Velociraptor: Cross-Platform Quantitative Search Using Hallmark Cell Features

A key challenge for single cell discovery analysis is to identify new cell types, describe them quantitatively, and seek these novel cells in new studies often using a different platform. Over the last decade, tools were developed to address identification and quantitative description of cells in human tissues and tumors. However, automated validation of populations at the single cell level has struggled due to the cytometry field's reliance on hierarchical, ordered use of features and on platform-specific rules for data processing and analysis. Here we present Velociraptor, a workflow that implements Marker Enrichment Modeling in three cross-platform modules: 1) identification of cells specific to disease states, 2) description of hallmark features for each cell and population, and 3) searching for cells matching one or more hallmark feature sets in a new dataset. A key advance is that Velociraptor registers cells between datasets, including between flow cytometry and quantitative imaging using different, overlapping feature sets. Four datasets were used to challenge Velociraptor and reveal new biological insights. Working at the individual sample level, Velociraptor tracked the abundance of clinically significant glioblastoma brain tumor cell subsets and characterized the cells that predominate in recurrent tumors as a close match for rare, negative prognostic cells originally observed in matched pre-treatment tumors. In patients with inborn errors of immunity, Velociraptor identified genotype-specific cells associated with GATA2 haploinsufficiency. Finally, in cross-platform analysis of immune cells in multiplex imaging of breast cancer, Velociraptor sought and correctly identified memory T cell subsets in tumors. Different phenotypic descriptions generated by algorithms or humans were shown to be effective as search inputs, indicating that cell identity need not be described in terms of per-feature cutoffs or strict hierarchical analyses. Velociraptor thus identifies cells based on hallmark feature sets, such as protein expression signatures, and works effectively with data from multiple sources, including suspension flow cytometry, imaging, and search text based on known or theoretical cell features.

IL-8 Instructs Macrophage Identity in Lateral Ventricle Contacting Glioblastoma

Adult IDH-wildtype glioblastoma (GBM) is a highly aggressive brain tumor with no established immunotherapy or targeted therapy. Recently, CD32+ HLA-DRhi macrophages were shown to have displaced resident microglia in GBM tumors that contact the lateral ventricle stem cell niche. Since these lateral ventricle contacting GBM tumors have especially poor outcomes, identifying the origin and role of these CD32+ macrophages is likely critical to developing successful GBM immunotherapies. Here, we identify these CD32+ cells as M_IL-8 macrophages and establish that IL-8 is sufficient and necessary for tumor cells to instruct healthy macrophages into CD32+ M_IL-8 M2 macrophages. In ex vivo experiments with conditioned medium from primary human tumor cells, inhibitory antibodies to IL-8 blocked the generation of CD32+ M_IL-8 cells. Finally, using a set of 73 GBM tumors, IL-8 protein is shown to be present in GBM tumor cells in vivo and especially common in tumors contacting the lateral ventricle. These results provide a mechanistic origin for CD32+ macrophages that predominate in the microenvironment of the most aggressive GBM tumors. IL-8 and CD32+ macrophages should now be explored as targets in combination with GBM immunotherapies, especially for patients whose tumors present with radiographic contact with the ventricular-subventricular zone stem cell niche.

An immunosuppressed microenvironment distinguishes lateral ventricle-contacting glioblastomas

Radiographic contact of glioblastoma (GBM) tumors with the lateral ventricle and adjacent stem cell niche correlates with poor patient prognosis, but the cellular basis of this difference is unclear. Here, we reveal and functionally characterize distinct immune microenvironments that predominate in subtypes of GBM distinguished by proximity to the lateral ventricle. Mass cytometry analysis of IDH-wildtype human tumors identified elevated T cell checkpoint receptor expression and greater abundance of a specific CD32+CD44+HLA-DRhigh macrophage population in ventricle-contacting GBM. Multiple computational analysis approaches, phospho-specific cytometry, and focal resection of GBMs confirmed and extended these findings. Phospho-flow quantified cytokine-induced immune cell signaling in ventricle-contacting GBM revealing differential signaling between GBM subtypes. Subregion analysis within a given tumor supported initial findings and revealed intratumoral compartmentalization of T cell memory and exhaustion phenotypes within GBM subtypes. Collectively, these results characterize immunotherapeutically targetable features of macrophages and suppressed lymphocytes in glioblastomas defined by MRI-detectable lateral ventricle contact.

A modular, multi-arm concentric tube robot system with application to transnasal surgery for orbital tumors

In the development of telemanipulated surgical robots, a class of continuum robots known as concentric tube robots has drawn particular interest for clinical applications in which space is a major limitation. One such application is transnasal surgery, which is used to access surgical sites in the sinuses and at the skull base. Current techniques for performing these procedures require surgeons to maneuver multiple rigid tools through the narrow confines of the nasal passages, leaving them with limited dexterity at the surgical site. In this article, we present a complete robotic system for transnasal surgery featuring concentric tube manipulators. It illustrates a bagging concept for sterility, and intraoperatively interchangeable instruments that work in conjunction with it, which were developed with operating room workflow compatibility in mind. The system also includes a new modular, portable surgeon console, a variable view-angle endoscope to facilitate surgical field visualization, and custom motor control electronics. Furthermore, we demonstrate elastic instability avoidance for the first time on a physical prototype in a geometrically accurate surgical scenario, which facilitates use of higher curvature tubes than could otherwise be used safely in this application. From a surgical application perspective, this article presents the first robotic approach to removing tumors growing behind the eyes in the orbital apex region, which has not been attempted previously with a surgical robot.

Unsupervised machine learning reveals risk stratifying glioblastoma tumor cells

A goal of cancer research is to reveal cell subsets linked to continuous clinical outcomes to generate new therapeutic and biomarker hypotheses. We introduce a machine learning algorithm, Risk Assessment Population IDentification (RAPID), that is unsupervised and automated, identifies phenotypically distinct cell populations, and determines whether these populations stratify patient survival. With a pilot mass cytometry dataset of 2 million cells from 28 glioblastomas, RAPID identified tumor cells whose abundance independently and continuously stratified patient survival. Statistical validation within the workflow included repeated runs of stochastic steps and cell subsampling. Biological validation used an orthogonal platform, immunohistochemistry, and a larger cohort of 73 glioblastoma patients to confirm the findings from the pilot cohort. RAPID was also validated to find known risk stratifying cells and features using published data from blood cancer. Thus, RAPID provides an automated, unsupervised approach for finding statistically and biologically significant cells using cytometry data from patient samples.

