Diverse Synaptic Distributions of G Protein-coupled Estrogen Receptor 1 in Monkey Prefrontal Cortex with Aging and Menopause.

Age- and menopause-related impairment in working memory mediated by the dorsolateral prefrontal cortex (dlPFC) occurs in humans and nonhuman primates. Long-term cyclic 17ß-estradiol treatment rescues cognitive deficits in aged ovariectomized rhesus monkeys while restoring highly plastic synapses. Here we tested whether distributions of G protein-coupled estrogen receptor 1 (GPER1) within monkey layer III dlPFC synapses are sensitive to age and estradiol, and coupled to cognitive function. Ovariectomized young and aged monkeys administered vehicle or estradiol were first tested on a delayed response test of working memory. Then, quantitative serial section immunoelectron microscopy was used to determine the distributions of synaptic GPER1. GPER1-containing nonperforated axospinous synapse density was reduced with age, and partially restored with estrogen treatment. The majority of synapses expressed GPER1, which was predominately localized to presynaptic cytoplasm and mitochondria. GPER1 was also abundant at plasmalemmas, and within cytoplasmic and postsynaptic density (PSD) domains of dendritic spines. GPER1 levels did not differ with age or treatment, and none of the variables examined were tightly associated with cognitive function. However, greater representation of GPER1 subjacent to the PSD accompanied higher synapse density. These data suggest that GPER1 is positioned to support diverse functions key to synaptic plasticity in monkey dlPFC.

Estrogen Restores Multisynaptic Boutons in the Dorsolateral Prefrontal Cortex while Promoting Working Memory in Aged Rhesus Monkeys.

Humans and nonhuman primates are vulnerable to age- and menopause- related decline in working memory, a cognitive function reliant on area 46 of the dorsolateral prefrontal cortex (dlPFC). We showed previously that presynaptic mitochondrial number and morphology in monkey dlPFC neurons correlate with working memory performance. The current study tested the hypothesis that the types of synaptic connections these boutons form are altered with aging and menopause in rhesus monkeys and that these metrics may be coupled with mitochondrial measures and working memory. Using serial section electron microscopy, we examined the frequencies and characteristics of nonsynaptic, single-synaptic, and multisynaptic boutons (MSBs) in the dlPFC. In contrast to our previous observations in the monkey hippocampal dentate gyrus, where MSBs comprised ∼40% of boutons, the vast majority of dlPFC boutons were single-synaptic, whereas MSBs constituted a mere 10%. The frequency of MSBs was not altered by normal aging, but decreased by over 50% with surgical menopause induced by ovariectomy in aged monkeys. Cyclic estradiol treatment in aged ovariectomized animals restored MSB frequencies to levels comparable to young and aged premenopausal monkeys. Notably, the frequency of MSBs positively correlated with working memory scores, as measured by the average accuracy on the delayed response (DR) test. Furthermore, MSB incidence positively correlated with the number of healthy straight mitochondria in dlPFC boutons and inversely correlated with the number of pathological donut-shaped mitochondria. Together, our data suggest that MSBs are coupled to cognitive function and mitochondrial health and are sensitive to estrogen. Significance statement: Many aged menopausal individuals experience deficits in working memory, an executive function reliant on recurrent firing of prefrontal cortex (PFC) neurons. However, little is known about the organization of presynaptic inputs to these neurons and how they may be altered with aging and menopause. Multisynaptic boutons (MSBs) were of particular interest, because they form multiple synapses and can enhance coupling between presynaptic and postsynaptic neurons. We found that higher MSB frequency correlated with better working memory performance in rhesus monkeys. Additionally, aged surgically menopausal monkeys experienced a 50% loss of MSBs that was restored with cyclic estradiol treatment. Together, our findings suggest that hormone replacement therapy benefits cognitive aging, in part by retaining complex synaptic organizations in the PFC.

Differential induction of plasma cells by isoforms of human TACI.

Subjects with common variable immune deficiency may have mutations in transmembrane activator calcium modulator and cyclophilin ligand interactor (TACI). Unlike the murine gene, human TACI undergoes alternative messenger (m)RNA splicing to produce isoforms with 1 or 2 ligand-binding domains. Because both isoforms are found in human B cells, we compared their functions in transduced murine B and human pre-B cells. Although murine cells and pre-B cells transduced with the long TACI isoform retained surface CD19 and immunoglobulin G, cells transduced with the short TACI isoform completely lost these B-cell characteristics. Expression of the short TACI isoform produced intense nuclear factor κB activation, nuclear p65 translocation, and colocalization with myeloid differentiation factor 88 and calcium-modulating cyclophilin ligand. The short TACI-transduced cells became larger and CD138 positive, demonstrated upregulated BLIMP1 and XBP1 mRNA, and acquired the morphology of plasma cells. In contrast, cells bearing the long isoform had significantly less BLIMP1 and XBP1 mRNA and, for human pre-B cells, remained CD138 negative. Although human B cells express both isoforms, the short isoform predominates in CD27(+) B cells, toll-like receptor 9-activated peripheral B cells, and splenic marginal zone B cells. Although the transcriptional controls for alternative splicing of isoforms remain unknown, differential signals via isoforms may control plasma-cell generation in humans.

Presynaptic mitochondrial morphology in monkey prefrontal cortex correlates with working memory and is improved with estrogen treatment.

Humans and nonhuman primates are vulnerable to age- and menopause-related decline in working memory, a cognitive function reliant on the energy-demanding recurrent excitation of neurons within Brodmann's Area 46 of the dorsolateral prefrontal cortex (dlPFC). Here, we tested the hypothesis that the number and morphology (straight, curved, or donut-shaped) of mitochondria in dlPFC presynaptic boutons are altered with aging and menopause in rhesus monkeys (Macaca mulatta) and that these metrics correlate with delayed response (DR) accuracy, a well-characterized measure of dlPFC-dependent working memory. Although presynaptic bouton density or size was not significantly different across groups distinguished by age or menses status, DR accuracy correlated positively with the number of total and straight mitochondria per dlPFC bouton. In contrast, DR accuracy correlated inversely with the frequency of boutons containing donut-shaped mitochondria, which exhibited smaller active zone areas and fewer docked synaptic vesicles than those with straight or curved mitochondria. We then examined the effects of estrogen administration to test whether a treatment known to improve working memory influences mitochondrial morphology. Aged ovariectomized monkeys treated with vehicle displayed significant working memory impairment and a concomitant 44% increase in presynaptic donut-shaped mitochondria, both of which were reversed with cyclic estradiol treatment. Together, our data suggest that hormone replacement therapy may benefit cognitive aging, in part by promoting mitochondrial and synaptic health in the dlPFC.

The Top 100 Cited Articles on Cervical Disc Arthroplasty: A Bibliometric Analysis.

STUDY DESIGN: Bibliometric analysis. OBJECTIVE: Cervical disc arthroplasty (CDA) has emerged as an effective surgical intervention for degenerative cervical disc disease with potential advantages over traditional cervical fusion. This bibliometric analysis aimed to assess the current state of research on CDA by analyzing the relevant literature using bibliometric indicators. SUMMARY OF BACKGROUND DATA: Web of Science Core Collection. METHODS: A comprehensive search was conducted using the Web of Science database, for articles related to CDA published in the last 19 years. The top 100 articles were reviewed using bibliometric analysis. Publication trends, citation patterns, authorship, and collaboration networks were analyzed using VOSviewer and the Bibliometrix package in RStudio. RESULTS: The results revealed a significant increase in the number of publications related to CDA over the past 2 decades, with most of the articles being published in orthopedic and spine surgery journals. The most frequently cited articles were related to clinical outcomes, complications, and biomechanical studies of CDA. Co-authorship analysis identified influential authors and collaborative networks, highlighting the multidisciplinary nature of CDA research involving neurosurgeons, orthopedic surgeons, and engineers. Overall, this bibliometric analysis provides a comprehensive overview of the current state of research on CDA, highlighting the key research themes, influential authors, and collaborative networks in the field. CONCLUSION: These findings can serve as a guide for researchers, clinicians, and policymakers to identify knowledge gaps, research trends, and future directions in the field of CDA.

Synaptic distributions of GluA2 and PKMζ in the monkey dentate gyrus and their relationships with aging and memory.

Rhesus monkeys provide a valuable model for studying the neurobiological basis of cognitive aging, because they are vulnerable to age-related memory decline in a manner similar to humans. In this study, young and aged monkeys were first tested on a well characterized recognition memory test (delayed nonmatching-to-sample; DNMS). Then, electron microscopic immunocytochemistry was performed to determine the subcellular localization of two proteins in the hippocampal dentate gyrus (DG): the GluA2 subunit of the glutamate AMPA receptor and the atypical protein kinase C ζ isoform (PKMζ). PKMζ promotes memory storage by regulating GluA2-containing AMPA receptor trafficking. Thus, we examined whether the distribution of GluA2 and PKMζ is altered with aging in DG axospinous synapses and whether it is coupled with memory deficits. Monkeys with faster DNMS task acquisition and more accurate recognition memory exhibited higher proportions of dendritic spines coexpressing GluA2 and PKMζ. These double-labeled spines had larger synapses, as measured by postsynaptic density area, than single-labeled and unlabeled spines. Within this population of double-labeled spines, aged monkeys compared with young expressed a lower density of synaptic GluA2 immunogold labeling, which correlated with lower recognition accuracy. Additionally, higher density of synaptic PKMζ labeling in double-labeled spines correlated with both faster task acquisition and better retention. Together, these findings suggest that age-related impairment in maintenance of GluA2 at the synapse in the primate hippocampus is coupled with memory deficits.

The 100 Top-Cited Articles on Robotic Neurosurgery: A Bibliometric Analysis.

BACKGROUND: Robotic neurosurgery is a rapidly advancing field with numerous applications in various subspecialties, including spine, functional, skull base, and cerebrovascular. This study aims to provide a comprehensive analysis of the most-cited articles on robotic neurosurgery. METHODS: The Web of Science database was used to collect data, and bibliometric analysis was performed using VOSviewer and RStudio. Network analysis techniques such as co-occurrence, coauthorship, bibliographic coupling, and thematic mapping analyses were used to identify the top 100 most cited articles, major contributors, emerging trends, and noteworthy themes in the field. RESULTS: The results showed that there has been a steady increase in the number of publications on robotic neurosurgery since 1991, with an exponential growth in the number of citations. The United States was the most common country of origin for articles, followed by Canada. The most productive authors in this field were Burton S.A. and Gerszten P.C., while the University of Pittsburgh was the most productive institution, and Neurosurgery was the most productive journal. Themes such as robotics, back pain, and prostate cancer, as well as trends in developing new technologies and improving the precision of surgical procedures, were identified. CONCLUSIONS: This study provides a comprehensive analysis of the most-cited articles on robotic neurosurgery. The broad range of topics and techniques explored emphasize the importance of continued innovation and investigation. Ultimately, the study's findings provide valuable guidance for future research and contribute to advancing our understanding of this critical area of study.

Da Vinci Meets Globus Excelsius GPS: A Totally Robotic Minimally Invasive Anterior and Posterior Lumbar Fusion.

BACKGROUND: Minimally invasive approaches to the spine via anterior and posterior approaches have been increasing in popularity, culminating in the development of robot-assisted spinal fusions. The da Vinci surgical robot has been used for anterior lumbar interbody fusion (ALIF), with promising results. Similarly, multiple spinal robots have been developed to assist placement of posterior pedicle screws. However, no previous cases have reported on using robots for both anterior and posterior fixation in a single surgery. We present a technical note on the first reported case of a totally robotic minimally invasive anterior and posterior lumbar fusion and instrumentation. METHODS: A 65-year-old man with chronic low back pain and left greater than right lower extremity radiculopathy was found to have grade 1 spondylolisthesis at L5/S1 that worsened on standing upright. He underwent ALIF using a da Vinci robotic approach, followed by percutaneous posterior instrumented fusion with the Globus Excelsius GPS robot. RESULTS: The patient did well postoperatively, with improvement of back and leg pain at 3 months follow-up. Radiography confirmed appropriate placement of the interbody cage and pedicle screws. CONCLUSIONS: All-robotic placement of both ALIF and posterior lumbar pedicle fixation may be safe, feasible, and efficacious.

Schottky-Diode Design for Future High-Speed Telecommunications.

The impact of 5G communication is expected to be widespread and transformative. It promises to provide faster mobile broadband speeds, lower latency, improved network reliability and capacity, and more efficient use of wireless technologies. The Schottky diode, a BN/GaN layered composite contacting bulk aluminum, is theoretically plausible to harvest wireless energy above X-band. According to our first principle calculation, the insertion of GaN layers dramatically influences the optical properties of the layered composite. The relative dielectric constant of BN/GaN layered composite as a function of layer-to-layer separation is investigated where the optimized dielectric constant is ~2.5. To push the dielectric constant approaching ~1 for high-speed telecommunication, we upgrade our BN-based Schottky diode via nanostructuring, and we find that the relative dielectric constant of BN monolayer (semiconductor side) can be minimized to ~1.5 only if it is deposited on an aluminum monolayer (metal side). It is rare to find a semiconductor with a dielectric constant close to 1, and our findings may push the cut-off frequency of the Al/BN-based rectenna to the high-band 5G network.

Evidence for reduced experience-dependent dendritic spine plasticity in the aging prefrontal cortex.

Cognitive functions that require the prefrontal cortex are highly sensitive to aging in humans, nonhuman primates, and rodents, although the neurobiological correlates of this vulnerability remain largely unknown. It has been proposed that dendritic spines represent the primary site of structural plasticity in the adult brain, and recent data have supported the hypothesis that aging is associated with alterations of dendritic spine morphology and plasticity in prefrontal cortex. However, no study to date has directly examined whether aging alters the capacity for experience-dependent spine plasticity in aging prefrontal neurons. To address this possibility, we used young, middle-aged, and aged rats in a behavioral stress paradigm known to produce spine remodeling in prefrontal cortical neurons. In young rats, stress resulted in dendritic spine loss and altered patterns of spine morphology; in contrast, spines from middle-aged and aged animals were remarkably stable and did not show evidence of remodeling. The loss of stress-induced spine plasticity observed in aging rats occurred alongside robust age-related reductions in spine density and shifts in remaining spine morphology. Together, the data presented here provide the first evidence that experience-dependent spine plasticity is altered by aging in prefrontal cortex, and support a model in which dendritic spines become progressively less plastic in the aging brain.

Clinical Trials in Spinal Tumors: A Two-Decade Review.

OBJECTIVE: Clinical trials are essential for assessing the advancements in spine tumor therapeutics. The purpose of the present study was to characterize the trends in clinical trials for primary and metastatic tumor treatment during the past 2 decades. METHODS: The ClinicalTrials.gov database was queried using the search term "spine" for all interventional studies from 1999 to 2020 with the categories of "cancer," "neoplasm," "tumor," and/or "metastasis." The tumor type, phase data, enrollment numbers, and home institution country were recorded. The sponsor was categorized as an academic institution, industry, government, or other and the intervention type as procedure, drug, device, radiation therapy, or other. The frequency of each category and the cumulative frequency during the 20-year period were calculated. RESULTS: A total of 106 registered trials for spine tumors were listed. All, except for 2, that had begun before 2008 had been completed. An enrollment of 51-100 participants (29.8%) was the most common, and most were phase II studies (54.4%). Most of the studies had examined metastatic tumors (58.5%), and the number of new trials annually had increased 3.4-fold from 2009 to 2020. Most of the studies had been conducted in the United States (56.4%). The most common intervention strategy was radiation therapy (32.1%), although from 2010 to 2020, procedural studies had become the most frequent (2.4/year). Most of the studies had been sponsored by academic institutions (63.2%), which during the 20-year period had sponsored 3.2-fold more studies compared with the industry partners. CONCLUSIONS: The number of clinical trials for spine tumor therapies has rapidly increased during the past 15 years, owing to studies at U.S. academic medical institutions investigating radiosurgery for the treatment of metastases. Targeted therapies for tumor subtypes and sequelae have updated international best practices.

The Impact of American Society of Anesthesiologists Status on Cost of Care and Length of Stay Following Posterior Cervical Decompression and Fusion.

BACKGROUND: Increased posterior cervical decompression and fusion (PCDF) procedures over the past decade have raised the prospect of bundled payment plans. The American Society of Anesthesiologists (ASA) Physical Status Classification system may enable accurate estimation of health care costs, length of stay (LOS), and other postoperative outcomes in patients undergoing PCDF. METHODS: Low (I and II) versus high (III and IV) ASA class was used to evaluate 971 patients who underwent PCDF between 2008 and 2016 at a single institution. Demographics were compared using univariate analysis. Cost of care, LOS, and postoperative complications were compared using multivariable logistic and linear regression, controlling for sex, age, length of surgery, and number of segments fused. RESULTS: The high ASA class cohort was older (mean age 62 years vs. 55 years, P < 0.0001) and had higher Elixhauser comorbidity index scores (P < 0.0001). ASA class was independently associated with longer LOS (2.1 days, 95% confidence interval [CI] 1.3-2.9, P < 0.0001) and higher cost ($2936, 95% CI $1457-$4415, P < 0.0001). Patients with high ASA class were more likely to have a nonhome discharge (3.9, 95% CI 2.8-5.6, P < 0.0001), delayed extubation (3.2, 95% CI 1.4-7.3, P = 0.006), intensive care unit stay (2.4, 95% CI 1.5 3.7, P = 0.0001), in-hospital complications (1.5, 95% CI 1.0-2.2, P = 0.03), and 30-day (3.2, 95% CI 1.5-6.8, P = 0.003) and 90-day (3.2, 95% CI 1.8-5.7, P = 0.0001) readmission. CONCLUSIONS: High ASA class is strongly associated with increased costs, LOS, and adverse outcomes following PCDF and could be useful for preoperative prediction of these outcomes.

Current innovation in virtual and augmented reality in spine surgery.

In spinal surgery, outcomes are directly related both to patient and procedure selection, as well as the accuracy and precision of instrumentation placed. Poorly placed instrumentation can lead to spinal cord, nerve root or vascular injury. Traditionally, spine surgery was performed by open methods and placement of instrumentation under direct visualization. However, minimally invasive surgery (MIS) has seen substantial advances in spine, with an ever-increasing range of indications and procedures. For these reasons, novel methods to visualize anatomy and precisely guide surgery, such as intraoperative navigation, are extremely useful in this field. In this review, we present the recent advances and innovations utilizing simulation methods in spine surgery. The application of these techniques is still relatively new, however quickly being integrated in and outside the operating room. These include virtual reality (VR) (where the entire simulation is virtual), mixed reality (MR) (a combination of virtual and physical components), and augmented reality (AR) (the superimposition of a virtual component onto physical reality). VR and MR have primarily found applications in a teaching and preparatory role, while AR is mainly applied in hands-on surgical settings. The present review attempts to provide an overview of the latest advances and applications of these methods in the neurosurgical spine setting.

Comparison of Anterior and Posterior Surgical Approaches for Treatment of Thoracic Myelopathy.

OBJECTIVE: To study a large multi-institutional sample of patients undergoing anterior versus posterior approaches for surgical decompression of thoracic myelopathy. METHODS: The American College of Surgeons National Surgical Quality Improvement Program was queried for patients who underwent decompression for thoracic myelopathy between 2007 and 2015 via anterior or posterior approaches. Patients were excluded if they were undergoing surgery for tumors to isolate a degenerative cohort. Demographics, patient comorbidities, operative details, and postoperative complications were compared between the 2 cohorts. RESULTS: Although there were no differences in age (P = 0.06), sex (P = 0.72), or American Society of Anesthesiologists class (P = 0.59), there were higher rates of steroid use (P = 0.01) and hematologic disorders that predispose to bleeding (P = 0.04) at baseline in the posterior approach cohort. The posterior approach patients had longer operative times (P = 0.03), but there were no differences in length of stay (P = 0.64). Although there were no significant differences in the rates of major organ system complications or return to the operating room (P = 0.52), the posterior approach cohort displayed a trend toward increased severe adverse complications (29.8% vs. 17.6%, P = 0.28) compared with the anterior approach cohort. CONCLUSION: Although the anterior approach to surgical decompression of thoracic myelopathy demonstrated a lower complication rate, this result did not reach statistical significance. The anterior approach was associated with significantly shorter mean operative time, but otherwise there were no significant differences in operative or postoperative outcomes. These findings may support the favorability of the anterior approach but warrant further investigation in a larger study.

Surgeon experience influences patient characteristics and outcomes in spine deformity surgery.

PURPOSE: To characterize differences in patient demographics and outcomes by surgeon experience in a cohort of patients undergoing adult spinal deformity surgery. METHODS: Patients undergoing degenerative spinal deformity were included. Patients whose surgeons graduated from fellowship ≤ 5 years prior to surgery versus > 5 years were compared. Multivariable linear and logistic regression, controlling for age, sex, comorbidity burden, number of segments fused, blood loss and operative time were used to evaluate differences in outcomes. Characteristics of operative invasiveness were plotted against surgeons' level of experience, and trends in these measures were assessed with univariate linear regression. RESULTS: Three-hundred sixty-three patients were included. 147 patients' surgeons had ≤ 5 years of experience. Patient demographics were evenly matched. Patients with junior surgeons had more pre-existing medical complications, and senior surgeons were less likely to take care of patients with Medicare/Medicaid (p < 0.001). Junior surgeons were more likely to operate on non-elective patients (p < 0.001). Patients of junior surgeons received larger fusions (9.6 vs. 7.6 segments fused, p < 0.001). There were no differences in complication rates or death. Patients of junior surgeons had longer overall length of stays (p = 0.037) and higher rates of nonhome discharge (OR 2.0, p < 0.001), 30- and 90-day (p < 0.005) ED visits, and higher costs (+ $8548, 95% CI: $1596 to $15,502; p = 0.016). CONCLUSION: Junior surgeons tend to perform more extensive deformity operations on more medically complex patients compared to senior surgeons, associated with higher costs and more resource utilization than senior surgeons.

Application of Cooperative Game Theory Principles to Interpret Machine Learning Models of Nonhome Discharge Following Spine Surgery.

STUDY DESIGN: Retrospective analysis of prospectively acquired data. OBJECTIVE: The aim of this study was to identify interaction effects that modulate nonhome discharge (NHD) risk by applying coalitional game theory principles to interpret machine learning models and understand variable interaction effects underlying NHD risk. SUMMARY OF BACKGROUND DATA: NHD may predispose patients to adverse outcomes during their care. Previous studies identified potential factors implicated in NHD; however, it is unclear how interaction effects between these factors contribute to overall NHD risk. METHODS: Of the 11,150 reviewed cases involving procedures for degenerative spine conditions, 1764 cases (15.8%) involved NHD. Gradient boosting classifiers were used to construct predictive models for NHD for each patient. Shapley values, which assign a unique distribution of the total NHD risk to each model variable using an optimal cost-sharing rule, quantified feature importance and examined interaction effects between variables. RESULTS: Models constructed from features identified by Shapley values were highly predictive of patient-level NHD risk (mean C-statistic = 0.91). Supervised clustering identified distinct patient subgroups with variable NHD risk and their shared characteristics. Focused interaction analysis of surgical invasiveness, age, and comorbidity burden suggested age as a worse risk factor than comorbidity burden due to stronger positive interaction effects. Additionally, negative interaction effects were found between age and low blood loss, indicating that intraoperative hemostasis may be critical for reducing NHD risk in the elderly. CONCLUSION: This strategy provides novel insights into feature interactions that contribute to NHD risk after spine surgery. Patients with positively interacting risk factors may require special attention during their hospitalization to control NHD risk.Level of Evidence: 3.

Comparison of Surgical Outcomes of Microdiskectomy Procedures by Patient Admission Status.

OBJECTIVE: We sought to compare the cost and in-hospital outcomes following lumbar microdiskectomy procedures by admission type. METHODS: Patients undergoing lumbar microdiskectomy at a single institution from 2008 to 2016 following an elective admission (EL) were compared against those who were admitted from the emergency department (ED) or from elsewhere within or outside the hospital system (TR) for their perioperative outcomes and cost. Multivariable modeling controlled for age, sex, self-reported race, Elixhauser comorbidity score, payer type, number of segments, and procedure length. RESULTS: Of the 1249 patients included in this study, 1116 (89.4%) were admitted electively while 123 (9.8%) were admitted from the ED and 10 (0.8%) were transferred from other hospitals. EL patients had significantly lower comorbidity burdens (P < 0.0001). Univariate and multivariable analyses revealed that transfer admission patients experienced significantly longer hospitalizations (ED: +1.7 days; P < 0.0001; TR: +5.3 days; P < 0.0001) and higher direct costs (ED: $1889; P < 0.0001; TR: $7001; P < 0.0001) compared with EL patients. Despite these risks, ED and TR patients only had increased odds of nonhome discharge compared with EL patients (ED: 3.4; P = 0.002; TR: 7.9; P = 0.02). CONCLUSIONS: Patients admitted as transfers and from the ED had significantly increased hospitalization lengths of stay and direct costs compared with electively admitted patients.

Multidisciplinary management of metastatic spine disease: initial symptom-directed management.

In the past 2 decades, a deeper understanding of the cancer molecular signature has resulted in longer longevity of cancer patients, hence a greater population, who potentially can develop metastatic disease. Spine metastases (SM) occur in up to 70% of cancer patients. Familiarizing ourselves with the key aspects of initial symptom-directed management is important to provide SM patients with the best patient-specific options. We will review key components of initial symptoms assessment such as pain, neurological symptoms, and spine stability. Radiographic evaluation of SM and its role in management will be reviewed. Nonsurgical treatment options are also presented and discussed, including percutaneous procedures, radiation, radiosurgery, and spine stereotactic body radiotherapy. The efforts of a multidisciplinary team will continue to ensure the best patient care as the landscape of cancer is constantly changing.

Predicting Trends in Cervical Spinal Surgery in the United States from 2020 to 2040.

OBJECTIVE: We sought to predict surgical volumes for 2 common cervical spine procedures from 2020 to 2040. METHODS: Using the National Inpatient Sample from 2003-2016, nationwide estimates of anterior cervical diskectomy and fusion (ACDF) and posterior cervical decompression and fusion (PCDF) volumes were calculated using International Classification of Diseases, Ninth and Tenth Revision (ICD-9, ICD-10) procedure codes. With data from the U.S. Census Bureau, estimates of the U.S. population were used to create Poisson models controlling for age and sex. Age was categorized into ranges (<25 years old, 25-34, 35-44, 45-54, 55-64, 65-74, 75-84, and >85), and estimates of surgical volume for each age group were created. RESULTS: From 2020-2040, increases in surgical volume from 13.3% (153,288-173,699) and 19.3% (29,620-35,335) are expected for ACDF and PCDF, respectively. For ACDF, the largest increases are expected in the 45-54 (42,077-49,827) and 75-84 (8065-14,862) age groups, whereas for PCDF, the largest increases will be seen in the 75-84 (3710-6836) age group. In accordance with an aging population, modest increases will be seen for ACDF (858-1847) and PCDF (730-1573) in the >85-year-old cohort. CONCLUSIONS: As expected, large growth in cervical spine surgical volumes is likely to be seen, which could indicate a need for increased numbers of spinal neurosurgeons and orthopedic surgeons. Further studies are needed to investigate the needs of the field in light of these expected increases in volume.

Lower Mortality and Morbidity with Low-Molecular-Weight Heparin for Venous Thromboembolism Prophylaxis in Spine Trauma.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: The objective of this study was to evaluate outcomes between patients receiving LMWH versus UH in a retrospective cohort of patients with spine trauma. SUMMARY OF BACKGROUND DATA: Although multiple clinical trials have been conducted, current guidelines do not have enough evidence to suggest low-molecular-weight heparin (LMWH) or unfractionated heparin (UH) for venous thromboembolism (VTE) prophylaxis in spine trauma. METHODS: Patients with spine trauma in the Trauma Quality Improvement Program datasets were identified. Those who died, were transferred within 72 hours, were deemed to have a fatal injury, were discharged within 24 hours, suffered from polytrauma, or were missing data for VTE prophylaxis were excluded. A propensity score was created using age, sex, severity of injury, time to prophylaxis, presence of a cord injury, and altered mental status or hypotension upon arrival, and inverse probability weighted logistic regression modeling was used to evaluate mortality, venous thromboembolic, return to operating room, and total complication rates. E values were used to calculate the likelihood of unmeasured confounders. RESULTS: Those receiving UH (n = 7172) were more severely injured (P < 0.0001), with higher rates of spinal cord injury (32.26% vs. 25.32%, P < 0.0001) and surgical stabilization (29.52% vs. 22.94%, P < 0.0001) compared to those receiving LMWH (n = 20,341). Patients receiving LMWH had lower mortality (odds ratio [OR]: 0.47; 95% CI: 0.42-0.53; P < 0.001; E = 3.68), total complication (OR: 0.92; 95% CI: 0.88-0.95; P < 0.001; E = 1.39), and VTE event (OR: 0.80; 95% CI: 0.72-0.88; P < 0.001; E = 1.81) rates than patients receiving UH. There were no differences in rates of unplanned return to the operating room (OR: 1.01; 95% CI: 0.80-1.27; P = 0.93; E = 1.11). CONCLUSION: There is an association between lower mortality and receiving LMWH for VTE prophylaxis in patients with spine trauma. A large randomized clinical trial is necessary to confirm these findings. LEVEL OF EVIDENCE: 3.