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This video article presents a case study of a 70-year-old male with medically refractory essential tremor treated with magnetic resonance-guided focused ultrasound (MRgFUS). Following an initial successful ablation of the right thalamus, the patient underwent left-sided thalamotomy. After two tractography-guided sonications, the authors observed a significant reduction in his right-hand tremor with no immediate side effects. Postprocedure evaluation revealed sustained tremor reduction with minimal side effects, showcasing bilateral MRgFUS as an effective, noninvasive option for essential tremor management. The video can be found here: https://stream.cadmore.media/r10.3171/2024.7.FOCVID2483., Competing Interests: Disclosures Dr. Shah reported consulting fees from Insightec outside the submitted work. Dr. Harward reported consulting fees from Insightec during the conduct of the study.Dr. Shah reported consulting fees from Insightec outside the submitted work. Dr. Harward reported consulting fees from Insightec during the conduct of the study., (© 2024, The Authors.)

Background Context: Low back pain (LBP) remains the leading cause of disability globally. In recent years, machine learning (ML) has emerged as a potentially useful tool to aid the diagnosis, management, and prognostication of LBP., Purpose: In this review, we assess the scope of ML applications in the LBP literature and outline gaps and opportunities., Study Design/setting: A scoping review was performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines., Methods: Articles were extracted from the Web of Science, Scopus, PubMed, and IEEE Xplore databases. Title/abstract and full-text screening was performed by two reviewers. Data on model type, model inputs, predicted outcomes, and ML methods were collected., Results: In total, 223 unique studies published between 1988 and 2023 were identified, with just over 50% focused on low-back-pain detection. Neural networks were used in 106 of these articles. Common inputs included patient history, demographics, and lab values (67% total). Articles published after 2010 were also likely to incorporate imaging data into their models (41.7% of articles). Of the 212 supervised learning articles identified, 168 (79.4%) mentioned use of a training or testing dataset, 116 (54.7%) utilized cross-validation, and 46 (21.7%) implemented hyperparameter optimization. Of all articles, only 8 included external validation and 9 had publicly available code., Conclusions: Despite the rapid application of ML in LBP research, a majority of articles do not follow standard ML best practices. Furthermore, over 95% of articles cannot be reproduced or authenticated due to lack of code availability. Increased collaboration and code sharing are needed to support future growth and implementation of ML in the care of patients with LBP., Competing Interests: Declaration of competing interest One or more of the authors declare financial or professional relationships on ICMJE-TSJ disclosure forms., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: There are critical disparities in the neurosurgical care provided around the globe due to challenges in resource allocation, training, and infrastructure. Global neurosurgical collaborations have replaced classical mission trips to address these disparities. However, the development of these collaborations and the impact of research funding on their growth have not yet been systematically studied. In this article, we use a graph theoretical approach to investigate trends in funding and co-authorship between and among authors from high-income countries (HICs) and authors from low- and middle-income countries (LMICs)., Methods: A bibliometric search of the global neurosurgical literature returned 307 articles between 1985 and 2020. A connectivity analysis was conducted to compute the number of co-authorships between HIC-HIC, LMIC-HIC, and LMIC-LMIC authors. The number of connections, summarized as either a global sum of connections or an average number of connections per manuscript, were analyzed in the context of time and funding through parametric statistical tests., Results: An exponential increase in co-authorship collaboration was observed over time, especially after 2015. Notably, LMIC-LMIC collaborations appear to be rising at over twice the rate of other collaboration types. The presence of funding, in general, was associated with increased co-authorship of manuscripts by LMIC and HIC authors together (P = 0.033). A significant majority of the funding associated with LMIC-HIC co-authorships was supplied through charitable organizations and government grants (P = 0.034, P = 0.009, respectively). Most LMIC-LMIC co-authorships had no funding., Conclusions: This work shows significant and rapid growth in international neurosurgical partnerships, especially in HIC-LMIC and LMIC-LMIC collaborations. Also, a significant positive relationship exists between research funding and LMIC-HIC co-authorship trends. This work encourages us as a community to continue to expand our translational collaborations with LMIC neurosurgeons and establish funding mechanisms independent of HIC authors., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Cervical spine injuries (CSIs) are heterogeneous in nature and often lead to long-term disability and morbidity. However, there are few recent and comprehensive epidemiological studies on CSI. The objective of this study was to characterize recent trends in CSI patient demographics, incidence, etiology, and injury level. The National Electronic Injury Surveillance System was used to extract data on CSIs from 2002 to 2022. Weighted national estimates of CSI incidence were computed using yearly population estimates interpolated from U.S. census data. Data analysis involved extracting additional information from patient narratives to categorize injury etiology (i.e., fall) and identify CSI level. K-means clustering was performed on cervical levels to define upper versus lower cervical injuries. Appropriate summary statistics including mean with 95% confidence intervals and frequency were reported for age, sex, race, ethnicity, etiology, and disposition. Age between groups was compared using an independent weighted Z -test. All categorical variables were compared using Pearson chi-squared tests with Bonferroni correction for multiple comparisons. Ordinary least squares linear regression was used to quantify the rate of change of various metrics with time. A total of 11,822 patient records met the study criteria. The mean age of patients was 62.4 ± 22.7 years, 52.4% of whom were male and 61.4% of whom were White, 7.4% were Black, 27.8% were not specified, and the remaining comprised a variety of ethnicities. The most common mechanism of CSI was a fall (67.3%). There was a significant increase in the incidence of cervical injuries between 2003 and 2022 ( p < 0.001). Unbiased K-means clustering defined upper cervical injuries as C1-C3 and lower cervical injuries as C4-C7. The mean age of patients with upper CSIs was 72.3 ± 19.6, significantly greater than the age of those with lower CSIs (57.1 ± 23.1, p < 0.001). Compared with lower CSI, White patients were more likely to have an upper CSI (67.4% vs. 73.7%; p < 0.001). While Black/African American (7.5% vs. 3.8%) and Hispanic (2.5% vs. 1.0%) patients were more likely to have a lower CSI ( p < 0.001). Our study identified a significant increase in the incidence of CSIs over time, which was associated with increasing patient age. Our study detected a pragmatic demarcation of classifying upper injuries as C1-C3 and lower cervical injuries as C4-C7. Upper injuries were seen more often in older, White females who were treated and admitted, and lower injuries were seen more often in young, Black male patients who were released without admission.

Background: Essential tremor (ET) is one of the most common movement disorders worldwide. In medically refractory ET, deep brain stimulation (DBS) of the ventral intermediate nucleus of the thalamus is the current standard of care. However, DBS carries an inherent 2% to 3% risk of hemorrhage, a risk that can be much higher in patients with concomitant coagulopathy. Magnetic resonance imaging-guided focused ultrasound (MRgFUS) thalamotomy is a surgical alternative that is highly effective in treating ET, with no reports of intracranial hemorrhage to date., Observations: This is the first documented case of successful MRgFUS thalamotomy in a patient with von Willebrand disease (VWD). A 60-year-old left-handed male had medically refractory ET, VWD type 2B, and a family history of clinically significant hemorrhage after DBS. He underwent right-sided MRgFUS thalamotomy and received a perioperative course of VONVENDI (recombinant von Willebrand factor) to ensure appropriate hemostasis. Postprocedure imaging confirmed a focal lesion in the right thalamus without evidence of hemorrhage. The patient reported 90% improvement of his left-hand tremor and significant improvement in his quality of life without obvious side effects., Lessons: MRgFUS thalamotomy with peri- and postoperative hematological management is a promising alternative to DBS for patients with underlying coagulopathies.