Mechatronic Design of a Two-Arm Concentric Tube Robot System for Rigid Neuroendoscopy

Open surgical approaches are still often employed in neurosurgery, despite the availability of neuroendoscopic approaches that reduce invasiveness. The challenge of maneuvering instruments at the tip of the endoscope makes neuroendoscopy demanding for the physician. The only way to aim tools passed through endoscope ports is to tilt the entire endoscope; but, tilting compresses brain tissue through which the endoscope passes and can damage it. Concentric tube robots can provide necessary dexterity without endoscope tilting, while passing through existing ports in the endoscope and carrying surgical tools in their inner lumen. In this paper we describe the mechatronic design of a new concentric tube robot that can deploy two concentric tube manipulators through a standard neuroendoscope. The robot uses a compact differential drive and features embedded motor control electronics and redundant position sensors for safety. In addition to the mechatronic design of this system, this paper contributes experimental validation in the context of colloid cyst removal, comparing our new robotic system to standard manual endoscopy in a brain phantom. The robotic approach essentially eliminated endoscope tilt during the procedure (17.09° for the manual approach vs. 1.16° for the robotic system). The robotic system also enables a single surgeon to perform the procedure - typically in a manual approach one surgeon aims the endoscope and another operates the tools delivered through its ports.

Single-cell systems neuroimmunology reveals a highly immunosuppressive microenvironment in human glioblastomas contacting the ventricular stem cell niche

Glioblastomas make up more than 60% of adult primary brain tumors and carry a 15 month overall survival despite aggressive standard-of-care therapy. Recent advances in immunotherapy offer an appealing alternative that may improve outcomes for patients with glioblastoma; however, clinical trials have proven unsuccessful due in part to a lack of predictive features that may inform responsiveness to immunotherapy. We have recently shown a strong correlation between 1) immune infiltration, 2) tumor cell phenotype, and 3) patient outcome. Further, patients whose tumors demonstrate radiographic contact with the ventricular-subventricular zone (V-SVZ) have reduced survival compared to patients whose tumors do not contact the V-SVZ. We therefore hypothesized that the V-SVZ acts as a previously unappreciated immunosuppressive microenvironment within the brain that promotes tumor growth by suppressing anti-tumor immunity. Primary human glioblastomas were disaggregated into single-cell suspensions and mass cytometry (CyTOF) measured >30 parameters in thirteen immune populations infiltrating human glioblastomas. Cutting-edge machine-learning tools identified key differences in the abundance and phenotypes of T cells, B cells, NK cells, microglia, and peripheral macrophages infiltrating ventricle-contacting gliomas. Further, enriched expression of immune checkpoint receptors (PD-1, TIGIT, LAG-3, TIM3) correlated with ventricular contact and outcome. These results provide key insights into the immune microenvironment of glioblastomas and elucidate several clinically actionable immunotherapeutic targets that may be used to optimize treatment strategies for glioblastoma patients based on V-SVZ contact status.

A Retrospective Cohort Study of Longitudinal Audiologic Assessment in Single and Fractionated Stereotactic Radiosurgery for Vestibular Schwannoma

BACKGROUND

Fractionated stereotactic radiosurgery (SRS) for vestibular schwannomas (VS) has been theorized to allow for tumor control with higher rates of hearing preservation in selected patients with useful hearing. However, there is a paucity of literature with formal audiologic measures of hearing preservation to support the standard use of fractionated SRS in VS. We hypothesized that fractionation would diminish the amount of hearing damage.

OBJECTIVE

To evaluate the relationship between audiologic performance and SRS fractionation scheme.

METHODS

We performed an IRB-approved retrospective review of patients treated with 1, 3, or 5 fraction SRS for VS at our institution from 1998 to 2016. Pre- and post-SRS audiograms with speech awareness threshold (SAT) in treated and contralateral ears were obtained. Contralateral ear measurements were used for hearing normalization to account for presbycusis.

RESULTS

Fifty-six patients with median audiologic follow-up 2.0 yr (mean 2.66 yr, min-max 0.50-9.45 yr) were included. Patients treated with single fractionation had a significantly worsened SAT (dB) compared to patients treated with 5 fractions (P = .008) and compared to all multifraction patients (P = .009) at 12 to 24 mo follow-up.

CONCLUSION

This retrospective analysis supports the use of fractionated SRS to preserve hearing in patients with VS. SAT can be used as an objective metric of hearing response to radiosurgery.

Tumor Progression Following Petroclival Meningioma Subtotal Resection: A Volumetric Study

BACKGROUND

One study has investigated postoperative growth rates following subtotal resection of petroclival meningiomas utilizing linear measurements, which are insensitive to the multidimensional complex growth of meningiomas, to estimate tumor volume.

OBJECTIVE

To describe petroclival meningioma growth patterns following less-than-complete resection utilizing volumetric analysis and to identify variables associated with tumor progression.

METHODS

Patients with surgically resected WHO grade I petroclival meningiomas were retrospectively reviewed (1999-2015). Image analysis software was utilized to perform volumetric analyses of tumor size and growth on serial MRI studies. The impact of preoperative and postoperative variables on tumor growth after subtotal resection was analyzed. An increase in tumor volume of at least 20% was defined as "tumor growth."

RESULTS

Twenty-three patients had immediate preoperative and serial postoperative MRI studies available for review. The mean preoperative tumor volume was 20.9 cm3 (range 0.4-54.6). The mean extent of resection was 75.5% (range 31.5%-100.0%). At a mean follow-up of 24.8 mo, 12 tumors (66.7%) exhibited radiological tumor growth, while 6 tumors did not change in size. The median annual volumetric growth rate was 2.82 cm3/yr (range -0.34 to 10.1). Extent of resection and immediate postoperative tumor volume were significantly correlated with the annual volumetric growth rate following resection. At last follow-up, 3 (13%) patients required further intervention.

CONCLUSION

The majority of petroclival meningiomas exhibit growth following subtotal resection. Extent of resection is strongly associated with risk for disease progression following surgery.

MR-conditional steerable needle robot for intracerebral hemorrhage removal

BACKGROUND

Intracerebral hemorrhage (ICH) is one of the deadliest forms of stroke in the USA. Conventional surgical techniques such as craniotomy or stereotactic aspiration disrupt a large volume of healthy brain tissue in their attempts to reach the surgical site. Consequently, the surviving patients suffer from debilitating complications.

METHODS

We fabricated a novel MR-conditional steerable needle robot for ICH treatment. The robot system is powered by a custom-designed high power and low-cost pneumatic motor. We tested the robot's targeting accuracy and MR-conditionality performance, and performed phantom evacuation experiment under MR image guidance.

RESULTS

Experiments demonstrate that the robotic hardware is MR-conditional; the robot has the targeting accuracy of 1.26 ± 1.22 mm in bench-top tests. With real-time MRI guidance, the robot successfully reached the desired target and evacuated an 11.3 ml phantom hematoma in 9 min.

CONCLUSION

MRI-guided steerable needle robotic system is a potentially feasible approach for ICH treatment by providing accurate needle guidance and intraoperative surgical outcome evaluation.

