Stereoscopic Monitoring technique for motor area tumors

BACKGROUND AND OBJECTIVES

The balance between a comprehensive intraoperative-neuromonitoring (IONM) for both upper and lower limb while ensuring the reliability of motor-evoked potentials (MEPs) is paramount in motor area surgery. It's commonly hard to obtain a good simultaneous stimulation of both upper/lower limb, a series of factors can bias MEP accuracy and inappropriate stimulation intensity can result in unreliable monitoring. The presented IONM technique is based on the concurrent use of both transcranial and strip electrodes to facilitate a simultaneous monitoring of both upper and lower limb at optimized stimulation intensities, increasing IONM accuracy, during motor-area surgery.

METHODS

Ten nonconsecutive motor area tumors were studied. A good visualization of both limbs was observed in the series, at a low amperage (1.2mA from strip-electrode and 165,3mA from transcranial-electrode).

RESULTS

Our analysis confirm concordance between IONM data and postoperative outcome: a MEP reduction >20% and >50% was coherent with postoperative mRS changes, without false negative IONM.

CONCLUSION

The technique demonstrated to be accurate in providing a good simultaneous neurophysiological evaluation of both upper/lower limb with an optimized and stimulation amplitude; it warrants a low encumbrance of electrodes in the surgical field. Results confirm its feasibility and reliability. Considering the relatively small sample, this study represents a "proof of concept" rather than an applicability study.

Posterior cranial fossa surgery with a 3D Exoscope: a single-center survey-based analysis and a literature review

BACKGROUND

The potential advantages of exoscopy have been discussed theoretically for a long time. Such a concept holds significance, especially in the specific setting of the posterior cranial fossa (PCF), characterized by complex anatomy and long and narrow surgical corridors with relatively extreme working angles.

AIM

We aimed to: 1) analyze the institutional preliminary case-based data on the use of the Robotic 3D Exoscope AEOS Aesculap in three different PCF approaches: retrosigmoid (RSA), midline suboccipital (MSA), and supra cerebellar infratentorial (SIA) via feedbacks was collected using a 20-point questionnaire. 2) perform a comprehensive review of the literature concerning the use of EX in PCF surgery RESULTS: A total of 38 patients with neurosurgical pathologies underwent a neurosurgical procedure using the EX (Robotic 3D exoscope AEOS Aesculap) at our institution between January and March 2022. 21 surgeons were involved in the abovementioned PCF surgeries and answered the questionnaire. The main perceived advantages were in terms of ergonomics (67%) and magnification (52%) and visualization of extreme angles. The main reported disadvantage was color vision (16, 76%), followed by manual mobility (24%). Concerning the review, the search of the literature yielded a total of 177 results. Upon full-text review, 17 articles were included, including 153 patients.

CONCLUSIONS

In conclusion, our study provides a comprehensive evaluation of the advantages and challenges associated with using the exoscope in posterior fossa surgery, setting a precedent as the first to report on a questionnaire-based analysis of exoscope utilization in this specific domain.

The prevalence of imposter syndrome among neurosurgeons in Europe: An EANS YNC survey

Introduction

Imposter syndrome (IS), characterized by persistent doubts about one's abilities and fear of exposure as a fraud, is a prevalent psychological condition, particularly impacting physicians. In neurosurgery, known for its competitiveness and demands, the prevalence of IS remains high.

Research question

Recognizing the limited literature on IS within the neurosurgical community, this European survey aimed to determine its prevalence among young neurosurgeons and identify associated factors.

Material and methods

The survey, conducted by the Young Neurosurgeon Committee of the European Association of Neurosurgical Societies, gathered responses from 232 participants. The survey included demographics, the Clance Imposter Phenomenon Survey (CIPS), and an analysis of potential compensatory mechanisms.

Results

Nearly 94% of respondents exhibited signs of IS, with the majority experiencing moderate (36.21%) or frequent (40.52%) symptoms. Analyses revealed associations between IS and factors such as level of experience, sex, and board-certification.

Discussion and conclusion

The findings suggest a significant prevalence of IS among young neurosurgeons, with notable associations with sex and level of experience. Compensatory mechanisms, such as working hours, article reading, and participation in events, did not show significant correlations with IS. Notably, male sex emerged as an independent protective factor against frequent/intense IS, while reading more than five articles per week was identified as a risk factor. The identification of protective and risk factors, particularly the influence of gender and reading habits, contributes valuable insights for developing targeted interventions to mitigate IS and improve the well-being of neurosurgeons.

Do Minimally Invasive Approaches to Pediatric Orbital Tumors Provide an Advantage on Outcome and Efficiency?

OBJECTIVE

The present study evaluated whether minimally invasive approaches to orbital lesions could improve surgical, clinical, and aesthetic outcomes compared with more invasive ones. This is the first study specifically addressing this topic in children.

METHODS

Children consecutively operated on from January 2010 to January 2020 were analyzed. Thirty patients matched the inclusion criteria and were divided into group A: 14 cases treated with traditional surgical approaches; and group B: 16 cases managed by minimally invasive approaches.

RESULTS

There were no significant differences between the 2 groups in terms of demographic data and extent of tumor resection. Mean surgical time for the approach (40 minutes vs. 70 minutes, P < 0.0001), surgical complication such as periorbital edema (37% vs. 78%, P = 0.02) and dural tear (0 vs. 21%, P = 0.05), and procedures cost (P < 0.0001) were significantly reduced in group B. Regarding clinical outcomes, group B showed a significant reduction both in terms of postoperative pain (mean score based on visual pain scale was 2.9 vs. 4.1 P = 0.003) and mean hospitalization time (4.5 days vs. 5.5 days, P = 0.0004). The cosmetic outcome according to the Sloan classification was significantly better in group B as well (81% vs. 36% class I patients, P = 0.005).

CONCLUSIONS

The use of mini-invasive approaches to orbital tumor has clear advantages in terms of surgical, clinical, and cosmetic outcomes in comparable patients; therefore, they should be preferred whenever feasible. Craniotomic approaches remain necessary for very large tumors.

Navigating Complexity: A Comprehensive Approach to Middle Cerebral Artery Aneurysms

Background: The concept of aneurysm "complexity" has undergone significant changes in recent years, with advancements in endovascular treatments. However, surgical clipping remains a relevant option for middle cerebral artery (MCA) aneurysms. Hence, the classical criteria used to define surgically complex MCA aneurysms require updating. Our objective is to review our institutional series, considering the impacts of various complexity features, and provide a treatment strategy algorithm. Methods: We conducted a retrospective review of our institutional experience with "complex MCA" aneurysms and analyzed single aneurysmal-related factors influencing treatment decisions. Results: We identified 14 complex cases, each exhibiting at least two complexity criteria, including fusiform shape (57%), large size (35%), giant size (21%), vessel branching from the sac (50%), intrasaccular thrombi (35%), and previous clipping/coiling (14%). In 92% of cases, the aneurysm had a wide neck, and 28% exhibited tortuosity or stenosis of proximal vessels. Conclusions: The optimal management of complex MCA aneurysms depends on a decision-making algorithm that considers various complexity criteria. In a modern medical setting, this process helps clarify the choice of treatment strategy, which should be tailored to factors such as aneurysm morphology and patient characteristics, including a combination of endovascular and surgical techniques.

