The Western giants of the neuroanatomical past: an ode to yesterday. Part II.

"The history of the world is the biography of the great man. And I said: the great man always acts like a thunder. He storms the skies, while others are waiting to be stormed," said Thomas Carlyle. In this historical vignette, we study the contribution to neuroanatomy, of greats from the past. What led them to find the basis of topography and anatomical localization? How did they unravel the pathways of cerebrospinal fluid and cortical structure of the human brain? To understand this, we study the paths of Pierre Paul Broca, Richard L. Heschl, Hubert von Luschka, Carl Wernicke, Hans Chiari, Ludwig Edinger, and Carl Westphal, Korbinian Brodmann, and Walter Dandy.

Does Small Aneurysm Size (<10 mm) Predict Complete Occlusion After Flow Diversion? A Surpass Evolve Single-Center Study.

BACKGROUND: Long-term safety and efficacy outcomes of Surpass Evolve flow diverter (SEFD) in treatment of intracranial aneurysms are lacking. Factors predicting complete aneurysm occlusion are elusive in literature. METHODS: A retrospective review of all consecutive aneurysms treated with SEFD from February 2020 to July 2022, at a single comprehensive stroke center. RESULTS: Fifty-one patients with 80 aneurysms were included. Mean target aneurysm size was 5.6 mm and mean neck-width 3.42 mm. Small aneurysms (<10 mm) were 75% (n=60), while 25% were >10 mm. Unruptured were 71 (88.7%), previously ruptured were 8 (10%), and partially thrombosed 2.3% (n=1). Mean SEFDs used per patient were 1.07 and 40% (n=22) procedures were performed transradially. Mean procedure time was 59.1 minutes. The technical success rate for device deployment was 100%. Raymond Roy (RR) class I occlusion at 6 month (n=73) was seen among 56.2% (n=41), at 1 year (n=35) among 85.7% (n=30) and at 2 year (n=18) among 88.8% (n=16) aneurysms. Aneurysm size <10 mm significantly predicted RR-I occlusion outcome (odds ratio [OR]: 2.16; confidence interval [CI]: 0.02-4.29) at 6 months. Age, gender, smoking status, hypertension, location of aneurysm, and rupture status did not predict RR-I occlusion outcome. No mortality or permanent neurological morbidity was observed in the cohort. Major complications seen in 7.2% (n=4) patients were stent thrombosis (n=1, 1.8%), carotid-cavernous fistula (n=1, 1.8%) and transient ischemia in 2 (3.6%). Non-flow limiting stenosis was observed in 3 (5.4%) patients. CONCLUSION: SEFD gives good aneurysm occlusion rates with favorable long-term safety profile and low rate of thromboembolic complications. Small aneurysm size (<10 mm) was associated with complete aneurysm occlusion at 6-month angiographic follow-up. CLINICAL IMPACT: As Surpass Evolve is a newer generation Flow diverter of the Stryker Surpass FDs, with its improved design and applicability in intracranial aneurysms, we believe that more physicians will be encouraged to use this device worldwide.

The western giants of neuroanatomical past: an ode to yesterday - Part I.

"The only history is a mere question of one's struggle inside oneself. But that is the joy of it. One need neither discover Americas nor conquer nations, and yet one has as great a work as Columbus or Alexander to do," said David H. Lawrence. In this historical vignette, we look at the lives of certain western giants of neuroanatomy from the past. To understand the origin of today's advancements and successes in neurosurgery, a strong foothold on the path taken by anatomical greats is necessary. What curiosity inspired them to search the meaning of the human nervous system? Learning this from the paths of Herophilus, Galen, Franciscus Sylvius, Thomas Willis, Alexander Monro secundus, Luigi Rolando, François Magendie, and Martin Rathke, will propel us to create a better future for our successors.

Microsurgical Management of a Middle Cranial Fossa Dural Arteriovenous Fistula After Failed Embolization: 2-Dimensional Operative Video.

Dural arteriovenous fistulas (DAVFs) are intracranial vascular lesions with abnormal communication between the dural arteries and dural and/or cortical venous systems. While benign DAVFs, like Cognard I and IIa/Borden I, can be observed, higher-grade DAVFs, such as Cognard IIb-V/Borden II and III, should be treated.1,2 This video article depicts the microsurgical management after embolization of a middle cranial fossa Cognard IV DAVF with venous varices causing mass effect in the right thalamus, basal ganglia, and posterior limb of the right internal capsule. Initial attempts at embolization showed persistent arterial supply from the right ophthalmic artery and distal right internal maxillary artery, with sustaining cortical venous reflux. Microsurgical clipping was chosen because of venous congestion, associated risk of hemorrhage, and corresponding neurological symptoms. The patient consented to the procedure. Intraoperative angiography revealed successful obliteration of the fistula, and postoperative imaging displayed no residual DAVF and thrombosed venous varices without complications. The patient showed remarkable improvement, with a resolution of neurological deficits on discharge to rehabilitation. This case highlights the potential efficacy of direct clipping after unsuccessful endovascular intervention for DAVFs. Understanding the angioarchitecture with identification of the fistulous point, using intraoperative imaging modalities, and ensuring comprehensive exposure are crucial steps in such microsurgical interventions.

Neurovascular considerations in patients with Down syndrome and moyamoya syndrome.

In this article, we describe a rare and complex case of moyamoya syndrome in a 7-year-old boy with Down syndrome and atlantoaxial subluxation. The patient presented with an ischemic stroke in the left hemisphere and cervical cord compression with increased cord edema. Diagnostic digital subtraction angiography revealed unique patterns of vascular involvement, with retrograde flow through the anterior spinal artery, ascending cervical artery, occipital artery, and multiple leptomeningeal arteries compensating for bilateral vertebral artery occlusion. This case underscores the underreported phenomenon of upward retrograde flow through the anterior spinal artery in bilateral vertebral artery occlusion. We address the rare manifestation of posterior circulation involvement in moyamoya syndrome, highlighting the importance of considering atlantoaxial instability as a contributing factor, as the absence of atlantoaxial stability is a risk factor for vertebral artery dissection. This study contributes valuable insights into the intricate relationship of moyamoya syndrome, Down syndrome, and atlantoaxial instability, urging clinicians to consider multifaceted approaches in diagnosis and treatment. It also emphasizes the potential significance of the anterior spinal artery as a compensatory pathway in complex vascular scenarios.

Brain abscesses following carotid blowout syndrome: a case report.

We report a case of intracranial abscesses development in a patient with head and neck cancer after emergent treatment of carotid blowout syndrome with coil embolization. Our patient is a 60-year-old male who presented with hemoptysis and hematemesis, which raised concerns for impending carotid blowout syndrome. Endovascular occlusion was successfully achieved, and the patient was discharged in stable condition. Ten days later, the patient reported headaches and right facial pain, and magnetic resonance imaging revealed multiple intracranial abscesses. Broad-spectrum intravenous antibiotics were administered, leading to a variable response with some abscesses decreasing in size and others increasing. Seven weeks from discharge, the patient had no neurological deficits, and all abscesses had decreased in size.

Radially adjustable stent retriever for mechanical thrombectomy in acute ischemic stroke: Improved first-pass effect with rapid-inflation deflation technique.

INTRODUCTION: Evidence for improved first-pass effect with the novel radially adjustable radio-opaque stent retriever Tigertriever is lacking. OBJECTIVE: To compare improvement in first pass success with Tigertriever using two different techniques-rapid inflation deflation (RID) and suction thrombectomy (ST). METHODS: Retrospective analysis of patients with acute ischemic stroke who underwent mechanical thrombectomy with Tigertriever at a single comprehensive stroke center. RESULTS: Thirty patients were included. Mean age was 72.8 years. Twelve patients (48%) experienced successful first passes with Tigertriever. Successful revascularization (modified thrombolysis in cerebral infarction (mTICI) 2b/3) was achieved in all (100%) patients who received RID or ST technique for thrombectomy. Good clinical outcome (modified Rankin score = 0-2) was noted in 40% (n = 10). Total mortality in the cohort was 8% (n = 2). RID and ST groups comprised of 10 and 15 patients, respectively. Five patients underwent MT with Tigertriever as a rescue device. RID VS ST: No difference was noted in mean age (p = 0.27), gender (p = 0.29), location of occlusion (p = 0.46), and device used for first pass (p = 0.57). A 70% first-pass success rate in RID group and 37.5% in ST group was noticed (p = 0.06). Mean time from groin puncture to reperfusion (TICI 2b//3) was statistically similar (p = 0.29, RID: 19.9 min vs ST: 25 min). Both groups noted a 100% complete recanalization rate. The rate of mortality between the two groups were not statistically different (p = 0.46). CONCLUSION: The preliminary first-pass success rates of RID technique with Tigertriever compared to ST technique, are encouraging. Longitudinal studies with longer follow up are needed to elucidate the smaller learning curve with this device.