Objective: Spinal pathologies are prevalent in Nigeria, though epidemiological data remains sparse. This systematic review used pooled patient-level data from across the country to generate a standardized epidemiological reference., Methods: Four research databases and gray literature sources were searched. Risk of bias assessment was conducted using Risk of Bias in Non-Randomised Studies - of Interventions and Cochrane's risk of bias tool. We descriptively analyzed all article metrics and statistically analyzed relevant data variables via paired t-test and χ 2 independence tests (α = 0.05)., Results: One hundred twenty-seven articles, comprising a patient cohort of 8425 patients, were analyzed. Most were retrospective cohort studies (46.5%) and case reports/series (31.5%), with an overall moderate-high risk of bias. Most studies were published in the last 20 years. Most patients were male (∼2.5 males per female), with an average age of 43.2 years (±16.4). Clinical diagnoses spanned the breadth of spinal neurosurgery. Approximately 45.0% of patients had complete spinal impairment. Pain (41.7%) was the most reported presenting feature. X-ray (45.1%) was the most common investigation used. Intervertebral disc herniation (18.9%) was the most prevalent imaging finding on MRI. Most patients were managed nonoperatively (57.8%), with a favorable outcome in 27.4% of patients. Posttreatment complications included pressure sores, infection, and motor deficits., Conclusions: This systematic review and pooled analysis provide an epidemiological overview of spinal neurosurgery in Nigeria over the last 60 years and serves as a useful reference to direct future global research in this arena., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: Access to neuro-oncologic care in Nigeria has grown exponentially since the first reported cases in the mid-1960s. In this systematic review and pooled analysis, we characterize the growth of neurosurgical oncology in Nigeria and build a reference paper to direct efforts to expand this field., Methods: We performed an initial literature search of several article databases and gray literature sources. We included and subsequently screened articles published between 1962 and 2021. Several variables were extracted from each study, including the affiliated hospital, the number of patients treated, patient sex, tumor pathology, the types of imaging modalities used for diagnosis, and the interventions used for each individual. Change in these variables was assessed using Chi-squared independence tests and univariate linear regression when appropriate., Results: A total of 147 studies were identified, corresponding to 5,760 patients. Over 4000 cases were reported in the past 2 decades from 21 different Nigerian institutions. The types of tumors reported have increased over time, with increasingly more patients being evaluated via computed tomography (CT) and magnetic resonance imaging (MRI). There is also a prevalent use of radiotherapy, though chemotherapy remains an underreported treatment modality., Conclusions: This study highlights key trends regarding the prevalence and management of neuro-oncologic pathologies within Nigeria. Further studies are needed to continue to learn and guide the future growth of this field in Nigeria., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: Despite 6 decades of existence, neurosurgery is still in the developing stages in Nigeria. In this era of collaborative health system capacity-building in low- and middle-income countries, this article reviews past efforts and future prospects for collaborative neurosurgical development in Nigeria., Methods: A bibliometric review of the Nigerian neurosurgical literature and data from a structured survey of Nigerian neurosurgeons and residents provided details of current local and international collaborations for neurosurgical research, service delivery, training, and capacity building. These were analyzed to provide an overview of the role of collaborations in sustainable neurosurgical development in Nigeria and to recommend approaches to enhance neurosurgical capacity., Results: In 1023 peer-reviewed neurosurgery publications from Nigeria, there were 4618 authors with 3688 from 98 Nigerian institutions and 930 from 296 foreign institutions in 70 countries. While there were significant research collaborations amongst Nigerian institutions, the most common were with institutions in the US, United Kingdom, and Cameroon. From the survey, 62 of 149 respondents (41.6%) from 32 health facilities noted their institution's involvement in capacity-building neurosurgical collaborations. These collaborations involved 22 Nigerian institutions and 13 foreign institutions in 9 countries and were mostly for training and workforce development (78.1%), and research and data management (59.4%). The majority of foreign institutions were from the US and United Kingdom., Conclusions: Current and previous neurosurgical collaborations have led to sustainable progress in Nigeria. Further local, regional, and international collaborations would enhance the capacity to address the needs and challenges affecting neurosurgery in Nigeria., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: This study aims to provide a comprehensive overview of pediatric neurosurgery in Nigeria, since 1962, by assessing epidemiological data, management strategies, and case outcomes., Methods: A systematic bibliometric review of Nigerian neurosurgical literature was reported with the PRISMA guidelines. The Risk of Bias Assessment Tool was applied to all nonrandomized studies, and a descriptive analysis was performed for all variables., Results: We identified 12,295 pediatric patients from 196 published studies. Most publications (72.4%) occurred in the recent 2 decades, of which 40.3% were observational case reports/series. The patients were predominantly male (57.2%) and aged 0-18 years, with the majority (66.1%) belonging to the 0-5 age range. Most patients (63.4%) presented between 1-12 months. The most common presenting feature was altered consciousness (7.7%), with computed tomography (38.8%) being the most frequently utilized diagnostic imaging modality. The diagnoses with the greatest prevalence (60.2%) were congenital abnormalities such as hydrocephalus and neural tube defects. 57.5% of cases received surgical therapy, with ventriculoperitoneal shunt placement being the most noticeable procedure performed (36.4%). Complications were identified in 9.5% of cases, with a 4.5% death rate. The Glasgow Outcome Score (95.7%) was the primary outcome measure utilized, with positive outcomes reported in 59.3% of cases., Conclusions: This review provides significant epidemiological data which emphasizes the country's enormous burden of pediatric neurosurgical cases. The findings can help guide clinical decisions as well as future research and policy development., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: Vascular neurosurgery has developed significantly in Nigeria, but its burden and challenges remain unclear. This study systematically reviewed vascular neurosurgical literature from Nigeria., Methods: Four research databases and gray literature sources were searched from 1962-2021. ROBINS-I tool was used to assess risk of bias. Descriptive, narrative, and statistical analyses were conducted on all variables. Where appropriate, paired t-tests and Chi-squared independence tests were used (α = 0.05)., Results: 56 articles were included and 3203 patients pooled for analysis. Risk of bias was moderate-high. Most articles were published over the last 20 years with retrospective cohort studies and case reports being the most common study designs. The cohort had a relatively even gender split and an average age of 49 years (±22). Cerebrovascular accidents accounted for over 85% of diagnoses, with most etiologies being traumatic. Headache and motor deficit were the most prevalent clinical features. X-ray and carotid angiography were the most commonly reported imaging modalities, closely followed by computed tomography (CT) and CT angiography. The top two radiological diagnoses were ischemic cerebrovascular disease and intracerebral hematoma. Aneurysmal clipping and hematoma evacuation were the most commonly reported treatment modalities. Outcome at last follow-up was favorable in 48%. The mortality rate was 6%. Post-treatment complications included chest infection and rebleeding., Conclusions: This study illustrates the epidemiological burden of neurovascular pathology (based on the available data in published literature) in Nigeria, and raises awareness amongst service providers and researchers of the attendant challenges and epochal trends seen within vascular neurosurgery in Nigeria., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: This study investigates the scope, trends, and challenges of neurosurgical research in Nigeria since inception of the specialty in 1962., Methods: A bibliometric review of the neurosurgical literature from Nigeria was performed. Variables extracted included year and journal of publication, article topic, article type, research type, study design, article focus area, and limitations. Descriptive and quantitative analyses were performed for all variables. Trends of research publications were described in three periods: pioneering (1962-1981), recession (1982-2001), and resurgent (2002-2021)., Results: Of the 1023 included articles, 10.0% were published in the pioneering period, 9.2% in the recession period, and 80.8% in the resurgent period. Papers were predominantly published in World Neurosurgery (4.5%) and Nigerian Journal of Clinical Practice (4.0%). A total of 79.9% of the 4618 authors were from Nigerian institutions; 86.3% of the articles covered clinical research and were mainly focused on service delivery and epidemiology (89.9%). The most prominent topics were traumatic brain injury (25.8%) and central nervous system malignancy (21.4%). Only 4.4% of the publications received funding, mostly from agencies in the United States (31.7%). Barriers to neurosurgical research included lack of clinical databases (18.0%), increasing burden of disease (12.5%), and diagnostic challenges (12.4%)., Conclusions: Neurosurgical research in Nigeria continues to grow due to increased training, workforce, and infrastructural improvements. Addressing the major challenges through establishment of research databases, development of evidence-based management guidelines, and increasing research training, funding and opportunities can increase research capacity in Nigeria., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: Neurotrauma is a significant cause of morbidity and mortality in Nigeria. We conducted this systematic review to generate nationally generalizable reference data for the country., Methods: Four research databases and gray literature sources were electronically searched. Risk of bias was assessed using the Risk of Bias in Non-Randomized Studies of Interventions and Cochrane's risk of bias tools. Descriptive analysis, narrative synthesis, and statistical analysis (via paired t-tests and χ 2 independence tests) were performed on relevant article metrics (α = 0.05)., Results: We identified a cohort of 45,763 patients from 254 articles. The overall risk of bias was moderate to high. Most articles employed retrospective cohort study designs (37.4%) and were published during the last 2 decades (81.89%). The cohort's average age was 32.5 years (standard deviation, 20.2) with a gender split of ∼3 males per female. Almost 90% of subjects were diagnosed with traumatic brain injury, with road traffic accidents (68.6%) being the greatest cause. Altered consciousness (48.4%) was the most commonly reported clinical feature. Computed tomography (53.5%) was the most commonly used imaging modality, with skull (25.7%) and vertebral fracture (14.1%) being the most common radiological findings for traumatic brain injury and traumatic spinal injury, respectively. Two-thirds of patients were treated nonoperatively. Outcomes were favorable in 63.7% of traumatic brain injury patients, but in only 20.9% of traumatic spinal injury patients. Pressure sores, infection, and motor deficits were the most commonly reported complications in the latter., Conclusions: This systematic review and pooled analysis demonstrate the significant burden of neurotrauma across Nigeria., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Subcallosal cingulate (SCC) deep brain stimulation (DBS) is an emerging therapy for refractory depression. Good clinical outcomes are associated with the activation of white matter adjacent to the SCC. This activation produces a signature cortical evoked potential (EP), but it is unclear which of the many pathways in the vicinity of SCC is responsible for driving this response. Individualized biophysical models were built to achieve selective engagement of two target bundles: either the forceps minor (FM) or cingulum bundle (CB). Unilateral 2 Hz stimulation was performed in seven patients with treatment-resistant depression who responded to SCC DBS, and EPs were recorded using 256-sensor scalp electroencephalography. Two distinct EPs were observed: a 120 ms symmetric response spanning both hemispheres and a 60 ms asymmetrical EP. Activation of FM correlated with the symmetrical EPs, while activation of CB was correlated with the asymmetrical EPs. These results support prior model predictions that these two pathways are predominantly activated by clinical SCC DBS and provide first evidence of a link between cortical EPs and selective fiber bundle activation., Competing Interests: Competing interests statement:C.C.M. is a paid consultant for Boston Scientific, Co., receives royalties from Hologram Consultants, Neuros Medical, Ceraxis, and Qr8 Health, and is a shareholder in the following companies: Hologram Consultants, Surgical Information Sciences, CereGate, Cardionomic, Enspire DBS. All other authors declare that they have no competing interests. H.S.M. receives consulting and IP licensing fees from Abbott Labs. K.S.C. is a paid consultant for Abbott Labs.

Objective: Deep brain stimulation (DBS) is a well-established treatment for Parkinson's disease (PD) and essential tremor (ET). Although the prevalence of PD and ET can vary by sex and race, little is known about the accessibility of neurosurgical treatments for these conditions. In this nationwide study, the authors aimed to characterize trends in the use of DBS for the treatment of PD and ET and to identify disparities in the neurosurgical treatment of these diseases based on ethnic, racial, sex, insurance, income, hospital, and geographic factors., Methods: Using the dates January 1, 2012, to December 31, 2019, the authors queried the National Inpatient Sample database for all discharges with an ICD-9 or ICD-10 diagnosis of PD or ET. Among these discharges, the DBS rates were reported for each subgroup of race, ethnicity, and sex. To develop national estimates, all analyses were weighted., Results: Among 2,517,639 discharges with PD, 29,820 (1.2%) received DBS, and among 652,935 discharges with ET, 11,885 (1.8%) received DBS. Amid the PD cases, Black patients (n = 405 [0.2%], OR 0.16, 95% CI 0.12-0.20) were less likely than White patients (n = 23,975 [1.2%]) to receive DBS treatment, as were Hispanic patients (n = 1965 [1.1%], OR 0.76, 95% CI 0.65-0.88), whereas Asian/Pacific Islander patients (n = 855 [1.5%]) did not statistically differ from White patients. Amid the ET cases, Black (n = 230 [0.8%], OR 0.39, 95% CI 0.27-0.56), Hispanic (n = 215 [1.0%], OR 0.39, 95% CI 0.28-0.55), and Asian/Pacific Islander (n = 55 [1.0%], OR 0.51, 95% CI 0.28-0.93) patients were less likely than White patients (n = 10,440 [1.9%]) to receive DBS. Females were less likely than males to receive DBS for PD (OR 0.69, p < 0.0001) or ET (OR 0.70, p < 0.0001)., Conclusions: The authors describe significant racial and sex-based differences in the utilization of DBS for the treatment of PD and ET. Further research is required to ascertain the causes of these disparities, as well as any differences in access to specialty neurosurgical care and referral for neuromodulation approaches.