Reducing the Gap in Neurosurgical Education in LMICs: A Report of a Non-Profit Educational Program

INTRODUCTION

Central to neurosurgical care, neurosurgical education is particularly needed in low- and middle-income countries (LMICs), where opportunities for neurosurgical training are limited due to social and economic constraints and an inadequate workforce. The present paper aims (1) to evaluate the validity and usability of a cadaver-free hybrid system in the context of LMICs and (2) to report their learning needs and whether the courses meet those needs via a comprehensive survey.

METHODS

From April to November 2021, a non-profit initiative consisting of a series of innovative cadaver-free courses based on virtual and practical training was organized. This project emerged from a collaboration between the Young Neurosurgeons Forum of the World Federation of Neurological Societies (WFNS), the NIHR Global Health Research Group on Neurotrauma, and UpSurgeOn, an Italian hi-tech company specialized in simulation technologies, creator of the UpSurgeOn Box, a hyper-realistic simulator of cranial approaches fused with augmented reality. Over that period, 11 cadaver-free courses were held in LMICs using remote hands-on Box simulators.

RESULTS

One hundred sixty-eight participants completed an online survey after course completion of the course. The anatomical accuracy of simulators was overall rated high by the participant. The simulator provided a challenging but manageable learning curve, and 86% of participants found the Box to be very intuitive to use. When asked if the sequence of mental training (app), hybrid training (Augmented Reality), and manual training (the Box) was an effective method of training to fill the gap between theoretical knowledge and practice on a real patient/cadaver, 83% of participants agreed. Overall, the hands-on activities on the simulators have been satisfactory, as well as the integration between physical and digital simulation.

CONCLUSIONS

This project demonstrated that a cadaver-free hybrid (virtual/hands-on) training system could potentially participate in accelerating the learning curve of neurosurgical residents, especially in the setting of limited training possibilities such as LMICs, which were only worsened during the COVID-19 pandemic.

Predictive value of intraoperative vagus nerve corticobulbar motor evoked potentials to assess the risk of dysphagia in fourth ventricle surgery

OBJECTIVE

Dysphagia is a significant complication in fourth ventricle surgery. Corticobulbar motor evoked potentials (CB-MEPs) of the lower cranial nerves may provide real-time information possibly correlating with postoperative swallowing dysfunction, and the vagus nerves may prove ideal for this purpose. However, the literature is heterogeneous, non-systematic, and inconclusive on this topic. The object of this retrospective study was to evaluate the correlation between CB-MEPs of the vagus nerve and postoperative worsening or new-onset swallowing deficits in intraaxial fourth ventricle surgery.

METHODS

In 21 consecutive patients undergoing surgery for fourth ventricle intraaxial tumors between February 2018 and October 2022, endotracheal tubes with two applied electrodes contacting the vocal cords were used to record vagus nerve MEPs including values at baseline, the end of surgery, and the minimum value during the operation. From the mean value of right and left vagus nerve MEP amplitudes, the minimum-to-baseline amplitude ratio (MBR) and final-to-baseline amplitude ratio (FBR) were calculated. These indexes were correlated with postoperative swallowing function.

RESULTS

Given their clinical significance, receiver operating characteristic curves were obtained to evaluate the performance of these indexes in predicting postoperative swallowing function. The area under the curve (AUC) was 0.850 (p < 0.001) and the best cutoff for FBR was 67.55% for the worsening of swallowing in the postoperative period. The AUC was 0.750 (p = 0.026) and the best cutoff was 46.37% in MBR for the absence of a swallowing disorder at the late follow-up.

CONCLUSIONS

This study confirmed that vagus nerve MEPs are reliable predictors of postoperative swallowing function in fourth ventricle surgery and can be feasibly used as an intraoperative monitoring technique.

Applicability and efficacy of ultrasound elastography in neurosurgery: a systematic review of the literature

INTRODUCTION

Neurosurgery is one of the fields in which intraoperative imaging is paramount. One of these main imaging tools that have been acquiring the interest of the neurosurgical community is Ultrasound elastography (USE), which is an imaging technology sensitive to tissue stiffness. Here we present a systematic review of the use of USE in neurosurgery.

EVIDENCE ACQUISITION

A systematic review of the literature has been performed, according to the PRISMA guideline, for the last 30 years on 3 different databases (MEDLINE, Scopus, and Cochrane), to gather all the studies on the use of ultrasound elastography for neurosurgical pathologies, including both clinical and laboratory studies.

EVIDENCE SYNTHESIS

A total of 15 articles met the inclusion criteria. USE has widely and safely been used especially for oncological lesions (meningiomas and gliomas) and focal cortical dysplasia. However, there are also encouraging laboratory studies about its application for the management of traumatic brain injury, and ischemic stroke.

CONCLUSIONS

This systematic review showed that, despite the lack of strong evidence, USE is a valid intraoperative tool, especially in oncological neurosurgery.

Neuromodulation for Brain Tumors: Myth or Reality? A Narrative Review

In recent years, research on brain cancers has turned towards the study of the interplay between the tumor and its host, the normal brain. Starting from the establishment of a parallelism between neurogenesis and gliomagenesis, the influence of neuronal activity on the development of brain tumors, particularly gliomas, has been partially unveiled. Notably, direct electrochemical synapses between neurons and glioma cells have been identified, paving the way for new approaches for the cure of brain cancers. Since this novel field of study has been defined "cancer neuroscience", anticancer therapeutic approaches exploiting these discoveries can be referred to as "cancer neuromodulation". In the present review, we provide an up-to-date description of the novel findings and of the therapeutic neuromodulation perspectives in cancer neuroscience. We focus both on more traditional oncologic approaches, aimed at modulating the major pathways involved in cancer neuroscience through drugs or genetic engineering techniques, and on electric stimulation proposals; the latter is at the cutting-edge of neuro-oncology.

Is There a Role for Intraoperative Neuromonitoring in Intradural Extramedullary Spine Tumors? Results and Indications from an Institutional Series

While intraoperative neurophysiological monitoring (IONM) is considered a standard for intramedullary spinal cord tumor surgery, the effective role of IONM in intradural extramedullary (IDEM) tumors is still debated. We present the results of 60 patients affected by IDEM tumors undergoing surgery with the aid of IONM. Each patient was evaluated according to the modified McCormick scale (MMS) at admission, discharge and at follow-up. During surgery, motor evoked potentials (MEPs) and somatosensory evoked potentials (SEPs) were studied using the Medtronic NIM-eclipse^® 32-channel system (Medtronic Xomed, Inc. 6743 Southpoint Drive North Jacksonville FL USA). Patients' age, gender and tumor location did not affect MMS modifications. Tumors involving more than three levels had an increased likelihood of MMS worsening, while meningioma pathology was associated with worse preoperative and 1-year follow-up MMS. No MEP amplitude ratio was able to predict clinical variations, while intraoperative SEP worsening was associated with 100% risk of poor MMS at discharge and with 50% risk of poor MMS at long-term follow-up. In our opinion, SEP monitoring is a valid tool that may contribute to the preservation of the patient's neurological status. MEP monitoring is not mandatory in IDEM surgery while more studies are required to explore the feasibility and the role of D-wave in this kind of surgery.