Flow Diversion for Treatment of Anterior Inferior Cerebellar Artery Aneurysms: Mechanism and Pitfalls from a Novel Management Strategy.

BACKGROUND: Anterior inferior cerebellar artery (AICA) aneurysms present a challenge for neurosurgeons and neurointerventionalists alike. METHODS: Cases of AICA aneurysms managed with endovascular flow diversion at our institute are reviewed with their angiographic outcomes. RESULTS: Both direct and indirect flow diversion provide complete aneurysm occlusion at follow-up. We propose a stratified method of approaching AICA aneurysms based on location, rupture status, and neck size. CONCLUSIONS: Careful evaluation of preoperative parameters is paramount in deciding between a surgical or a neuroendovascular approach. Low-profile stents in the future may assist in direct flow diversion of AICA trunk aneurysms. In addition, neurosurgeons need to be well versed in endovascular approaches.

Surpass embolization of intracranial aneurysms: Perspective from a 2-year longitudinal follow-up study across high volume comprehensive stroke centers.

BACKGROUND: Surpass Streamline (SS; Stryker©) is an over-the-wire first-generation flow diverter (FD). There is a scarcity of data on real-world outcomes and complications of this FD. METHODS: A retrospective review of consecutive cases between January 2019 and July 2021 at two high-volume comprehensive stroke centers, involving SS was conducted. RESULTS: Fifty-five patients harbored 69 treated aneurysms, of which 96% were in the internal carotid petrous to terminus segments and 88% were <10 mm in size, and 12% measuring 10-24 mm. Raymond Roy Grade 1 occlusion was noted in 55 aneurysms (79.7%) at 1 year. Median follow-up duration was 26 months (mean = 26.06). Major complications were seen in eight patients (14.5%; 95% CI 6.5-26.7) and mortality attributable to SS stenting complications occurred in two (4.3%) patients. Four (7.2%) had ophthalmologic thromboembolic complications and two had (3.6%) ischemic complications. Procedural complications occurred in 10 patients (18.18%; 95% CI 9.1-30.9). Technical complications during procedure (n = 3, 5.3%) were: "confirmed" distal middle cerebral artery (MCA) guidewire perforation; "suspected" distal MCA guidewire perforation causing post-procedural subarachnoid hemorrhage and internal carotid artery dissection causing ischemic stroke. Seizures were seen in 5 (9.09%) and carotid-cavernous fistula in 1 (1.8%). Multivariate regression analysis showed technical challenges significantly predicted occurrence of major complications (p = 0.001; R2 = 0.39, F(13,43) = 2.15, p = 0.029). Univariate analysis showed technical challenges significantly predicted ophthalmological complications (R2 = 0.06, F(1,55) = 4.04, p = 0.049) and major complications (R2 = 0.21, F(1,55) = 15.11, p = 0.0002). CONCLUSION: Large-scale future registry should focus on national data regarding SS safety, technical challenges, and procedural complications. We present one of the longest follow-ups for SS in literature.

Applying Shear Wave and Magnetic Resonance Elastography to Grade Brain Tumors: Systematic Review and Meta-Analysis.

