Trends in United States neurosurgery residency education and training over the last decade (2009-2019).

OBJECTIVE: Postgraduate training in medicine has been under scrutiny in the last 10 years, with a focus on improving residents' education. The aim of this study was to quantify trends in neurosurgery residency (NSR) training and education over the last 10 years. METHODS: The authors assessed Accreditation Council for Graduate Medical Education (ACGME), National Resident Matching Program, and American Board of Neurological Surgeons records and searched PubMed to collate 2009-2019 data. Analyzed trends included residents' demographic data, programs' characteristics, graduation and attrition rates, match data, resident case logs, and qualitative educational curriculum changes. RESULTS: Significant increases in residents' demographic data (p < 0.05) included the number of female residents (from 12.7% to 17.6%) and the absolute number of residents (from 1112 to 1462). Age (mean 28.8 years), ethnicity, and number of residents per program (mean 13 residents per program) were unchanged. There were 16 new ACGME NSR programs, with currently 115 programs nationwide. The number of applicants per year (324 applicants per year) and the matching rate (mean 64%) remained stable. The mean attrition rate of 2.6% (range 2%-4%) was higher than the mean 2.1% ACGME attrition rate, a rate that decreased from 3% in 2009 to 1.6% in 2019. Education curriculum changes aimed at the standardization of training across the US included residents' boot camp (2009), the Milestones project (2012), and mandatory 7-year training initiated in 2013. An increase in endovascular, functional, trauma, and spine resident caseload was noted. The number of yearly publications about US NSR education has significantly increased (p < 0.05). CONCLUSIONS: NSR education has received greater attention over the last decade in the US. Standardization of training has been implemented. A steady number of students remain interested in neurosurgery, with an increased number of women entering the field. Attention to wellness, in addition to high-quality education, should be further assessed as a factor to improve the overall NSR training and retention rate.

Introduction: Endovascular Neurosurgery.

Remarkable developments in the field of endovascular neurosurgery have been witnessed in the last decade. The success of endovascular therapy for ischemic stroke treatment is now irrefutable, making it an accepted standard of care. Endovascular treatment of cerebral aneurysms is no longer limited to primary coiling but now includes options such as stent or balloon assistance and flow diversion and applications utilizing neck reconstruction, intrasaccular, and bifurcation-specific devices. Balloons, liquid embolic agents, and flow-directed catheters have revolutionized the treatment of arteriovenous malformations and fistulae. The ongoing development of endovascular tools has led to novel and expanding approaches (for example, transvenous arteriovenous malformation embolization and transradial access). With improved technology, transposterior communicating artery access and other endovascular strategies are being applied successfully across the anterior and posterior circulations and to lesions once deemed only surgically approachable. Yet, we would be remiss to attribute the successes of endovascular strategies only to the development of their tools. Improvements in both noninvasive and angiographic imaging (such as three-dimensional road map guidance) have provided a greater understanding of pathologic entities and allowed the pursuit of endovascular cures.In this issue of Neurosurgical Focus, we present a wide range of endovascular strategies for a variety of neurovascular pathologies. We hope this video supplement will not only demonstrate the applicability of tried-and-true endovascular strategies to difficult clinical situations but also highlight new and developing endovascular technologies. We thank the authors for their outstanding contributions.

Stent anchor technique to reduce microcatheter loop for stent-assisted coiling of anterior communicating artery aneurysm.

Stent-assisted coiling offers a potential solution for coil embolization of broad-based aneurysms. Challenges associated with navigating a microcatheter beyond these aneurysms sometimes require looping the microcatheter within the aneurysm dome. Reducing microcatheter loops within domes can be difficult, and anchor techniques have been described, including balloon anchor, stent-retriever anchor, and stent anchor techniques. The authors present a patient requiring stent-assisted coiling of an anterior communicating artery aneurysm in whom a stent anchor technique was used to reduce a microcatheter loop within an aneurysm dome before coil embolization. Postembolization angiographic runs showed complete coil occlusion of the aneurysm with approximately 35% packing density.The video can be found here: https://youtu.be/zHR1ZOArUro.

