Tumors are characterized by a multitude of genetic and epigenetic alterations, including a deregulation of the metabolism, driving migration and infiltration. To mimic the energetic landscape of in vivo tumors, 3D models surpass traditional 2D cultures, by introducing regions of different nutrient and oxygen supply. Yet, the analysis of metabolic processes in 3D cultures, including the mitochondrial answer and extracellular fluxes is more challenging. The extracellular flux analyzer is a powerful tool for investigating cellular metabolism, offering valuable insights that can drive advancements in biomedical research, but protocols for analysis of 3D cultures are sparse. Here, we present a protocol for optimized extracellular flux analysis, starting from the choice of the 3D culture model, dependencies on 3D culture size and testing multiple normalization approaches for two different glioblastoma and two primary cell lines. It was demonstrated that our approach was feasible for different glioblastoma cell lines, showing cell type and spheroid size dependent responses to metabolic challenges. In addition, normalization approaches using essentially 2D characteristics of spheroids were found insufficient to account for different spheroid sizes and cell lines. The data showed that using bio-printed spheroids with magnetic beads, combined with normalization to the median values of an experiment and the initially seeded cell number, delivered the most reliable results. Thus, we provided an approach that enables a straightforward and reproducible generation of 3D cell cultures and offer strategies to optimize metabolic measurements within these cultures.

Introduction:Postoperative imaging surveillance is essential in the management of glioma patients. However, new or progressive contrast-enhancing lesions do not always indicate true tumor recurrence. Foreign body granulomas (FBG), also known as textilomas, may arise as inflammatory reactions to hemostatic or sealing materials used during surgery and can closely mimic tumor progression on MRI. Distinguishing between these entities remains a major diagnostic challenge with important therapeutic implications. Methods:We retrospectively analyzed glioma re-operations performed for suspected recurrence at a tertiary neurosurgical center between 2016 and 2020. Demographic data, tumor histology, intraoperative foreign material, adjuvant therapy, and time to re-operation were assessed. Histological findings were classified as recurrence or no tumor. Preoperative MRI was reviewed according to RANO criteria, with emphasis on diffusion-weighted imaging and apparent diffusion coefficient (ADC) values. Univariate analyses were conducted. Results:Of 211 glioma patients, 38 (18 %) underwent re-operation for suspected recurrence. Histological recurrence was confirmed in 27 cases (71.1 %), while 11 (28.9 %) showed no tumor. Foreign material was identified in three non-tumor cases; the remaining showed post-inflammatory or unclear changes. All non-tumor cases had been radiologically classified as progressive disease. ADC values tended to be lower in the non-tumor group, suggesting diffusion restriction, but without statistical significance. Oxidized cellulose was frequently used in both groups. Conclusion:FBG are a relevant and likely underrecognized differential diagnosis in suspected glioma recurrence. Conventional MRI and RANO criteria alone may be insufficient. Diffusion-weighted imaging may provide additional clues but is not definitive. Increased awareness and multidisciplinary evaluation are essential to avoid unnecessary interventions and overtreatment.

BACKGROUND/OBJECTIVES:Vestibular schwannoma (VS) is the most common benign tumor in the cerebellopontine angle. In preliminary studies, macrophage infiltration has been suggested to influence disease progression. However, the infiltration of other immune cells in VS remains largely unexplored. The aim of this study was to comprehensively characterize the immune cells in sporadic VS. METHODS:Cryosections of five tumor samples from VS patients with different tumor volumes were examined. The abundance of fourteen immune-cell markers, one vascular marker, and two tumor markers were detected using multi-epitope ligand cartography (MELC). This enabled the spatial distribution and colocalization of immune- and tumor cell markers to be examined. Furthermore, using qPCR and bulk RNAseq, the mRNA levels of the immune-cell markers were examined in 204 VS samples of different tumor sizes. RESULTS:VSs with greater tumor volumes showed an increased number of immune cells, more precisely T-helper cells (TH cells), cytotoxic T cells (Tc cells), CD68+, and CD163+ macrophages, as well as CD279+ (PD-1) and CTLA4+ cells (p < 0.05). In addition, an increased number of CD274+ (PD-L1) tumor cells were detected in VSs with higher tumor volume (p < 0.05). CONCLUSIONS:These results indicate that an increased diversity of immune-cell subtypes influences VS tumor size. Thus, novel diagnostic and therapeutic options could be developed by targeting the tumor-associated immune-cell populations in VSs.