BACKGROUND: Reports find that magnetic resonance elastography (MRE) and shear wave elastography (SWE) can classify intracranial tumors according to stiffness. However, systematic syntheses of these articles are lacking. In this report, a systematic review and meta-analysis was performed to evaluate whether SWE and MRE can predict meningioma and glioma grades. METHODS: PubMed and Scopus were searched between February 10, 2022. and March 2, 2022. using manual search criteria. Eight out of 106 non-duplicate records were included, encompassing 84 patients with low-grade tumors (age 42 ± 13 years, 71% female) and 92 patients with high-grade tumors (age 50 ± 13 years, 42% female). Standardized mean difference in stiffness between high-grade and low-grade tumors were measured using a forest plot. The I2, χ2, and t tests were performed, and bubble plots were constructed to measure heterogeneity. An adapted QUADAS-2 scale evaluated study quality. Additionally, a funnel plot was constructed, and an Egger's intercept test determined study bias. RESULTS: Low-grade tumors were stiffer than high-grade tumors (Cohen's D = -1.25; 95% CI -1.88, -0.62). Moderate heterogeneity was observed (I2 = 67%; P = 0.006) but controlling for publication year (I2 = 0.2%) and age (I2 = 0.0%-17%) reduced heterogeneity. Included studies revealed unclear or high bias for the reference standard and flow and timing (>50%). CONCLUSIONS: Elastography techniques have potential to grade tumors intraoperatively and postoperatively. More studies are needed to evaluate the clinical utility of these technologies.

Network analysis of neurosurgical literature: an increased focus on training during the COVID-19 pandemic.

The COVID-19 pandemic led to stringent guidelines to restrict the conduct of non-emergent surgical procedures. Consequently, neurosurgery departments experienced a decline in case volumes and greater educational time being spent on virtual research projects. In our report, we reveal how neurosurgical research has changed during the pandemic compared to the pre-pandemic phase. The WebOfScience database was searched for neurosurgical articles published between 2012-2019 (pre-pandemic) and 2020-2022 (pandemic). From this data, the keywords, terms, and countries were analyzed using networks formed by the VOS Viewer software. In addition, the analysis was repeated for neurosurgical articles specific to COVID-19. Network analyses of terms and keywords revealed an increased popularity of virtual research projects, including case reports, meta-analyses, reviews, surveys, and database studies. Additionally, there was increased interest in research pertaining to neurosurgical education during the post-pandemic era, including topics regarding virtual training modalities, mental health, and telemedicine. Our bibliometrics analysis suggests that the impact of COVID-19 restrictions on hospital systems affected neurosurgical training programs. Future investigations should explore the effects of the trainee experience during the COVID-19 pandemic on the outlook for neurosurgical education.

Trends in Global Research for Treating Intracranial Aneurysms: A Bibliometric Analysis.

OBJECTIVE: Although significant advancements have been made in the detection, surveillance, and treatment of intracranial aneurysms, research and care can differ vastly based on location. Currently, there is lack of knowledge regarding the trends in literature and how the field is evolving with new technology. Here, we use bibliometric analysis to visualize the knowledge structure of the field and identify global research trends in intracranial aneurysm treatment. METHODS: The Web of Science Core Collection was queried for primary research and review articles related to intracranial aneurysm treatment. Four thousand seven hundred and 2 relevant documents were collected and publications over time on different treatment types and publications and citations of journals were collected. VOS viewer was used for the following: 1) identify relationships between keywords, 2) identify co-authorship patterns among organizations and countries, and 3) analyze citation patterns of countries, organizations, and journals. RESULTS: Our results show that research in flow diversion increased at a rapid rate but tended to have low link strength with keywords related to evaluating patient risk and mortality. The highest publication producing countries were the United States of America, Japan, and China, although China had fewer citations relative to its peers. Korean organizations showed less international collaboration. The USA has been the leader in terms of productivity and collaboration in the field, as have several US-based journals such as Journal of Neurosurgery, Neurosurgery, and World Neurosurgery. CONCLUSIONS: Evaluating the safety of flow diversion treatment remains a pressing area of research. Chinese and Korean organizations may be of interest for global collaborations.

Safety and Effectiveness of Expandable Intravertebral Implant Use for Thoracolumbar Burst Fractures.