Objective: Traumatic brain injury (TBI) carries a major global burden of disease; however, it is well established that patients in low- and middle-income countries, such as those in Africa, have higher mortality rates. Pediatric TBI, specifically, is a documented cause for concern as injuries to the developing brain have been shown to lead to cognitive, psychosocial, and motor problems in adulthood. The purpose of this study was to investigate the reported demographics, causes, management, and outcomes of pediatric TBI in Africa., Methods: A literature search was conducted using PubMed, Global Index Medicus, Embase, Scopus, Google Scholar, African Journals Online, and Web of Science. Various combinations of "traumatic brain injury," "head injury," "p(a)ediatric," "Africa," and country names were used. Relevant primary data published in the English language were included and subjected to a risk of bias analysis. Variables included age, sex, TBI severity, TBI cause, imaging findings, treatment, complications, and outcome., Results: After screening, 45 articles comprising 11,635 patients were included. The mean patient age was 6.48 ± 2.13 years, and 66.3% of patients were male. Of patients with reported data, mild, moderate, and severe TBIs were reported in 57.6%, 14.5%, and 27.9% of patients, respectively. Road traffic accidents were the most reported cause of pediatric TBI (50.53%) followed by falls (25.18%). Skull fractures and intracerebral contusions were the most reported imaging findings (28.32% and 16.77%, respectively). The most reported symptoms included loss of consciousness (24.4%) and motor deficits (17.1%). Surgical management was reported in 28.66% of patients, with craniotomy being the most commonly reported procedure (15.04%). Good recovery (Glasgow Outcome Scale score 5, Glasgow Outcome Scale-Extended score 7-8) was reported in 47.17% of patients. Examination of the period post-2015 demonstrated increased spread in the literature regarding pediatric TBI in Africa., Conclusions: This study provides a comprehensive overview of the literature regarding pediatric TBI in Africa and how it has evolved alongside global neurosurgical efforts. Although there has been increased involvement from various African countries in the neurosurgical literature, there remains a relative paucity of data on this subject. Standardized reporting protocols for patient care may aid in future studies seeking to synthesize data. Finally, further studies should seek to correlate the trends seen in this study, with primary epidemiological data to gain deeper insight into the disease burden of pediatric TBI in Africa.

Objective: Racial disparities are ubiquitous across medicine in the US. This study aims to assess the evidence of racial disparities within neurosurgery and across its subspecialties, with a specific goal of quantifying the distribution of articles devoted to either identifying, understanding, or reducing disparities., Methods: The authors searched the MEDLINE, EMBASE, and Scopus databases by using keywords to represent the concepts of neurosurgery, patients, racial disparities, and specific study types. Two independent reviewers screened the article titles and abstracts for relevance. A third reviewer resolved conflicts. Data were then extracted from the included articles and each article was categorized into one of three phases: identifying, understanding, or reducing disparities. This review was conducted in accordance with the PRISMA Extension for Scoping Reviews (PRISMA-ScR) guidelines., Results: Three hundred seventy-one studies published between 1985 and 2023 were included. The distribution of racial disparities literature was not equally spread among specialties, with spine representing approximately 48.3% of the literature, followed by tumor (22.1%) and general neurosurgery (12.9%). Most studies were dedicated to identifying racial disparities (83.6%). The proportion of literature devoted to understanding and reducing disparities was much lower (15.1% and 1.3%, respectively). Black patients were the most negatively impacted racial/ethnic group in the review (63.3%). The Hispanic or Latino ethnic group was the second most negatively impacted (25.1%). The following categories-other outcomes (28.0%), the offering of treatment (21.6%), complications (18.6%), and survival (16.7%)-represented the most frequently measured outcomes., Conclusions: Although strides have been taken to identify racial disparities within neurosurgery, fewer studies have focused on understanding and reducing these disparities. The tremendous rise of literature within this domain but the relative paucity of solutions necessitates the study of targeted interventions to provide equitable care for all patients undergoing neurosurgical treatment.

Competing Interests: The authors have no financial or other competing interests to disclose, and the work is not under consideration for publication by any other journal or in any other form.

Introduction: Epilepsy is considered one of the most burdensome neurologic diseases by the World Health Organization due to the high risk of morbidity and mortality. Few studies have investigated the epidemiology of idiopathic epilepsy in Sub-Saharan Africa (SSA). This study aims to characterize the disease burden of epilepsy among the older population in SSA via a large international database., Methods: Descriptive epidemiological data from the Global Burden of Disease (GBD) database was collected for idiopathic epilepsy in all regions of SSA. The "older" population was defined as 55 years of age and above. The variables of interest included mortality, incidence, prevalence, and disability-adjusted life years (DALYs) rates per one hundred thousand populations., Results: The average mortality rate was highest in Western SSA (6.34 per 100,000), and all regions were significantly higher than the global average (p < 0.001). DALYs and incidence rates of idiopathic epilepsy in all regions of SSA were significantly higher than the global averages (p < 0.01). Globally, the older population had a significantly higher mortality rate than the younger population (2.78 vs 1.62, respectively; p < 0.01). The older population had a higher mortality rate than the younger population in each region of SSA (p < 0.01). Conversely, for DALYs, the younger population had a higher disease burden than the older population globally and in each region of SSA (p < 0.01)., Conclusion: This study is the first to examine the epidemiologic profile of idiopathic epilepsy in the older population in SSA. Our results indicate that, when compared with the global population, older adults in SSA suffer a greater disease burden and mortality. This study reports the immense need for increased resources and awareness regarding epilepsy in the elderly population of Africa., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have seemed to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Despite more than six decades of extensive research, the etiology of moyamoya disease (MMD) remains unknown. Inflammatory or autoimmune (AI) processes have been suggested to instigate or exacerbate the condition, but the data remains mixed. The objective of the present systematic review was to summarize the available literature investigating the association of MMD and AI conditions as a means of highlighting potential treatment strategies for this subset of moyamoya patients. Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the PubMed, Embase, Scopus, Web of Science, and Cochrane databases were queried to identify studies describing patients with concurrent diagnoses of MMD and AI disease. Data were extracted on patient demographics, clinical outcomes, and treatment. Stable or improved symptoms were considered favorable outcomes, while worsening symptoms and death were considered unfavorable. Quantitative pooled analysis was performed with individual patient-level data. Of 739 unique studies identified, 103 comprising 205 unique patients (80.2% female) were included in the pooled analysis. Most patients (75.8%) identified as Asian/Pacific Islanders, and the most commonly reported AI condition was Graves' disease (57.6%), with 55.9% of these patients presenting in a thyrotoxic state. Of the 148 patients who presented with stroke, 88.5% of cases (n = 131) were ischemic. Outcomes data was available in 152 cases. There were no significant baseline differences between patients treated with supportive therapy alone and those receiving targeted immunosuppressant therapy. Univariable logistic regression showed that surgery plus medical therapy was more likely than medical therapy alone to result in a favorable outcome. On subanalysis of operated patients, 94.1% of patients who underwent combined direct and indirect bypass reported favorable outcomes, relative to 76.2% of patients who underwent indirect bypass and 82% who underwent direct bypass (p < 0.05). On univariable analysis, the presence of multiple AI disorders was associated with worse outcomes relative to having a single AI disorder. Autoimmune diseases have been uncommonly reported in patients with MMD, but the presence of multiple AI comorbidities portends poorer prognosis. The addition of surgical intervention appears to improve outcomes and for patients deemed surgical candidates, combined direct and indirect bypass appears to offer better outcomes that direct or indirect bypass alone., (© 2023. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Objective: The rates of women and underrepresented racial and ethnic minority (UREM) students successfully matching into neurosurgical residency are extremely low and do not reflect the makeup of the general population. As of 2019, only 17.5% of neurosurgical residents in the United States were women, 4.95% were Black or African American, and 7.2% were Hispanic or Latinx. Earlier recruitment of UREM students will help to diversify the neurosurgical workforce. Therefore, the authors developed a virtual educational event for undergraduate students entitled "Future Leaders in Neurosurgery Symposium for Underrepresented Students'' (FLNSUS). The primary objectives of the FLNSUS were to expose attendees to 1) neurosurgeons from diverse gender, racial, and ethnic backgrounds; 2) neurosurgical research; 3) opportunities for neurosurgical mentorship; and 4) information about life as a neurosurgeon. The authors hypothesized that the FLNSUS would increase student self-confidence, provide exposure to the specialty, and reduce perceived barriers to a neurosurgical career., Methods: To measure the change in participant perceptions of neurosurgery, pre- and postsymposium surveys were administered to attendees. Of the 269 participants who completed the presymposium survey, 250 participated in the virtual event and 124 completed the postsymposium survey. Paired pre- and postsurvey responses were used for analysis, yielding a response rate of 46%. To assess the impact of participant perceptions of neurosurgery as a field, pre- and postsurvey responses to questions were compared. The change in response was analyzed, and a nonparametric sign test was performed to check for significant differences., Results: According to the sign test, applicants showed increased familiarity with the field (p < 0.001), increased confidence in their abilities to become neurosurgeons (p = 0.014), and increased exposure to neurosurgeons from diverse gender, racial, and ethnic backgrounds (p < 0.001 for all categories)., Conclusions: These results reflect a significant improvement in student perceptions of neurosurgery and suggest that symposiums like the FLNSUS may promote further diversification of the field. The authors anticipate that events promoting diversity in neurosurgery will lead to a more equitable workforce that will ultimately translate to enhanced research productivity, cultural humility, and patient-centered care in neurosurgery.

Background: Here, we evaluate the evolution and growth of global neurosurgery publications over time, further focusing on the contributions and impact of authors in low- and middle-income countries (LMICs)., Methods: In this systematic bibliometric analysis, we conducted a two-stage blinded screening process of global neurosurgery publications from 5 databases from inception through July 2021. Articles involving multi-national/multi-institutional research collaborations, detailing any area of global neurosurgery collaboration, or influencing global neurosurgery practice were included. Statistical hypothesis testing was conducted to analyze trends and hypotheses of LMIC authorship contributions., Results: The number of global neurosurgery publications has soared in the last decade. Overall, authors from HIC countries were most commonly from the US (41.1%), Canada (4.0%), and the UK (3.9%), while authors from LMIC countries were most commonly from Uganda (4.2%), Tanzania (2.6%), Cameroon (1.8%), and India (1.8%). Over a quarter (28%) of publications had no LMIC authors, while only 11% had 3 or more LMIC authors. The proportion of LMIC authors (LMIC-R) was not correlated with the citation rate of individual articles or with the year of publication, and a positive trend emerged when the LMIC-R of top-publishing LMICs was individually examined and compared to the year of publication., Conclusions: Despite recent growth, the number of global neurosurgery publications arising from LMICs pales in comparison to those from HICs. Collaborative efforts between certain HICs and LMICs have likely contributed to the observed increase in LMIC author independence over time., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: The high unmet neurosurgical burden in low- and middle-income countries has necessitated multiple global neurosurgical collaborations. We identified these collaborations and their peer-reviewed journal publications and evaluated them using a modified version of the Framework for Assessment of InteRNational Surgical Success (FAIRNeSS)., Methods: A systematic literature review yielded 265 articles describing neurosurgery-focused collaborations. A subset of 101 papers from 17 collaborations were evaluated with the modified FAIRNeSS criteria. Analysis of trends was performed for both individual articles and collaborations., Results: Most of the articles were general reviews (64), and most focused on clinical research (115). The leading collaboration focus was workforce and infrastructure development (45%). Composite FAIRNeSS scores ranged from 7/34 to 30/34. Average FAIRNeSS scores for individual articles ranged from 0.25 to 26.75, while collaboration-wide FAIRNeSS score averages ranged from 5.25 to 20.04. There was significant variability within each subset of FAIRNeSS indicators (P value <0.001). Short-term goals had higher scores than medium- and long-term goals (P value <0.001). Collaboration composite scores correlated with the number of papers published (R 2  = 0.400, P = 0.007) but not with the number of years active (R 2  = 0.072, P = 0.3). Finally, the overall agreement between reviewers was 53.5%, and the overall correlation was 38.5%., Conclusions: Global neurosurgery has no established metrics for evaluating collaborations; therefore, we adapted the FAIRNeSS criteria to do so. The criteria may not be well suited for measuring the success and sustainability of global neurosurgery collaborations, creating a need to develop a more applicable alternate set of metrics., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objective: Africa contributes significantly to the global neurosurgical disease burden but has only 1% of the neurosurgery workforce. This study appraises the neurosurgical workforce and training capacity in Africa and projects the workforce capacity by 2030., Methods: The authors conducted a systematic review of the online literature on neurosurgical workforce and training in Africa obtained from three journal databases (PubMed, Embase, and African Index Medicus), as well as from a gray literature search, between September and December 2020. Included literature passed a two-level screening conducted using a systematic review software by a team of two independent reviewers. Data were extracted from selected articles and documented and analyzed on spreadsheets., Results: One hundred and fifty-nine eligible articles were analyzed: 1974 neurosurgeons serve 1.3 billion people in Africa (density 0.15 per 100,000 persons, ratio 1:678,740), with uneven distribution between the regions. North Africa has 64.39% of the neurosurgical workforce (n = 1271), followed by Southern Africa (12.66%, n = 250), West Africa (11.60%, n = 229), East Africa (8.26%, n = 163), and Central Africa (3.09%, n = 61). At an exponential growth rate of 7.03% (95% CI 5.83%-8.23%) per annum, Africa will have 3418 (95% CI 1811-6080) neurosurgeons by 2030, with a deficit of 5191 neurosurgeons, based on population workforce targets. In terms of training, there are 106 neurosurgery training institutions in 26 African countries. North Africa has 52 training centers (49.05%), West Africa 23 (21.70%), East Africa 15 (14.15%), Southern Africa 14 (13.21%), and Central Africa 2 (1.89%). The major regional training programs are those of the West African College of Surgeons (24 sites in 7 countries) and the College of Surgeons of East, Central, and Southern Africa (17 sites in 8 countries)., Conclusions: The study is limited as it is based on the online literature, some of which includes modeled estimates with questionable reliability. However, the results indicate that while countries in North Africa are expected to surpass their population workforce requirements, sub-Saharan African countries are likely to have significant workforce deficits accentuated by the paucity of neurosurgery training programs. To meet the 2030 population workforce requirements, the continent's exponential growth rate should be scaled up to 15.87% per annum. Scaling up neurosurgical training would help to meet this target and requires collaborative efforts from continental, regional, and national agencies and international organizations.