Is There a Role for Machine Learning in Liquid Biopsy for Brain Tumors? A Systematic Review

The paucity of studies available in the literature on brain tumors demonstrates that liquid biopsy (LB) is not currently applied for central nervous system (CNS) cancers. The purpose of this systematic review focused on the application of machine learning (ML) to LB for brain tumors to provide practical guidance for neurosurgeons to understand the state-of-the-art practices and open challenges. The herein presented study was conducted in accordance with the PRISMA-P (preferred reporting items for systematic review and meta-analysis protocols) guidelines. An online literature search was launched on PubMed/Medline, Scopus, and Web of Science databases using the following query: "((Liquid biopsy) AND (Glioblastoma OR Brain tumor) AND (Machine learning OR Artificial Intelligence))". The last database search was conducted in April 2023. Upon the full-text review, 14 articles were included in the study. These were then divided into two subgroups: those dealing with applications of machine learning to liquid biopsy in the field of brain tumors, which is the main aim of this review (n = 8); and those dealing with applications of machine learning to liquid biopsy in the diagnosis of other tumors (n = 6). Although studies on the application of ML to LB in the field of brain tumors are still in their infancy, the rapid development of new techniques, as evidenced by the increase in publications on the subject in the past two years, may in the future allow for rapid, accurate, and noninvasive analysis of tumor data. Thus making it possible to identify key features in the LB samples that are associated with the presence of a brain tumor. These features could then be used by doctors for disease monitoring and treatment planning.

Decompression with or without Fusion for Lumbar Synovial Cysts—A Systematic Review and Meta-Analysis

The management of symptomatic lumbar synovial cysts (LSC) is still a matter of debate. Previous systematic reviews did not stratify data according to different treatment techniques or incompletely reported comparative data on patients treated with lumbar posterior decompression (LPD) and lumbar decompression and fusion (LDF). The aim of our study was to compare LPD and LDF via a systematic review and meta-analysis of the existing literature. The design of this study was in accordance with the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The review questions were as follows: among patients suffering from symptomatic lumbar synovial cysts (population) and treated with either posterior lumbar decompression or posterior decompression with fusion (intervention), who gets the best results (outcome), in terms of cyst recurrence, reoperation rates, and improvement of postoperative symptoms (comparison)? The search of the literature yielded a total of 1218 results. Duplicate records were then removed (n = 589). A total of 598 articles were screened, and 587 records were excluded via title and abstract screening; 11 studies were found to be relevant to our research question and were assessed for eligibility. Upon full-text review, 5 were excluded because they failed to report any parameter separately for both LPD and LDF. Finally, 6 studies for a total of 657 patients meeting the criteria stated above were included in the present investigation. Our analysis showed that LDF is associated with better results in terms of lower postoperative back pain and cyst recurrence compared with LPD. No differences were found in reoperation rates and complication rates between the two techniques. The impact of minimally invasive decompression techniques on the different outcomes in LSC should be assessed in the future and compared with instrumentation techniques.

The Extracellular Matrix in Glioblastomas: A Glance at Its Structural Modifications in Shaping the Tumoral Microenvironment-A Systematic Review

BACKGROUND AND AIM

While many components of the ECM have been isolated and characterized, its modifications in the specific setting of GBMs have only been recently explored in the literature. The aim of this paper is to provide a systematic review on the topic and to assess the ECM's role in shaping tumoral development.

METHODS

An online literature search was launched on PubMed/Medline and Scopus using the research string "((Extracellular matrix OR ECM OR matrix receptor OR matrix proteome) AND (glioblastoma OR GBM) AND (tumor invasion OR tumor infiltration))", and a systematic review was conducted in accordance with the PRISMA-P guidelines.

RESULTS

The search of the literature yielded a total of 693 results. The duplicate records were then removed (n = 13), and the records were excluded via a title and abstract screening; 137 studies were found to be relevant to our research question and were assessed for eligibility. Upon a full-text review, 59 articles were finally included and were summarized as follows based on their focus: (1) proteoglycans; (2) fibrillary proteins, which were further subdivided into the three subcategories of collagen, fibronectin, and laminins; (3) glycoproteins; (4) degradative enzymes; (5) physical forces; (6) and glioma cell and microglia migratory and infiltrative patterns.

CONCLUSIONS

Our systematic review demonstrates that the ECM should not be regarded anymore as a passive scaffold statically contributing to mechanical support in normal and pathological brain tissue but as an active player in tumor-related activity.

A Study on the Role of Intraoperative Corticobulbar Motor Evoked Potentials for Improving Safety of Cerebellopontine Angle Surgery in Elderly Patients

Preservation of facial nerve function (FNF) during neurosurgery for cerebellopontine angle (CPA) tumors is paramount in elderly patients. Corticobulbar facial motor evoked potentials (FMEPs) allow assessment intraoperatively of the functional integrity of facial motor pathways, thus improving safety. We aimed to evaluate the significance of intraoperative FMEPs in patients 65 years and older. A retrospective cohort of 35 patients undergoing CPA tumors resection was reported; outcomes of patients aged 65-69 years vs. ≥70 years were compared. FMEPs were registered both from upper and lower face muscles, and amplitude ratios (minimum-to-baseline, MBR; final-to-baseline, FBR; and recovery value, FBR minus MBR) were calculated. Overall, 78.8% of patients had a good late (at 1 year) FNF, with no differences between age groups. In patients aged ≥70 years, MBR significantly correlated with late FNF. At receiver operating characteristics (ROC) analysis, in patients aged 65-69 years, FBR (with 50% cut-off value) could reliably predict late FNF. By contrast, in patients aged ≥70 years, the most accurate predictor of late FNF was MBR, with 12.5% cut-off. Thus, FMEPs are a valuable tool for improving safety in CPA surgery in elderly patients as well. Considering literature data, we noticed higher cut-off values for FBR and a role for MBR, which suggests an increased vulnerability of facial nerves in elderly patients compared to younger ones.

Surgical and Clinical Outcomes of Microvascular Decompression: A Comparative Study between Young and Elderly Patients

Microvascular decompression (MVD) is the only etiological technique for the treatment of trigeminal neuralgia (TN). Whilst there is a consensus MVD is likely effective regardless of age, the elderly population is thought to be more prone to have a higher rate of surgical complication, morbidity, and mortality. The main objective of our single-center, retrospective study was to analyze the surgical and clinical outcomes of MVD in TN elderly patients. From a surgical series of patients with TN who had undergone MVD from April 2018 to April 2022, 76 patients who matched the inclusion criteria were divided into two groups: twenty-five (32.9%) patients were older than 65 years and included in the elderly group, while the remaining fifty-one (61.1%) patients were below 65 years included in the non-elderly one. There were no differences between the groups in terms of acute pain relief (APR), Barrow Neurological Index (BNI) at follow-up, complications, and recurrence rate. In multivariate analysis (Cox proportional hazards regression analysis) the presence of an offending artery with nerve root distortion/indentation emerged as the only independent prognostic factor for pain-free survival (p = 0.0001). Our data endorse MVD as a safe and effective surgical procedure also for elderly patients with TN.

