was to evaluate opportunities for early clinical exposure to neurosurgery at US allopathic medical schools and to assess associations between early exposure and recruitment into neurosurgery. METHODS: The authors conducted a standardized review of online curriculum documentation for all US allopathic medical schools, including descriptive review of opportunities for clinical neurosurgical training among medical students. Chi-square analysis was used to compare baseline characteristics of institutions. Logistic regression was performed to assess factors predictive of early exposure to clinical neurosurgery, defined as completion of a formal rotation at least 6 months prior to Electronic Residency Application Service submission. RESULTS: Among 155 allopathic US medical schools, 143 are fully accredited by the Liaison Committee on Medical Education. Eleven schools have no affiliated hospitals with a neurosurgery practice, and 26 do not have an American Association of Neurological Surgeons (AANS) medical student chapter. Overall, 94 (60.6%) have a traditional preclinical curriculum lasting 21-25 months, 50 (32.3%) offer an intermediate preclinical period of 15-20 months, and 11 (7.1%) report a short preclinical curriculum of 12-14 months. Early formal exposure to clinical neurosurgery was offered by 113 schools (72.9%). Early clinical exposure to neurosurgery was associated with a short (100%) or intermediate (76%) preclinical curriculum, as compared with a traditional curriculum (68.1%; p = 0.066). Early exposure was significantly associated with a shorter preclinical curriculum (OR 0.784, p = 0.005). AANS medical student chapters were present at a high majority of schools with early exposure (OR 4.114, p = 0.006). Medical schools with a higher percentage of graduating medical students matching into neurosurgery were associated with a shorter preclinical curriculum length (ß = -0.287, p < 0.001), were more commonly private medical schools (ß = 0.338, p < 0.001), and had early clinical exposure to neurosurgery (ß = 0.191, p = 0.032). CONCLUSIONS: Early exposure to clinical neurosurgery is available at most US allopathic medical schools and is associated with shorter preclinical curricula and institutions with AANS medical student chapters. Medical schools with a higher proportion of medical students entering neurosurgery had a shorter preclinical curriculum length and early clinical exposure to neurosurgery. Further study is recommended to characterize the impact of early exposure on long-term pedagogical outcomes.

Endoscope-Assisted Pedicled Maxillary Artery to Middle Cerebral Artery Bypass: An Anatomic Feasibility Study.

BACKGROUND: Extracranial to intracranial bypass is used to augment and/or replace the intracranial circulation for various pathologies. The superficial temporal artery is the mainstay donor for pedicled bypasses to the anterior circulation but can be limited by its variable size, low native flow rates, and potential scalp complications. Interposition grafts such as the radial artery or greater saphenous vein are alternatives but are sometimes limited by size mismatch, length needed to reach the extracranial circulation, and loss of inherent vascular elasticity. Interposition grafts between the maxillary artery (IMA) and middle cerebral artery (MCA) address these limitations. OBJECTIVE: To explore the feasibility of harvesting the IMA through an endoscopic transnasal, transmaxillary approach to perform a direct IMA to MCA bypass. METHODS: Combined transcranial and endoscopic endonasal dissections were performed in embalmed human cadavers to harvest the IMAs for intracranial transposition and direct anastomosis to the MCA. Donor and recipient vessel calibers were measured and recorded. RESULTS: A total of 8 procedures were performed using the largest and distal-most branches of the IMA (the sphenopalatine branch and the descending palatine branch) as pedicled conduits to second division of middle cerebral artery (M2) recipients. The mean diameter of the IMA donors was 1.89 mm (SD ± 0.42 mm), and the mean diameter of the recipient M2 vessels was 1.90 mm (SD ± 0.46 mm). CONCLUSION: Endoscopic harvest of the IMA using a transnasal, transmaxillary approach is a technically feasible option offering an excellent size match to the M2 divisions of the MCA and the advantages of a relatively short, pedicled donor vessel.

The Perceived Utility of 3 Online Resources for Medical Student Neurosurgery Education.

OBJECTIVE: Neurosurgery has a high barrier of educational access for medical students. The Medical Student Neurosurgery Training Center (MSNTC) is a novel online learning platform that provides on-site and virtual training opportunities and resources that aim to increase student access to neurosurgical education. The objective of this article was to describe student-reported utility of Medical Student Neurosurgery Training Center educational resources. METHODS: A Qualtrics survey was sent to attendees after the 2020 Virtual Neurosurgery Training Camp. Ratings were quantified on modified 5-point Likert scales and compared using Wilcoxon rank sum tests, with a P value of 0.05. RESULTS: Response was obtained from 119 (25.2%) of 473 Virtual Neurosurgery Training Camp registrants. Of respondents, 65 (54.6%) reported prior use of Brain & Spine Report (BSR), 68 (57.14%) reported use of the Video Library (VL), and 78 (65.5%) reported use of the Global Events Calendar (GEC). Among respondents who previously used the BSR, VL, or GEC, mean ratings of usefulness were 3.94 ± 1.01, 4.06 ± 0.91, and 4.10 ± 0.99, respectively. Medical students with a neurosurgery interest group at their home institution reported greater utility of the BSR (P = 0.0008), VL (P = 0.0018), and GEC (P = 0.0250). Medical students with a home program reported greater utility of the BSR (P = 0.0079), and international students reported greater utility of the VL (P = 0.0447). CONCLUSIONS: Medical Student Neurosurgery Training Center resources appear to have promising preliminary benefits for students. Increasing medical student awareness, continued development of these resources, and objectively assessing outcomes in neurosurgery education are warranted.

A retrospective anatomical study of the cerebral dural venous sinus outflow pathways utilizing three-dimensional rotational venography.

OBJECTIVE: Proper blood flow is essential for the maintenance of homeostasis for the human cerebrum. The dural venous sinuses comprise the dominant cerebral venous outflow path. Understanding the spatial configuration of the dural venous sinuses can provide valuable insight into several pathological conditions. Previously, only two-dimensional or cadaveric data have been used to understand cerebral outflow. For the first time, we applied three-dimensional rotational venography (3D-RV) to study and provide detailed quantitative morphological measurements of the terminal cerebral venous sinus system in several pathological states. SUBJECTS AND METHODS: Patients who underwent a 3D-RV procedure were identified by reviewing our local institution's endovascular database. Patients with high-quality angiographic images were selected. Eighteen patients were included (37.1 ± 3.8 years). Sinuses were divided into four segments, starting at the torcula and ending at the internal jugular vein. Segment length, 3D displacement, and cross-sectional area were measured. RESULTS: The transverse sinus (60.2 mm) was the longest segment, followed by the sigmoid sinus (55.1 mm). Cross-sectional areas were smallest at the middle of the transverse sinus (21.3 mm2) but increased at the sigmoid sinus (33.5 mm2) and at the jugular bulb (49.7 mm2). The only variation in displacements of venous flow was at the sigmoid-jugular junction, where 55% of cases had lateral displacements versus 45% medial, and 78% superior versus 22% inferior. CONCLUSIONS: We describe the terminal venous sinus system of patients with a variety of diagnoses, detailing segment length, cross-sectional area, and 3D path.

Optimizing the residency application process: insights from neurological surgery during the pandemic virtual application cycle.

OBJECTIVE: In this article, the authors describe the impact of the COVID-19 virtual match cycle and discuss approaches to optimize future cycles through applicant and neurosurgical education leadership insights. METHODS: Anonymous surveys of neurosurgery program leaders (program directors and program chairs), program administrators (PAs), and 2020-2021 neurosurgery residency match applicants were distributed by the SNS, in conjunction with the Association of Resident Administrators in Neurological Surgery and AANS Young Neurosurgeons Committee. RESULTS: Responses were received from 77 (67.0%) of 115 PAs, 119 (51.7%) of 230 program leaders, and 124 (44.3%) of 280 applicants representing geographically diverse regions. During the virtual application cycle relative to the previous year, programs received more Electronic Residency Application Service applications (mean 314.8 vs 285.3, p < 0.0001) and conducted more applicant interviews (mean 45.2 vs 39.9, p = 0.0003). More than 50% of applicants applied to > 80 programs; 60.3% received ≤ 20 interview invitations, and 9% received > 40 invitations. Overall, 65% of applicants completed ≤ 20 interviews, whereas 34.7% completed > 20 interviews. Program leaders described one 4-week home subinternship (93.3%) and two 4-week external subinternships (68.9%) as optimal neurosurgical exposure; 62.8% of program leaders found the standardized letter of recommendation template to be somewhat (47.5%) or significantly (15.3%) helpful. Applicants, PAs, and program leaders all strongly preferred a hybrid model of in-person and virtual interview options for future application cycles over all in-person or all virtual options. Ninety-three percent of applicants reported matching within their top 10-ranked programs, and 52.9% of programs matched residents within the same decile ranking as in previous years. CONCLUSIONS: Optimizing a national strategy for the neurosurgery application process that prioritizes equity and reduces costs, while ensuring adequate exposure for applicants to gain educational opportunities and evaluate programs, is critical to maintain a successful training system.