Using a Guided Machine Learning Ensemble Model to Predict Discharge Disposition following Meningioma Resection

Objective  Machine learning (ML) algorithms are powerful tools for predicting patient outcomes. This study pilots a novel approach to algorithm selection and model creation using prediction of discharge disposition following meningioma resection as a proof of concept. Materials and Methods  A diversity of ML algorithms were trained on a single-institution database of meningioma patients to predict discharge disposition. Algorithms were ranked by predictive power and top performers were combined to create an ensemble model. The final ensemble was internally validated on never-before-seen data to demonstrate generalizability. The predictive power of the ensemble was compared with a logistic regression. Further analyses were performed to identify how important variables impact the ensemble. Results  Our ensemble model predicted disposition significantly better than a logistic regression (area under the curve of 0.78 and 0.71, respectively, p  = 0.01). Tumor size, presentation at the emergency department, body mass index, convexity location, and preoperative motor deficit most strongly influence the model, though the independent impact of individual variables is nuanced. Conclusion  Using a novel ML technique, we built a guided ML ensemble model that predicts discharge destination following meningioma resection with greater predictive power than a logistic regression, and that provides greater clinical insight than a univariate analysis. These techniques can be extended to predict many other patient outcomes of interest.

Abstract 364: Mass cytometry of human glioblastoma characterizes more than 99 percent of cells and reveals intratumoral cell subsets defined by contrasting signaling network profiles

Background: Glioblastoma (GBM) remains largely incurable despite intense study of resected tissue. Prior studies have revealed GBM cell subsets (Patel et al., Science 2014) and have implicated subset emergence as a potential mechanism of poor outcome in other cancer types. Signaling in rare cells or a mix of cell subsets may enable therapy resistance and recurrence of GBM. For example, STAT3 RNA expression has been previously shown to correlate with poor outcome in GBM (Jahani-Asl et al., Nat Neurosci 2016 and TCGA). The complexity of GBM, combined with the interconnectedness between cancer and host cells in the microenvironment, means that a single cell biology approach is needed to comprehensively characterize patient biopsy cells and determine how protein expression, signaling, and functional capabilities impact treatment response.

Methods: We developed a novel mass cytometry approach to characterize human GBM that identified ~90-95% of tumor cells (Leelatian & Doxie et al., Cytometry B 2016). Here, we applied this approach using a newly created 35-antibody mass cytometry panel focused on basal phospho-protein signaling. The published panel of 16 identity proteins included SOX2, CD44, Nestin, PDGFRα, S100B, and NCAM. This panel was augmented to measure 10 additional proteins and 9 phospho-proteins including p-STAT3, p-EGFR, and p-NFκB. Signaling measurements were chosen to match prior single cell studies of signaling networks that stratified clinical outcomes in blood cancers (Irish et al., Cell 2004; PNAS 2010, Levine et al., Cell 2015). Between 10,000 and 250,000 viable cells were characterized for each tumor (N = 7). Tumors were collected with informed consent and in accord with the Declaration of Helsinki.

Results: This new 35-antibody mass cytometry panel positively identified >99% of GBM cells. Subsets of GBM cells displayed protein expression that matched previously observed transcriptional molecular subclasses (Verhaak et al., Cancer Cell 2010 and TCGA). Strikingly, this panel revealed novel GBM cell subsets defined by contrasting basal signaling profiles. An inverse correlation was observed between baseline STAT3 phosphorylation and the abundance of CD45+ leukocytes. Additionally, similar signaling patterns were seen in cells that expressed proteins associated with distinct functions, such as proliferation and migration.

Conclusions: The correlation between low STAT3 signaling and high immune cell abundance provides evidence for the idea that an intimate relationship exists between immune cells and GBM tumor growth and survival. Moreover, single cell analysis may reveal biomarkers of treatment response and allow prediction of clinical outcomes. The abnormal signaling mechanisms observed here in some GBM cell subsets should be studied further as potential targets for novel cancer-selective combination therapies.

Citation Format: Nalin Leelatian, Justine Sinnaeve, Bret C. Mobley, Akshitkumar M. Mistry, Daniel Liu, Kyle D. Weaver, Reid C. Thompson, Lola B. Chambless, Rebecca A. Ihrie, Jonathan M. Irish. Mass cytometry of human glioblastoma characterizes more than 99 percent of cells and reveals intratumoral cell subsets defined by contrasting signaling network profiles [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 364. doi:10.1158/1538-7445.AM2017-364

Decreased survival in glioblastomas is specific to contact with the ventricular-subventricular zone, not subgranular zone or corpus callosum

The clinical effect of radiographic contact of glioblastoma (GBM) with neurogenic zones (NZ)-the ventricular-subventricular (VSVZ) and subgranular (SGZ) zones-and the corpus callosum (CC) remains unclear and, in the case of the SGZ, unexplored. We investigated (1) if GBM contact with a NZ correlates with decreased survival; (2) if so, whether this effect is associated with a specific NZ; and (3) if radiographic contact with or invasion of the CC by GBM is associated with decreased survival. We retrospectively identified 207 adult patients who underwent cytoreductive surgery for GBM followed by chemotherapy and/or radiation. Age, preoperative Karnofsky performance status score (KPS), and extent of resection were recorded. Preoperative MRIs were blindly analyzed to calculate tumor volume and assess its contact with VSVZ, SGZ, CC, and cortex. Overall (OS) and progression free (PFS) survivals were calculated and analyzed with multivariate Cox analyses. Among the 207 patients, 111 had GBM contacting VSVZ (VSVZ+GBMs), 23 had SGZ+GBMs, 52 had CC+GBMs, and 164 had cortex+GBMs. VSVZ+, SGZ+, and CC+ GBMs were significantly larger in size relative to their respective non-contacting controls. Multivariate Cox survival analyses revealed GBM contact with the VSVZ, but not SGZ, CC, or cortex, as an independent predictor of lower OS, PFS, and early recurrence. We hypothesize that the VSVZ niche has unique properties that contribute to GBM pathobiology in adults.

Single cell analysis of human tissues and solid tumors with mass cytometry

BACKGROUND

Mass cytometry measures 36 or more markers per cell and is an appealing platform for comprehensive phenotyping of cells in human tissue and tumor biopsies. While tissue disaggregation and fluorescence cytometry protocols were pioneered decades ago, it is not known whether established protocols will be effective for mass cytometry and maintain cancer and stromal cell diversity.

METHODS

Tissue preparation techniques were systematically compared for gliomas and melanomas, patient derived xenografts of small cell lung cancer, and tonsil tissue as a control. Enzymes assessed included DNase, HyQTase, TrypLE, collagenase (Col) II, Col IV, Col V, and Col XI. Fluorescence and mass cytometry were used to track cell subset abundance following different enzyme combinations and treatment times.

RESULTS

Mechanical disaggregation paired with enzymatic dissociation by Col II, Col IV, Col V, or Col XI plus DNase for 1 h produced the highest yield of viable cells per gram of tissue. Longer dissociation times led to increasing cell death and disproportionate loss of cell subsets. Key markers for establishing cell identity included CD45, CD3, CD4, CD8, CD19, CD64, HLA-DR, CD11c, CD56, CD44, GFAP, S100B, SOX2, nestin, vimentin, cytokeratin, and CD31. Mass and fluorescence cytometry identified comparable frequencies of cancer cell subsets, leukocytes, and endothelial cells in glioma (R = 0.97), and tonsil (R = 0.98).