Glioblastoma is the most lethal and frequent type of primary brain tumors, characterized by a high proliferative and infiltrative capacity. Here, we used live cell imaging to analyze the effect of cell density variations on the migratory capacity of established and primary glioblastoma cell lines. We found that proliferation events promoted local velocity of glioblastoma cells, up to three cell-length away from the proliferation event. Furthermore, two phenotypes were found when subjecting glioblastoma cells to a cell density gradient. While one phenotype was characterized by the active migration of cells, independent of proliferation, the other was mostly driven by cell proliferation. Lastly, the analysis of the effects of an overall increasing cell density demonstrated that cells showing signs of self-organization, forming liquid crystal-like structures are able to maintain a high migratory potential even for high cell densities. Notably, the emergence of small-scale liquid crystal-like order was associated with a better maintenance of cellular migration, even in cell populations that were largely in a state of migratory arrest. Thus, structure formation might help glioblastoma cells to move efficiently in states of high confinement, thereby maintaining infiltrative properties.

Background:Glioblastoma (GBM) is the most aggressive primary brain tumor in adults. Dexamethasone (DEX) is commonly used to manage peritumoral edema, but its impact on overall survival (OS) and progression-free survival (PFS) remains unclear across treatment phases. Methods:In this retrospective single-center study, we analyzed data from 106 GBM patients treated between 2016 and 2020 at the University Hospital Halle. We examined the effects of DEX on OS and PFS during the preoperative, postoperative, and adjuvant therapy phases using Kaplan-Meier and Cox regression analyses. Cutoff analyses identified phase-specific DEX dose thresholds. Results:Preoperatively, DEX had no significant effect on OS (HR: 0.998, p = 0.379) or PFS (HR: 0.998, p = 0.373), though a positive trend is possible. Postoperatively, DEX was associated with improved OS (HR: 0.995, p = 0.017) and PFS (HR: 0.995, p = 0.029). Conversely, during adjuvant therapy, higher DEX doses trended toward worse OS (HR: 1.001, p = 0.069) and PFS (p = 0.258). Patients not receiving DEX during adjuvant therapy had significantly longer OS (17.9 vs. 6.4 months, p < 0.001) and PFS (9 vs. 4.6 months, p = 0.007). Conclusion:DEX influences survival outcomes differently across treatment phases. Higher doses may be beneficial pre- and postoperatively but detrimental during adjuvant therapy. These findings underscore the importance of phase-specific DEX dosing and support further research into optimal corticosteroid strategies in GBM care.

Advancements in neurosurgery have transformed the field, enabling safer, minimally invasive procedures supported by modern navigation, neuromonitoring, and intraoperative imaging techniques. The integration of robotics and navigation systems further enhances surgical precision, while advanced imaging modalities like intraoperative MRI and CT scans allow real-time visualization, facilitating more accurate tumor removal and hardware placement. Emerging technologies such as virtual reality and augmented reality are revolutionizing surgical planning, education, and patient-specific modeling. Despite these innovations, the application and education regarding these tools remain limited. This study aims to provide a comprehensive report on the availability of advanced techniques and facilities, as well as the quality of education imparted in Germany. To address this, a nationwide survey was conducted among 89 departments to evaluate the availability and utilization of modern neurosurgical technologies. The survey revealed that university hospitals tend to possess more advanced equipment, perform higher surgical volumes, and offer 24/7 services more frequently than other centers. Techniques such as intraoperative neuromonitoring, neuronavigation, and advanced imaging are widely available, particularly in academic centers; however, gaps exist in their consistent implementation across all hospitals. Residency programs increasingly incorporate training in these innovative techniques, with a strong correlation between university hospital status and educational opportunities. The survey highlights the need for broader dissemination of these technologies and standardized training to ensure all centers can provide high-quality, around-the-clock neurosurgical care. Overall, ongoing research, technological integration, and education are vital for advancing neurosurgical outcomes and expanding access to cutting-edge treatments across Germany.

Title: Standards for Reporting of Diagnostic Accuracy using Intraoperative Neurophysiological Monitoring (STARD-IONM) Objective: Intraoperative neurophysiological monitoring (IONM) plays a critical role in preserving functional integrity during surgery, yet it is challenging to compare studies due to methodological heterogeneity and inconsistent reporting. We developed the STARD-IONM extension to improve the transparency, completeness, and comparability of IONM studies. Methods: The STARD-IONM initiative followed a three-phase consensus. Phase 1 convened a IONM expert panel to discuss and define the rationale and scope. Phase 2 involved structured item-level review of existing STARD items in the context of IONM, applied to published studies with iterative feedback. Phase 3 will include broader community engagement via preprints, outreach to professional societies, and public commentary. Results: A review of IONM studies revealed the underreporting of at key methodological items such as handling missing data (7%), adverse events (11%), and blinding (22%). A STARD-IONM checklist with recommendations for reporting IONM studies with IONM specific examples were developed. Community feedback emphasized challenges unique to IONM, including the classification of reversible IONM changes, and variability in reference standards. Conclusions: The STARD-IONM framework addresses critical gaps in the reporting of diagnostic accuracy studies involving IONM. It represents an application of the STARD criteria, wherein the original checklist has been adapted and supplemented with guidelines for IONM studies. Significance: Standardized reporting will facilitate enhanced adherence to methodological standards, increase reproducibility and strengthen the evidence base for the safe and effective use of IONM, which is expected to improve clinical decision-making. Keywords: Intraoperative neurophysiological monitoring, STARD-IONM, reporting guidelines, Diagnostic accuracy, methodological quality, clinical decision-making ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement International Federation of Clinical Neurophysiology ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors

Glioblastoma is the most lethal and frequent type of primary brain tumors, characterized by a high proliferative and infiltrative capacity, leading to frequent recurrences after therapy. Here, we used live cell imaging to analyze the effect of cell density variations on the migratory capacity of established and primary glioblastoma cell lines. We found that proliferation events promoted local velocity of glioblastoma cells, but had only a small effect on large spatial scales. Furthermore, two phenotypes were found when subjecting glioblastoma cells to cell density gradient. One phenotype was characterized by the active migration of cells, independent of proliferation, while the other was mostly driven by cell proliferation. Lastly, the analysis of effects of an overall increasing cell density demonstrated that cells showing signs of self-organization, forming liquid crystal-like structures, are able to escape the expected cell-density induced migratory arrest. Notably, the emergence of small-scale liquid crystal-like order was associated with a promotion of cellular migration, even in cell populations that were largely in a state of migratory arrest. Thus, structure formation could help glioblastoma cells to move efficiently in states of high confinement, maintaining infiltrative properties.

Introduction Posterior reversible encephalopathy syndrome (PRES) is an acute form of encephalopathy. Main characteristic of this syndrome is the development of subcortical/cortical edema in the occipital lobes. The most common causes are diseases such as pre-eclampsia, autoimmune diseases, allogeneic stem cell transplantation and after treatment with immunosuppressants or cytostatics. However, PRES is also occasionally observed in connection with neurosurgical procedures, particularly in the posterior fossa in pediatric patients. Research Question PRES in adults is extremely rare. After cranial surgery, the impaired consciousness caused by this syndrome may be misdiagnosed. Material and Methods We present a rare case of PRES associated with vestibular schwannoma (VS) surgery and metronidazole use and have conducted a literature review. Results We found only two cases of PRES after surgery of a VS in the literature and three cases in connection with the administration of metronidazole. All cases involved women but the onset of symptoms was highly variable. The constellation of surgery and administration of metronidazole has not yet been described. Discussion and Conclusion The purpose of this review is to raise awareness of a very rare complication such as PRES in this setting. Antibiotics should be chosen carefully after such an operation, as this syndrome can be triggered by certain substances.

The ability to integrate semantic information into the context of a sentence is essential for human communication. Several studies have shown that the predictability of a final keyword based on the sentence context influences semantic integration on the behavioral, neurophysiological, and neural level. However, the architecture of the underlying network interactions for semantic integration across the lifespan remains unclear. In this study, 32 healthy participants (30-75 years) performed an auditory cloze probability task during functional magnetic resonance imaging (fMRI), requiring lexical decisions on the sentence's final words. Semantic integration demands were implicitly modulated by presenting sentences with expected, unexpected, anomalous, or pseudoword endings. To elucidate network interactions supporting semantic integration, we combined univariate task-based fMRI analyses with seed-based connectivity and between-network connectivity analyses. Behavioral data revealed typical semantic integration effects, with increased integration demands being associated with longer response latencies and reduced accuracy. Univariate results demonstrated increased left frontal and temporal brain activity for sentences with higher integration demands. Between-network interactions highlighted the role of task-positive and default mode networks for sentence processing with increased semantic integration demands. Furthermore, increasing integration demands led to a higher number of behaviorally relevant network interactions, suggesting that the increased between-network coupling becomes more relevant for successful task performance as integration demands increase. Our findings elucidate the complex network interactions underlying semantic integration across the aging continuum. Stronger interactions between various task-positive and default mode networks correlated with more efficient processing of sentences with increased semantic integration demands. These results may inform future studies with healthy old and clinical populations.

BACKGROUND AND OBJECTIVE:Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), is a common complication in craniotomy patients. The duration of surgery has been identified as a risk factor for the development of VTE. In a pilot study, the use of intermittent pneumatic venous compression (IPC) dramatically reduced the incidence of VTE. Despite randomization, a significant difference in the duration of surgery between the groups limited the validity of this result. The study was underpowered to compensate for this problem. We now present the protocol of a multicenter trial. METHODS:All patients receive medical compression stockings and low-molecular-weight heparin from the first postoperative day. The therapy group receives IPC stockings intraoperatively. Postoperatively, all patients receive lower-extremity duplex sonography to detect/exclude DVT within the first 7 postoperative days. Contrast-enhanced chest CT is the gold standard for the detection of PE and is performed in cases of clinical suspicion of PE. EXPECTED OUTCOMES:The incidence of VTE is the primary end point. The distinction between symptomatic and asymptomatic, etiologies, influence of lesion type, duration of surgery, and mortality will be evaluated as secondary end points. The pilot study showed a VTE incidence of 26% in the control group vs 7% in the treatment group. To avoid overly optimistic treatment effect assumptions, we assume VTE rates of 9% and 24% in the treatment and control groups, respectively, and thus calculated a number of 127 patients per treatment group. DISCUSSION:If this trial shows that intraoperative IPC reduces the risk of VTE to the extent observed in our pilot study (number needed to treat: 5.24), the potential benefit to neurosurgical patients would be significant. The results would potentially influence treatment guidelines by providing the high-quality evidence needed to make robust recommendations.

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), is a common complication in craniotomy patients and is associated with increased morbidity and mortality. The duration of surgery is a known risk factor. Other factors such as positioning and tumor entity have hardly been investigated or are controversial. In two pilot studies, the determination of plasma D-dimer concentration led to a high detection rate of DVT, while the use of intermittent pneumatic venous compression (IPC) drastically reduced the incidence of VTE. In the present study we investigated the efficacy of the two approaches, either alone or in combination, in a large patient cohort. 1759 patients who underwent elective craniotomy between 2009 and 2023 were retrospectively analyzed. The staggered use of D-dimer determination and intraoperative use of IPC resulted in 3 groups: Group 1: no procedure; Group 2: D-dimer evaluation; Group 3: IPC and D-dimer evaluation. If the D-dimer level was ≥ 2 mg/l (Fibrinogen equivalent units; FEU), venous ultrasound was performed. Age, gender, tumor entity, duration and extent of surgery, patient positioning, type of VTE were also recorded and analyzed. The introduction of postoperative D-dimer evaluation increased the rate of detection of thrombosis from 1.7

Language is organized in large-scale networks in the human brain that show a strong potential for flexible interactions and adaptation. Neuroplasticity is the central mechanism that allows such dynamic modulation to changing conditions across the life span and is particularly important for network reorganization after brain lesions. Most studies on language reorganization focused on language recovery after stroke. Yet, a strong degree of adaptive neuroplasticity can also be observed in patients with brain tumors in language-eloquent brain areas. This review discusses key mechanisms for neural reorganization in patients with brain tumors. Our main aim is to elucidate the underlying mechanisms for intra- and interhemispheric plasticity in the language network in these patients. The following reorganization patterns are discussed: 1) Persisting function within the tumor; 2) Reorganization in perilesional regions; 3) Reorganization in a distributed network of the affected hemisphere; 4) Reorganization to the contralesional hemisphere. In this context, we shed light on language-related reorganization patterns in frontal and temporo-parietal areas and discuss their functional relevance. We also address tumor-related changes in structural and functional connectivity between eloquent brain regions. Thereby, we aim to expand the general understanding of the plastic potential of the neural language network and facilitate clinical decision-making processes for effective, function-preserving tumor treatment.

Background: Analyses of collective cell migration and orientation phenomena are needed to assess the behavior of multicellular clusters. While some tools to the authors' knowledge none is capable to analyze collective migration, cellular orientation and proliferation in phase contrast images simultaneously.Methods: We provide a tool based to analyze phase contrast images of dense cell layers. PIV is used to calculate velocity fields, while the structure tensor provides cellular orientation. An artificial neural network is used to identify cell division events, allowing to correlate migratory and organizational phenomena with cell density.Conclusion: The presented tool allows the simultaneous analysis of collective cell behavior from phase contrast images in terms of migration, (self-)organization and proliferation.

Objective: The goal of awake craniotomy in glioma patients is sparing of cognitive function. Previous investigations suggest that patients in the postoperative state may reach their preoperative level regarding domain-based criteria. Data on significant postoperative improvement beyond the preoperative level is sparse. This article examines the prospective neuropsychological assessment of a glioma patient who underwent awake craniotomy and has shown functional improvement exceeding preoperative levels. Methods: A 34-year-old patient with high premorbid cognitive function level who underwent awake craniotomy for left frontal oligodendroglioma was neuropsychologically assessed and took part in a fMRI-examination at 3 different time points. Results: Preoperative examination revealed severe isolated impairment of working memory, long-term narrative memory in free recall and recognition, and alertness with intact language production and comprehension. After transient global aphasia in the postoperative state, the follow-up examination showed significant improvement in memory and attention exceeding the preoperative level. Conclusions: Tumor location is an important factor in terms of surgical procedures. Cognitive impairment is, however, not always associated with a specific location. Mechanical pressure of the tumor might have led to the isolated consolidation deficit which fully recovered after tumor removal. Psychological disorders should be taken into account regarding prodromal symptoms of neurooncological diseases.

Purpose: Cranioplasty is most commonly performed after decompressive hemicraniectomy and serves on the one hand for protection of the underlying brain tissue, on the other hand this surgery is also indicated for cosmetic reasons. In addition, patients may experience clinical improvement after this procedure, which can be explained by normalization of the CSF (Cerebrospinal fluid) and cerebral blood flow. However, this (usually underestimated) procedure is associated with one of the the highest complication rates in neurosurgery. Results: We report a case with a fatal outcome after routine cranioplasty utilizing PEEK (polyetheretherketone) implant due to a cerebrospinal fluid fistula. Conclusion: Cranioplasty after decompressive hemicraniectomy can restore aesthetics, ensures protection, and often leads to neurologic improvement in patients. However, it is one of the procedures with the highest complication rates in neurosurgery, and it should not be underestimated. The use of a drain with suction can have fatal consequences, especially when dural integrity is compromised and when there is intracranial room for considerable volume shift, e.g. after hemispheric infarction.

BACKGROUND:The data on handling of spontaneous, nontraumatic subarachnoid hemorrhage (SAH) with negative initial digital subtraction angiography (DSA) are still inconclusive. The intention of this study was to evaluate the requirement of repeat DSA in patients with negative initial DSA and to compare the clinical outcomes of these cases.METHODS:In a retrospective study, we reviewed patients with SAH and negative initial DSA treated in our department from January 2006 until December 2017. The patients were divided according to an established radiographic classification into perimesencephalic (pm) and nonperimesencephalic (npm) SAH. An interventional neuroradiologist and a neurosurgeon reviewed all DSA scans.RESULTS:In all, 52 patients with negative initial DSA, comprising 36 (69.2%) patients with pm and 16 (30.8%) patients with npm bleeding pattern, were included. All patients underwent a second and 23 of these patients underwent a third DSA. In these 23 patients, subarachnoid blood distribution in the initial computed tomography (CT) scan was suspicious for the presence of aneurysm. In total, two aneurysms were detected during the second DSA (diagnostic yield: 3.85%). Both were in the pm group (diagnostic yield: 5.6%). The second repeat DSA did not show any causative vascular lesion. Complications after the DSA occurred in only 2 of 127 patients (1.6%). The rate of complications concerning vasospasm (pm 52.8%, npm 56.3%), hydrocephalus (pm 47.2%, npm 50%), and the need for temporary or permanent shunt (pm 44.4%, npm 50%) was similar in both groups and there was no statistically significant difference.CONCLUSION:Repeat DSA after negative initial DSA in pm SAH had a diagnostic yield of 5.6%. However, a second repeat DSA cannot be recommended in case of SAH with initial negative DSA. The pm SAH should not be underrated concerning the occurrence of complications and cared with a high level of surveillance.

Surgical site infections (SSIs) after craniotomy lead to additional morbidity and mortality for patients, which are related to higher costs for the healthcare system. