Gliomagenesis is orchestrated by the Oct3/4 regulatory network

BACKGROUND

Glioblastoma multiforme (GBM) is a lethal brain tumor characterized by developmental hierarchical phenotypic heterogeneity, therapy resistance and recurrent growth. Neural stem cells (NSCs) from human central nervous system (CNS), and glioblastoma stem cells from patient-derived GBM (pdGSC) samples were cultured in both 2D well-plate and 3D monoclonal neurosphere culture system (pdMNCS). The pdMNCS model shows promise to establish a relevant 3D-tumor environment that maintains GBM cells in the stem cell phase within suspended neurospheres.

METHODS

Utilizing the pdMNCS, we examined GBM cell-lines for a wide spectrum of developmental cancer stem cell markers, including the early blastocyst inner-cell mass (ICM)-specific Nanog, Oct3/4,B, and CD133.

RESULTS

We observed that MNCS epigenotype is recapitulated using gliomasphere-derived cells. CD133, the marker of GSC is robustly expressed in 3D-gliomaspheres and localized within the plasma membrane compartment. Conversely, gliomasphere cultures grown in conventional 2D culture quickly lost CD133 expression, indicating its variable expression is dependent on cell-culture conditions. Incomplete differentiation of cytoskeleton microtubules and intermediate filaments (IFs) of patient derived cells, similar to commercially available GBM cell lines, was seen. Subsequently, in order to determine whether Oct3/4 it was necessary for CD133 expression and cancer stemness, we transfected 2D and 3D culture with siRNA against Oct3/4 and found a significant reduction in gliomasphere formation.

CONCLUSIONS

These results suggest that expression of Oct3/4,A- and CD133 suppress differentiation of GSCs.

Clinical safety and feasibility of a novel implantable neuroimmune modulation device for the treatment of rheumatoid arthritis: initial results from the randomized, double-blind, sham-controlled RESET-RA study

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that causes persistent synovitis, bone damage, and progressive joint destruction. Neuroimmune modulation through electrical stimulation of the vagus nerve activates the inflammatory reflex and has been shown to inhibit the production and release of inflammatory cytokines and decrease clinical signs and symptoms in RA. The RESET-RA study was designed to determine the safety and efficacy of an active implantable device for treating RA.

METHODS

The RESET-RA study is a randomized, double-blind, sham-controlled, multi-center, two-stage pivotal trial that enrolled patients with moderate-to-severe RA who were incomplete responders or intolerant to at least one biologic or targeted synthetic disease-modifying anti-rheumatic drug. A neuroimmune modulation device (SetPoint Medical, Valencia, CA) was implanted on the left cervical vagus nerve within the carotid sheath in all patients. Following post-surgical clearance, patients were randomly assigned (1:1) to active stimulation or non-active (control) stimulation for 1 min once per day. A predefined blinded interim analysis was performed in patients enrolled in the study's initial stage (Stage 1) that included demographics, enrollment rates, device implantation rates, and safety of the surgical procedure, device, and stimulation over 12 weeks of treatment.

RESULTS

Sixty patients were implanted during Stage 1 of the study. All device implant procedures were completed without intraoperative complications, infections, or surgical revisions. No unanticipated adverse events were reported during the perioperative period and at the end of 12 weeks of follow-up. No study discontinuations were due to adverse events, and no serious adverse events were related to the device or stimulation. Two serious adverse events were related to the implantation procedure: vocal cord paresis and prolonged hoarseness. These were reported in two patients and are known complications of surgical implantation procedures with vagus nerve stimulation devices. The adverse event of vocal cord paresis resolved after vocal cord augmentation injections with filler and speech therapy. The prolonged hoarseness had improved with speech therapy, but mild hoarseness persists.

CONCLUSIONS

The surgical procedures for implantation of the novel neuroimmune modulation device for the treatment of RA were safe, and the device and its use were well tolerated.

TRIAL REGISTRATION

NCT04539964; August 31, 2020.

Inter-Specimen Analysis of Diverse Finite Element Models of the Lumbar Spine

Over the past few decades, there has been a growing popularity in utilizing finite element analysis to study the spine. However, most current studies tend to use one specimen for their models. This research aimed to validate multiple finite element models by comparing them with data from in vivo experiments and other existing finite element studies. Additionally, this study sought to analyze the data based on the gender and age of the specimens. For this study, eight lumbar spine (L2-L5) finite element models were developed. These models were then subjected to finite element analysis to simulate the six fundamental motions. CT scans were obtained from a total of eight individuals, four males and four females, ranging in age from forty-four (44) to seventy-three (73) years old. The CT scans were preprocessed and used to construct finite element models that accurately emulated the motions of flexion, extension, lateral bending, and axial rotation. Preloads and moments were applied to the models to replicate physiological loading conditions. This study focused on analyzing various parameters such as vertebral rotation, facet forces, and intradiscal pressure in all loading directions. The obtained data were then compared with the results of other finite element analyses and in vivo experimental measurements found in the existing literature to ensure their validity. This study successfully validated the intervertebral rotation, intradiscal pressure, and facet force results by comparing them with previous research findings. Notably, this study concluded that gender did not have a significant impact on the results. However, the results did highlight the importance of age as a critical variable when modeling the lumbar spine.

A New Method to Evaluate Pressure Distribution Using a 3D-Printed C2-C3 Cervical Spine Model with an Embedded Sensor Array

Cervical degenerative disc diseases such as myelopathy and radiculopathy often require conventional treatments like artificial cervical disc replacement or anterior cervical discectomy and fusion (ACDF). When designing a medical device, like the stand-alone cage, there are many design inputs to consider. However, the precise biomechanics of the force between the vertebrae and implanted devices under certain conditions require further investigation. In this study, a new method was developed to evaluate the pressure between the vertebrae and implanted devices by embedding a sensor array into a 3D-printed C2-C3 cervical spine. The 3D-printed cervical spine model was subjected to a range of axial loads while under flexion, extension, bending and compression conditions. Cables were used for the application of a preload and a robotic arm was used to recreate the natural spine motions (flexion, extension, and bending). To verify and predict the total pressure between the vertebrae and the implanted devices, a 3D finite element (FE) numerical mathematical model was developed. A preload was represented by applying 22 N of force on each of the anterior tubercles for the C2 vertebra. The results of this study suggest that the sensor is useful in identifying static pressure. The pressure with the robot arm was verified from the FE results under all conditions. This study indicates that the sensor array has promising potential to reduce the trial and error with implants for various surgical procedures, including multi-level artificial cervical disk replacement and ACDF, which may help clinicians to reduce pain, suffering, and costly follow-up procedures.

A Review of Finite Element Modeling for Anterior Cervical Discectomy and Fusion

The cervical spine poses many complex challenges that require complex solutions. Anterior cervical discectomy and fusion (ACDF) has been one such technique often employed to address such issues. In order to address the problems with ACDF and assess the modifications that have been made to the technique over time, finite element analyses (FEA) have proven to be an effective tool. The variations of cervical spine FEA models that have been produced over the past couple of decades, particularly more recent representations of more complex geometries, have not yet been identified and characterized in any literature. Our objective was to present material property models and cervical spine models for various simulation purposes. The outlining and refinement of the FEA process will yield more reliable outcomes and provide a stable basis for the modeling protocols of the cervical spine.

Effect of graded posterior element and ligament removal on annulus stress and segmental stability in lumbar spine stenosis: a finite element analysis study

The study aimed to investigate the impact of posterior element and ligament removal on the maximum von Mises stress, and maximum shear stress of the eight-layer annulus for treating stenosis at the L3-L4 and L4-L5 levels in the lumbar spine. Previous studies have indicated that laminectomy alone can result in segmental instability unless fusion is performed. However, no direct correlations have been established regarding the impact of posterior and ligament removal. To address this gap, four models were developed: Model 1 represented the intact L2-L5 model, while model 2 involved a unilateral laminotomy involving the removal of a section of the L4 inferior lamina and 50% of the ligament flavum between L4 and L5. Model 3 consisted of a complete laminectomy, which included the removal of the spinous process and lamina of L4, as well as the relevant connecting ligaments between L3-L4 and L4-L5 (ligament flavum, interspinous ligament, supraspinous ligament). In the fourth model, a complete laminectomy with 50% facetectomy was conducted. This involved the same removals as in model 3, along with a 50% removal of the inferior/superior facets of L4 and a 50% removal of the facet capsular ligaments between L3-L4 and L4-L5. The results indicated a significant change in the range of motion (ROM) at the L3-L4 and L4-L5 levels during flexion and torque situations, but no significant change during extension and bending simulation. The ROM increased by 10% from model 1 and 2 to model 3, and by 20% to model 4 during flexion simulation. The maximum shear stress and maximum von-Mises stress of the annulus and nucleus at the L3-L4 levels exhibited the greatest increase during flexion. In all eight layers of the annulus, there was an observed increase in both the maximum shear stress and maximum von-Mises stress from model 1&2 to model 3 and model 4, with the highest rate of increase noted in layers 7&8. These findings suggest that graded posterior element and ligament removal have a notable impact on stress distribution and range of motion in the lumbar spine, particularly during flexion.

In Vitro and In Vivo Drug-Response Profiling Using Patient-Derived High-Grade Glioma

BACKGROUND

Genomic profiling cannot solely predict the complexity of how tumor cells behave in their in vivo microenvironment and their susceptibility to therapies. The aim of the study was to establish a functional drug prediction model utilizing patient-derived GBM tumor samples for in vitro testing of drug efficacy followed by in vivo validation to overcome the disadvantages of a strict pharmacogenomics approach.

METHODS

High-throughput in vitro pharmacologic testing of patient-derived GBM tumors cultured as 3D organoids offered a cost-effective, clinically and phenotypically relevant model, inclusive of tumor plasticity and stroma. RNAseq analysis supplemented this 128-compound screening to predict more efficacious and patient-specific drug combinations with additional tumor stemness evaluated using flow cytometry. In vivo PDX mouse models rapidly validated (50 days) and determined mutational influence alongside of drug efficacy. We present a representative GBM case of three tumors resected at initial presentation, at first recurrence without any treatment, and at a second recurrence following radiation and chemotherapy, all from the same patient.

RESULTS

Molecular and in vitro screening helped identify effective drug targets against several pathways as well as synergistic drug combinations of cobimetinib and vemurafenib for this patient, supported in part by in vivo tumor growth assessment. Each tumor iteration showed significantly varying stemness and drug resistance.

CONCLUSIONS

Our integrative model utilizing molecular, in vitro, and in vivo approaches provides direct evidence of a patient's tumor response drifting with treatment and time, as demonstrated by dynamic changes in their tumor profile, which may affect how one would address that drift pharmacologically.

Upregulation of the Oct3/4 Network in Basal Breast Cancer Is Associated with Its Metastatic Potential and Shows Tissue Dependent Variability

Adaptive plasticity of Breast Cancer stem cells (BCSCs) is strongly correlated with cancer progression and resistance, leading to a poor prognosis. In this study, we report the expression profile of several pioneer transcription factors of the Oct3/4 network associated with tumor initiation and metastasis. In the triple negative breast cancer cell line (MDA-MB-231) stably transfected with human Oct3/4-GFP, differentially expressed genes (DEGs) were identified using qPCR and microarray, and the resistance to paclitaxel was assessed using an MTS assay. The tumor-seeding potential in immunocompromised (NOD-SCID) mice and DEGs in the tumors were also assessed along with the intra-tumor (CD44+/CD24-) expression using flow cytometry. Unlike 2-D cultures, the Oct3/4-GFP expression was homogenous and stable in 3-D mammospheres developed from BCSCs. A total of 25 DEGs including Gata6, FoxA2, Sall4, Zic2, H2afJ, Stc1 and Bmi1 were identified in Oct3/4 activated cells coupled with a significantly increased resistance to paclitaxel. In mice, the higher Oct3/4 expression in tumors correlated with enhanced tumorigenic potential and aggressive growth, with metastatic lesions showing a >5-fold upregulation of DEGs compared to orthotopic tumors and variability in different tissues with the highest modulation in the brain. Serially re-implanting tumors in mice as a model of recurrence and metastasis highlighted the sustained upregulation of Sall4, c-Myc, Mmp1, Mmp9 and Dkk1 genes in metastatic lesions with a 2-fold higher expression of stem cell markers (CD44+/CD24-). Thus, Oct3/4 transcriptome may drive the differentiation and maintenance of BCSCs, promoting their tumorigenic potential, metastasis and resistance to drugs such as paclitaxel with tissue-specific heterogeneity.

Biomechanical Study of Cervical Endplate Removal on Subsidence and Migration in Multilevel Anterior Cervical Discectomy and Fusion

Study Design

This study compares four cervical endplate removal procedures, validated by finite element models.

Purpose

To characterize the effect of biomechanical strength and increased contact area on the maximum von Mises stress, migration, and subsidence between the cancellous bone, endplate, and implanted cage.

Overview of Literature

Anterior cervical discectomy and fusion (ACDF) has been widely used for treating patients with degenerative spondylosis. However, no direct correlations have been drawn that incorporate the impact of the contact area between the cage and the vertebra/endplate.

Methods

Model 1 (M1) was an intact C2C6 model with a 0.5 mm endplate. In model 2 (M2), a cage was implanted after removal of the C4-C5 and C5-C6 discs with preservation of the osseous endplate. In model 3 (M3), 1 mm of the osseous endplate was removed at the upper endplate. Model 4 (M4) resembles M3, except that 3 mm of the osseous endplate was removed.

Results

The range of motion (ROM) at C2C6 in the M2-M4 models was reduced by at least 9º compared to the M1 model. The von Mises stress results in the C2C3 and C3C4 interbody discs were significantly smaller in the M1 model and slightly increased in the M2-M3 and M3-M4 models. Migration and subsidence decreased from the M2-M3 model, whereas further endplate removal increased the migration and subsidence as shown in the transition from M3 to M4.

Conclusions

The M3 model had the least subsidence and migration. The ROM was higher in the M3 model than the M2 and M4 models. Endplate preparation created small stress differences in the healthy intervertebral discs above the ACDF site. A 1 mm embedding depth created the best balance of mechanical strength and contact area, resulting in the most favorable stability of the construct.

Robotic Replica of a Human Spine Uses Soft Magnetic Sensor Array to Forecast Intervertebral Loads and Posture after Surgery

Cervical disc implants are conventional surgical treatments for patients with degenerative disc disease, such as cervical myelopathy and radiculopathy. However, the surgeon still must determine the candidacy of cervical disc implants mainly from the findings of diagnostic imaging studies, which can sometimes lead to complications and implant failure. To help address these problems, a new approach was developed to enable surgeons to preview the post-operative effects of an artificial disc implant in a patient-specific fashion prior to surgery. To that end, a robotic replica of a person's spine was 3D printed, modified to include an artificial disc implant, and outfitted with a soft magnetic sensor array. The aims of this study are threefold: first, to evaluate the potential of a soft magnetic sensor array to detect the location and amplitude of applied loads; second, to use the soft magnetic sensor array in a 3D printed human spine replica to distinguish between five different robotically actuated postures; and third, to compare the efficacy of four different machine learning algorithms to classify the loads, amplitudes, and postures obtained from the first and second aims. Benchtop experiments showed that the soft magnetic sensor array was capable of precisely detecting the location and amplitude of forces, which were successfully classified by four different machine learning algorithms that were compared for their capabilities: Support Vector Machine (SVM), K-Nearest Neighbor (KNN), Random Forest (RF), and Artificial Neural Network (ANN). In particular, the RF and ANN algorithms were able to classify locations of loads applied 3.25 mm apart with 98.39% ± 1.50% and 98.05% ± 1.56% accuracies, respectively. Furthermore, the ANN had an accuracy of 94.46% ± 2.84% to classify the location that a 10 g load was applied. The artificial disc-implanted spine replica was subjected to flexion and extension by a robotic arm. Five different postures of the spine were successfully classified with 100% ± 0.0% accuracy with the ANN using the soft magnetic sensor array. All results indicated that the magnetic sensor array has promising potential to generate data prior to invasive surgeries that could be utilized to preoperatively assess the suitability of a particular intervention for specific patients and to potentially assist the postoperative care of people with cervical disc implants.

Advances in CSF shunt devices and their assessment for the treatment of hydrocephalus

INTRODUCTION

Hydrocephalus is a neurological disorder caused by excessive accumulation of the cerebrospinal fluid (CSF) in the ventricles of the brain. It can be treated by diverting the extra fluid to different parts of the body using a device called a shunt. This paper reviews different shunt devices that are used for this purpose.

AREAS COVERED

Shunts have high failure rates either due to infection or mechanical failure, therefore there is still ongoing work to address these two main handicaps. They require additional devices for performance assessment. Here, the paper also reviews different approaches for assessing shunt limitations. Moreover, future prospects are also discussed.

EXPERT OPINION

This study shows that shunt devices still remain an important treatment option for hydrocephalus. However, further efforts are required to design more advanced shunts, to eliminate high failure rates in clinical use. Sophisticated sensor systems that can accurately detect and regulate changes in CSF drainage to optimize drainage for individual needs. Moreover, shunt infection problem is still present despite recent improvements such as antibiotic impregnated catheters.

Cage-screw and anterior plating combination reduces the risk of micromotion and subsidence in multilevel anterior cervical discectomy and fusion-a finite element study

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion (ACDF) is widely used to treat patients with spinal disorders, where the cage is a critical component to achieve satisfactory fusion results. However, it is still not clear whether a cage with screws or without screws will be the best choice for long-term fusion as the micromotion (sliding distance) and subsidence (penetration) of the cage still take place repeatedly.

PURPOSE

This study aims to examine the effect of cage-screws on the biomechanical characteristics of the human spine, implanted cage, and associate hardware by comparing the micromotion and subsidence.

STUDY DESIGN

A finite element (FE) analysis study.

METHODS

A FE model of a C3-C5 cervical spine with ACDF was developed. The spinal segment was modeled with the removal of the anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), and discectomy was then implanted with a cage-screw system. Three models were analyzed: the first was the original spine (S1 model), the second, S2, was implanted with cages and anterior plating, and the third, S3, was implanted with a cage-screw system in addition to the anterior plate. All investigations were under 1 N•m in flexion, extension, lateral bending, and axial rotation situations.

RESULTS

Finite element analysis (FEA) demonstrated that range of motion (ROM) at C3-C4 in the S2 model was significantly reduced more than that in the S3 model, while the ROM at both C4-C5 in the S3 model was reduced more than that in the S2 model in all simulations. The ROM at C3-C5 in the S1 model was reduced by over 5° in the S2 and S3 models in all loading conditions. The micromotion and subsidence at all contacts of C3-C5 in the S3 model were lower than that in the S2 model in all flexion, extension, bending, and axial simulations. The subsidence and micromotion could be seen in the barrier area of the S2 model, while they occurred near the edge of the screw in the S3 model.

CONCLUSIONS

These results showed that the cage-screw and anterior plating combination has promising potential to reduce the risk of micromotion and subsidence of implanted cages in two or more level ACDFs.

CLINICAL SIGNIFICANCE

The use of double segmental fixation with cage-screw anterior plating combination constructs may increase the stiffness of the construct and reduce the incidence of clinical and radiographic pseudarthrosis following multilevel ACDF, which in turn, could decrease the need for revision surgeries or supplemental posterior fixation.

First-in-Human Experience With Integration of a Hydrocephalus Shunt Device Within a Customized Cranial Implant

BACKGROUND

Implantable shunt devices are critical and life saving for hydrocephalus patients. However, these devices are fraught with high complication rates including scalp dehiscence, exposure, and extrusion. In fact, high shunt valve profiles are correlated with increased complications compared to those with lower profiles. As such, we sought a new method for integrating shunt valves for those challenging patients presenting with scalp-related complications.

OBJECTIVE

To safely implant and integrate a hydrocephalus shunt valve device within a customized cranial implant, in an effort to limit its high-profile nature as a main contributor to shunt failure and scalp breakdown, and at the same time, improve patient satisfaction by preventing contour deformity.

METHODS

A 64-yr-old male presented with an extruding hydrocephalus shunt valve and chronic, open scalp wound. The shunt valve was removed and temporary shunt externalization was performed. He received 2 wk of culture-directed antibiotics. Next, a contralateral craniectomy was performed allowing a new shunt valve system to be implanted within a low-profile, customized cranial implant. All efforts were made, at the patient's request, to decrease the high-profile nature of the shunt valve contributing to his most recent complication.

RESULTS

First-in-human implantation was performed without complication. Postoperative shunt identification and programming was uncomplicated. The high-profile nature of the shunt valve was decreased by 87%. At 10 mo, the patient has experienced no complications and is extremely satisfied with his appearance.

CONCLUSION

This first-in-human experience suggests that a high-profile hydrocephalus shunt device may be safely integrated within a customized cranial implant.

MDNA55: A locally administered IL4 guided toxin as a targeted treatment for recurrent glioblastoma

2039

Background: IL4 receptor (IL4R) is frequently and intensely expressed on a variety of human cancers and is associated with poor survival outcomes. Determining the role of the IL4R biomarker in glioblastoma (GBM) will be important for treatment with targeted therapies such as the IL4 fusion toxin MDNA55. Methods: A classification for IL4Rα expression in GBM tissues by H-Score was developed using a validated immunohistochemistry-based approach. MDNA55-05 is an open-label study of MDNA55 administered intratumorally via convection enhanced delivery in recurrent GBM. Levels of IL4Rα expression were assessed retrospectively in 24 subjects in the clinical trial and were correlated with GBM history, imaging responses and survival outcomes following treatment with MDNA55 to explore clinical validation. Results: Range, linearity, specificity and sensitivity testing using a rabbit polyclonal antibody to IL4Rα were performed using normal cortex (negative control) and a panel of normal human tissues and GBM cases from tissue banks. A total of 41 GBM samples were screened and grouped by reactivity thresholds: H-Scores ≥50 were observed in 95% of cases (39/41), H-Scores ≥200 were observed in 51% of cases (21/41), and H-Scores ≥250 were observed in 24% of cases (10/41). GBM tissues obtained at initial diagnosis from subjects enrolled in the trial show that moderate/high IL4R expression (H-Score > 75) was associated with shorter time to first relapse when compared to subjects with low IL4R expression (H-Score ≤ 75) (10.3 mos vs. 16.7 mos, respectively) after upfront standard-of-care treatment, consistent with published findings that IL4R expression is associated with more aggressive disease. Remarkable decreases in tumor size seen in some subjects following MDNA55 treatment were associated only with moderate/high IL4R expression and survival rate at 12 months in this group was also improved (OS12 = 55%) compared to subjects with low IL4R expression (OS12 = 30%). Conclusions: Treatment options for patients with recurrent GBM are very limited and positive outcomes remain rare. Targeting therapies such as MDNA55 by IL4R status may improve patient outcomes and help guide patient selection strategies for future clinical studies. Clinical trial information: NCT02858895.

Spinal Radiosurgery for Metastatic Disease of the Spine

Background

Metastatic tumor in the spinal column is common, causing symptomatic spinal cord compression in approximately 25,000 patients annually. Although surgical treatment of spinal metastases has become safer, less invasive, and more efficacious in recent years, there remains a subset of patients for whom other treatment modalities are needed. Stereotactic radiosurgery, which has long been used in the treatment of intracranial lesions, has recently been applied to the spine and enables the effective treatment of metastatic lesions.

Methods

We review the evolution of stereotactic radiosurgery and its applications in the spine, including a description of two commercially available systems.

Results

Although a relatively new technique, the use of stereotactic radiosurgery in the spine has advanced rapidly in the past decade. Spinal stereotactic radiosurgery is an effective and safe modality for the treatment of spinal metastatic disease.

Conclusions

Future challenges involve the refinement of noninvasive fiducial tracking systems and the discernment of optimal doses needed to treat various lesions. Additionally, dose-tolerance limits of normal structures need to be further developed. Increased experience will likely make stereotactic radiosurgery of the spine an important treatment modality for a variety of metastatic lesions.

Surgical Treatment for Leptomeningeal Disease

BACKGROUND

Advancements in cancer treatment have led to more cases of leptomeningeal disease, which requires a multimodal approach.

METHODS

Treatment modalities are reviewed from a neurosurgical standpoint, focusing on intrathecal chemotherapy and shunting devices. Potential complications and how to avoid them are discussed.

RESULTS

The Ommaya reservoir and the chemoport are used for administering intrathecal chemotherapy. Use of ventriculo-lumbar perfusion can efficiently deliver chemotherapeutic agents and improve intracerebral pressure. Shunting systems, in conjunction with all of their variations, address the challenge of hydrocephalus in leptomeningeal carcinomatosis. Misplaced catheters, malfunction of the system, and shunt-related infections are known complications of treatment.

CONCLUSIONS

From an oncological perspective, the surgical treatment for leptomeningeal disease is limited; however, neurosurgery can be used to aid in the administration of chemotherapy and address the issue of hydrocephalus. Minimizing surgical complications is important in this sensitive patient population.

Cerebrospinal Fluid and Hydrocephalus: Physiology, Diagnosis, and Treatment

BACKGROUND

Cerebrospinal fluid (CSF) is found around and inside the brain and vertebral column. CSF plays a crucial role in the protection and homeostasis of neural tissue.

METHODS

Key points on the physiology of CSF as well as the diagnostic and treatment options for hydrocephalus are discussed.

RESULTS

Understanding the fundamentals of the production, absorption, dynamics, and pathophysiology of CSF is crucial for addressing hydrocephalus. Shunts and endoscopic third ventriculostomy have changed the therapeutic landscape of hydrocephalus.

CONCLUSIONS

The treatment of hydrocephalus in adults and children represents a large part of everyday practice for the neurologist, both in benign cases and cancer-related diagnoses.

Resection of the First Rib With Preservation of the T1 Nerve Root in Pancoast Tumors of the Lung

BACKGROUND

Surgical outcomes for Pancoast (superior sulcus) tumors of the lung have significantly changed during the last few decades and have improved with use of curative-intent surgery by utilizing en bloc complete resections.

METHODS

A retrospective analysis was conducted of 11 selected patients treated at Moffitt Cancer Center from 2007 to 2016. Data from patient records were collected and analyzed.

RESULTS

All 11 patients with a Pancoast tumor involving the first rib had their T1 root preserved at surgery. In 10 patients (90.9%), the tumor was removed en bloc. Clear margins of resection were documented in 4 cases (36.0%). No patient developed postoperative hand weakness, but 3 patients (27.3%) had minor postoperative complications, including air leak, chylothorax, and pericardial effusion. One iatrogenic injury to the subclavian artery was reported during surgery; the injury was subsequently repaired. No operative mortality was reported.

CONCLUSIONS

Radical resection of Pancoast tumors is considered to be safe, and preserving the T1 nerve root provides more favorable, functional outcomes.

Central Nervous System Cancers, Version 1.2015

The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Central Nervous System (CNS) Cancers provide interdisciplinary recommendations for managing adult CNS cancers. Primary and metastatic brain tumors are a heterogeneous group of neoplasms with varied outcomes and management strategies. These NCCN Guidelines Insights summarize the NCCN CNS Cancers Panel's discussion and highlight notable changes in the 2015 update. This article outlines the data and provides insight into panel decisions regarding adjuvant radiation and chemotherapy treatment options for high-risk newly diagnosed low-grade gliomas and glioblastomas. Additionally, it describes the panel's assessment of new data and the ongoing debate regarding the use of alternating electric field therapy for high-grade gliomas.

Robotics in Neurosurgery: Evolution, Current Challenges, and Compromises

BACKGROUND

Advances in technology have pushed the boundaries of neurosurgery. Surgeons play a major role in the neurosurgical field, but robotic systems challenge the current status quo. Robotic-assisted surgery has revolutionized several surgical fields, yet robotic-assisted neurosurgery is limited by available technology.

METHODS

The literature on the current robotic systems in neurosurgery and the challenges and compromises of robotic design are reviewed and discussed.

RESULTS

Several robotic systems are currently in use, but the application of these systems is limited in the field of neurosurgery. Most robotic systems are suited to assist in stereotactic procedures. Current research and development teams focus on robotic-assisted microsurgery and minimally invasive surgery. The tasks of miniaturizing the current tools and maximizing control challenge manufacturers and hinder progress. Furthermore, loss of haptic feedback, proprioception, and visualization increase the time it takes for users to master robotic systems.

CONCLUSIONS

Robotic-assisted surgery is a promising field in neurosurgery, but improvements and breakthroughs in minimally invasive and endoscopic robotic-assisted surgical systems must occur before robotic assistance becomes commonplace in the neurosurgical field.

Is early vertebroplasty/kyphoplasty justified in multiple myeloma given the rapid vertebral fracture progression?

Xiao R, Miller JA, Margetis K, et al. Radiographic progression of vertebral fractures in patients with multiple myeloma. Spine J 2016:16:822-32 (in this issue).

Transdiscal mid- and upper thoracic vertebroplasty: first description of 2 exemplary cases

Kyphoplasty and vertebroplasty are established treatment methods to reinforce fractured vertebral bodies. In cases of previous pedicle screw instrumentation, vertebral body cannulation may be challenging. The authors describe, for the first time, an approach through the adjacent inferior vertebra and disc space in the thoracic spine for cement augmentation. A 78-year-old woman underwent posterior fusion with pedicle screws after vertebrectomy and reconstruction with cement and Steinmann pins for a pathological T-7 fracture. Two months later she developed a compression fracture of the vertebral body at the lower part of the construct, and a vertebroplasty was performed. Because a standard transpedicular route was not available, an inferior transdiscal trajectory was used for the cement injection. A 73-year-old man with a history of rheumatoid arthritis underwent cervicothoracic fusion posteriorly for subluxation. He developed pain in the upper thoracic area, and the authors performed a transdiscal vertebroplasty at T-2. The standard transpedicular route was not possible. The vertebral body was satisfactorily filled up with cement. Clinically both patients benefited significantly in terms of back pain and showed an uneventful follow-up of 3 months. Transdiscal vertebroplasty can achieve good results in the mid- and upper thoracic spine when a standard transpedicular trajectory is not possible, and can therefore be a good alternative in select cases.

Central nervous system cancers, version 2.2014. Featured updates to the NCCN Guidelines

The NCCN Guidelines for Central Nervous System Cancers provide multidisciplinary recommendations for the clinical management of patients with cancers of the central nervous system. These NCCN Guidelines Insights highlight recent updates regarding the management of metastatic brain tumors using radiation therapy. Use of stereotactic radiosurgery (SRS) is no longer limited to patients with 3 or fewer lesions, because data suggest that total disease burden, rather than number of lesions, is predictive of survival benefits associated with the technique. SRS is increasingly becoming an integral part of management of patients with controlled, low-volume brain metastases.

Spinal neoplastic instability: biomechanics and current management options

BACKGROUND

Often the spine is afflicted from primary or metastatic neoplastic disease, which can lead to instability. Instability can cause deformity, pain, and spinal cord compression and is an indication for surgery. Although overt instability is uniformly agreed upon, it is sometimes difficult for specialists to agree on subtle degrees of instability due to lack of objective criteria.

METHODS

In this article, treatment options and the spine instability neoplastic system are discussed and the neoplastic instability literature is reviewed.

RESULTS

The Spinal Instability Neoplastic Score helps specialists determine whether instability is present and when surgery may be indicated. However, other parameters such as spinal cord compression and extent of disease dictate whether surgery is the most appropriate option. A wide range of fusion techniques exists, each one tailored to the location of the lesion and goals for surgery.

CONCLUSIONS

To optimize results, expert knowledge on the techniques and patient selection is of importance. Furthermore, a multidisciplinary approach is required because treatment of neoplastic disease is multimodal.

Controversial issues in kyphoplasty and vertebroplasty in malignant vertebral fractures

BACKGROUND

Kyphoplasty (KP) and vertebroplasty (VP) have been successfully employed in the treatment of pathological vertebral fractures.

METHODS

A critical review of the medical literature was performed and controversial issues were analyzed.

RESULTS

Evidence supports KP as the treatment of choice to control fracture pain and the possible restoration of sagittal balance, provided that no overt instability or myelopathy is present, the fracture is painful and other pain generators have been excluded, and positive radiological findings are present. Unilateral procedures yield similar results to bilateral ones and should be pursued whenever feasible. Biopsy should be routinely performed and 3 to 4 levels may be augmented in a single operation. Higher cement filling appears to yield better results. Radiotherapy is complementary with KP and VP but must be individualized.

CONCLUSIONS

In cases of painful cancer fractures, if overt instability or myelopathy is not present, unilateral KP should be pursued, whenever feasible, followed by radiotherapy. The technological advances in hardware and biomaterials, as well as combining KP with other modalities, will help ensure a safe and more effective procedure. Address.

Management of locally advanced pancoast (superior sulcus) tumors with spine involvement

BACKGROUND

The preferred treatment for locally aggressive lung cancers is triple modality therapy with concurrent and induction chemotherapy with radiation therapy followed by surgery. Patients with locally advanced T4 Pancoast tumors with spine involvement, without mediastinal N2 lymph node involvement and without distant metastases, are appropriate candidates for complete resection with subsequent spine reconstruction. This review addresses the questions of whether triple modality therapy with complete en bloc resection of locally advanced Pancoast tumors offers an advantage in terms of overall survival and complication rates compared with other therapeutic modalities or therapies with incomplete resection.

METHODS

A comprehensive literature search was conducted using common medical databases. Inclusion and exclusion criteria for the articles were prospectively defined. The articles were independently reviewed and a consensus decision was made about each article. Selected papers were graded by level of evidence.

RESULTS

A total of 1,001 abstracts and 93 articles fulfilled the criteria; from these studies, 14 were included in this systematic review. No level 1 study was found in this search. Four level 2 studies and 10 level 3 retrospective case series were found. The overall 5-year survival rate reported in these studies ranged from 37% to 59% and the mortality rate ranged from 0% to 6.9%.

CONCLUSIONS

Evidence suggests that triple modality therapy with complete resection of locally advanced Pancoast tumors with involvement of the spine offers an advantage over other therapeutic modalities or therapies with incomplete resections.

Spinal tumor surgery: management and the avoidance of complications

BACKGROUND

Complication avoidance is paramount to the success of any surgical procedure. In the case of spine tumor surgery, the risk of complications is increased because of the primary disease process and the radiotherapy and chemotherapeutics used to treat the disease. If complications do occur, then life-saving adjuvant treatment must be delayed or withheld until the issue is resolved, potentially impacting overall disease control.

METHODS

We reviewed the literature and our own best practices to provide recommendations on complication avoidance as well as the management of complications that may occur. Appropriate workup of suspected complications and treatment algorithms are also discussed.

RESULTS

Appropriate patient selection and a multidisciplinary workup are imperative in the setting of spinal tumors. Intraoperative complications may be avoided by employing proper surgical technique and an understanding of the pathological changes in anatomy. Major postoperative issues include wound complications and spinal reconstruction failure. Preoperative surgical planning must include postoperative reconstruction. Patients undergoing spinal tumor resection should be closely monitored for local tumor recurrence, recurrence along the biopsy tract, and for distant metastatic disease. Any suspected recurrence should be closely watched, biopsied if necessary, and promptly treated.

CONCLUSIONS

Because patients with spinal tumors are normally treated with a multidisciplinary approach, emphasis should be placed on the recognition of surgical complications beyond the surgical setting.

Palliative strategies for the management of primary and metastatic spinal tumors

BACKGROUND

Technological advances during the last few decades have improved the success rate of surgery for the treatment of malignant spinal tumors. Nonetheless, many patients present with widespread tumor burden and minimal life expectancy, which excludes them from being surgical candidates. For these patients, palliative management is recommended.

METHODS

The authors reviewed prospective and retrospective clinical studies as well as case series regarding palliative treatments for primary and metastatic spinal tumors.

RESULTS

Analgesics, ranging from nonopioids to strong opioids, may be used depending on the degree of pain. Steroids may also improve pain relief, although they are associated with a number of adverse events. Vertebroplasty and kyphoplasty are conservative treatments with high rates of pain relief and vertebral body stabilization. Radiotherapy is the gold standard for palliative management, with approximately 60% of patients experiencing a decrease in tumor-related spinal pain and up to 35% experiencing complete relief. Stereotactic radiosurgery delivers high doses of radiation to patients to provide pain relief while also sparing delicate anatomical structures.

CONCLUSION

Palliative management of spinal tumors is diverse. Analgesics may be used in conjunction with radiotherapy and/or kyphoplasty or vertebroplasty to offer pain relief.

Neurotrophin signaling via TrkB and TrkC receptors promotes the growth of brain tumor-initiating cells

Neurotrophins and their receptors are frequently expressed in malignant gliomas, yet their functions are largely unknown. Previously, we have shown that p75 neurotrophin receptor is required for glioma invasion and proliferation. However, the role of Trk receptors has not been examined. In this study, we investigated the importance of TrkB and TrkC in survival of brain tumor-initiating cells (BTICs). Here, we show that human malignant glioma tissues and also tumor-initiating cells isolated from fresh human malignant gliomas express the neurotrophin receptors TrkB and TrkC, not TrkA, and they also express neurotrophins NGF, BDNF, and neurotrophin 3 (NT3). Specific activation of TrkB and TrkC receptors by ligands BDNF and NT3 enhances tumor-initiating cell viability through activation of ERK and Akt pathways. Conversely, TrkB and TrkC knockdown or pharmacologic inhibition of Trk signaling decreases neurotrophin-dependent ERK activation and BTIC growth. Further, pharmacological inhibition of both ERK and Akt pathways blocked BDNF, and NT3 stimulated BTIC survival. Importantly, attenuation of BTIC growth by EGFR inhibitors could be overcome by activation of neurotrophin signaling, and neurotrophin signaling is sufficient for long term BTIC growth as spheres in the absence of EGF and FGF. Our results highlight a novel role for neurotrophin signaling in brain tumor and suggest that Trks could be a target for combinatorial treatment of malignant glioma.

Axial rotation mechanics in a cadaveric lumbar spine model: a biomechanical analysis

BACKGROUND CONTEXT

Postoperative patient motions are difficult to directly control. Very slow quasistatic motions are intuitively believed to be safer for patients, compared with fast dynamic motions, because the torque on the spine is reduced. Therefore, the outcomes of varying axial rotation (AR) angular loading rate during in vitro testing could expand the understanding of the dynamic behavior and spine response.

PURPOSE

To observe the effects of the loading rate in AR mechanics of lumbar cadaveric spines via in vitro biomechanical testing.

STUDY DESIGN

An in vitro biomechanical study in lumbar cadaveric spines.

METHODS

Fifteen lumbar cadaveric segments (L1-S1) were tested with varying loading frequencies of AR. Five different frequencies were normalized with the base line frequency (0.125 Hz n=15) in this analysis: 0.05 Hz (n=6), 0.166 Hz (n=6), 0.2 Hz (n=10), 0.25 Hz (n=10), and 0.4 Hz (n=8).

RESULTS

The lowest frequency (0.05 Hz) revealed significant differences (p<.05) for all parameters (torque, passive angular velocity, axial velocity [AV], axial reaction force [RF], and energy loss [EL]) with respect to all other frequencies. Significant differences (p<.05) were observed in the following: torque (0.4 Hz with respect to 0.2 Hz and 0.25 Hz), passive sagittal angular velocity (SAV) (0.4 Hz with respect to all other frequencies; 0.166 Hz with respect to 0.25 Hz), axial linear velocity (0.4 Hz with respect to all other frequencies), and RF (0.4 Hz with respect to 0.2 Hz and 0.25 Hz). Strong correlations (R2>0.75, p<.05) were observed between RF with intradiscal pressure (IDP) and AR angular displacement with IDP. Intradiscal pressure (p<.05) was significantly larger in 0.2 Hz in comparison with 0.125 Hz.

CONCLUSIONS

Evidences suggest that measurements at very small frequencies (0.05 Hz) of torque, SAV, AV, RF, and EL are significantly reduced when compared with higher frequencies (0.166 Hz, 0.2 Hz, 0.25 Hz, and 0.4 Hz). Higher frequencies increase torque, RF, passive SAV, and AV. Higher frequencies induce a greater IDP in comparison with lower frequencies.

Treatment of metastatic spinal lesions with a navigational bipolar radiofrequency ablation device: a multicenter retrospective study

BACKGROUND

Spinal metastatic lesions are a common occurrence among oncology patients and contribute to significant morbidity. Treatment options have been limited in their effectiveness and scope to this point.

OBJECTIVE

This study aims to report the safety and efficacy of radiofrequency ablation (RFA) of malignant spinal lesions using a novel RFA bipolar tumor ablation system which includes a navigational electrode containing 2 active thermocouples.

STUDY DESIGN

IRB approved multicenter retrospective review of patients receiving RFA as a treatment of metastatic osseous lesions between March 2012 and March 2013.

SETTING

This study consists of patients from 5 large academic centers.

METHOD

One hundred twenty-eight metastatic lesions were identified in 92 patients who underwent a total of 96 procedures. Cement augmentation was performed when the vertebral body was at risk or had a pathological fracture. Visual analogue scale (VAS) scores were obtained preoperatively as well as postoperatively at the one week, one month, and 6 month time points. Interval change in the patients' pain medications was recorded. Postoperative imaging was used to assess tumor burden at the treated level when available.

RESULTS

RFA was technically successful in all of the lesions without complication or thermal injury. Our study demonstrated significant (P < 0.01) decreases in the VAS scores at one week, one month, and 6 months postoperatively. In our largest center, 54% of our patients experienced a decrease and 30% had no change in their pain medications postoperatively. Sixty-two percent of the spinal lesions in this largest institution were located in the posterior vertebral body. Post-ablation imaging confirmed size of ablation zones consistent with that measured by the thermocouples.

LIMITATIONS

The main limitations of this study are the heterogeneous patient population, data set, and potential confounding variable of concurrent cement augmentation.

CONCLUSION

The STAR System is an RFA device that was safely and effectively used in the treatment of spine metastatic osseous lesions. This new device allows RFA treatment of previously untreatable lesions with resultant reduction in pain that was not controlled by systemic or radiation therapy.

Surgical Management of Primary and Metastatic Spinal Tumors

Background

The axial skeleton is a common site for primary tumors and metastatic disease, with metastatic disease being much more common. Primary and metastatic spinal tumors have a diverse range of aggressiveness, ranging from benign lesions to highly infiltrative malignant tumors.

Methods

The authors reviewed the results of articles describing the treatment and outcomes of patients with metastatic disease or primary tumors of the spinal column.

Results

En bloc resection is the mainstay of treatment for malignant primary tumors of the spinal column. Intralesional resection is generally appropriate for benign primary tumors. Low-quality evidence supports the use of chemotherapy in select primary tumors; however, radiation therapy is often used for incompletely resected or unresectable lesions. Surgical considerations for the treatment of metastatic disease are more nuanced and require that the health care professional consider patient performance status and the pathology of the primary tumor.

Conclusions

The treatment of metastatic and primary tumors of the spinal column requires a multidisciplinary approach in order to offer patients the best opportunity for long-term survival.

Feasibility and biomechanical performance of a novel transdiscal screw system for one level in non-spondylolisthetic lumbar fusion: an in vitro investigation

BACKGROUND CONTEXT

The bilateral pedicle screw system (BPSS) is currently the "gold standard" fusion technique for spinal instability. A new stabilization system that provides the same level of stability through a less invasive procedure will have a high impact on clinical practice. A new transdiscal screw system is investigated as a promising minimally invasive device.

PURPOSE

To evaluate the feasibility of a novel transdiscal screw in spinal fixation as an alternative to BPSS, with and without an interbody cage, in non-spondylolisthesis cases.

STUDY DESIGN

An in vitro biomechanical study in lumbar cadaveric spines.

METHODS

Twelve lumbar cadaveric segments (L4-S1) were tested under flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Six treatments were simulated as follows: (1) intact, (2) bilateral facetectomy at L4-L5, (3) transdiscal screw system, (4) BPSS, (5) BPSS with transforaminal lumbar interbody cage, and (6) transdiscal screws with transforaminal interbody cage. Specimens were randomly divided into two testing groups: Group 1 (n=6) was tested under the first five conditions, in the order presented, whereas Group 2 (n=6) was tested under the first, second, third, fourth, and sixth conditions, with the fourth condition preceding the third. Range of motion (ROM) and neutral zone stiffness (NZS) were estimated and normalized with respect to the intact condition to explore statistical differences among treatments using non-parametric approaches.

RESULTS

Significant differences in FE ROM were observed in the pedicle screws-cage condition with respect to the facetectomy (p<.01), the pedicle screw (p=.03), and the transdiscal screw (p<.02) conditions. All fixation constructs significantly restricted LB and AR ROM (p<.01) with respect to facetectomy. In terms of stiffness, the pedicle screw and the transdiscal screw systems increased (p<.01) LB and AR NZS with respect to facetectomy. The pedicle screws-cage condition significantly increased flexion and extension stiffness with respect to all other conditions (p<.05). However, LB NZS for the pedicle screws-cage and the transdiscal screws-cage condition could not be explored due to a testing order bias effect. There was not enough evidence to state any difference between the pedicle and transdiscal screw conditions in terms of ROM or NZS.

CONCLUSIONS

Transdiscal and pedicle screw systems showed comparable in vitro biomechanical performance in the immediate stabilization of a complete bilateral facetectomy. The pedicle screws-cage condition was the most stable in FE motion; however, comparison with respect to the transdiscal screws-cage condition could not be investigated.

Primary Spine Tumors: Diagnosis and Treatment

Background

Primary tumors are rare and those localized to a single location offer the potential for cure. To achieve this, early recognition of the primary tumor and proper workup and treatment are essential.

Methods

The authors reviewed the literature and best practices to provide recommendations on primary spine tumor treatment. Appropriate workup of primary spine tumors and treatment algorithms are also discussed.

Results

Patients suspected of a primary spine tumor should undergo fine-needle aspirate biopsy following consultation with the surgical team to ensure the biopsy tract is surgically resectable should the need arise. Once pathology is confirmed, metastatic workup should be performed to guide the level of treatment. If a localized lesion with poor radiation and chemotherapeutic response is diagnosed, then en bloc resection may be required for cure. If en bloc resection is not feasible or metastatic lesions are present, then radiation and medical oncology specialists must work in conjunction with the surgical team to determine the best treatment options.

Conclusions

Patients with suspected primary tumors of the spine should be treated in a multidisciplinary fashion from the outset. With thoughtful management, these lesions offer the opportunity for surgical cure.

Central nervous system cancers

Primary and metastatic tumors of the central nervous system are a heterogeneous group of neoplasms with varied outcomes and management strategies. Recently, improved survival observed in 2 randomized clinical trials established combined chemotherapy and radiation as the new standard for treating patients with pure or mixed anaplastic oligodendroglioma harboring the 1p/19q codeletion. For metastatic disease, increasing evidence supports the efficacy of stereotactic radiosurgery in treating patients with multiple metastatic lesions but low overall tumor volume. These guidelines provide recommendations on the diagnosis and management of this group of diseases based on clinical evidence and panel consensus. This version includes expert advice on the management of low-grade infiltrative astrocytomas, oligodendrogliomas, anaplastic gliomas, glioblastomas, medulloblastomas, supratentorial primitive neuroectodermal tumors, and brain metastases. The full online version, available at NCCN. org, contains recommendations on additional subtypes.

In vitro evaluation of a lateral expandable cage and its comparison with a static device for lumbar interbody fusion: a biomechanical investigation

OBJECT

Through in vitro biomechanical testing, the authors compared the performance of a vertically expandable lateral lumbar interbody cage (EC) under two different torque-controlled expansions (1.5 and 3.0 Nm) and with respect to an equivalent lateral lumbar static cage (SC) with and without pedicle screw fixation.

METHODS

Eleven cadaveric human L2-3 segments were evaluated under the following conditions: 1) intact; 2) discectomy; 3) EC under 1.50 Nm of torque expansion (EC-1.5Nm); 4) EC under 3.00 Nm of torque expansion (EC-3.0Nm); 5) SC; and 6) SC with a bilateral pedicle screw system (SC+BPSS). Load-displacement behavior was evaluated for each condition using a combination of 100 N of axial preload and 7.5 Nm of torque in flexion and extension (FE), lateral bending (LB), and axial rotation (AR). Range of motion (ROM), neutral zone stiffness (NZS), and elastic zone stiffness (EZS) were statistically compared among conditions using post hoc Wilcoxon signed-rank comparisons after Friedman tests, with a significance level of 0.05. Additionally, any cage height difference between interbody devices was evaluated. When radiographic subsidence was observed, the specimen's data were not considered for the analysis.

RESULTS

The final cage height in the EC-1.5Nm condition (12.1 ± 0.9 mm) was smaller (p < 0.001) than that in the EC-3.0Nm (13.9 ± 1.1 mm) and SC (13.4 ± 0.8 mm) conditions. All instrumentation reduced (p < 0.01) ROM with respect to the injury and increased (p ≤ 0.01) NZS in flexion, extension, and LB as well as EZS in flexion, LB, and AR. When comparing the torque expansions, the EC-3.0Nm condition had smaller (p < 0.01) FE and AR ROM and greater (p ≤ 0.04) flexion NZS, extension EZS, and AR EZS. The SC condition performed equivalently (p ≥ 0.10) to both EC conditions in terms of ROM, NZS, and EZS, except for EZS in AR, in which a marginal (p = 0.05) difference was observed with respect to the EC-3.0Nm condition. The SC+BPSS was the most rigid construct in terms of ROM and stiffness, except for 1) LB ROM, in which it was comparable (p = 0.08) with that of the EC-1.5Nm condition; 2) AR NZS, in which it was comparable (p > 0.66, Friedman test) with that of all other constructs; and 3) AR EZS, in which it was comparable with that of the EC-1.5Nm (p = 0.56) and SC (p = 0.08) conditions.

CONCLUSIONS

A 3.0-Nm torque expansion of a lateral interbody cage provides greater immediate stability in FE and AR than a 1.5-Nm torque expansion. Moreover, the expandable device provides stability comparable with that of an equivalent (in size, shape, and bone-interface material) SC. Specifically, the SC+BPSS construct was the most stable in FE motion. Even though an EC may seem a better option given the minimal tissue disruption during its implantation, there may be a greater chance of endplate collapse by over-distracting the disc space because of the minimal haptic feedback from the expansion.

Biomechanical comparison of a two-level anterior discectomy and a one-level corpectomy, combined with fusion and anterior plate reconstruction in the cervical spine

BACKGROUND

Common fusion techniques for cervical degenerative diseases include two-level anterior discectomy and fusion and one-level corpectomy and fusion. The aim of the study was to compare via in-vitro biomechanical testing the effects of a two-level anterior discectomy and fusion and a one-level corpectomy and fusion, with anterior plate reconstruction.

METHODS

Seven fresh frozen human cadaveric spines (C3-T1) were dissected from posterior musculature, preserving the integrity of ligaments and intervertebral discs. Initial biomechanical testing consisted of no-axial preload and 2Nm in flexion-extension, lateral bending and axial rotation. Thereafter, discectomies were performed at C4-5 and C5-6 levels, then two interbody cages and an anterior C4-C5-C6 plate was implanted. The flexibility tests were repeated and followed by C5 corpectomy and C4-C6 plate reconstruction. Biomechanical testing was performed again and statistical comparisons among the means of range of motion and axial rotation energy loss were investigated.

FINDINGS

The two-level cage-plate construct had significantly lower range of motion than the one-level corpectomy-plate construct (P≤0.03). Axial rotation energy loss was significantly (P≤0.03) greater for the corpectomy-plate construct than for the two-level cage-plate construct and the intact condition.

INTERPRETATION

A two-level cage-plate construct provides greater stability in flexion, extension and lateral bending motions when compared to a one-level corpectomy-plate construct. A two-level cage-plate is more likely to maintain axial balance by reducing the energy lost in axial rotation.

Biomechanical analysis of an interspinous fusion device as a stand-alone and as supplemental fixation to posterior expandable interbody cages in the lumbar spine

OBJECT

In this paper the authors evaluate through in vitro biomechanical testing the performance of an interspinous fusion device as a stand-alone device, after lumbar decompression surgery, and as supplemental fixation to expandable cages in a posterior lumbar interbody fusion (PLIF) construct.

METHODS

Nine L3-4 human cadaveric spines were biomechanically tested under the following conditions: 1) intact/control; 2) L3-4 left hemilaminotomy with partial discectomy (injury); 3) interspinous spacer (ISS); 4) bilateral pedicle screw system (BPSS); 5) bilateral hemilaminectomy, discectomy, and expandable posterior interbody cages with ISS (PLIF-ISS); and 6) PLIF-BPSS. Each test consisted of 100 N of axial preload with ± 7.5 Nm of torque in flexion-extension, right/left lateral bending, and right/left axial rotation. Significant changes in range of motion (ROM), neutral zone stiffness (NZS), elastic zone stiffness (EZS), and energy loss (EL) were explored among conditions using nonparametric Friedman test and Wilcoxon signed-rank comparisons (p ≤ 0.05).

RESULTS

The injury increased ROM in flexion (p = 0.01), left bending (p = 0.03), and right/left rotation (p < 0.01) and also decreased NZS in flexion (p = 0.01) and extension (p < 0.01). Both the ISS and BPSS reduced flexion-extension ROM and increased flexion-extension stiffness (NZS and EZS) with respect to the injury and intact conditions (p < 0.05), but the ISS condition provided greater resistance than BPSS in extension for ROM, NZS, and EZS (p < 0.01). The BPSS increased the rigidity (ROM, NZS, and EZS) of the intact model in lateral bending and axial rotation (p ≤ 0.01), except in EZS for left rotation (p = 0.23, Friedman test). The incorporation of posterior cages marginally increased (p = 0.05) the EZS of the BPSS construct in flexion but these interbody devices provided significant stability to the ISS construct in lateral bending and axial rotation for ROM (p = 0.02), in lateral bending for NZS (p = 0.02), and in flexion/axial rotation for EZS (p ≤ 0.03); however, both PLIF constructs demonstrated equivalent ROM and stiffness (p ≥ 0.16), except in lateral bending where the PLIF-BPSS was more stable (p = 0.02). In terms of EL, the injury increased EL in flexion-extension (p = 0.02), the ISS increased EL for lateral bending and axial rotation (p ≤ 0.03), and the BPSS decreased EL in lateral bending (p = 0.02), with respect to the intact condition. The PLIF-ISS decreased lateral bending EL with respect to the ISS condition (p = 0.02), but not enough to be smaller or, at least, equivalent, to that of the PLIF-BPSS construct (p = 0.02).

CONCLUSIONS

The ISS may be a suitable device to provide immediate flexion-extension balance after a unilateral laminotomy, but the BPSS provides greater immediate stability in lateral bending and axial rotation motions. Both PLIF constructs performed equivalently in flexion-extension and axial rotation, but the PLIF-BPSS construct is more resistant to lateral bending motions. Further biomechanical and clinical evidence is required to strongly support the recommendation of a stand-alone interspinous fusion device or as supplemental fixation to expandable posterior interbody cages.

The actual management of tumor and vertebral compression fractures

Tumor related fractures of the spine frequently dictate surgical management. The most critical factors influencing the need and type of surgery are degree of epidural cord compression, radiosensitivity of the tumor, presence of spinal instability and patient medical status/ estimated survivorship. There is a wide spectrum of therapeutic options: major en bloc resections in primary or oligometastatic disease; decompression and fusion in non-radiosensitive tumors with cord compression followed by adjuvant radiation therapy (RT); kyphoplasty/ vertebroplasty for stable compression fractures or minimally invasive corpectomy for more unstable fractures and RT- only for radiosensitive tumors not causing overt instability. Radiation therapy has always been essential component of the treatment algorithm although it has been displaced from principal treatment modality in the last 2 decades. However, the advent of more targeted and efficient forms of RT (radiosurgery) may be a new treatment paradigm for more radioresistant tumors and may obviate the need for major operations.

Comparing effects of kyphoplasty, vertebroplasty, and non-surgical management in a systematic review of randomized and non-randomized controlled studies

PURPOSE

To determine if differences in safety or efficacy exist between balloon kyphoplasty (BKP), vertebroplasty (VP) and non-surgical management (NSM) for the treatment of osteoporotic vertebral compression fractures (VCFs).

METHODS

As of February 1, 2011, a PubMed search (key words: kyphoplasty, vertebroplasty) resulted in 1,587 articles out of which 27 met basic selection criteria (prospective multiple-arm studies with cohorts of ≥ 20 patients). This systematic review adheres to preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines.

RESULTS

Pain reduction in both BKP (-5.07/10 points, P < 0.01) and VP (-4.55/10, P < 0.01) was superior to that for NSM (-2.17/10), while no difference was found between BKP/VP (P = 0.35). Subsequent fractures occurred more frequently in the NSM group (22 %) compared with VP (11 %, P = 0.04) and BKP (11 %, P = 0.01). BKP resulted in greater kyphosis reduction than VP (4.8º vs. 1.7°, P < 0.01). Quality of life (QOL) improvement showed superiority of BKP over VP (P = 0.04), along with a trend for disability improvement (P = 0.08). Cement extravasation was less frequent in the BKP (P = 0.01). Surgical intervention within the first 7 weeks yielded greater pain reduction than VCFs treated later.

CONCLUSIONS

BKP/VP provided greater pain relief and fewer subsequent fractures than NSM in osteoporotic VCFs. BKP is marginally favored over VP in disability improvement, and significantly favored in QOL improvement. BKP had a lower risk of cement extravasation and resulted in greater kyphosis correction. Despite this analysis being restricted to Level I and II studies, significant heterogeneity suggests that the current literature is delivering inconsistent messages and further trials are needed to delineate confounding variables.

Biomechanical comparison of anterior cervical spine instrumentation techniques with and without supplemental posterior fusion after different corpectomy and discectomy combinations: Laboratory investigation

OBJECT

The objective of this study was to compare the stiffness and range of motion (ROM) of 4 cervical spine constructs and the intact condition. The 4 constructs consisted of 3-level anterior cervical discectomy with anterior plating, 1-level discectomy and 1-level corpectomy with anterior plating, 2-level corpectomy with anterior plating, and 2-level corpectomy with anterior plating and posterior fixation.

METHODS

Eight human cadaveric fresh-frozen cervical spines from C2-T2 were used. Three-dimensional motion analysis with an optical tracking device was used to determine motion following various reconstruction methods. The specimens were tested in the following conditions: 1) intact; 2) segmental construct with discectomies at C4-5, C5-6, and C6-7, with polyetheretherketone (PEEK) interbody cage and anterior plate; 3) segmental construct with discectomy at C6-7 and corpectomy of C-5, with PEEK interbody graft at the discectomy level and a titanium cage at the corpectomy level; 4) corpectomy at C-5 and C-6, with titanium cage and an anterior cervical plate; and 5) corpectomy at C-5 and C-6, with titanium cage and an anterior cervical plate, and posterior lateral mass screw-rod system from C-4 to C-7. All specimens underwent a pure moment application of 2 Nm with regards to flexion-extension, lateral bending, and axial rotation.

RESULTS

In all tested motions the statistical comparison was significant between the intact condition and the 2-level corpectomy with anterior plating and posterior fixation construct. All other statistical comparisons between the instrumented constructs were not statistically significant except between the 3-level discectomy with anterior plating and the 2-level corpectomy with anterior plating in axial rotation. There were no statistically significant differences between the 1-level discectomy and 1-level corpectomy with anterior plating and the 2-level corpectomy with anterior plating in any tested motion. There was also no statistical significance between the 3-level discectomy with anterior plating and the 2-level corpectomy with anterior plating and posterior fixation.

CONCLUSIONS

This study demonstrates that segmental plate fixation (3-level discectomy) affords the same stiffness and ROM as circumferential fusion in 2-level cervical spine corpectomy in the immediate postoperative setting. This obviates the need for staged circumferential procedures for multilevel cervical spondylotic myelopathy. Given that the posterior segmental instrumentation confers significant stability to a multilevel cervical corpectomy, the surgeon should strongly consider the placement of segmental posterior instrumentation to significantly improve the overall stability of the fusion construct after a 2-level cervical corpectomy.

Temporal bone meningiomas

Meningiomas involving the temporal bone may originate from arachnoid cell nests present within the temporal bone (intratemporal), but more frequently originate from arachnoid cell nests of the posterior or middle cranial fossa with secondary invasion of the TB (extratemporal). In this study, we retrospectively reviewed the charts of 13 patients with meningiomas involving the temporal bone who underwent surgery. Tumors of the posterior fossa with only temporal bone hyperostosis, but without invasion, were excluded. Patients presented primarily with otologic symptoms and signs. The tumors originated in the temporal bone (5/13), jugular foramen (4/13), petroclival region (2/13), the asterion (1/13) or the internal auditory meatus (1/13). All of the intratemporal meningiomas had the radiological appearance of en-plaque menigiomas. The tumor extended into the middle ear (11/13), eustachian tube (5/13), and/or the labyrinth (3/13). A gross total resection was achieved in 11 patients and a subtotal resection in 2 patients. The lower cranial nerves were infiltrated by tumor in 4 patients, and were sacrificed. At a mean follow-up of approximately 6 years, 12 patients are currently alive and doing well and 1 died from tumor progression. Six patients showed tumor recurrence and were reoperated on (5/6) or followed conservatively (1/6). Surgical treatment of temporal bone meningiomas is associated with high recurrence rate due to indiscreet tumor margins. Combined surgical approaches (temporal craniotomy and mastoidectomy) by neurosurgical and otological teams are recommended for meningiomas originating in the temporal bone.

Asterion meningiomas

Asterion meningiomas arise from the posterior petrous ridge at the junction of the transverse and sigmoid sinuses (sinodural angle). The authors retrospectively reviewed the charts of seven patients with asterion meningiomas who underwent a Simpson I tumor resection by either the petrosal or suboccipital approach. Patients presented with headaches, dizziness, ataxia, or seizures. Preoperative angiograms and intraoperative observations confirmed occlusion of the transverse and sigmoid sinuses by tumor, thrombus, or both in four of the patients. In all cases, tumor infiltrated the sinuses and the sinuses were ligated without adverse sequelae. Temporal bone invasion was seen in one patient who had the only tumor recurrence. Postoperatively, there were two transient CSF leaks. Asterion meningiomas can be completely resected with a low incidence of major morbidity. In this small series, a patent transverse/sigmoid sinus was resected in three patients without sequelae. We believe that in young patients with asterion meningiomas a nondominant transverse/sigmoid sinus should be resected if the torcula is patent. More research is needed to determine the safety of resecting a patent dominant transverse/sigmoid sinus.