PURPOSE: To determine the safety and effectiveness of an expandable intravertebral implant (Spinejack; Stryker, Kalamazoo, Michigan) as a treatment option for patients with thoracolumbar spine burst fractures without fracture-related neurologic deficit. MATERIALS AND METHODS: Imaging studies before and after expandable intravertebral implantation and medical records of 33 patients, 11 (33.3%) men and 22 (66.6%) women with an overall mean age of 71.7 years ± 8.3, were reviewed for 60 thoracolumbar Magerl Type A3 injuries secondary to osteoporosis, trauma, or malignancy. The mean follow-up time was 299 days. RESULTS: Implantation of an expandable intravertebral device resulted in a statistically significant reduction in bone fragment retropulsion (mean ± SD, 0.64 mm ± 16.4; P < .001), reduction in the extent of canal compromise (mean, 5.5%; P < .001), increased central canal diameter (mean ± SD, 0.71 mm ± 1.3; P < .001), and restoration of vertebral body height, with a mean increase of 5.0 mm (P < .001). However, the implantation did not result in a statistically significant kyphosis reduction (mean, 1.38°; P = .10). All patients except for 1 reported improvement in pain after surgery, with a mean improvement of 1.54 on a 4-point pain scale (P < .001). No clinically significant adverse events were reported. CONCLUSIONS: This study suggests that expandable intravertebral device implantation is a safe and effective treatment for thoracolumbar vertebral burst fractures in patients without fracture-related neurologic deficit. Although implantation did not result in a statistically significant reduction in kyphotic angle, it offered significant improvement in pain, vertebral body height, fracture fragment retropulsion, and central canal diameter compromise.

Gearing Up for the U.S. Medical Licensing Examination Step 1 Pass/Fail Transition, Evaluating the Role of Research Productivity as an Alternative During the Neurosurgical Residency Selection Process: An Overview.

Neurosurgery residency programs are the most competitive among the surgical specialties for applicants to match into. U.S. Medical Licensing Examination (USMLE) step 1 scores are staple and pivotal in narrowing down applicants for granting interviews and ranking in the match process. The upcoming transition from a numeric to binary step 1 scoring shifts the emphasis on using the status quo Step 2 Clinical Knowledge numeric scoring as the only objective measure. It can prove insubstantial for accurate assessment of competencies, further urging residency programs to widen their selection protocols to allow multiple assessments of competency. Research experience has consistently proved to result in higher successful match rates, and a positive correlation is seen with the number of research publications and Hirsch indices. However, with a predicted emphasis on research with the shift in scoring practices, these tools provide inadequate insight into authorship, contributions, type of publications, and community impact, warranting the need to include supplementary modifications, surrogates, or alternatives to such tools for a more comprehensive and equitable assessment of research. This study summarizes the role of research in the neurosurgical match process, describes nuances in research evaluation, and introduces novel Hirsch indices and additional strategies to address these nuances for equitable evaluation of research productions.

Management paradigms of persistent primitive trigeminal artery aneurysms: A systematic review and analysis of techniques and complications from 1960s to 2022: From conservative to surgical to endovascular, how far along the right path are we?

INTRODUCTION: Aneurysms of persistent primitive trigeminal artery (PPTAAs) are increasingly reported and commonly managed by endovascular (EN) techniques. There are no systematic reviews or meta-analyses which analyse outcomes and complications of treatment modalities for PPTAAs. We aim to highlight the change in trend of management of PPTAAs and to identify clinical and radiological parameters which may influence management paradigms. METHODOLOGY: A systematic search of literature was done in PubMed, Embase, Google Scholar, Cochrane library and Medline using keywords 'persistent primitive trigeminal artery', 'aneurysms', 'embolization', 'surgical clipping', etc. Only cases reporting aneurysms of PPTA were included. Three subgroups, such as conservative, open surgical (OS) and EN interventional, were studied for outcome evaluation. In the EN subgroup, relation of clinical and radiological parameters with outcome (complete/partial occlusion) was analysed using Microsoft Excel Data Analysis ToolPak. RESULTS: Of the 101 articles found eligible for assessment, 54 were analysed quantitatively. Mortality in the conservative group was 12.5% and OS group was 9.09%. After EN treatment, complete angiographic occlusion was seen in 88.89% PPTAAs and 5.5% warranted retreatment. In the EN subgroup, location (p=0.17), shape (p=0.69), Saltzman circulation (p=0.26) or status of rupture (p=0.08) did not significantly impact angiographic occlusion outcome. Multivariate regression analysis showed 6.6% influence of independent variables, that is, age, gender, aneurysm location, side, shape (saccular/fusiform), rupture status and type of Saltzman circulation on aneurysm occlusion outcome [F(7,27) =1.34] (p=0.27). Total mortality reported in the EN group was 8.57%. CONCLUSION: Clinical or radiological parameters do not influence angiographic occlusion outcome. Although EN techniques are successful, meticulous reporting of outcomes and complications is important.

Sequential aneurysms with incidental persistent primitive trigeminal artery: Is this association purely coincidental? A case study and review of the literature in search for a pathobiological mechanism.

Background: The appearance of sequential bilateral aneurysms in patients with persistent primitive trigeminal artery (PTA) is not described in the literature. No clear guidelines on screening and follow-up of patients with incidental PTAs for the detection of associated lesions have been established. Case Description: A 55-year-old lady presented with occasional headaches. Detailed evaluation showed a left ophthalmic segment internal carotid artery (ICA) aneurysm measuring (11.2 × 5.5) mm. A bovine aortic arch configuration (type III) and a persistent left PTA were identified. A pipeline flex flow diverter was placed and aneurysm was coiled. Follow-up angiography after 6 months showed a completely occluded aneurysm with preserved PTA and a new aneurysm in the right ICA ophthalmic segment measuring 3.5 × 1.5 mm. It was followed up serially with angiography which revealed significant increase in 6 months. The base measured 5.4 mm and two blebs 3.1 mm and 2.5 mm had appeared on the dome. A SUPRASS flow diverter was placed across this aneurysm. Serial follow-up showed complete occlusion of the left aneurysm and significant reduction in filling of the right aneurysm. A review of the literature identified 34 cases of incidental PTAs associated with 50 aneurysms with increased prevalence of anterior circulation aneurysms in patients with incidental PTA. Conclusion: Sequential angiography of a patient with incidental PTA and an ICA aneurysm shows presence of a new aneurysm in contralateral circulation and its progression in size and morphology. Detailed large-scale studies are needed to assess the impact of incidental PTA on aneurysm development and management.

Outcomes of Mechanical Thrombectomy for Ischemic Stroke in Nonagenarians: A 10-Year Institutional Experience.

BACKGROUND: Nonagenarians have been underrepresented in stroke trials that established endovascular treatment as the standard for acute ischemic stroke (AIS). Evidence remains inconclusive regarding the efficacy of thrombectomy in this population. OBJECTIVES: To report our experience with thrombectomy in nonagenarians with stroke, and to identify predictors of mortality. We further investigated the effects of first-pass reperfusion and the addition of intravenous thrombolysis (IVT) on achieving better outcomes. MATERIALS AND METHODS: Data was collected for consecutively treated patients at three affiliated comprehensive stroke centers from 2010 to 2021. We included patients ≥90 years-old with AIS secondary to large vessel occlusion. Bivariate analyses were performed using the Mann-Whitney U test for continuous variables, and χ2 and Fisher's exact tests, respectively, for nominal and ordinal variables. RESULTS: Thirty-two nonagenarians underwent thrombectomy, of whom 25 (81%) had prestroke mRS ≤2. Thrombectomies were performed using stents (2, 6.7%), aspiration (8, 26.7%), or a combination of both (20, 66.7%). Successful recanalization was achieved in 97%. Procedural complications occurred in 2 (6.3%) and intracranial hemorrhage in 3 (9.4%). Sixteen patients (50%) were discharged home or to rehabilitation, 9 (28.2%) to nursing home or hospice, and 7 (21.9%) died during hospitalization. Only 2 (6%) patients had mRS ≤2 at discharge. No independent predictors of in-hospital mortality were identified, and neither first-pass reperfusion nor the addition of IVT correlated with improvement in clinical outcome. CONCLUSIONS: Although thrombectomy is safe for nonagenarian stroke and can achieve excellent recanalization, high mortality and poor functional status remain high given the advanced age and frailty of this population.