The prevalence of imposter syndrome among young neurosurgeons and residents in neurosurgery: a multicentric study

OBJECTIVE

Imposter syndrome (IS) occurs when high-achieving individuals have a pervasive sense of self-doubt combined with fear of being exposed as a fraud, despite objective measures of success. This is one of the main causes of burnout among professionals, threatening their mental health and general well-being. The prevalence and severity of IS among neurosurgery residents and young neurosurgeons has not been yet studied. The primary outcomes of this study were the prevalence and severity of IS.

METHODS

An anonymous cross-sectional survey including both a demographic questionnaire (Clance Imposter Phenomenon Survey) and compensatory mechanisms was distributed to young neurosurgeons and residents in neurosurgery in Italy.

RESULTS

A total of 103 responses were collected. The prevalence rate was 81.6%. Among the respondents with IS, 42.7% showed moderate signs, 27.2% frequent, and only 11.7% had an intense symptomatology. Level of education, female sex, and academic achievements were all identified as predictive factors of IS.

CONCLUSIONS

A total of 81.6% of respondents reported potentially significant levels. The implications of IS on both the outcomes in patients and the well-being of neurosurgeons should be evaluated in future studies.

Glioma-Associated Microglia Characterization in the Glioblastoma Microenvironment through A ‘Seed-and Soil’ Approach: A Systematic Review

Background and aim: Ever since the discovery of tumor-associated immune cells, there has been growing interest in the understanding of the mechanisms underlying the crosstalk between these cells and tumor cells. A “seed and soil” approach has been recently introduced to describe the glioblastoma (GBM) landscape: tumor microenvironments act as fertile “soil” and interact with the “seed” (glial and stem cells compartment). In the following article, we provide a systematic review of the current evidence pertaining to the characterization of glioma-associated macrophages and microglia (GAMs) and microglia and macrophage cells in the glioma tumor microenvironment (TME). Methods: An online literature search was launched on PubMed Medline and Scopus using the following research string: “((Glioma associated macrophages OR GAM OR Microglia) AND (glioblastoma tumor microenvironment OR TME))”. The last search for articles pertinent to the topic was conducted in February 2022. Results: The search of the literature yielded a total of 349 results. A total of 235 studies were found to be relevant to our research question and were assessed for eligibility. Upon a full-text review, 58 articles were included in the review. The reviewed papers were further divided into three categories based on their focus: (1) Microglia maintenance of immunological homeostasis and protection against autoimmunity; (2) Microglia crosstalk with dedifferentiated and stem-like glioblastoma cells; (3) Microglia migratory behavior and its activation pattern. Conclusions: Aggressive growth, inevitable recurrence, and scarce response to immunotherapies are driving the necessity to focus on the GBM TME from a different perspective to possibly disentangle its role as a fertile ‘soil’ for tumor progression and identify within it feasible therapeutic targets. Against this background, our systematic review confirmed microglia to play a paramount role in promoting GBM progression and relapse after treatments. The correct and extensive understanding of microglia–glioma crosstalk could help in understanding the physiopathology of this complex disease, possibly opening scenarios for improvement of treatments.

Intraoperative Corticobulbar Motor Evoked Potential in Cerebellopontine Angle Surgery: A Clinically Meaningful Tool to Predict Early and Late Facial Nerve Recovery

BACKGROUND

Intraoperative neuromonitoring is crucial for facial nerve preservation in cerebellopontine angle (CPA) surgery. Among the available techniques, the role of intraoperative corticobulbar facial motor evoked potentials (FMEPs) is unclear.

OBJECTIVE

To evaluate the significance of intraoperative FMEPs as indicators for early and late postoperative facial nerve function (FNF) in CPA tumor resection and the feasibility of their integration with standard monitoring techniques.

METHODS

An institutional series of 83 patients who underwent surgery under intraoperative monitoring for CPA extra-axial tumor resection was reported. A pair of needle electrodes was used to record FMEP from orbicularis oculi (OOc) and orbicularis oris (OOr) muscles at baseline, at the end of surgery and minimum values recorded. From FMEP amplitudes, minimum-to-baseline amplitude ratio (MBR), final-to-baseline amplitude ratio (FBR), and recovery value, intended as FBR minus MBR, were calculated. These indices were correlated with early and late postoperative FNF.

RESULTS

Our analysis demonstrated that higher FBR (both from OOc and OOr) and MBR (from OOr only) were associated with a good early and late FNF; a higher MBR from OOc was significantly associated with a good late FNF. The most accurate index in predicting early FNF was FBR measured from OOr with a cutoff of 35.56%, whereas the most accurate index in predicting late FNF was FBR as measured from OOc with a cutoff of 14.29%.

CONCLUSION

Our study confirmed that FMEPs are reliable predictors of early and late postoperative FNF in CPA surgery and could be easily integrated with standard intraoperative neuromonitoring techniques.

Immunoregulatory effects of glioma-associated stem cells on the glioblastoma peritumoral microenvironment: a differential PD-L1 expression from core to periphery?

OBJECTIVE

Glioma-associated stem cells (GASCs) have been indicated as possible players in supporting growth and recurrence in glioblastoma. However, their role in modulating immune response in the peritumoral area has not yet been described. In this study, the authors aimed to investigate programmed death-ligand 1 (PD-L1) differential expression at the protein level in GASCs derived from different tumor areas (core, periphery, and surrounding healthy brain).

METHODS

Tumor tissue samples were collected from patients who underwent surgery for a histopathologically confirmed diagnosis of glioblastoma. Sampling sites were confirmed via neuronavigation and categorized on 5-aminolevulinic acid (5-ALA) fluorescence as bright (ALA+), pale (ALA PALE), or negative (ALA-), which corresponds to the tumor mass, infiltrated peritumoral area, and healthy brain, respectively, during surgery. GASCs were first isolated from the 3 regions and analyzed; then Western blot analysis was used to evaluate the level of PD-L1 expression in the GASCs.

RESULTS

Overall, 7 patients were included in the study. For all patients, the mean values ± SD of PD-L1 expression in GASCs for ALA+, ALA PALE, and ALA- were 1.12 ± 1.14, 0.89 ± 0.63, and 0.57 ± 0.18, respectively. The differentially expressed values of PD-L1 in GASCs sampled from the 3 areas were found to be significant (p < 0.05) for 3 of the 7 patients: patient S470 (ALA+ vs ALA- and ALA PALE vs ALA-), patient S473 (ALA+ vs ALA PALE and ALA PALE vs ALA-), and patient S509 (ALA+ vs ALA-).

CONCLUSIONS

This analysis showed, for the first time, that GASCs expressed a constitutive level of PD-L1 and that PD-L1 expression in GASCs was not uniform among patients or within the same patient. GASC analysis combined with 5-ALA-guided sampling (from core to periphery) made it possible to highlight the role of the tumor microenvironment at the infiltrating margin, which might cause clinical resistance, opening interesting perspectives for the future.

Machine Learning-Based Prediction of Early Recurrence in Glioblastoma Patients: A Glance Towards Precision Medicine

BACKGROUND

Ability to thrive and time-to-recurrence following treatment are important parameters to assess in patients with glioblastoma multiforme (GBM), given its dismal prognosis. Though there is an ongoing debate whether it can be considered an appropriate surrogate endpoint for overall survival in clinical trials, progression-free survival (PFS) is routinely used for clinical decision-making.