Deployment of distal posterior cerebral artery flow diverter in tortuous anatomy.

Progressive deconstruction with flow diversion using a Pipeline embolization device (PED; Medtronic) can be utilized to promote thrombosis of broad-based fusiform aneurysms. Current flow diverters require a 0.027-inch microcatheter for deployment. The authors present a patient with a fusiform P2-3 junction posterior cerebral artery aneurysm in which they demonstrate the importance of haptics in microwire manipulation to recognize large-vessel anatomy versus perforator anatomy that may overlap, especially when access is needed in distal tortuous circulations. In addition, the authors demonstrate the need for appropriate visualization before PED deployment. Postembolization runs demonstrated optimal wall apposition with contrast stasis within the aneurysm dome.The video can be found here: https://youtu.be/8kfsSvN3XqM.

KX2-361: a novel orally bioavailable small molecule dual Src/tubulin inhibitor that provides long term survival in a murine model of glioblastoma.

PURPOSE: A major challenge to developing new therapies for patients with malignant brain tumors is that relatively few small molecule anticancer drugs penetrate the blood-brain barrier (BBB) well enough to provide therapeutically effective concentrations in brain tissue before drug exposure in non-CNS tissues results in unacceptable toxicity. METHODS: KX2-361, a member of a novel family of compounds with Src-kinase and tubulin polymerization inhibitory activity, demonstrates good oral bioavailability and readily crosses the BBB in mice. The objective of this study was to investigate the activity of KX2-361 against human and murine glioma cells and assess its therapeutic effect in a syngeneic orthotopic model of glioblastoma. RESULTS: In addition to reducing the level of Src autophosphorylation in the GL261 murine glioblastoma cell line, KX2-361 binds directly to tubulin and disrupts microtubule architecture in glioma cells maintained in culture. CONCLUSIONS: The drug is active in vivo against orthotopic GL261 gliomas in syngeneic C57BL/6 mice. Long term survival is not observed in mice lacking an adaptive immune system, indicating that KX2-361 works in concert with the host immune system to control tumor growth and promote long-term survival in the GL261 glioma model.

"Contrast-less" stent-assisted coiling of an A1 aneurysm.

BACKGROUND: Iodine-based contrast medium used in diagnostic and therapeutic cerebrovascular imaging may cause renal toxicity, especially in patients with underlying renal impairment. Contrast dilution may impede efforts of the neurointerventionalist to treat intracranial vascular pathology. METHODS: A 36-year-old man with renal impairment presented with an unruptured A1 segment anterior cerebral artery aneurysm. Previously obtained magnetic resonance angiography was fused with intraoperative noncontrast computed tomography and live 2-dimensional fluoroscopic images. The aneurysm was successfully treated with stent-assisted coil embolization without the use of contrast. RESULTS: Neurointervention without contrast was feasible, and although the presented case is one example, the imaging fusion techniques used in this case can substantially decrease the exposure to contrast and subsequent risk of renal injury during intracranial procedures. CONCLUSIONS: Further development of and experience with this technique is needed to improve its safety and efficacy.

Surgical Strategies in the Treatment of Giant Pituitary Adenomas.

BACKGROUND AND OBJECTIVES: The management of giant pituitary adenomas (GPAs) is challenging due to associated endocrinopathies and the close proximity of these tumors to critical structures, such as the optic nerves, structures of the cavernous sinus, and hypothalamus. The objective of this review article was to summarize the current management strategies for giant pituitary adenomas, including the role of open and endoscopic surgical approaches and the role of medical and radiation therapy in conjunction with surgery. METHODS: We conducted a retrospective review of GPAs operated at our institute between January 2010 and March 2023. Surgical approaches, extent of resection, and associated complications were documented. Furthermore, we conducted a thorough literature review to identify relevant studies published in the past decade, which were incorporated along with insights gained from our institutional case series of GPAs to analyze and integrate both the existing knowledge base and our institution's firsthand experience in the management of GPAs. RESULTS: A total of 46 giant pituitary adenomas (GPAs) were operated on, using various surgical approaches. Transsphenoidal approach was used in 25 cases and a staged approach using transsphenoidal and pterional was used in 15 cases. Other approaches included transcortical-transventricular, transcallosal, pterional/orbitozygomatic, and subfrontal approaches. Complications and technical nuances were reported. CONCLUSION: The management of giant pituitary adenomas remains complex, often involving several modalities-open or endoscopic resection, radiosurgery, and medical management of both the tumor and associated endocrinopathies. Surgical resections are often challenging procedures that require careful consideration of several factors, including patient characteristics, tumor location, and size, and the experience and skill of the surgical team.

Evolution of Transradial Access for Mechanical Thrombectomy-A Single Center Experience.

BACKGROUND: Transradial access (TRA) recently has gained popularity among neurointerventionalists. However, hesitation to its use for mechanical thrombectomy (MT) remains. OBJECTIVE: To evaluate and describe the evolution of TRA for MT. METHODS: We performed a retrospective analysis of patients undergoing TRA for MT. We performed a chronological ternary analysis to assess the impact of experience. We assessed the impact of a guide catheter designed specifically for TRA. RESULTS: We identified 53 patients who underwent TRA for MT. There was a statistically significant decrease in contrast use (148.9 vs 109.3 vs 115.2 cc), procedure time (62.4 vs 44.7 vs 41.3 minutes), fluoroscopy time (39.2 vs 44.7 vs 41.3 minutes), and puncture-to-recanalization time (40.6 vs 27.3 vs 29.4) over time. There was trend toward improved thrombolysis in cerebral infarction ≥ 2b recanalization rate (72.2% vs 77.8% vs 100%) over time. The introduction of a radial-specific catheter had a statistically significant positive impact on contrast use (133.8 vs 93 cc, P = .043), procedure time (54.2 vs 36.4 minutes, P = .003), fluoroscopy time (33.7 vs 19.8 minutes, P = .004), puncture-to-recanalization time (35.8 vs 25.1 minutes, P = .016), and thrombolysis in cerebral infarction ≥ 2b recanalization rate (71.4% vs 100%, P = .016). CONCLUSION: TRA is a safe and effective route of endovascular access for MT. Experience with this technique improves its efficacy and efficiency. The introduction of a TRA-specific catheter expands the armamentarium of the neurointerventionalist and may facilitate lesion access during MT procedures. Continued development of radial-specific devices may further improve MT outcomes.

Femoral access site complications following neurointerventional procedures: economic implications at a single center.

OBJECTIVE: Transfemoral access (TFA) has been the traditional route of arterial access for neurointerventional procedures. Femoral access site complications may occur in 2%-6% of patients. Management of these complications often requires additional diagnostic tests or interventions, each of which may increase the cost of care. The economic impact of a femoral access site complication has not yet been described. The objective of this study was to evaluate the economic consequences of femoral access site complications. METHODS: The authors conducted a retrospective review of patients undergoing neuroendovascular procedures at their institute and identified those who experienced femoral access site complications. The subset of patients experiencing these complications during elective procedures was matched in a 1:2 fashion to a control group undergoing similar procedures and not experiencing an access site complication. RESULTS: Femoral access site complications were identified in 77 patients (4.3%) over a 3-year period. Thirty-four of these complications were considered major, requiring blood transfusion or additional invasive treatment. There was a statistically significant difference in total cost ($39,234.84 vs $23,535.32, p = 0.001), total reimbursement ($35,500.24 vs $24,861.71, p = 0.020) and reimbursement minus cost (-$3734.60 vs $1326.39, p = 0.011) between the complication and control cohorts in elective procedures, respectively. CONCLUSIONS: Although occurring relatively infrequently, femoral artery access site complications increase the cost of care for patients undergoing neurointerventional procedures; how this influences the cost effectiveness of neurointerventional procedures warrants further investigation.

Multimodal monitoring to guide neurosurgical intervention in high-grade aneurysmal subarachnoid hemorrhage: illustrative case.

BACKGROUND: Multimodal monitoring to guide medical intervention in high-grade aneurysmal subarachnoid hemorrhage (aSAH) is well described. Multimodal monitoring to guide surgical intervention in high-grade aSAH has been less studied. OBSERVATIONS: Intracranial pressure (ICP), brain lactate to pyruvate ratio (L/P ratio), and brain parenchymal oxygen tension (pO2) were used as surrogates for clinical status in a comatose man after high-grade aSAH. Acute changes in ICP, L/P ratio, and pO2 were used to identify brain injury from both malignant cerebral edema and delayed cerebral ischemia, respectively, and decompressive hemicraniectomy with clot evacuation and intraarterial nimodipine were used to treat these conditions. The patient showed marked improvement in multimodal parameters following each intervention and eventually recovered to a modified Rankin score of 2. LESSONS: In patients with a limited neurological examination due to severe acute brain injury in the setting of aSAH, multimodal monitoring can be used to guide surgical treatment. With prompt, aggressive, maximal medical and surgical interventions, otherwise healthy individuals may retain the capacity for close to full recovery from seemingly catastrophic aSAH.

The Rist radial access system: a multicenter study of 152 patients.

BACKGROUND: Transradial access (TRA) for neurointervention is becoming increasingly popular as experience with the technique grows. Despite reasonable efficacy using femoral catheters off-label, conversion to femoral access occurs in approximately 8.6-10.3% of TRA cases, due to an inability of the catheter to track into the vessel of interest, lack of support, or radial artery spasm. METHODS: This is a multicenter, retrospective case series of patients undergoing neurointerventions using the Rist Radial Access System. We also present our institutional protocol for using the system. RESULTS: 152 patients were included in the cohort. The most common procedure was flow diversion (28.3%). The smallest radial diameter utilized was 1.9 mm, and 44.1% were performed without an intermediate catheter. A majority of cases (96.1%) were completed successfully; 3 (1.9%) required conversion to a different radial catheter, 2 (1.3%) required conversion to femoral access, and 1 (0.7%) was aborted. There was 1 (0.7%) minor access site complication and 4 (2.6%) neurological complications. CONCLUSIONS: The Rist catheter is a safe and effective tool for a wide range of complex neurointerventions, with lower conversion rates than classically reported.

Carotid artery stenting in a patient with an anomalous vertebral artery origin from the external carotid artery.

The existence of carotid basilar anastomoses has been well documented embryologically, anatomically, and, in the case of the persistent trigeminal and hypoglossal arteries, angiographically. Conversely, anomalous origins of the vertebral arteries (VA) are not very common with an incidence ranging from 3% to 8%. Multiple variations of the VA origin have been reported in the literature, including arising from the aortic arch, from the common, internal, or external carotid arteries and subclavian branches.1 There are only four cases reported in the literature of VA origin from the external carotid artery.2-5 We report the fifth case in which the anomalous origin was identified during the investigation of an acute ischemic stroke. Video 1 emphasizes the importance of anatomical knowledge prior to endovascular or surgical interventions. It also highlights technical nuances of carotid artery stenting in a patient with anomalous VA origin from the external carotid artery. neurintsurg;13/10/974/V1F1V1Video 1.

Surgical Resection of Clinoidal Meningiomas without Routine Use of Clinoidectomy.

OBJECTIVE: Meningiomas of the anterior clinoid process (ACP) present significant surgical challenges given their anatomic relation to critical neurovascular structures. Routine anterior clinoidectomy is often described as a critical step in the resection of these tumors to reduce recurrence and improve visual outcomes. Anterior clinoidectomy, however, is not without risk and its benefits have not been clearly delineated. We present the outcomes of our series of surgically managed ACP meningiomas in which an anterior clinoidectomy was not routinely employed. METHODS: A retrospective review of all ACP meningiomas operated on between August 1997 and March 2019 was conducted. Patients with a recurrent tumor or with <6 months of follow-up were excluded. Resection was typically carried out via a frontotemporal craniotomy followed by intradural removal of the tumor. Anterior clinoidectomy was only performed if hyperostosis of the ACP caused mass effect on the optic nerve. RESULTS: Twenty-nine patients were included in this study. Anterior clinoidectomy was performed in 3 patients (10.3%). Gross total resection was achieved in 22 patients (75.9%). Of the 21 patients (72.4%) who presented with visual deficits, vision improved in 18 patients (85.7%) and worsened in 2 (9.5%). Tumor recurrence occurred in 5 patients (17.2%) at a mean follow-up of 64.9 months. Perioperative morbidity was 10.3%. Permanent morbidity and mortality were 6.9% (vision deterioration) and 0%, respectively. CONCLUSIONS: Resection of ACP meningiomas without routine anterior clinoidectomy minimizes potential risk while achieving gross total resection, recurrence, and visual improvement rates comparable with those in previously reported series.

Pre-operative embolization followed by clipping of Cognard type V dural arteriovenous fistula.

This article has been retracted because it describes the use of an investigative agent that has not been approved by the Food and Drug Administration.

Anatomical Predictors of Transcranial Surgical Access to the Suprasellar Space.

Objective The suprasellar space is a common location for intracranial lesions. The position of the optic chiasm (prefixed vs. postfixed) results in variable sizes of operative corridors and is thus important to identify when choosing a surgical approach to this region. In this study, we aim to identify relationships between suprasellar anatomy and external cranial metrics to guide in preoperative planning. Methods T2-weighted magnetic resonance images (MRIs) from 50 patients (25 males and 25 females) were analyzed. Various intracranial and extracranial metrics were measured. Statistical analysis was performed to determine any associations between metrics. Results Interoptic space (IOS) size correlated with interpupillary distance (IPD; a = 7.3, 95% confidence interval [CI] = 4.5-10.0, R 2 = 0.3708, p = 0.0009). IOS size also correlated with fixation of the optic chiasm, for prefixed chiasms ( n = 7), the mean IOS is 205.14 mm 2 , for normal chiasm position ( n = 33) the mean IOS is 216.94 mm 2 and for postfixed chiasms ( n = 10) the mean IOS is 236.20 mm 2 ( p = 0.002). IPD correlates with optic nerve distance (OND; p = 0.1534). Cranial index does not predict OND, IPD, or IOS. Conclusion This study provides insight into relationships between intracranial structures and extracranial metrics. This is the first study to describe a statistically significant correlation between IPD and IOS. Surgical approach can be guided in part by the size of the IOS and its correlates. Particularly small intraoptic space may guide the surgeon away from a subfrontal approach.

Antitumor cytotoxic T-cell response induced by a survivin peptide mimic.

Survivin is a tumor-associated antigen with significant potential as a cancer vaccine target. We have identified a survivin peptide mimic containing human MHC class I epitopes and a potential class II ligand that induces a potent antitumor response in C57BL/6 mice with GL261 cerebral gliomas. This peptide is able to elicit both CD8+ CTL and T helper cell responses in C57BL/6 mice. The corresponding region of the human survivin molecule represented by peptide SVN53-67 is 100% homologous to the murine protein, but SVN53-67 is weakly immunogenic in man. We evaluated several amino acid substitutions in putative human MHC I anchor positions in SVN53-67 to identify potential peptide mimics that could provide an enhanced antitumor immune response against human glioma and primary central nervous system lymphoma (PCNSL) cells in culture. We evaluated survivin peptides with predicted binding to human HLA-A*0201 antigen using peptide-loaded dendritic cells from PBMC of patients with these malignancies. One alteration (M57) led to binding to HLA-A*0201 with significantly higher affinity. We compared the ability of autologous dendritic cells loaded with SVN53-67 peptide and SVN53-67/M57 in CTL assays against allomatched and autologous, survivin-expressing, human malignant glioma and PCNSL cells. Both SVN53-67 and SVN53-67/M57 produced CTL-mediated killing of malignant target cells; however, SVN53-67/M57 was significantly more effective than SVN53-67. Thus, SVN53-67/M57 may act as a peptide mimic to induce an enhanced antitumor CTL response in tumor patients. The use of SVN53-67/M57 as a cancer vaccine might have application for cancer vaccine therapy.