Objective: Traumatic brain injury (TBI) disproportionately affects low- and middle-income countries (LMICs). In these settings, accurate patient prognostication is both difficult and essential for high-quality patient care. With the ultimate goal of enhancing TBI triage in LMICs, we aim to develop the first deep learning model to predict outcomes after TBI and compare its performance with that of less complex algorithms., Methods: TBI patients' data were prospectively collected in Kampala, Uganda, from 2016 to 2020. To predict good versus poor outcome at hospital discharge, we created deep neural network, shallow neural network, and elastic-net regularized logistic regression models. Predictors included 13 easily acquirable clinical variables. We assessed model performance with 5-fold cross-validation to calculate areas under both the receiver operating characteristic curve and precision-recall curve (AUPRC), in addition to standardized partial AUPRC to focus on comparisons at clinically relevant operating points., Results: We included 2164 patients for model training, of which 12% had poor outcomes. The deep neural network performed best as measured by the area under the receiver operating characteristic curve (0.941) and standardized partial AUPRC in region maximizing recall (0.291), whereas the shallow neural network was best by the area under the precision-recall curve (0.770). In several other comparisons, the elastic-net regularized logistic regression was noninferior to the neural networks., Conclusions: We present the first use of deep learning for TBI prognostication, with an emphasis on LMICs, where there is great need for decision support to allocate limited resources. Optimal algorithm selection depends on the specific clinical setting; deep learning is not a panacea, though it may have a role in these efforts., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Spinal cord stimulation (SCS) effectively reduces opioid usage in some patients, but preoperatively, there is no objective measure to predict who will most benefit., Objective: To predict successful reduction or stabilization of opioid usage after SCS using machine learning models we developed and to assess if deep learning provides a significant benefit over logistic regression (LR)., Methods: We used the IBM MarketScan national databases to identify patients undergoing SCS from 2010 to 2015. Our models predict surgical success as defined by opioid dose stability or reduction 1 year after SCS. We incorporated 30 predictors, primarily regarding medication patterns and comorbidities. Two machine learning algorithms were applied: LR with recursive feature elimination and deep neural networks (DNNs). To compare model performances, we used nested 5-fold cross-validation to calculate area under the receiver operating characteristic curve (AUROC)., Results: The final cohort included 7022 patients, of whom 66.9% had successful surgery. Our 5-variable LR performed comparably with the full 30-variable version (AUROC difference <0.01). The DNN and 5-variable LR models demonstrated similar AUROCs of 0.740 (95% CI, 0.727-0.753) and 0.737 (95% CI, 0.728-0.746) ( P = .25), respectively. The simplified model can be accessed at SurgicalML.com ., Conclusion: We present the first machine learning-based models for predicting reduction or stabilization of opioid usage after SCS. The DNN and 5-variable LR models demonstrated comparable performances, with the latter revealing significant associations with patients' pre-SCS pharmacologic patterns. This simplified, interpretable LR model may augment patient and surgeon decision making regarding SCS., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Background: Current traumatic brain injury (TBI) prognostic calculators are commonly used to predict the mortality and Glasgow Outcome Scale, but these outcomes are most relevant for severe TBI. Because mild and moderate TBI rarely reaches severe outcomes, there is a need for novel prognostic endpoints., Objective: To generate machine learning (ML) models with a strong predictive capacity for trichotomized discharge disposition, an outcome not previously used in TBI prognostic models. The outcome can serve as a proxy for patients' functional status, even in mild and moderate patients with TBI., Methods: Using a large data set (n = 5292) of patients with TBI from a quaternary care center and 84 predictors, including vitals, demographics, mechanism of injury, initial Glasgow Coma Scale, and comorbidities, we trained 6 different ML algorithms using a nested-stratified-cross-validation protocol. After optimizing hyperparameters and performing model selection, isotonic regression was applied to calibrate models., Results: When maximizing the microaveraged area under the receiver operating characteristic curve during hyperparameter optimization, a random forest model exhibited top performance. A random forest model was also selected when maximizing the microaveraged area under the precision-recall curve. For both models, the weighted average area under the receiver operating characteristic curves was 0.84 (95% CI 0.81-0.87) and the weighted average area under the precision-recall curves was 0.85 (95% CI 0.82-0.88)., Conclusion: Our group presents high-performing ML models to predict trichotomized discharge disposition. These models can assist in optimization of patient triage and treatment, especially in cases of mild and moderate TBI., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Objective: Modern cerebrovascular bypass surgery uses either extracranial-intracranial (EC-IC) or intracranial-intracranial (IC-IC) approaches. Compared with EC-IC bypasses, IC-IC bypasses allow neurosurgeons to safely address tumors, aneurysms, and other lesions using shorter grafts that are well matched to the size of recipient vessels. Fewer than 100 articles have been published on IC-IC bypasses compared with more than 1000 on EC-IC bypasses. This study examined the increase of interest and innovation in IC-IC bypass., Methods: PubMed and Web of Science were searched using keywords specific to IC-IC bypass, yielding 717 articles supplemented with 36 reports from other databases and gray literature. The articles were reviewed, and 98 articles were selected for further evaluation. Final articles were categorized as innovations or retrospective studies. Publication metrics were passed through an analytic program to assess statistical measures of growth., Results: The number of publications describing innovations (n = 52) and retrospective studies (n = 46) in IC-IC surgical techniques increased exponentially (R 2  = 0.983 and R 2  = 0.993, respectively), with both interest and research in the field increasing. The rate of publications in each group also increased. In recent years, increasing numbers of global institutions have researched and published on IC-IC bypasses., Conclusions: As more work is undertaken on IC-IC bypasses, it is critical for knowledge to be shared through research, collaboration, publication, and early teaching within residency training programs. This field has increased exponentially in the past 2 decades and has yet to reach an inflection point, indicating possible additional interest and growth over time., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Machine learning (ML) holds promise as a tool to guide clinical decision making by predicting in-hospital mortality for patients with traumatic brain injury (TBI). Previous models such as the international mission for prognosis and clinical trials in TBI (IMPACT) and the corticosteroid randomization after significant head injury (CRASH) prognosis calculators can potentially be improved with expanded clinical features and newer ML approaches., Objective: To develop ML models to predict in-hospital mortality for both the high-income country (HIC) and the low- and middle-income country (LMIC) settings., Methods: We used the Duke University Medical Center National Trauma Data Bank and Mulago National Referral Hospital (MNRH) registry to predict in-hospital mortality for the HIC and LMIC settings, respectively. Six ML models were built on each data set, and the best model was chosen through nested cross-validation. The CRASH and IMPACT models were externally validated on the MNRH database., Results: ML models built on National Trauma Data Bank (n = 5393, 84 predictors) demonstrated an area under the receiver operating curve (AUROC) of 0.91 (95% CI: 0.85-0.97) while models constructed on MNRH (n = 877, 31 predictors) demonstrated an AUROC of 0.89 (95% CI: 0.81-0.97). Direct comparison with CRASH and IMPACT models showed significant improvement of the proposed LMIC models regarding AUROC (P = .038)., Conclusion: We developed high-performing well-calibrated ML models for predicting in-hospital mortality for both the HIC and LMIC settings that have the potential to influence clinical management and traumatic brain injury patient trajectories., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Background: Laser ablation (LA) is used as an upfront treatment in patients with deep seated newly diagnosed Glioblastoma (nGBM)., Objective: To evaluate the outcomes of LA in patients with nGBM and compare them with a matched biopsy-only cohort., Methods: Twenty-four nGBM patients underwent upfront LA at Cleveland clinic, Washington University in St. Louis, and Yale University (6/2011-12/2014) followed by chemo/radiotherapy. Also, 24 out of 171 nGBM patients with biopsy followed by chemo/radiotherapy were matched based on age (< 70 vs ≥ 70), gender, tumor location (deep vs lobar), and volume (<11 cc vs ≥11 cc). Progression-free survival (PFS), overall survival (OS), and disease-specific PFS and OS were outcome measures. Three prognostic groups were identified based on extent of tumor ablation by thermal-damage-threshold (TDT)-lines., Results: The median tumor volume in LA (n = 24) and biopsy only (n = 24) groups was 9.3 cm3 and 8.2 cm3 respectively. Overall, median estimate of OS and PFS in LA cohort was 14.4 and 4.3 mo compared to 15.8 mo and 5.9 mo for biopsy only cohort. On multivariate analysis, favorable TDT-line prognostic groups were associated with lower incidence of disease specific death (P = .03) and progression (P = .05) compared to other groups including biopsy only cohort. Only age (<70 yr, P = .02) and tumor volume (<11 cc, P = .03) were favorable prognostic factors for OS., Conclusion: The maximum tumor coverage by LA followed by radiation/chemotherapy is an effective treatment modality in patients with nGBM, compared to biopsy only cohort. The TDT-line prognostic groups were independent predictor of disease specific death and progression after LA., (Copyright © 2018 by the Congress of Neurological Surgeons.)