OBJECTIVE

To investigate whether machine learning (ML)-based models can reliably stratify newly diagnosed GBM patients into prognostic subclasses on PFS basis, identifying those at higher risk for an early recurrence (≤6 mo).

METHODS

Data were extracted from a multicentric database, according to the following eligibility criteria: histopathologically verified GBM and follow-up >12 mo: 474 patients met our inclusion criteria and were included in the analysis. Relevant demographic, clinical, molecular, and radiological variables were selected by a feature selection algorithm (Boruta) and used to build a ML-based model.

RESULTS

Random forest prediction model, evaluated on an 80:20 split ratio, achieved an AUC of 0.81 (95% CI: 0.77; 0.83) demonstrating high discriminative ability. Optimizing the predictive value derived from the linear and nonlinear combinations of the selected input features, our model outperformed across all performance metrics multivariable logistic regression.

CONCLUSION

A robust ML-based prediction model that identifies patients at high risk for early recurrence was successfully trained and internally validated. Considerable effort remains to integrate these predictions in a patient-centered care context.

Medico-legal issues: perception, awareness and behavioral changes among Italian Neurosurgical community. A survey-based analysis

BACKGROUND AND AIM

Despite the rising trend of medicolegal challenges in Italy, there is a significant lack of literature on this topic. To provide better understanding of awareness towards medico-legal aspects, defensive behaviours, consent taking practice and, in general, perceptions of Italian neurosurgeons on this issue, a cross sectional survey was conducted.

METHODS

A questionnaire covering various aspects of medicolegal issues, in an anonymous online form, was sent to neurosurgeons practicing in Italy via email - through a national mailing list - and social media platforms. Data collection period was 01/11/2020-31/12/2020.

RESULTS

A total of 64 single responses were included. We assessed: 1) Awareness of Italian neurosurgeons about legal framework: a very low level of knowledge has been reported - 87,5% was unaware even of the terms and conditions outlined by the contract with the Institution, 75,6% of respondents stated they didn't know the main body of law that govern the medical community; 2) Perception towards defensive medicine: 92.2% believed that they were not trained to face possible medico-legal issues but only few tried to acquire more knowledge about medical legal issues, such as learning how to obtain a proper informed consent for a surgical procedure (34.4%).

CONCLUSION

This study marks the first survey to identify the perceptions among Italian neurosurgeons of medical legal issues and related "defensive medicine" practices: this is of relevance given its exorbitant cost in terms of public expenditure, psychological burden and its relevant impact on health care delivery.

Machine Learning-Based Prediction of 6-Month Postoperative Karnofsky Performance Status in Patients with Glioblastoma: Capturing the Real-Life Interaction of Multiple Clinical and Oncologic Factors

OBJECTIVE

Ability to thrive after invasive and intensive treatment is an important parameter to assess in patients with glioblastoma multiforme (GBM). Karnofsky Performance Status (KPS) is used to identify those patients suitable for postoperative radiochemotherapy. The aim of the present study is to investigate whether machine learning (ML)-based models can reliably predict patients' KPS 6 months after surgery.

METHODS

A cohort of 416 patients undergoing surgery for a histopathologically confirmed GBM were collected from a multicentric database and split into a training and hold-out test set in an 80:20 ratio. Worsening of KPS at 6 months after surgery (compared with preoperative KPS) occurred in 138 patients (33.2%). Relevant preoperative, intraoperative, and immediately postoperative variables were selected by a recursive features selection algorithm (Boruta) and used to build 2 ML-based predictive models.

RESULTS

A random forest classifier and a random forest regressor were trained to predict 6 months postoperative KPS as a categorical (worsening vs. stable/improving) and continuous variables; they achieved, respectively, an area under the curve of 0.81 (95% confidence interval, 0.76-0.84) and a mean absolute error of 4.4 (95% confidence interval, 4.0-4.7). Leveraging the predictive value resulting from the combination of independent variables, the random forest classifier outperformed conventional statistics (area under the curve improvement of +21%).

CONCLUSIONS

Two robust ML-based prediction models were successfully trained and internally validated. Considerable effort remains to improve the interpretation of the results when these predictions are used in a patient-centered care context.

Predicting meningioma consistency and brain-meningioma interface with intraoperative strain ultrasound elastography: a novel application to guide surgical strategy

OBJECTIVE

Providing new tools to improve surgical planning is considered a main goal in meningioma treatment. In this context, two factors are crucial in determining operating strategy: meningioma-brain interface and meningioma consistency. The use of intraoperative ultrasound (ioUS) elastosonography, a real-time imaging technique, has been introduced in general surgery to evaluate similar features in other pathological settings such as thyroid and prostate cancer. The aim of the present study was to evaluate ioUS elastosonography in the intraoperative prediction of key intracranial meningioma features and to evaluate its application in guiding surgical strategy.

METHODS

An institutional series of 36 meningiomas studied with ioUS elastosonography is reported. Elastographic data, intraoperative surgical findings, and corresponding preoperative MRI features were classified, applying a score from 0 to 2 to both meningioma consistency and meningioma-brain interface. Statistical analysis was performed to determine the degree of agreement between meningioma elastosonographic features and surgical findings, and whether intraoperative elastosonography was a better predictor than preoperative MRI in assessing meningioma consistency and slip-brain interface, using intraoperative findings as the gold standard.

RESULTS

A significantly high degree of reliability and agreement between ioUS elastographic scores and surgical finding scores was reported (intraclass correlation coefficient = 0.848, F = 12.147, p < 0.001). When analyzing both consistency and brain-tumor interface, ioUS elastography proved to have a rather elevated sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive (LR+) and negative likelihood ratio (LR-). This consideration was true especially for meningiomas with a hard consistency (sensitivity = 0.92, specificity = 0.96, PPV = 0.92, NPV = 0.96, LR+ = 22.00, LR- = 0.09) and for those presenting with an adherent slip-brain interface (sensitivity = 0.76, specificity = 0.95, PPV = 0.93, NPV = 0.82, LR+ = 14.3, LR- = 0.25). Furthermore, predictions derived from ioUS elastography were found to be more accurate than MRI-derived predictions, as demonstrated by McNemar's test results in both consistency (p < 0.001) and interface (p < 0.001).

CONCLUSIONS

While external validation of the data is needed to transform ioUS elastography into a fully deployable clinical tool, this experience confirmed that it may be integrated into meningioma surgical planning, especially because of its rapidity and cost-effectiveness.

Heterogeneity Matters: Different Regions of Glioblastoma Are Characterized by Distinctive Tumor-Supporting Pathways

Simple Summary

5-ALA Fluorescence Guided Surgery aims at extending the boundaries of glioblastoma (GBM) resection. It is based on the use of a fluorescent dye, 5-aminolevulinic acid (5-ALA). Depending on the fluorescence levels, it is possible to distinguish the core of the tumor, the infiltrating borders and the healthy tissue. Since GBM progression is supported by tumor cells and their interaction with the surrounding microenvironment, we hypothesized that 5-ALA intensity could identify microenvironments with different tumor supporting properties. Taking advantage of glioma-associated stem cells; a human in vitro model of the glioma microenvironment, we demonstrate that all regions of the tumor support the tumor growth, but through different pathways. This study highlights the importance of understanding the TME to obtain key information on GBM biology and develop new therapeutic approaches.