Transradial approach for neurointerventions: a systematic review of the literature.

BACKGROUND: Despite the recent increase in the number of publications on diagnostic cerebral angiograms using transradial access (TRA), there have been relatively few regarding TRA for neurointerventional cases. Questions of feasibility and safety may still exist among physicians considering TRA for neurointerventional procedures. METHODS: A systematic literature review was performed following PRISMA guidelines. Three online databases (MedLine via PubMed, Scopus and Embase) were searched for articles published between January 2000 and December 2019. Search terms included "Transradial access", "Radial Access", "Radial artery" AND "Neurointerventions". The reference lists of selected articles and pertinent available non-systematic analysis were reviewed for other potential citations. Primary outcomes measured were access site complications and crossover rates. RESULTS: Twenty-one studies (n=1342 patients) were included in this review. Two of the studies were prospective while the remaining 19 were retrospective. Six studies (n=616 patients) included TRA carotid stenting only. The rest of the studies included treatment for cerebral aneurysms (n=423), mechanical thrombectomy (n=127), tumor embolization (n=22), and other indications (n=154) such as angioplasty and stenting for vertebrobasilar stenosis, balloon test occlusion, embolization of dural arteriovenous fistula and arteriovenous malformation, chemotherapeutic drug delivery, intra-arterial thrombolysis, and arterial access during a venous stenting procedure. Two (0.15%) major complications and 37 (2.75%) minor complications were reported. Sixty-four (4.77%) patients crossed over to transfemoral access for completion of the procedure. Seven (0.52%) patients crossed over due to access failure and 57 (4.24%) patients crossed over to TFA due to inability to cannulate the target vessel. CONCLUSION: This systematic review demonstrates that TRA has a relatively low rate of access site complications and crossovers. With increasing familiarity, development of TRA-specific neuroendovascular devices, and the continued reports of its success in the literature, TRA is expected to become more widely used by neurointerventionalists.

Dual Microwire Rail Technique to Advance a Microcatheter Past the Ostium of a Dissecting Carotid Artery Aneurysm for Flow Diverter Deployment: 2-Dimensional Operative Video.

Flow diversion using a Pipeline embolization device (PED; Medtronic, Dublin, Ireland) is an effective therapy for treating cavernous aneurysms. Currently, flow diverters require a 0.027-inch microcatheter for deployment. To navigate across these aneurysms, a 0.014-inch microwire is used, which often does not offer a sturdy enough rail to advance a 0.027-inch microcatheter past dissecting artery aneurysm ostia. We present a patient with a right cavernous dissecting carotid artery aneurysm. A step off between the 0.027-inch VIA microcatheter (MicroVention Terumo, Tustin, California) and 0.014-inch Synchro 2 microwire (Stryker Neurovascular, Fremont, California) resulted in difficulty with navigation of the microcatheter across the dissected portion of the aneurysm. A dual microwire rail technique involving two 0.014-inch Synchro 2 microwires was used to advance the VIA microcatheter past the dissecting artery aneurysm ostia for PED deployment. The introduction of the second microwire eliminated the step off between the microwire and microcatheter, providing a stronger rail and easier navigation of the microcatheter, without aggressive pushing. Postembolization runs showed optimal wall apposition and contrast stasis within the aneurysm, with successful flow diversion of the aneurysm. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary.