A Cadaveric Comparison of Discectomy Performance During Transforaminal Lumbar Interbody Fusion Approach Using an Endoscopic Technique versus a Minimally Invasive Tubular Approach.

STUDY DESIGN: Cadaveric study. OBJECTIVE: Compare discectomy performance between transforaminal lumbar interbody fusion (TLIF) done via an endoscopic versus a tubular technique. SUMMARY OF BACKGROUND DATA: Performance of an adequate discectomy is essential to lumbar fusion when performing a TLIF. Previous cadaveric studies comparing open and minimally invasive techniques have reported 36.6%-80% discectomy. There is controversy whether an endoscopic TLIF (E-TLIF) can allow for an adequate discectomy. MATERIALS/METHODS: An E-TLIF was performed on 14 discs (T12-L5) and a minimally invasive tubular TLIF (T-TLIF) was performed on 15 discs (T12-L4, L5-S1). Fellowship trained surgeons performed the TLIFs. Each disc was transected after discectomy and a digital image was analyzed using an imaging processing software to determine the percent of discectomy. Each quadrant of the discectomy was compared. Quadrant one was defined as the left posterior-ipsilateral quadrant of the disc, with each quadrant numbered 2-4 clockwise around the disc. The time to perform the discectomy was compared. Pedicle screws were placed contralaterally to the TLIF and the change in interpedicular distance was compared between techniques after expandable cage implantation as a marker for indirect decompression. A student's t-test was used to determine statistical significance. RESULTS: There was no difference in discectomy performance between techniques (48.86%+/-6.98% T-TLIF vs. 50.26%+/-7.38% E-TLIF, P=0.61). There was no statistical difference between T-TLIF vs E-TLIF at quadrants 1, 3 and 4. There was a difference in discectomy performance at quadrant 2 (39.02%+/-10.18% T-TLIF vs 50.13%+/-14.00% E-TLIF, P=0.02). There was no statistical difference between interpedicular distance created (2.20 mm+/-1.97 mm T-TLIF vs 1.36 mm+/-1.82 mm E-TLIF, P=0.24). E-TLIF took less time than MIS-TLIF (20.00 min+/-7.12 min vs 15.22 min+/-4.42 min, P=0.048). CONCLUSION: Our cadaveric study demonstrates that an adequately performed E-TLIF discectomy may be comparable to a T-TLIF discectomy. Further research is required to maximize the efficiency and instrumentation of this technique.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Utility of the Hospital Frailty Risk Score for Predicting Adverse Outcomes in Degenerative Spine Surgery Cohorts.

BACKGROUND: As spine surgery becomes increasingly common in the elderly, frailty has been used to risk stratify these patients. The Hospital Frailty Risk Score (HFRS) is a novel method of assessing frailty using International Classification of Diseases, Tenth Revision (ICD-10) codes. However, HFRS utility has not been evaluated in spinal surgery. OBJECTIVE: To assess the accuracy of HFRS in predicting adverse outcomes of surgical spine patients. METHODS: Patients undergoing elective spine surgery at a single institution from 2008 to 2016 were reviewed, and those undergoing surgery for tumors, traumas, and infections were excluded. The HFRS was calculated for each patient, and rates of adverse events were calculated for low, medium, and high frailty cohorts. Predictive ability of the HFRS in a model containing other relevant variables for various outcomes was also calculated. RESULTS: Intensive care unit (ICU) stays were more prevalent in high HFRS patients (66%) than medium (31%) or low (7%) HFRS patients. Similar results were found for nonhome discharges and 30-d readmission rates. Logistic regressions showed HFRS improved the accuracy of predicting ICU stays (area under the curve [AUC] = 0.87), nonhome discharges (AUC = 0.84), and total complications (AUC = 0.84). HFRS was less effective at improving predictions of 30-d readmission rates (AUC = 0.65) and emergency department visits (AUC = 0.60). CONCLUSION: HFRS is a better predictor of length of stay (LOS), ICU stays, and nonhome discharges than readmission and may improve on modified frailty index in predicting LOS. Since ICU stays and nonhome discharges are the main drivers of cost variability in spine surgery, HFRS may be a valuable tool for cost prediction in this specialty.

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.

The case for T2 pedicle subtraction osteotomy in the surgical treatment of rigid cervicothoracic deformity.

OBJECTIVE: Rigid cervicothoracic kyphotic deformity (CTKD) remains a difficult pathology to treat, especially in the setting of prior cervical instrumentation and fusion. CTKD may result in chronic neck pain, difficulty maintaining horizontal gaze, and myelopathy. Prior studies have advocated for the use of C7 or T1 pedicle subtraction osteotomies (PSOs). However, these surgeries are fraught with danger and, most significantly, place the C7, C8, and/or T1 nerve roots at risk. METHODS: The authors retrospectively reviewed their experience with performing T2 PSO for the correction of rigid CTKD. Demographics collected included age, sex, details of prior cervical surgery, and coexisting conditions. Perioperative variables included levels decompressed, levels instrumented, estimated blood loss, length of surgery, length of stay, complications from surgery, and length of follow-up. Radiographic measurements included C2-7 sagittal vertical axis (SVA) correction, and changes in the cervicothoracic Cobb angle, lumbar lordosis, and C2-S1 SVA. RESULTS: Four male patients were identified (age range 55-72 years). Three patients had undergone prior posterior cervical laminectomy and instrumented fusion and developed postsurgical kyphosis. All patients underwent T2 PSO: 2 patients received instrumentation at C2-T4, and 2 patients received instrumentation at C2-T5. The median C2-7 SVA correction was 3.85 cm (range 2.9-5.3 cm). The sagittal Cobb angle correction ranged from 27.8° to 37.6°. Notably, there were no neurological complications. CONCLUSIONS: T2 PSO is a powerful correction technique for the treatment of rigid CTKD. Compared with C7 or T1 PSO, there is decreased risk of injury to intrinsic hand muscle innervators, and there is virtually no risk of vertebral artery injury. Laminectomy may also be safer, as there is less (or no) scar tissue from prior surgeries. Correction at this distal level may allow for a greater sagittal correction. The authors are optimistic that these findings will be corroborated in larger cohorts examining this challenging clinical entity.

Synaptic distributions of pS214-tau in rhesus monkey prefrontal cortex are associated with spine density, but not with cognitive decline.

Female rhesus monkeys and women are subject to age- and menopause-related deficits in working memory, an executive function mediated by the dorsolateral prefrontal cortex (dlPFC). Long-term cyclic administration of 17ß-estradiol improves working memory, and restores highly plastic axospinous synapses within layer III dlPFC of aged ovariectomized monkeys. In this study, we tested the hypothesis that synaptic distributions of tau protein phosphorylated at serine 214 (pS214-tau) are altered with age or estradiol treatment, and couple to working memory performance. First, ovariectormized young and aged monkeys received vehicle or estradiol treatment, and were tested on the delayed response (DR) test of working memory. Serial section electron microscopic immunocytochemistry was then performed to quantitatively assess the subcellular synaptic distributions of pS214-tau. Overall, the majority of synapses contained pS214-tau immunogold particles, which were predominantly localized to the cytoplasm of axon terminals. pS214-tau was also abundant within synaptic and cytoplasmic domains of dendritic spines. The density of pS214-tau immunogold within the active zone, cytoplasmic, and plasmalemmal domains of axon terminals, and subjacent to the postsynaptic density within the subsynaptic domains of dendritic spines, were each reduced with age. None of the variables examined were directly linked to cognitive status, but a high density of pS214-tau immunogold particles within presynaptic cytoplasmic and plasmalemmal domains, and within postsynaptic subsynaptic and plasmalemmal domains, accompanied high synapse density. Together, these data support a possible physiological, rather than pathological, role for pS214-tau in the modulation of synaptic morphology in monkey dlPFC.

Estrogen Alters the Synaptic Distribution of Phospho-GluN2B in the Dorsolateral Prefrontal Cortex While Promoting Working Memory in Aged Rhesus Monkeys.

Age- and menopause-related deficits in working memory can be partially restored with estradiol replacement in women and female nonhuman primates. Working memory is a cognitive function reliant on persistent firing of dorsolateral prefrontal cortex (dlPFC) neurons that requires the activation of GluN2B-containing glutamate NMDA receptors. We tested the hypothesis that the distribution of phospho-Tyr1472-GluN2B (pGluN2B), a predominant form of GluN2B seen at the synapse, is sensitive to aging or estradiol treatment and coupled to working memory performance. First, ovariectomized young and aged rhesus monkeys (Macaca mulatta) received long-term cyclic vehicle (V) or estradiol (E) treatment and were tested on the delayed response (DR) test of working memory. Then, serial section electron microscopic immunocytochemistry was performed to quantitatively assess the subcellular distribution of pGluN2B. While the densities of pGluN2B immunogold particles in dlPFC dendritic spines were not different across age or treatment groups, the percentage of gold particles located within the synaptic compartment was significantly lower in aged-E monkeys compared to young-E and aged-V monkeys. On the other hand, the percentage of pGluN2B gold particles in the spine cytoplasm was decreased with E treatment in young, but increased with E in aged monkeys. In aged monkeys, DR average accuracy inversely correlated with the percentage of synaptic pGluN2B, while it positively correlated with the percentage of cytoplasmic pGluN2B. Together, E replacement may promote cognitive health in aged monkeys, in part, by decreasing the relative representation of synaptic pGluN2B and potentially protecting the dlPFC from calcium toxicity.

Factors Affecting Length of Stay Following Elective Anterior and Posterior Cervical Spine Surgery.

Background Disease of the cervical spine is widely prevalent, most commonly secondary to degenerative disc changes and spondylosis. Objective The goal of the paper was to identify a possible discrepancy regarding the length of stay (LOS) between the anterior and posterior approaches to elective cervical spine surgery and identify contributing factors. Methods A retrospective study was performed on 587 patients (341 anterior, 246 posterior) that underwent elective cervical spinal surgery between October 2001 and March 2014. Pre- and intraoperative data were analyzed. Statistical analysis was performed using GraphPad Prism 5 (GraphPad Software, Inc., La Jolla, CA) and the Statistical Package for Social Sciences (SPSS) (IBM SPSS Statistics, Armonk, NY). Results Average LOS was 3.21 ± 0.32 days for patients that benefited from the anterior approach cervical spinal surgery and 5.28 ± 0.37 days for patients that benefited from the posterior approach surgery, P-value < 0.0001. Anterior patients had lower American Society of Anesthesiologists scores (2.43 ± 0.036 vs. 2.70 ± 0.044). Anterior patients also had fewer intervertebral levels operated upon (2.18 ± 0.056 vs. 4.11 ± 0.13), shorter incisions (5.49 ± 0.093 cm vs. 9.25 ± 0.16 cm), lower estimated blood loss (EBL) (183.8 ± 9.0 cc vs. 340.0 ± 8.7 cc), and shorter procedure times (4.12 ± 0.09 hours vs. 4.47 ± 0.10 hours). Chi-squared tests for hypertension, coronary artery disease, congestive heart failure, chronic obstructive pulmonary disease, and asthma showed no significant difference between groups. CONCLUSIONS: Patients with anterior surgery performed experienced a length of stay that was 2.07 days shorter on average. Higher EBL, longer incisions, more intervertebral levels, and longer operating time were significantly associated with the posterior approach. Future studies should include multiple surgeons. The goal would be to create a model that could accurately predict the postoperative length of stay based on patient and operative factors.