Middle meningeal artery embolization for chronic subdural hematoma in cancer patients with refractory thrombocytopenia.

OBJECTIVE: Surgical evacuation of chronic subdural hematoma (SDH) in cancer patients is often contraindicated owing to refractory thrombocytopenia. Middle meningeal artery embolization (MMAE) recently emerged as a potential alternative to surgical evacuation for patients with chronic SDH. The goal of this study was to evaluate the safety and efficacy of MMAE for chronic SDH in cancer patients with refractory thrombocytopenia. METHODS: A multiinstitutional registry was reviewed for clinical and radiographic outcomes of cancer patients with transfusion-refractory thrombocytopenia and baseline platelet count < 75 K/µl, who underwent MMAE for chronic SDH. RESULTS: MMAE was performed on a total of 31 SDHs in 22 patients, with a mean ± SD (range) platelet count of 42.1 ± 18.3 (9-74) K/µl. At the longest follow-up, 24 SDHs (77%) had reduced in size, with 15 (48%) showing > 50% reduction. Two patients required surgical evacuation after MMAE. There was only 1 procedural complication; however, 16 patients (73%) ultimately died of cancer-related complications. Median survival was significantly longer in the 16 patients with improved SDH than the 6 patients with worsened SDH after MMAE (185 vs 24 days, p = 0.029). Length of procedure, technical success rate, SDH size reduction, and complication rate were not significantly differ between patients who underwent transfemoral and transradial approaches. CONCLUSIONS: Transfemoral or transradial MMAE is a potential therapeutic option for thrombocytopenic cancer patients with SDH. However, treatment benefit may be marginal for patients with high disease burden and limited life expectancy. A prospective trial is warranted to address these questions.

Impact of histological clot composition on preprocedure imaging and mechanical thrombectomy.

INTRODUCTION: We studied the relationship of acute ischemic stroke (AIS) large-vessel occlusion clot composition with vessel recanalization and preprocedure imaging. SUBJECTS AND METHODS: Individual clots from AIS patients who underwent mechanical thrombectomy (MT) between September 2016 and September 2018 were examined. Clot composition was analyzed histologically through a trichrome staining and image segmentation, and the area occupied by red blood cells (RBCs), fibrin, or mixed composition was quantified. RESULTS: Forty-three patients (65.4 ± 12.7 years, 39% of females) who underwent 92 retrieval passes (mean 2.14, range 1-6) were included in this study. Fibrin (44%) occupied the greatest area, followed by mixed composition (34%) and RBCs (22%). A stent retriever was deployed in 81% of cases, 20 patients (47%) achieved first-pass efficacy (FPE) (thrombolysis in cerebral infarction [TICI] 2b-3 after first pass), 41 (95%) achieved successful revascularization (TICI 2b-3), and 21 (49%) had good outcome (modified Rankin Scale [mRS] ≤2) at 90 days. Hyperdense artery sign (HAS) on initial computed tomography was correlated with mixed clot composition (P = 0.01) and lack of fibrin content (P = 0.03). In the univariate analysis, FPE was associated with RBC clot area, atrial fibrillation, and occlusion location but not with fibrin clot area, mixed clot area, stroke etiology, thrombectomy technique, distal emboli, or 90-day mRS. In the multivariate analysis, FPE was significantly correlated with low RBC clot area (odd ratio = 0.96, confidence interval [0.92.99], P = 0.034) but not with atrial fibrillation or location. CONCLUSION: Our results suggest that HAS is correlated with mixed clot composition and lower fibrin content and that lower RBC clot composition is associated with FPE in patients undergoing MT.

Silk Vista Baby for the Treatment of Complex Posterior Inferior Cerebellar Artery Aneurysms.

BACKGROUND: Treatment of small-caliber vessel lesions using flow diverters remains challenging because of vasculature's narrow luminal diameter and tortuosity. This in turn makes navigation and delivery of conventional devices with standard microcatheters more difficult. The Silk Vista Baby (SVB, Balt) flow diversion device was designed for ease of use in vessels with a smaller diameter, distal lesions, and 0.017 ″ microcatheter delivery systems. OBJECTIVE: To report the outcomes of the SVB device on the treatment of posterior inferior cerebellar artery (PICA) aneurysms. METHODS: Databases from different centers were retrospectively reviewed for PICA aneurysms treated with SVB. Demographic information, clinical presentation, radiographic characteristics, procedural complications, and immediate postprocedure outcomes were obtained. RESULTS: Fourteen patients harboring 15 true PICA aneurysms were treated between January 2019 and June 2021. Nine were female (n = 9/14; 64.2%), and the mean age was 51 ± 14.9 years. Most patients had previously ruptured aneurysms, treated by another endovascular technique. Six aneurysms were located distally (n = 6/15; 40%). The mean neck size was 3 mm (SD 1.35, range 2.5-5 mm), whereas the mean PICA diameter was 1.6 mm (SD 0.26, range 1.5-1.7 mm). The mean length of follow-up was 6 months (SD 8.28, range 4.5-16 months). Treatment-related adverse events included 1 case of transient hypoesthesia. Two additional events were reported, but adjudicated as unrelated to the procedure. Complete occlusion, measured as Raymond-Roy class I, was achieved in all cases. CONCLUSION: The SVB device was safely and effectively used in the treatment of PICA aneurysms. The smaller delivery system profile reduces the risk of procedure complications and creates new treatment options for distal lesions.

Retreatment of Residual and Recurrent Aneurysms After Embolization With the Woven EndoBridge Device: Multicenter Case Series.

BACKGROUND: The Woven EndoBridge (WEB) device (Terumno Corp. [parent company of Microvention]) was approved by the U.S. Food and Drug Administration as the first intrasaccular device for intracranial aneurysm treatment in December 2018. Its use has become more common since then, but both trial results and postmarket experiences have raised questions about the efficacy in achieving complete aneurysm obliteration. Retreatment after WEB embolization has not been extensively discussed. OBJECTIVE: To discuss the incidence and retreatment of aneurysms after initial WEB embolization. METHODS: Retrospective review across 13 institutions identified all occurrences of WEB retreatment within neurovascular databases. Details regarding demographics, aneurysm characteristics, treatment considerations, clinical outcomes, and aneurysm occlusion were obtained and analyzed. RESULTS: Thirty aneurysms were retreated in 30 patients in a cohort of 342 WEB-treated aneurysms. The retreatment rate was 8.8%. Endovascular methods were used for 23 cases, and 7 were treated surgically. Two aneurysms presented with rehemorrhage after initial WEB embolization. Endovascular treatments included stent-assisted coiling (12), flow diversion (7), coiling (2), PulseRider (Johnson & Johnson)-assisted coiling (1), and additional WEB placement (1). Surgical treatments included primary clipping (6) and Hunterian ligation (1). There were no major complications within the study group. CONCLUSION: WEB retreatments were successfully performed by a variety of techniques, including stent-assisted coiling, clipping, and flow diversion as the most common. These procedures were performed safely with subsequent obliteration of most aneurysms. The potential need for retreatment of aneurysms should be considered during primary WEB treatments.

Crossing the Carotid Siphon: Techniques to Facilitate Distal Access in Tortuous Anatomy: 2-Dimensional Operative Video.

As capabilities for endovascular treatment of intracranial vascular pathologies continue to expand, the need for access to the distal internal carotid artery with rigid support catheter systems continues to increase. One of the dominant factors limiting this access is patient anatomy, specifically vessel tortuosity. Increased tortuosity of the carotid siphon is a frequently encountered anatomic variant and may complicate endovascular procedures in adults and children.1,2 Failed attempts to navigate the carotid siphon with a distal access catheter carry a risk of vessel injury and treatment failure. For this reason, techniques that aid in supporting safe advancement of a distal access catheter across a tortuous carotid siphon are essential.3,4 In this video, we demonstrate 2 ways in which this may be accomplished. The first technique uses a larger diameter microcatheter, such as the AXS Offset catheter (Stryker, Kalamazoo, Michigan), to increase support for the distal access catheter, while the second uses a buddy wire technique to accomplish this increased support. Both of these techniques can help increase the safety of navigating a tortuous carotid siphon and increase the likelihood of successful treatment. The procedures shown were performed with the informed consent of the patients.

Distal Access Catheters for Coaxial Radial Access for Posterior Circulation Interventions.

BACKGROUND: The neurointerventional field is moving towards transradial access (TRA). Among the favorable indications for TRA is for posterior circulation/vertebrobasilar interventions. For some neurointerventions, a triaxial system (guide catheter, distal access catheter [DAC], and microcatheter) is typically used for optimal support. We describe application of a new technique in which we forgo use of the guide catheter, using the DAC only for coaxial access via the radial approach and its potential advantages. METHODS: A retrospective review was performed of our institutional database for cases using our coaxial distal access catheter technique for posterior circulation interventions. Patient characteristics and radiographic and clinical information were reviewed. All reviews were approved by institutional review board and ethics committee, and all patient identifiers were removed. RESULTS: A total of 12 patients were found that met our criteria. Successful access and procedural completion was achieved in 11 of 12 (92%). Mechanical thrombectomy accounted for 7 cases; 2 of these patients were also stented via the same approach/technique. Other cases included 2 successful aneurysm treatments (1 flow diverter, 1 coil embolization), a balloon test occlusion for a cervical chordoma, and an arteriovenous malformation embolization. CONCLUSIONS: TRA with a distal access catheter provides support equivalent to a triaxial system with a coaxial construct in the posterior circulation. This has the advantage of using a smaller system in the radial and vertebrobasilar artery without losing stability. This technique can be used effectively and safely for a variety of posterior circulation neuroendovascular interventions.

Trapping and P2-P3 Posterior Inferior Cerebellar Artery Reanastomosis for Treatment of a Ruptured Fusiform Aneurysm: Application of Fourth-Generation Technique: 2-Dimensional Operative Video.

Aneurysms of the posterior inferior cerebellar artery (PICA) represent the second most common posterior circulation aneurysm and commonly have complex morphology. Various bypass options exist for PICA aneurysms,1-6 depending on their location relative to brainstem perforators and the vertebral artery, and the presence of nearby donor arteries. We present a case of a man in his late 40s who presented with 3 d of severe headache. He was found to have a fusiform right P2-segment PICA aneurysm. Preoperative angiogram demonstrated the aneurysm and a redundant P3 caudal loop that came in close proximity to the healthy P2 segment proximal to the aneurysm. The risks and benefits of the procedure were discussed with the patient, and they consented for a right far lateral approach craniotomy with partial condylectomy for trapping of the aneurysm with bypass. The aneurysm was trapped proximally and distally. The P3 was transected just distal to the aneurysm and brought toward the proximal P2 segment, facilitated by a lack of perforators on this redundant distal artery. An end-to-side anastomosis was performed. Postoperative angiogram demonstrated exclusion of the aneurysm and patent bypass. The patient recovered well and remained without any neurological deficit at 6-mo follow-up. This case demonstrates the use of a "fourth-generation"5,7,8 bypass technique. These techniques represent the next innovation beyond third-generation intracranial-intracranial bypass. In this type 4B reanastomosis bypass, an unconventional orientation of the arteries was used. Whereas reanastomosis is typically performed end-to-end, the natural course of these arteries and the relatively less-mobile proximal P2 segment made end-to-side the preferred option in this case. Fourth-generation bypass techniques open up more configurations for reanastomosis, using the local anatomy to the surgeon's advantage. The patient consented to the described procedure and consented to the publication of their image.

Burnout among medical students interested in neurosurgery during the COVID-19 era.

OBJECTIVE: The novel Coronavirus Disease 2019 (COVID-19) pandemic has posed unprecedented new stressors to medical student education. This national survey investigated the prevalence of burnout in U.S. medical students interested in pursuing neurosurgical residency during the COVID-19 pandemic. METHODS: A 24-question survey was sent to all American Association of Neurological Surgeons (AANS) medical student chapter members. The abbreviated Maslach Burnout Inventory (aMBI) was used to measure the following burnout metrics: emotional exhaustion, depersonalization, and personal accomplishment. Bivariate analyses were conducted and multivariate analyses were performed using a logistic regression models. RESULTS: 254 medical students were included (response rate of 14.5%). The majority were male (55.1%), White (66.1%), and between their 2nd and 3rd years in medical school (62.6%). Burnout was identified in 38 (15.0%) respondents, a rate lower than reported in the pre-COVID era. In multivariate analysis, burnout was significantly associated with choosing not to pursue, or feeling uncertain about pursuing, a medical career again if given the choice (OR = 3.40, p = 0.0075), having second thoughts about choosing to pursue neurosurgery (OR = 3.47, p = 0.0025), attending a medical program in the Northeast compared to the Southeast (OR = 0.32, p = 0.027) or Southwest U.S. (OR = 0.30, p = 0.046), and indicating that one's future clinical performance will have worsened due to COVID-19 (OR = 2.71, p = 0.025). CONCLUSIONS: Our study demonstrates relatively low rates of burnout among U.S. medical students interested in pursuing neurosurgery during the COVID-19 pandemic. Our findings also demonstrate multiple factors may aid in early identification of burnout, highlighting potential opportunities for intervention.