CONCLUSIONS

This investigation establishes standard procedures for preparing viable single cell suspensions that preserve the cellular diversity of human tissue microenvironments. © 2016 International Clinical Cytometry Society.

Risk of post-operative pneumocephalus in patients with obstructive sleep apnea undergoing transsphenoidal surgery

Patients undergoing transsphenoidal surgery (TSS) have an anterior skull base defect that limits the use of positive pressure ventilation post-operatively. Obstructive sleep apnea (OSA) can be seen in these patients and is treated with continuous positive airway pressure (CPAP). In our study we documented the incidence of pre-existing OSA and reported the incidence of diagnosed pneumocephalus and its relationship to OSA. A retrospective review was conducted from a surgical outcomes database. Electronic medical records were reviewed, with an emphasis on diagnosis of OSA and documented symptomatic pneumocephalus. A total of 324 patients underwent 349 TSS for sellar mass resection. The average body mass index of the study cohort was 32.5kg/m(2). Sixty-nine patients (21%) had documented OSA. Only 25 out of 69 (36%) had a documented post-operative CPAP plan. Out of all 349 procedures, there were two incidents of pneumocephalus diagnosed. Neither of the patients had pre-existing OSA. One in five patients in our study had pre-existing OSA. Most patients returned to CPAP use within several weeks of TSS for resection of a sellar mass. Neither of the patients with pneumocephalus had pre-existing OSA and none of the patients with early re-initiation of CPAP developed this complication. This study provides preliminary evidence that resuming CPAP early in the post-operative period might be less dangerous than previously assumed.

Short-term postoperative surveillance imaging may be unnecessary in elderly patients with resected WHO Grade I meningiomas

The optimal timing and frequency of postoperative imaging surveillance after a meningioma resection are not well-established. The low recurrence rates and slow growth of World Health Organization (WHO) Grade I meningiomas in particular have raised doubts about the utility of postoperative imaging surveillance. We sought to analyze the cost and utility of asymptomatic surveillance imaging in elderly patients after the resection of a WHO Grade I meningioma. We conducted a retrospective cohort study on 45 patients who had a primary WHO Grade I meningioma resected at our institution between 2001-2013 at or above the age of 60 with a minimum of 2 years of follow-up. All postoperative clinic notes were reviewed alongside imaging results to verify that patients were asymptomatic during the surveillance period. MRI and CT scan costs (all $USD) were estimated at $599.61 and $334.31 respectively based on the Centers for Medicare and Medicaid national averages. During an average follow-up period of 4.5 years, the average number of total imaging studies performed per asymptomatic patient was 3.58 with an average total cost of $2086.30 per patient. Forty-two (93%) patients had no new abnormal findings on any of their imaging. Three (7%) patients demonstrated either a new meningioma or progressive growth of the postoperative residual tumor on imaging. No asymptomatic patient underwent a reoperation. Our data suggest that elderly patients with resected WHO Grade I meningiomas are at low risk for recurrence and may not need asymptomatic surveillance imaging for the first several postoperative years.

Early postoperative emergency department presentation predicts poor long-term outcomes in patients surgically treated for meningioma

Previous authors have identified a number of factors that predict morbidity, mortality, and recurrence in patients undergoing resection of a meningioma. We sought to study a novel potential prognostic indicator: early postoperative visit to the emergency department (ED). We conducted a retrospective cohort study on 239 patients who underwent a meningioma resection at our institution between 2001 and 2013 with over 3 months of follow-up postoperatively. All postoperative entries in the medical record were reviewed to identify any ED visit with a neurologic or wound-related complaint within a 90 day postoperative period. The relationships between ED presentation, tumor grade, and extent of surgical resection with future risk of operative recurrence and mortality were analyzed using Fisher's exact test. Variables associated with increased risks of mortality or operative recurrence in a univariate analysis were then included in the multivariate logistic regression model. Patients with a postoperative ED visit were found to be significantly more likely to die during the follow-up period (23.0% versus 4.85%, p<0.0001) or develop an eventual operative recurrence (12.2% versus 3.0%, p=0.0131). Postoperative ED presentation was found to be associated with a higher risk of mortality and operative recurrence independent of pathological tumor grade (p<0.0001 and p=0.0102, respectively). Presentation to the ED is associated with significantly higher rates of future operative recurrence and mortality in patients with recent meningioma resections. This poor prognostic relationship is independent of tumor pathological grade. Increased vigilance and follow-up may be warranted in such patients.

Factors Associated with Low Socioeconomic Status Predict Poor Postoperative Follow-up after Meningioma Resection

Objectives To quantify the rates of loss of follow-up after meningioma resection and to identify any key demographical associations. Design Retrospective cohort. Setting Vanderbilt University Medical Center, 2001-2013. Participants A total of 281 patients surgically treated for an intracranial meningioma at a single institution between 2001 and 2013. Main Outcome Measures Patient clinical follow-up within the first postoperative year. Results A history of tobacco use (p < 0.0001), ongoing alcohol abuse at time of presentation (p = 0.0014), Medicaid coverage (p < 0.0001), and lack of a college degree (p < 0.0001) were all found to be predictors of loss of follow-up at a statistically significant level. Conclusions Several factors associated with low socioeconomic status are predictors of poor clinical follow-up after meningioma resection. The health risk of poor follow-up in this patient population is significant, and increased measures are needed to ensure regular appointment attendance.

Imaging of Resected Nonfunctioning Pituitary Adenomas: The Cost of Surveillance

Objectives To determine the cost of annual magnetic resonance imaging (MRI) surveillance after resection of nonfunctioning pituitary adenomas (NFPAs) and its effectiveness in reducing visual compromise due to tumor recurrence. Design Retrospective case series. Setting Vanderbilt University Medical Center (2003-2011). Participants A total of 120 patients underwent primary transsphenoidal resection and surveillance of NFPAs between 2003 and 2011. Main Outcome Measures Time from initial surgery to most recent imaging or progression. Surveillance MRI costs according to Centers for Medicare and Medicaid database and visual field deficits. Results Patients received 382 surveillance scans at a total cost of $218,477.30. The median follow-up was 47 months (interquartile range [IQR]: 26-76), and the median interval between scans was 357 days (IQR: 225-434). Overall, 50 scans (13%) revealed tumor growth. The cost per scan revealing growth was $4,369.55. The cost to identify 19 patients (16%) with clinically significant growth was $11,498.80 per patient. A total of 5 of 19 patients (26%) experienced new visual deficits prior to intervention. Patients with visual decline tended to have longer scan intervals than those with preserved vision (mean: 239 versus 794 days; p = 0.0584). No patient with annual surveillance imaging experienced visual decline. Conclusions Annual MRI scans are a sensitive and cost-conscious method to identify NFPA recurrence prior to visual decline.

An experimental feasibility study on robotic endonasal telesurgery

BACKGROUND

Novel robots have recently been developed specifically for endonasal surgery. They can deliver several thin, tentacle-like surgical instruments through a single nostril. Among the many potential advantages of such a robotic system is the prospect of telesurgery over long distances.

OBJECTIVE

To describe a phantom pituitary tumor removal done by a surgeon in Nashville, Tennessee, controlling a robot located approximately 800 km away in Chapel Hill, North Carolina, the first remote telesurgery experiment involving tentacle-like concentric tube manipulators.

METHODS

A phantom pituitary tumor removal experiment was conducted twice, once locally and once remotely, with the robotic system. Robot commands and video were transmitted across the Internet. The latency of the system was evaluated quantitatively in both local and remote cases to determine the effect of the 800-km distance between the surgeon and robot.

RESULTS

We measured a control and video latency of < 100 milliseconds in the remote case. Qualitatively, the surgeon was able to carry out the experiment easily and observed no discernable difference between the remote and local cases.

CONCLUSION

Telesurgery over long distances is feasible with this robotic system. In the longer term, this may enable expert skull base surgeons to help many more patients by performing surgeries remotely over long distances.

Endonasal Skull Base Tumor Removal Using Concentric Tube Continuum Robots: A Phantom Study

Objectives The purpose of this study is to experimentally evaluate the use of concentric tube continuum robots in endonasal skull base tumor removal. This new type of surgical robot offers many advantages over existing straight and rigid surgical tools including added dexterity, the ability to scale movements, and the ability to rotate the end effector while leaving the robot fixed in space. In this study, a concentric tube continuum robot was used to remove simulated pituitary tumors from a skull phantom. Design The robot was teleoperated by experienced skull base surgeons to remove a phantom pituitary tumor within a skull. Percentage resection was measured by weight. Resection duration was timed. Setting Academic research laboratory. Main Outcome Measures Percentage removal of tumor material and procedure duration. Results Average removal percentage of 79.8 ± 5.9% and average time to complete procedure of 12.5 ± 4.1 minutes (n = 20). Conclusions The robotic system presented here for use in endonasal skull base surgery shows promise in improving the dexterity, tool motion, and end effector capabilities currently available with straight and rigid tools while remaining an effective tool for resecting the tumor.

Efficacy of local polymer-based and systemic delivery of the anti-glutamatergic agents riluzole and memantine in rat glioma models

OBJECT

The poor outcome of malignant gliomas is largely due to local invasiveness. Previous studies suggest that gliomas secrete excess glutamate and destroy surrounding normal peritumoral brain by means of excitotoxic mechanisms. In this study the authors assessed the effect on survival of 2 glutamate modulators (riluzole and memantine) in rodent glioma models.

METHODS

In an in vitro growth inhibition assay, F98 and 9L cells were exposed to riluzole and memantine. Mouse cerebellar organotypic cultures were implanted with F98 glioma cells and treated with radiation, radiation + riluzole, or vehicle and assessed for tumor growth. Safety and tolerability of intracranially implanted riluzole and memantine CPP:SA polymers were tested in F344 rats. The efficacy of these drugs was tested against the 9L model and riluzole was further tested with and without radiation therapy (RT).

RESULTS

In vitro assays showed effective growth inhibition of both drugs on F98 and 9L cell lines. F98 organotypic cultures showed reduced growth of tumors treated with radiation and riluzole in comparison with untreated cultures or cultures treated with radiation or riluzole alone. Three separate efficacy experiments all showed that localized delivery of riluzole or memantine is efficacious against the 9L gliosarcoma tumor in vivo. Systemic riluzole monotherapy was ineffective; however, riluzole given with RT resulted in improved survival.

CONCLUSIONS

Riluzole and memantine can be safely and effectively delivered intracranially via polymer in rat glioma models. Both drugs demonstrate efficacy against the 9L gliosarcoma and F98 glioma in vitro and in vivo. Although systemic riluzole proved ineffective in increasing survival, riluzole acted synergistically with radiation and increased survival compared with RT or riluzole alone.

Retrosigmoid craniotomy for resection of acoustic neuroma with hearing preservation: a video publication

In this publication, video format is utilized to review the operative technique of retrosigmoid craniotomy for resection of acoustic neuroma with attempted hearing preservation. Steps of the operative procedure are reviewed and salient principles and technical nuances useful in minimizing complications and maximizing efficacy are discussed. The video can be found here: http://youtu.be/PBE5rQ7B0Ls .

Temporal bone encephalocele and cerebrospinal fluid fistula repair utilizing the middle cranial fossa or combined mastoid–middle cranial fossa approach

Object

The goals of this study were to report the clinical presentation, radiographic findings, operative strategy, and outcomes among patients with temporal bone encephaloceles and cerebrospinal fluid fistulas (CSFFs) and to identify clinical variables associated with surgical outcome.

Methods

A retrospective case series including all patients who underwent a middle fossa craniotomy or combined mastoid–middle cranial fossa repair of encephalocele and/or CSFF between 2000 and 2012 was accrued from 2 tertiary academic referral centers.

Results

Eighty-nine consecutive surgeries (86 patients, 59.3% women) were included. The mean age at time of surgery was 52.3 years, and the left side was affected in 53.9% of cases. The mean delay between symptom onset and diagnosis was 35.4 months, and the most common presenting symptoms were hearing loss (92.1%) and persistent ipsilateral otorrhea (73.0%). Few reported a history of intracranial infection (6.7%) or seizures (2.2%).

Thirteen (14.6%) of 89 cases had a history of major head trauma, 23 (25.8%) were associated with chronic ear disease without prior operation, 17 (19.1%) occurred following tympanomastoidectomy, and 1 (1.1%) developed in a patient with a cerebral aqueduct cyst resulting in obstructive hydrocephalus. The remaining 35 cases (39.3%) were considered spontaneous. Among all patients, the mean body mass index (BMI) was 35.3 kg/m2, and 46.4% exhibited empty sella syndrome. Patients with spontaneous lesions were statistically significantly older (p = 0.007) and were more commonly female (p = 0.048) compared with those with nonspontaneous pathology. Additionally, those with spontaneous lesions had a greater BMI than those with nonspontaneous disease (p = 0.102), although this difference did not achieve statistical significance.

Thirty-two surgeries (36.0%) involved a middle fossa craniotomy alone, whereas 57 (64.0%) involved a combined mastoid–middle fossa repair. There were 7 recurrences (7.9%); 2 patients with recurrence developed meningitis. The use of artificial titanium mesh was statistically associated with the development of recurrent CSFF (p = 0.004), postoperative wound infection (p = 0.039), and meningitis (p = 0.014). Also notable, 6 of the 7 cases with recurrence had evidence of intracranial hypertension. When the 11 cases that involved using titanium mesh were excluded, 96.2% of patients whose lesions were reconstructed with an autologous multilayer repair had neither recurrent CSFF nor meningitis at the last follow-up.

Conclusions

Patients with temporal bone encephalocele and CSFF commonly present with persistent otorrhea and conductive hearing loss mimicking chronic middle ear disease, which likely contributes to a delay in diagnosis. There is a high prevalence of obesity among this patient population, which may play a role in the pathogenesis of primary and recurrent disease. A middle fossa craniotomy or a combined mastoid–middle fossa approach incorporating a multilayer autologous tissue technique is a safe and reliable method of repair that may be particularly useful for large or multifocal defects. Defect reconstruction using artificial titanium mesh should generally be avoided given increased risks of recurrence and postoperative meningitis.