Abstract

The glioblastoma microenvironment plays a substantial role in glioma biology. However, few studies have investigated its spatial heterogeneity. Exploiting 5-ALA Fluorescence Guided Surgery (FGS), we were able to distinguish between the tumor core (ALA+), infiltrating area (ALA-PALE) and healthy tissue (ALA−) of the glioblastoma, based on the level of accumulated fluorescence. The aim of this study was to investigate the properties of the microenvironments associated with these regions. For this purpose, we isolated glioma-associated stem cells (GASC), resident in the glioma microenvironment, from ALA+, ALA-PALE and ALA− samples and compared them in terms of growth kinetic, phenotype and for the expression of 84 genes associated with cancer inflammation and immunity. Differentially expressed genes were correlated with transcriptomic datasets from TCGA/GTEX. Our results show that GASC derived from the three distinct regions, despite a similar phenotype, were characterized by different transcriptomic profiles. Moreover, we identified a GASC-based genetic signature predictive of overall survival and disease-free survival. This signature, highly expressed in ALA+ GASC, was also well represented in ALA PALE GASC. 5-ALA FGS allowed to underline the heterogeneity of the glioma microenvironments. Deepening knowledge of these differences can contribute to develop new adjuvant therapies targeting the crosstalk between tumor and its supporting microenvironment.

State of the art of fluorescence guided techniques in neurosurgery

Achieving a safe and extensive neoplasm resection can be considered the main goal of brain tumor surgery. This paper is first aimed at providing an overview of the evolution of those tools serving the purpose. From the dawn of neurosurgery to the present days, major innovations have followed one another. However, those techniques may frequently lack of an instant biological feedback on the true extension and the infiltration of the tumor. Intraoperative fluorescence modalities could indeed fill this gap. Fluorescence guided surgery will be therefore introduced and discussed in this context. Our focus will be on the most common fluorescence techniques used in neurosurgery, namely 5-aminolevulinic acid, sodium fluorescein and in indocyanine green. Mode of action, strengths and weaknesses and level of evidence of each modality will be discussed.

"Dark corridors" in 5-ALA resection of high-grade gliomas: combining fluorescence-guided surgery and contrast-enhanced ultrasonography to better explore the surgical field

BACKGROUND

Increasing the extent of resection (EOR) is considered a main goal in high grade glioma (HGG) surgery. Significant advancements have been recently made to assist surgery: namely the use of 5-aminolevulinic acid (5ALA) and the application of contrast-enhanced ultrasound (CEUS) embody two of the most recently introduced tools in the neuro-oncology field. A combined approach including the two techniques has been suggested in literature. Our primary aim is to identify in which conditions CEUS final survey has a real impact in a 5-ALA guided context and assess which preoperative tumor characteristics, with specific attention to working corridors can predict strains of the fluorescence guided procedure and hence recommend the use of the combined technique.

METHODS

Forty-nine HGG glioma surgeries were performed at our institution with the abovementioned protocol between January 2016 and June 2016. Based on preoperative MRI, we stratified glioma characteristics according to three determinants: localization (deep versus superficial), size (<3.5 versus >3.5 cm) and shape (regular versus irregular).

RESULTS

CEUS modified 5-ALA guided resection in 11 cases (22.45%): this appeared to be associated with statistically significance to deep tumor localization (P=0.04) and irregular/multi-lobulated margins (P=0.003). On the other hand, tumor size alone did not appear as a statistically significant determinant.

CONCLUSIONS

When dark corridors are presents or when overlying brain parenchyma hinders illumination, drawbacks to the 5-ALA assistance can be expected, hence CEUS final survey has a crucial role of 'refinement'. In those selected cases, an integrated 5ALA+CEUS protocol was shown as advisable in EOR improvement.

5-Aminolevulinic Acid False Positives in Cerebral Neuro-Oncology: Not All That Is Fluorescent Is Tumor. A Case-Based Update and Literature Review

BACKGROUND

One of the most valuable innovations in high-grade glioma surgery is 5-aminolevulinic acid (5-ALA). Fluorescence is a specific and sensitive indicator of metabolically active tumor tissue. In the published literature, the main focus has been placed on false-negative cases, with only a few articles addressing false positivity. The aim of the article was to highlight settings in which 5-ALA fluorescence does not necessarily mean tumor and to point out conditions in which intraoperative 5-ALA fluorescence has to be critically interpreted.

METHODS

Using PubMed, a review of pertinent literature was done to specifically investigate all conditions, including non-neoplastic and other metabolically active lesions, that can mimic high-grade gliomas and cause a misleading intraoperative diagnosis. In addition, an institutional case characterized by strong 5-ALA fluorescence in radionecrosis is presented.

RESULTS

Literature results were grouped in 2 main categories according to the field of application: oncologic setting (9 articles and 1 institutional case) and nononcologic settings (5 articles).

CONCLUSIONS

As reported, 5-ALA-induced fluorescence is not limited to glioma but is also evident in nonglioma and non-neoplastic conditions. Critical interpretation of intraoperative fluorescence is therefore mandatory in recurrences and in atypical cases that might hinder alternative diagnoses.

Characterization of children with FLT3-ITD acute myeloid leukemia: a report from the AIEOP AML-2002 study group

Recurrent molecular markers have been routinely used in acute myeloid leukemia (AML) for risk assessment at diagnosis, whereas their post-induction monitoring still represents a debated issue. We evaluated the prognostic value and biological impact of minimal residual disease (MRD) and of the allelic ratio (AR) of FLT3-internal-tandem duplication (ITD) in childhood AML. We retrospectively screened 494 children with de novo AML for FLT3-ITD mutation, identifying 54 harboring the mutation; 51% of them presented high ITD-AR at diagnosis and had worse event-free survival (EFS, 19.2 versus 63.5% for low ITD-AR, <0.05). Forty-one percent of children with high levels of MRD after the 1st induction course, measured by a patient-specific real-time-PCR, had worse EFS (22.2 versus 59.4% in low-MRD patients, P<0.05). Next, we correlated these parameters with gene expression, showing that patients with high ITD-AR or persistent MRD had characteristic expression profiles with deregulated genes involved in methylation and acetylation. Moreover, patients with high CyclinA1 expression presented an unfavorable EFS (20.3 versus 51.2% in low CyclinA1 group, P<0.01). Our results suggest that ITD-AR levels and molecular MRD should be considered in planning clinical management of FLT3-ITD patients. Different transcriptional activation of epigenetic and oncogenic profiles may explain variability in outcome among these patients, for whom novel therapeutic approaches are desirable.

Can the presence of cat/dog at home be considered the only criterion of exposure to cat/dog allergens? A likely underestimated bias in clinical practice and in large epidemiological studies

An important aspect of allergic sensitization to furry animals is the association of dog and cat exposure in early childhood with the incidence of respective allergies later in life. This topic is very controversial, because some authors have found a "facilitating" effect, while others have noticed a "protective" or even no significant effect in individuals living in urban areas. It is likely that some biases could be responsible of these contradictory findings. Cat/dog ownership or their presence in indoor environments are considered usually the main criteria to assess the exposure to these pets in studies' questionnaires. Even in clinical practice "are there animals at home?" is the common query usually done when collecting anamnestic data. In our opinion, these commonly used questions should not be considered the main index of exposure to pet allergens, because they can lead to erroneous interpretation of the clinical significance of positive skin prick tests for pet allergens as well as of the real risk of exposure to allergens of dog/cat in epidemiological studies. Consequently, we suggest a new, more realistic, classification of modalities of exposure to pet allergens in "real life" based on five possible conditions.

The isochromosome i(7)(q10) carrying c.258+2t>c mutation of the SBDS gene does not promote development of myeloid malignancies in patients with Shwachman syndrome

Shwachman-Diamond syndrome (SDS) is an autosomal recessive disorder, characterized by exocrine pancreatic insufficiency, skeletal abnormalities and bone marrow (BM) dysfunction with an increased risk to develop myelodysplastic syndrome and/or acute myeloid leukaemia (MDS/AML). SDS is caused, in nearly 90% of cases, by two common mutations (that is, c.183_184TA>CT and c.258+2T>C) in exon 2 of the SBDS gene, localized on chromosome 7. Clonal chromosome anomalies are often found in the BM of SDS patients; the most frequent is an isochromosome for long arms of chromosome 7, i(7)(q10). We studied eight patients with SDS carrying the i(7)(q10) who were compound heterozygotes for SBDS mutations. By assessing the parental origin of the i(7)(q10) using microsatellite analysis, we inferred from the results which mutation was present in double dose in the isochromosome. We demonstrate that in all cases the i(7)(q10) carries a double dose of the c.258+2T>C, and we suggest that, as the c.258+2T>C mutation still allows the production of some amount of normal protein, this may contribute to the low incidence of MDS/AML in this subset of SDS patients.

The polymorphisms -318C>T in the promoter and 49A>G in exon 1 of CTLA4 and the risk of aplastic anemia in a Caucasian population

Aplastic anemia (AA) is a rare disease with a major autoimmune pathogenetic component. CTLA4 is a T-lymphocyte surface molecule involved in the maintenance of immune tolerance. Some polymorphisms associated with a reduced expression of CTLA4, and thus presumably with increased tendency to autoimmunity, have been associated with various autoimmune diseases. In this study, we evaluated the distribution of the low expression polymorphisms -318C > T and 49A > G of CTLA4 in a population of 67 patients with acquired AA and in 100 normal controls. There was no difference in the distribution of the tested polymorphism between patients and controls and, within the patient group, between those who responded to immunosuppression vs those who did not respond. This study indicates that the polymorphisms -318C > T and 49A > G of CTLA4 do not affect the risk of developing AA and do not influence the response to immunosuppression.

Relationship between Bet v 1 and Bet v 2 specific IgE and food allergy in children with grass pollen respiratory allergy

Grass allergy is the most common pollinosis in Northern Italy. Some patients with grass allergy show polysensitization against other pollens and plant-derived foods. In these patients oral allergic syndrome (OAS) is frequently associated. To evaluate the correlation between food allergy or food sensitization and specific IgE against panallergens such as Bet v 1 and Bet v 2, we studied 56 children (mean age: 8 years 5 months) suffering from respiratory allergy due to grass pollens were enrolled. Specific IgE against the most important food, inhalant allergen and Bet v 1, Bet v 2 were performed by ImmunoCAP technology (UniCAP 1000, Pharmacia Diagnostics, Uppsala, Sweden). We found 14 children (25%) sensitized to Bet v 1 and 13 (23%) to Bet v 2; in 24 cases (42.3%) a sensitization to at least one of the 2 panallergens was observed. Five of the 14 cases (36%) sensitized to Bet v 1 showed food allergy and 8 (57%) food sensitization; 6 (46%) of the 13 children sensitized to Bet v 2 showed food allergy and 7 (54%) food sensitization; only one case of Bet v 1 specific IgE without food allergy or sensitization was seen. Sixteen subjects (29%) showed food allergy (group A); 20 children (35.5%) multiple sensitizations to inhalant and at least one plant-derived food (group B); 20 subjects (35.5%) only inhalant allergens (group C). Sensitization to Bet v 1 (P<0.03) and Bet v 2 (P<0.009) is from a statistical point of view significantly higher in groups A and B than in group C. In the 16 patients with food allergy hazelnut was the major triggering food (50%), followed by peanut (38%), kiwi (31%), apple and walnut (19%). Specific IgE for Bet v 1 is more associated with nuts and legumes, while Bet v 2 is more related to fresh fruit and vegetables. In conclusion grass pollinosis is frequently associated with polysensitization to other pollen and food allergens. Bet v 1 and Bet v 2 specific IgE are significantly higher in these patients than in patients with grass monosensitization, and this sensitization may be considered a possible risk factors to evolve later into food allergy. Among the offending foods, legumes and the nut group are mostly related to Bet v 1, while vegetables and fresh fruits to Bet v 2.

Clinical effectiveness of a silk fabric in the treatment of atopic dermatitis

BACKGROUND

In children with atopic dermatitis (AD), eczema is easily aggravated by contact with irritant factors (e.g. aggressive detergents, synthetic and woollen clothes, climatic factors).

OBJECTIVES

To evaluate the effectiveness of a special silk fabric (MICROAIR DermaSilk) in the treatment of young children affected by AD with acute lesions at the time of examination.

METHODS

Forty-six children (mean age 2 years) affected by AD in an acute phase were recruited: 31 received special silk clothes (group A) which they were instructed to wear for a week; the other 15 served as a control group (group B) and wore cotton clothing. Topical moisturizing creams or emulsions were the only topical treatment prescribed in both groups. The overall severity of the disease was evaluated using the SCORAD index. In addition, the local score of an area covered by the silk clothes was compared with the local score of an uncovered area in the same child. All patients were evaluated at baseline and 7 days after the initial examination.

RESULTS

At the end of the study a significant decrease in AD severity was observed in the children of group A (mean SCORAD decrease from 43 to 30; P = 0.003). At the same time, the improvement in the mean local score of the covered area (from 32 to 18.6; P = 0.001) was significantly greater than that of the uncovered area (from 31 to 26; P = 0.112).

CONCLUSIONS

The use of special silk clothes may be useful in the management of AD in children.

A comparison of different allergometric tests, skin prick test, Pharmacia UniCAP and ADVIA Centaur, for diagnosis of allergic diseases in children

BACKGROUND

The diagnosis of allergic disease is performed by skin prick tests (SPT) or through the demonstration of specific IgE in a blood sample via an in vitro test. The measurement of IgE concentration against allergens provides critical information in clinical allergy. Standardized and reproducible methods contribute to the quality of diagnosis and treatment of allergic disease.

METHODS

In this study we evaluated the performance of a new specific IgE method, developed by ALK-Abellò for Bayer Diagnostics to run on their ADVIA Centaur immunoassay system. One hundred and fifty-one children with allergic diseases (both food and inhalant allergies) were tested for specific IgE (sIgE) via SPT and in vitro tests (UniCAP system, Pharmacia, and ADVIA Centaur immunoassay system, Bayer Diagnostics) and the test results were correlated with the clinical data.