Background: Poor durability of femoropopliteal artery (FPA) stenting is multifactorial, and severe FPA deformations occurring with limb flexion are likely involved. Different stent designs result in dissimilar stent-artery interactions, but the degree of these effects in the FPA is insufficiently understood., Objectives: To determine how different stent designs affect limb flexion-induced FPA deformations., Methods: Retrievable markers were deployed into n = 28 FPAs of lightly embalmed human cadavers. Bodies were perfused and CT images were acquired with limbs in the standing, walking, sitting, and gardening postures. Image analysis allowed measurement of baseline FPA foreshortening, bending, and twisting associated with each posture. Markers were retrieved and 7 different stents were deployed across the adductor hiatus in the same limbs. Markers were then redeployed in the stented FPAs, and limbs were reimaged. Baseline and stented FPA deformations were compared to determine the influence of each stent design., Results: Proximal to the stent, Innova, Supera, and SmartFlex exacerbated foreshortening, SmartFlex exacerbated twisting, and SmartControl restricted bending of the FPA. Within the stent, all devices except Viabahn restricted foreshortening; Supera, SmartControl, and AbsolutePro restricted twisting; SmartFlex and Innova exacerbated twisting; and Supera and Viabahn restricted bending. Distal to the stents, all devices except AbsolutePro and Innova exacerbated foreshortening, and Viabahn, Supera, Zilver, and SmartControl exacerbated twisting. All stents except Supera were pinched in flexed limb postures., Conclusions: Peripheral self-expanding stents significantly affect limb flexion-induced FPA deformations, but in different ways. Although certain designs seem to accommodate some deformation modes, no device was able to match all FPA deformations.

Following exposure to aversive stimuli, organisms budget their behaviors by augmenting defensive responses and reducing/suppressing non-defensive behaviors. This budgeting process must be flexible to accommodate modifications in the animal's internal and/or external state that require the normal balance between defensive and non-defensive behaviors to be adjusted. When exposed to aversive stimuli, the mollusk Aplysia budgets its behaviors by concurrently enhancing defensive withdrawal reflexes (an elementary form of learning known as sensitization) and suppressing feeding. Sensitization and feeding suppression are consistently co-expressed following different training protocols and share common temporal domains, suggesting that they are interlocked. In this study, we attempted to uncouple the co-expression of sensitization and feeding suppression using: 1) manipulation of the animal's motivational state through prolonged food deprivation and 2) extended training with aversive stimuli that induces sensitization lasting for weeks. Both manipulations uncoupled the co-expression of the above behavioral changes. Prolonged food deprivation prevented the expression of sensitization, but not of feeding suppression. Following the extended training, sensitization and feeding suppression were co-expressed only for a limited time (i.e., 24 h), after which feeding returned to baseline levels as sensitization persisted for up to seven days. These findings indicate that sensitization and feeding suppression are not interlocked and that their co-expression can be uncoupled by internal (prolonged food deprivation) and external (extended aversive training) factors. The different strategies, by which the co-expression of sensitization and feeding suppression was altered, provide an example of how budgeting strategies triggered by an identical aversive experience can vary depending on the state of the organism., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Although the study of calcium (Ca 2+ ) is classically associated with excitable cells such as myocytes or neurons, the ubiquity of this essential element in all cellular processes has led to interest in other cell types. The importance of Ca 2+ to apoptosis, cell signaling, and immune activation is of special import in cancer., Main: Here we review the current understanding of Ca 2+ in each of these processes vital to the initiation, spread, and drug resistance of malignancies. We describe the involvement of Ca 2+ , and Ca 2+ related proteins in cell cycle checkpoints and Ca 2+ dependent apoptosis and discuss their roles in cellular immortalization. The role of Ca 2+ in inter-cellular communication is also discussed in relevance to tumor-stromal communication, angiogenesis, and tumor microinvasion. The role that Ca 2+ plays in immune surveillance and evasion is also addressed. Finally, we discuss the possibility of targeting Ca 2+ singling to address the most pressing topics of cancer treatment: metastatic disease and drug resistance., Conclusion: This review discusses the current understanding of Ca 2+ in cancer. By addressing Ca 2+ facilitated angiogenesis, immune evasion, metastasis, and drug resistance, we anticipate future avenues for development of Ca 2+ as a nexus of therapy.

Background: High failure rates of femoropopliteal artery (FPA) interventions are often attributed in part to severe mechanical deformations that occur with limb movement. Axial compression and bending of the FPA likely play significant roles in FPA disease development and reconstruction failure, but these deformations are poorly characterized. The goal of this study was to quantify axial compression and bending of human FPAs that are placed in positions commonly assumed during the normal course of daily activities., Methods: Retrievable nitinol markers were deployed using a custom-made catheter system into 28 in situ FPAs of 14 human cadavers. Contrast-enhanced, thin-section computed tomography images were acquired with each limb in the standing (180 degrees), walking (110 degrees), sitting (90 degrees), and gardening (60 degrees) postures. Image segmentation and analysis allowed relative comparison of spatial locations of each intra-arterial marker to determine axial compression and bending using the arterial centerlines., Results: Axial compression in the popliteal artery (PA) was greater than in the proximal superficial femoral artery (SFA) or the adductor hiatus (AH) segments in all postures (P = .02). Average compression in the SFA, AH, and PA ranged from 9% to 15%, 11% to 19%, and 13% to 25%, respectively. The FPA experienced significantly more acute bending in the AH and PA segments compared with the proximal SFA (P < .05) in all postures. In the walking, sitting, and gardening postures, average sphere radii in the SFA, AH, and PA ranged from 21 to 27 mm, 10 to 18 mm, and 8 to 19 mm, whereas bending angles ranged from 150 to 157 degrees, 136 to 147 degrees, and 137 to 148 degrees, respectively., Conclusions: The FPA experiences significant axial compression and bending during limb flexion that occur at even modest limb angles. Moreover, different segments of the FPA appear to undergo significantly different degrees of deformation. Understanding the effects of limb flexion on axial compression and bending might assist with reconstructive device selection for patients requiring peripheral arterial disease intervention and may also help guide the development of devices with improved characteristics that can better adapt to the dynamic environment of the lower extremity vasculature., (Copyright © 2017 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Femoropopliteal artery (FPA) mechanics play a paramount role in pathophysiology and the artery's response to therapeutic interventions, but data on FPA mechanical properties are scarce. Our goal was to characterize human FPAs over a wide population to derive a constitutive description of FPA aging to be used for computational modeling. Fresh human FPA specimens ([Formula: see text]) were obtained from [Formula: see text] predominantly male (80 %) donors 54±15 years old (range 13-82 years). Morphometric characteristics including radius, wall thickness, opening angle, and longitudinal pre-stretch were recorded. Arteries were subjected to multi-ratio planar biaxial extension to determine constitutive parameters for an invariant-based model accounting for the passive contributions of ground substance, elastin, collagen, and smooth muscle. Nonparametric bootstrapping was used to determine unique sets of material parameters that were used to derive age-group-specific characteristics. Physiologic stress-stretch state was calculated to capture changes with aging. Morphometric and constitutive parameters were derived for seven age groups. Vessel radius, wall thickness, and circumferential opening angle increased with aging, while longitudinal pre-stretch decreased ([Formula: see text]). Age-group-specific constitutive parameters portrayed orthotropic FPA stiffening, especially in the longitudinal direction. Structural changes in artery wall elastin were associated with reduction of physiologic longitudinal and circumferential stretches and stresses with age. These data and the constitutive description of FPA aging shed new light on our understanding of peripheral arterial disease pathophysiology and arterial aging. Application of this knowledge might improve patient selection for specific treatment modalities in personalized, precision medicine algorithms and could assist in device development for treatment of peripheral artery disease.

High failure rates of femoropopliteal artery (FPA) interventions are often attributed to severe mechanical deformations that occur with limb movement. Torsion of the FPA likely plays a significant role, but is poorly characterized and the associated intramural stresses are currently unknown. FPA torsion in the walking, sitting and gardening postures was characterized in n = 28 in situ FPAs using intra-arterial markers. Principal mechanical stresses and strains were quantified in the superficial femoral artery (SFA), adductor hiatus segment (AH) and the popliteal artery (PA) using analytical modelling. The FPA experienced significant torsion during limb flexion that was most severe in the gardening posture. The associated mechanical stresses were non-uniformly distributed along the length of the artery, increasing distally and achieving maximum values in the PA. Maximum twist in the SFA ranged 10-13° cm -1 , at the AH 8-16° cm -1 , and in the PA 14-26° cm -1 in the walking, sitting and gardening postures. Maximum principal stresses were 30-35 kPa in the SFA, 27-37 kPa at the AH and 39-43 kPa in the PA. Understanding torsional deformations and intramural stresses in the FPA can assist with device selection for peripheral arterial disease interventions and may help guide the development of devices with improved characteristics., (© 2017 The Author(s).)

Background: Uncontrolled hemorrhage from vessel injuries within the torso remains a significant source of prehospital trauma mortality. Resuscitative endovascular balloon occlusion of the aorta can effectively control noncompressible hemorrhage, but this minimally invasive technique relies heavily on imaging not available in the field. Our goal was to develop morphometric roadmaps to enhance the safety and accuracy of fluoroscopy-free endovascular navigation of hemorrhage control devices., Methods: Three-dimensional reconstructions of computed tomographic angiography scans from 122 trauma patients (mean [SD] age, 47 [24] years; range 5-93 years; 64 males; 58 females) were used to measure centerline distances from femoral artery access sites to the major aortic branch artery origins. Morphometric roadmap equations were created using multiple linear regression analysis to predict distances to the origins of the major arteries in the chest, abdomen, and pelvis using torso length, demographics, and risk factors as independent variables. A 40-mm-long occlusion balloon was then virtually deployed targeting Zones 1 and 3 of the aorta using these equations. Balloon placement accuracy was determined by comparing predicted versus actual measured distances to the target zone locations within the aortas from the database., Results: Torso length and age were the strongest predictors of centerline distances from femoral artery access sites to the major artery origins. Male sex contributed to longer distances, while diabetes and smoking were associated with shorter distances. Hypertension, dyslipidemia, and coronary artery disease had no effect. With the use of morphometric roadmaps, virtual occlusion balloon placement accuracy was 100% for Zone 3 of the aorta, compared with 87% accuracy when using torso length alone., Conclusion: Morphometric roadmaps demonstrate a potential for improving the safety and accuracy of fluoroscopy-free aortic occlusion balloon delivery. Continued development of minimally invasive hemorrhage control techniques holds promise to improve prehospital mortality for patients with noncompressible exsanguinating torso injuries., Level of Evidence: Therapeutic study, level IV; diagnostic study, level III.

In situ longitudinal (axial) pre-stretch (LPS) plays a fundamental role in the mechanics of the femoropopliteal artery (FPA). It conserves energy during pulsation and prevents buckling of the artery during limb movement. We investigated how LPS is affected by demographics and risk factors, and how these patient characteristics associate with the structural and physiologic features of the FPA. LPS was measured in n=148 fresh human FPAs (14-80 years old). Mechanical properties were characterized with biaxial extension and histopathological characteristics were quantified with Verhoeff-Van Gieson Staining. Constitutive modeling was used to calculate physiological stresses and stretches which were then analyzed in the context of demographics, risk factors and structural characteristics. Age had the strongest negative effect (r=-0.812, p<0.01) on LPS and could alone explain 66% of LPS variability. Male gender, higher body mass index, hypertension, diabetes, coronary artery disease, dyslipidemia and tobacco use had negative effects on LPS, but only the effect of tobacco was not associated with aging. FPAs with less pre-stretch had thicker medial layers, but thinner intramural elastic fibers with less dense and more fragmented external elastic laminae. Elastin degradation was associated with decreased physiological tethering force and longitudinal stress, while circumferential stress remained constant. FPA wall pathology was negatively associated with LPS (r=-0.553, p<0.01), but the effect was due primarily to aging. LPS in the FPA may serve as an energy reserve for adaptive remodeling. Reduction of LPS due to degradation and fragmentation of intramural longitudinal elastin during aging can be accelerated in tobacco users., Statement of Significance: This work studies in situ longitudinal pre-stretch (LPS) in the human femoropopliteal artery. LPS has a fundamental role in arterial mechanics, but is rather poorly studied due to lack of direct in vivo measurement method. We have investigated LPS in the n=148 human femoropopliteal arteries in the context of subject demographics and risk factors, and structural and physiologic characteristics of the artery. Our results demonstrate that LPS reduces with age due to degradation and fragmentation of intramural elastin. LPS may serve as an energy reserve for adaptive remodeling, and reduction of LPS can be accelerated in tobacco users., (Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Generation of femtosecond pulses from a continuous-wave mode-locked chromium-doped forsterite (Cr (4+):Mg(2)SiO(4)) laser is reported. The forsterite laser was actively mode locked by using an acousto-optic modulator operating at 78 MHz with two Brewster high-dispersion glass prisms for intracavity chirp compensation. Transform-limited sub-100-fs pulses were routinely generated in the TEM(00) mode with 85 mW of continuous power (with 1% output coupler), tunable over 1230-1280 nm. The shortest pulses had a 60-fs pulse width.

Mode-locked operation of chromium-doped forsterite (Cr:Mg(2)SiO(4)) has been achieved for the first time to our knowledge. The chromium-doped forsterite laser has been mode locked by using two methods: active mode locking, which produced pulses as short as 31 ps tunable between 1204 and 1277 nm, and synchronously pumped mode locking, which produced pulses of 260-ps duration tunable between 1195 and 1295 nm.

The slope efficiency of the continuous-wave chromium-doped forsterite (Cr:Mg(2)SiO(4)) laser has been measured by using four different output mirrors. The maximum slope efficiency of 38% was achieved with an 11% output coupler. The extrapolated limiting slope efficiency in the absence of passive losses is estimated to be 65%. This value corresponds to an intrinsic quantum efficiency of 77%, which is similar to the efficiencies determined for mature tunable solid-state laser systems.