A Telerobotic System for Transnasal Surgery

Mechanics-based models of concentric tube continuum robots have recently achieved a level of sophistication that makes it possible to begin to apply these robots to a variety of real-world clinical scenarios. Endonasal skull base surgery is one such application, where their small diameter and tentacle like dexterity are particularly advantageous. In this paper we provide the medical motivation for an endonasal surgical robot featuring concentric tube manipulators, and describe our model-based design and teleoperation methods, as well as a complete system incorporating image-guidance. Experimental demonstrations using a laparoscopic training task, a cadaver reachability study, and a phantom tumor resection experiment illustrate that both novice and expert users can effectively teleoperate the system, and that skull base surgeons can use the robot to achieve their objectives in a realistic surgical scenario.

Forces Applied at the Skull Base during Transnasal Endoscopic Transsphenoidal Pituitary Tumor Excision

Objectives Our laboratory is developing a surgical robotic system to further improve dexterity and visualization that will allow for broader application of transnasal skull base surgery. To optimize this system, intraoperative force data are required. Using a modified curette, force data were recorded and analyzed during pituitary tumor excision. Design A neurosurgical curette was modified by the addition of a force sensor. The instrument was validated in an in vitro model to measure forces during simulated pituitary tumor excision. Following this, intraoperative force data from three patients during transnasal endoscopic excision of pituitary tumors was obtained. Setting Academic medical center. Main Outcome Measures Forces applied at the skull base during surgical excision of pituitary tumors. Results Average forces applied during in vitro testing ranged from 0.1 to 0.15 N. Average forces recorded during in vivo testing ranged from 0.1 to 0.5 N. Maximal forces occurred with collisions of the bony sella. The average maximal force was 1.61 N. There were no complications related to the use of the modified curette. Conclusions Forces to remove pituitary tumor are small and are similar between patients. The in vitro model presented here is adequate for further testing of a robotic skull base surgery system.

Identification of blood protein biomarkers that aid in the clinical assessment of patients with malignant glioma

Analyzing molecular biomarkers using blood is an important approach for clinical assessment of malignant glioma. We investigated a molecular proteomic biomarker-based approach for glioblastoma using patients' blood samples. The expression levels of a list of candidate proteins were quantified in plasma and serum samples from two different cohorts of patients with malignant glioma and normal controls. The biological function was studied for one of the identified markers. Additionally, the prognostic significance of protein marker expression was measured by survival analysis. As a result, protein biomarkers associated with malignant glioma were identified from the blood specimens and five of the protein biomarkers were common to both cohorts. Immunohistochemical analysis demonstrated that many of the protein biomarkers identified in peripheral blood specimens were expressed in malignant gliomas. Staining levels for one of the biomarkers, MIP-1α, was found to correlate with WHO grade among invasive gliomas, and we demonstrate that MIP-1α promotes human glioblastoma cell proliferation and migration. Additionally, four prognostic protein biomarkers were identified. In conclusion, we demonstrate that both peripheral blood plasma and serum specimens are highly valuable and complementary to each other in the quest for protein biomarkers of malignant glioma. Sets of novel protein biomarkers were identified that may aid in the diagnosis and prognosis of patients with malignant glioma.

Safety and cost effectiveness of early discharge following microscopic trans-sphenoidal resection of pituitary lesions

Background:

Inpatient hospitalization following trans-sphenoidal resection of a pituitary neoplasm has traditionally involved a hospital stay of 2 days or more. It has been the policy of the senior pituitary neurosurgeon (GSA) since February 2008 to allow discharge home on postoperative day (POD) 1 if thirst mechanism is intact and the patient is tolerating oral hydration. The goal of this study was to evaluate the safety and cost-effectiveness of this practice.

Methods:

We reviewed the charts of 30 patients, designated the early discharge group, who consecutively underwent microscopic trans-sphenoidal resection from February 2008 to December 2009. We then reviewed the charts of 30 patients, designated the standard discharge group, who consecutively underwent trans-sphenoidal resection from May 2007 to February 2008 before discharge home on POD1 was considered an appropriate option. Safety and cost-effectiveness of the two patient groups were retrospectively evaluated.

Results

Patients in the early discharge group went home, on average, on POD 1.3. Following exclusion of two outliers, the average date of discharge of patients in the standard discharge group was POD 2.2. The policy of early discharge saved an average of $1,949 per patient-approximately 4% the total cost of the procedure. Trends toward decreased costs did not reach statistical significance. While no patient suffered any measurable morbidity as a result of early discharge home, 1 in 3 patients in the early discharge group required unscheduled postoperative re-evaluation-a figure significantly higher than the standard discharge group.

Conclusions:

At a dedicated pituitary center with the resources to closely monitor outpatient endocrinological and postsurgical issues, early discharge home following trans-sphenoidal surgery is a safe option that is associated with an increase in the number of unscheduled postoperative visits and a trend toward lower costs.

Delayed cerebral radiation necrosis following treatment for a plasmacytoma of the skull

Background:

Cerebral radiation necrosis is a relatively common complication of radiation therapy for intracranial malignancies which can also rarely be encountered after radiation of extracranial lesions of the head and neck. We present the first reported case of cerebral radiation necrosis in a patient who underwent radiation therapy for a plasmacytoma of the skull.

Case Description:

A 68-year-old male with multiple myeloma presented with an enhancing right frontal mass, 8 years after receiving radiation therapy for a plasmacytoma of the left frontal skull. The patient underwent a diagnostic and therapeutic craniotomy for a presumed neoplastic lesion. The pathologic diagnosis made in this case was delayed radiation necrosis. The patient was followed for over a year during which this process continued to evolve before the ultimate resolution of his clinical symptoms and radiographic abnormality.

Conclusion:

This case highlights the importance of considering radiation necrosis in the differential diagnosis of any patient with an intracranial mass and a history of radiation for an extracranial head and neck malignancy, regardless of timing and laterality. This case also provides unique insights into the ongoing debate regarding the role of the aberrant immune response in the pathogenesis of delayed cerebral radiation necrosis.

Abstract LB-211: Identification of blood-based protein biomarker candidates for malignant glioma

A reliable, non-invasive and convenient method for detecting malignant gliomas progression and responsiveness to treatment will significantly increase the survival of patients. A protein biomarker-based method for high-grade glioma using patients’ blood samples was investigated. Using a multiplex Luminex immunoassay, 90 proteins associated with cancer were examined in the plasma from high-grade glioma patients (N=28) and non-cancer controls (N=367). Wilcoxon rank-sum test was performed to select the differentially expressed proteins. Receiver operating characteristics (ROC) curves were constructed to determine their diagnostic accuracy. A second cohort of serum samples from different GBM patients (N=20) and non-cancer controls (N=1278) was similarly analyzed. A total of 40 and 25 proteins were found to be significantly differentially expressed between the glioma and control groups (p &lt; 0.0005) using the plasma or serum samples, respectively. With ROC analyses, 19 and 9 proteins were found with area under the curve greater than 85% using the plasma or serum samples, respectively. Five protein biomarkers with an average of 87.2% sensitivity and 87.4% specificity were similarly identified in these two different cohorts of patients. In addition, four plasma protein biomarkers were found to be significantly associated with high-grade glioma patients’ survival. Immunohistochemistry (IHC) showed that human glioblastoma tissue positively expressed the identified protein biomarkers. Differential expression levels for one of the identified protein biomarkers, MIP 1-alpha, were further investigated using human glioma tissue microarray. Compared to grade II glioma tissues (N=22), MIP 1-alpha was found to be overexpressed in grade III (N=9) and grade IV (N=41) glioma tissues (p &lt; 0.0001). Furthermore, MIP 1-alpha was found to directly promote T98G glioma cell line proliferation and migration (p&lt;0.05) using WST-1 proliferation assay and wound closure assay, respectively. Overall, a blood-based protein signature for high-grade gliomas was identified which may offer a minimally-invasive approach for diagnosing high-grade glioma and monitoring for recurrence or response to therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-211.

Endoscopic, image-guided, transnasal instillation of (32)P for recurrent infrachiasmatic cystic craniopharyngioma

INTRODUCTION

The neurovascular and anatomic relationships surrounding craniopharyngiomas, and their tending to recur despite any method of primary treatment, has characterized this tumor as an exigent and frustrating clinical entity. Various strategies have been developed to deal with recurrences which include radical re-resection, stereotactic or localized radiotherapy, cyst fenestration, marsupialization or stent placement, and intracavitary therapies such as bleomycin or radionucleotides.

CASE REPORT

We present a case where the patient had previously experienced a transsphenoidal resection followed by a pterional, microsurgical resection of her craniopharyngioma at an outside hospital. The second recurrence was cystic, and confined to the sella. We elected to proceed with a minimally invasive, transnasal endoscopic approach for the instillation of phosphorus 32 radionucleotide into the cyst. There were no complications, and the patient was discharged home on postoperative day one. At six months, there was no progression of the cyst.

CONCLUSION

While intracystic adionucleotide therapies have been utilized for primary and secondary treatment of craniopharyngioma, to our knowledge, this is the first report of the delivery of this therapy by an endoscopic transsphenoidal route.

Anterior endoscopic skull-base surgery getting started: an otolaryngologist's perspective

PURPOSE OF REVIEW

Anterior endoscopic skull-base surgery is a relatively new field requiring new levels of cooperation between otolaryngology and neurosurgery. The formation of these teams is discussed along with their challenges.

RECENT FINDINGS

A significant amount of literature has been produced in the last few years, chronicling new and innovative techniques for anterior endoscopic skull-base surgery. These techniques are requiring close coordination between otolaryngologist and neurosurgeon in a multidisciplinary approach. However, there are obstacles to overcome in forming these teams.

SUMMARY

Anterior endoscopic skull-base surgery is a technically challenging skill set which requires multiple factors to perform successfully. Factors to overcome require surgical training, appropriate patient base, specialized equipment and institutional inertia. These obstacles may be overcome in the majority of centers.

Immunohistochemical Analysis of Metastatic Neoplasms of the Central Nervous System

Metastatic neoplasms to the central nervous system are often encountered in the practice of surgical neuropathology. It is not uncommon for patients with systemic malignancies to present to medical attention because of symptoms from a brain metastasis and for the tissue samples procured from these lesions to represent the first tissue available to study a malignancy from an unknown primary. In general surgical pathology, the evaluation of a metastatic neoplasm of unknown primary is a very complicated process, requiring knowledge of numerous different tumor types, reagents, and staining patterns. The past few years, however, have seen a remarkable refinement in the immunohistochemical tools at our disposal that now empower neuropathologists to take an active role in defining the relatively limited subset of neoplasms that commonly metastasize to the central nervous system. This information can direct imaging studies to find the primary tumor in a patient with an unknown primary, clarify the likely primary site of origin in patients who have small tumors in multiple sites without an obvious primary lesion, or establish lesions as late metastases of remote malignancies. Furthermore, specific treatments can begin and additional invasive procedures may be prevented if the neuropathologic evaluation of metastatic neoplasms provides information beyond the traditional diagnosis of "metastatic neoplasm." In this review, differential cytokeratins, adjuvant markers, and organ-specific antibodies are described and the immunohistochemical signatures of metastatic neoplasms that are commonly seen by neuropathologists are discussed.

Methylated tumor-specific DNA as a plasma biomarker in patients with glioma

OBJECTIVE

Patients with systemic malignancies have substantial quantities of tumor-specific DNA in their plasma which may serve as a potential biomarker for tumor burden. This approach has not been studied in gliomas.

METHODS

Methylation specific polymerase chain reaction (MSP) was used to determine the methylation status the promoters for p16/(INK4a), MGMT, p73, and RARbeta within glioma tissue and plasma. Blood was collected prior to craniotomy in 10 patients with glioma. DNA was extracted from tumor and plasma samples and assayed with MSP. Total plasma DNA also was quantified. Tumor-specific plasma DNA was defined as identification of the same methylated promoter (MP) in both tumor and plasma.

RESULTS

Total plasma DNA concentration was markedly elevated (mean 6,503 ng/ml, SEM 1,400 ng/ml). Glioma tissue contained methylation of at least one promoter in 9 out of 10 (90 percent) of patients studied. Of these patients, 6 out of 9 (67 percent) demonstrated methylation of at least one of the same promoters in plasma. Five of these had one MP identified in the plasma and one had 2 MP. Overall, glioma-specific plasma DNA was present in plasma of 6 out of 10 (60 percent) of patients. Each MP DNA marker found in the plasma also was present in the intracranial tumor.

CONCLUSIONS

Patients with high grade gliomas have large amounts of DNA in the plasma. Of these primary brain tumors, 90 percent contained methylated gene promoters, and in over 60 percent of these patients the same methylated promoters present in the tumor also were found in the plasma. This represents the first step to developing a quantitative plasma biomarker that could be used to monitor glioma status.

A method to track cortical surface deformations using a laser range scanner

This paper reports a novel method to track brain shift using a laser-range scanner (LRS) and nonrigid registration techniques. The LRS used in this paper is capable of generating textured point-clouds describing the surface geometry/intensity pattern of the brain as presented during cranial surgery. Using serial LRS acquisitions of the brain's surface and two-dimensional (2-D) nonrigid image registration, we developed a method to track surface motion during neurosurgical procedures. A series of experiments devised to evaluate the performance of the developed shift-tracking protocol are reported. In a controlled, quantitative phantom experiment, the results demonstrate that the surface shift-tracking protocol is capable of resolving shift to an accuracy of approximately 1.6 mm given initial shifts on the order of 15 mm. Furthermore, in a preliminary in vivo case using the tracked LRS and an independent optical measurement system, the automatic protocol was able to reconstruct 50% of the brain shift with an accuracy of 3.7 mm while the manual measurement was able to reconstruct 77% with an accuracy of 2.1 mm. The results suggest that a LRS is an effective tool for tracking brain surface shift during neurosurgery.

Successful transarterial Guglielmi detachable coil embolization of posttraumatic posterior communicating artery-cavernous sinus fistula: technical note

OBJECTIVE

Carotid-cavernous fistulae are uncommon but well-documented sequelae of craniofacial trauma. A rare subset may arise from the posterior communicating artery instead of from the carotid artery proper. The presentation is similar to that of carotid-cavernous fistulae, with ocular pain, chemosis, and proptosis being the common symptoms. The first successful transarterial coil embolization of this type of lesion is described.

METHODS

A 42-year-old man presented with severe craniocerebral injury, including multiple craniofacial fractures, after an industrial accident. He required emergent craniotomy for an open depressed cranial fracture and epidural hematoma. Six weeks after presentation, the patient began to exhibit progressive chemosis and proptosis. Magnetic resonance imaging revealed findings consistent with a carotid-cavernous fistula.

RESULTS

Angiography revealed a fistula between the posterior communicating artery and the cavernous sinus. The origin of the fistula in the posterior communicating artery was successfully obliterated with Guglielmi detachable coiling. Subsequent studies demonstrated no flow through the fistula and good opacification of the ipsilateral posterior cerebral artery by the vertebrobasilar system.

CONCLUSION

Posterior communicating artery-cavernous fistulae are a rare sequel of trauma. They may be treated successfully with the use of transarterial coil embolization.

Potentiation of chemotherapeutic agents following antagonism of nuclear factor kappa B in human gliomas

Future success using chemotherapy against human gliomas may result from exploiting unique molecular vulnerabilities of these tumors. Chemotherapy frequently results in DNA damage. When such damage is sensed by the cell, programmed cell death, or apoptosis, may be initiated. However, chemotherapy-induced DNA damage may activate nuclear factor kappa B (NF-kappaB) and block apoptosis. We inhibited NF-kappaB using a gene therapy approach to determine whether this would render human glioma cells more susceptible to chemotherapy. U87 and U251 glioma cell lines were infected with either treatment adenovirus containing the gene for a mutant non-degradable form of IkappaBalpha, which is an inhibitor of NF-kappaB nuclear translocation, or empty control virus. Following viral infection, cells were treated either with BCNU, carboplatin, tumor necrosis factor alpha (TNF-alpha), or SN-38. Chemotherapy resulted in a marked increase in active intranuclear NF-kappaB. This response was greatly decreased by insertion of the mutant repressor gene. Similarly, a significant increase in cell killing by all chemotherapy age was demonstrated following infection with treatment virus. Expression of the mutant repressor gene also resulted in increased apoptosis by TUNEL assay following chemotherapy. Numerous genes are responsible for glioma chemoresistance. DNA damage by chemotherapy may induce the antiapoptotic factor NF-kappaB and prevent programmed cell death. Insertion of a mutant inhibitor of NF-kappaB strips cells of this antiapoptotic defense and renders them more susceptible to killing by chemotherapy via increased apoptosis.

Complications of lumbar drainage after thoracoabdominal aortic aneurysm repair

OBJECTIVES

Paraplegia remains a frequent complication of thoracoabdominal aortic aneurysm (TAAA) repair. Many adjunct therapies have been developed to address this complication. Lumbar drainage is frequently used in an attempt to decrease intrathecal pressure and improve intramedullary perfusion pressure. The effectiveness of this therapy is unclear, and the complications of lumbar drainage used for this indication are unknown. We present a case of intraspinal hematoma with significant neurologic deficit after TAAA repair and review the associated complications of lumbar drains placed for TAAA.

METHODS

The charts of all patients undergoing operations for TAAA repair were reviewed. Patients who underwent perioperative placement of a lumbar drain were included regardless of aneurysm type or etiology. Demographics, Crawford grade, and perioperative parameters and complications were reviewed.

RESULTS

Sixty-five patients underwent TAAA repair with 62 (95%) receiving a preoperative lumbar drain. There were two (3.2%) intraspinal hemorrhagic complications, including one patient with a poor neurologic outcome. No infections or other complications directly related to drainage were identified. Multivariate logistic regression analysis failed to demonstrate a significant association between lumbar drain complications and perioperative and intraoperative parameters such as blood loss or hypotension, level of drain placement, and Crawford grade.

CONCLUSIONS

Lumbar drainage is a frequent adjunct to TAAA repair. However, placement of the drain itself can be associated with significant complications whose aggravating factors may be unidentifiable. Complications resulting from lumbar drainage should be considered in any patient who has postoperative lower extremity neurologic deficits.

Mechanical stability of polyethylene liners cemented into acetabular shells

Revision of well-fixed, metal-backed acetabular components for dislocation or polyethylene failure requires consideration of removing the entire construct or replacing the polyethylene liner only. For non-modular or first-generation modular components with poor locking mechanisms, one option is to cement undersized liners into well-fixed shells. The purpose of this study was to measure the stability of undersized liners cemented into metal acetabular shells and compare the results with those of modular components. Hooded polyethylene liners measuring 28 x 50 mm and 28 x 56 mm were cemented into 66-mm acetabular shells (Smith & Nephew, Inc., Memphis, TN) with Simplex-P polymethylmethacrylate cement (Howmedica, Inc., Rutherford, NJ) giving 4- and 2-mm cement mantles, respectively. The force required to lever-out the liners from the shells was measured using the protocol described by Tradonsky et al. Assemblies with 4-mm mantles dissociated at an average of 322 +/- 47 in-lbf.; however, the assemblies with 2-mm mantles would not dissociate before the polyethylene yielded at torques as high as 600 in-lbf. These results compare favorably with the previously reported range (43 to 684 in-lbf) for modular acetabular components. These results suggest that undersized polyethylene liners can be cemented into well-fixed acetabular shells and expected to be stable.

Effect of leukocyte-endothelial adhesion antagonism on neutrophil migration and neurologic outcome after cortical trauma

BACKGROUND

Administration of anti-CD11B, a monoclonal antibody directed against the leukocyte adhesion molecule CD11B, results in decreased neutrophil infiltration into injured tissue after experimental ischemia. We determined the effect of anti-CD11B administration on neutrophil migration and neurologic functioning after experimental cortical trauma.

METHODS

Injuries were produced by a pneumatic impactor. Treatment animals received anti-CD11B after injury. Neurologic functioning was quantitated at 1, 12, and 24 hours after injury. Neutrophil migration was assessed with the myeloperoxidase assay.

RESULTS

Neutrophil influx was increased in injured cortex after trauma. Anti-CD11B significantly reduced neutrophil influx. There was no significant improvement in neurologic functioning after MAb administration.

CONCLUSIONS

These results show there is marked neutrophil response to injury as produced with the pneumatic contusion model. This migration may be significantly attenuated by administration of a anti-CD11B.