RESULTS

Statistical analysis revealed no significant difference between the two in vitro tests compared with clinical history. The sensitivities and specificities are similar, but the UniCAP system method has higher sensitivity. In the children with cow's milk allergy, the UniCAP system has sensitivity of 91% and specificity of 70%; the ADVIA Centaur immunoassay has sensitivity of 82% and specificity of 74%. In hen's egg allergy, UniCAP system has 94% sensitivity and 64% specificity, and the ADVIA Centaur system has 88% sensitivity and 52% specificity. In inhalant allergies, the two methods show statistically similar performances for both grass pollen allergies (UniCAP sensitivity 100%, specificity 73%; ADVIA Centaur sensitivity 95%, specificity 79%) and in the dust mites allergies (UniCAP sensitivity 91%, specificity 62%; ADVIA Centaur sensitivity 86%, specificity 64%). In cat allergies, the systems showed equivalent results (UniCAP sensitivity 100%, specificity 71%; ADVIA Centaur sensitivity 100%, specificity 70%). Using the UniCAP system, the geometric mean of sIgE values in children with clinical allergy is significantly higher than in sensitized ones. The ADVIA Centaur system shows a similar trend with the exclusion of cow's milk and Dermatophagoides farinae allergens. With this last method the mean value of sIgE is higher in sensitized than in symptomatic children.

CONCLUSION

The new ADVIA Centaur method compares favorably with the results obtained on the UniCAP system. If other studies continue to confirm this data, then the advantages are numerous: the use of only a small quantity of serum (25 micro l per allergen), rapid turnaround time, minimal hands-on time, and no interference from IgG.

Role of glycemia in acute spinal cord injury. Data from a rat experimental model and clinical experience

While experimental and clinical evidence indicates that in brain injury blood glucose increases with injury severity and hyperglycemia worsens neurological outcome, the role of blood glucose in secondary mechanisms of neuronal damage after acute spinal cord injury has not yet been investigated. Data from spinal cord ischemia models suggests a deleterious effect of hyperglycemia, likely due to enhanced lactic acidosis, which is primarily dependent on the amount of glucose available to be metabolized. The purpose of this study is to summarize preliminary experimental and clinical observations on the role of blood glucose in acute spinal cord injury. Between 1995 and 1996 we used the New York University (NYU) rat spinal cord injury model to test the following hypotheses: 1) Blood glucose levels increase with injury severity. 2) Fasting protects from hyperglycemia and prevents secondary damage to the spinal cord. 3) Postinjury-induced hyperglycemia (dextrose 5% 2 gm/Kg) enhances spinal lesion volume. From a clinical perspective, we reviewed blood glucose records of 47 patients admitted to the Department of Neurosrgery in Verona, between 1991 and 1995, within 24 hours of acute spinal cord injury in order to determine: a) the incidence of hyperglycemia (> 140 mg/dl); b) the correlation between blood glucose and injury severity; and c) the role of methylprednisolone in affecting blood glucose. Results indicate that in a graded spinal cord injury model: 1) Early after injury, more severe contusions support significantly higher blood glucose levels. 2) Fasting overnight does not directly affect spinal cord lesion volume but influences blood gases, and we observed that a slightly systemic acidosis plays a minor neuroprotective role. Fasting also ensures more consistent normoglycemic baseline blood glucose values. 3) Postinjury-induced moderate hyperglycemia (160-190 mg/dl) does not significantly affect spinal cord injury. In the clinical study, we observed that during the first 24 hours after spinal cord injury: a) Glycemia ranges between 90 and 243 mg/dl (mean value 143 mg/dl), and close to 50% of the patients present blood glucose values higher than normal. b) Methylprednisolone administration is not associated to significantly higher blood glucose levels. c) There is a trend for larger glucose rises with more severe injury.

Extracellular pH changes and accompanying cation shifts during ouabain-induced spreading depression

Interstitial ionic shifts that accompany ouabain-induced spreading depression (SD) were studied in rat hippocampal and cortical slices in the presence and absence of extracellular Ca(2+). A double-barreled ion-selective microelectrode specific for H(+), K(+), Na(+), or Ca(2+) was placed in the CA1 stratum radiatum or midcortical layer. Superfusion of 100 microM ouabain caused a rapid, negative, interstitial voltage shift (2-10 mV) after 3-5 min. The negativity was accompanied by a rapid alkaline transient followed by prolonged acidosis. In media containing 3 mM Ca(2+), the alkalosis induced by ouabain averaged 0.07 +/- 0.01 unit pH. In media with no added Ca(2+) and 2 mM EGTA, the alkaline shift was not significantly different (0.09 +/- 0.02 unit pH). The alkaline transient was unaffected by inhibiting Na(+)-H(+) exchange with ethylisopropylamiloride (EIPA) or by blocking endoplasmic reticulum Ca(2+) uptake with thapsigargin or cyclopiazonic acid. Alkaline transients were also observed in Ca(2+)-free media when SD was induced by microinjecting high K(+). The late acidification accompanying ouabain-induced SD was significantly reduced in Ca(2+)-free media and in solutions containing EIPA. The ouabain-induced SD was associated with a rapid but relatively modest increase in [K(+)](o). In the presence of 3 mM external Ca(2+), the mean peak elevation of [K(+)](o) was 12 +/- 0.62 mM. In Ca(2+)-free media, the elevation of [K(+)](o) had a more gradual onset and reached a significantly larger peak value, which averaged 22 +/- 1.1 mM. The decrease in [Na(+)](o) that accompanied ouabain-induced SD was somewhat greater. The [Na(+)](o) decreased by averages of 40 +/- 7 and 33 +/- 3 mM in Ca(2+) and Ca(2+)-free media, respectively. In media containing 1.2 mM Ca(2+), ouabain-induced SD was associated with a substantial decrease in [Ca(2+)](o) that averaged 0.73 +/- 0. 07 mM. These data demonstrate that in comparison with conventional SD, ouabain-induced SD exhibits ion shifts that are qualitatively similar but quantitatively diminished. The presence of external Ca(2+) can modulate the phenomenon but is irrelevant to the generation of the SD and its accompanying alkaline pH transient. Significance of these results is discussed in reference to the propagation of SD and the generation of interstitial pH changes.

Xenotransplantation of transgenic oligodendrocyte-lineage cells into spinal cord-injured adult rats

Spinal cord trauma is associated not only with loss of nerve cells and fibers but also with damage to oligodendrocytes and demyelination. In order to assess the potential of transplanted oligodendrocyte-lineage cells to repair the demyelination that follows spinal cord injury, we have used donor glia derived from a transgenic mouse line containing the LacZ transgene under control of the myelin basic protein promoter. Glia derived from fetal or neonatal transgenic mice were injected into the spinal cords of immunosuppressed adult rats at the site of an experimental traumatic lesion 1-16 days after injury. Cells expressing LacZ were identified 15-18 days later in cryosections rostral and caudal to the transplant site, most conspicuously within white matter defects. Some of these cells within the dorsal columns gave rise to approximately 30- to 60-microns processes, consistent with myelin segments, which are oriented parallel to the fiber tract. Glial transplantation may thus be a feasible means of replacing damaged host oligodendrocytes with donor oligodendrocyte-lineage cells capable of reforming myelin and potentially restoring functional lost as a result of demyelination associated with spinal cord injury.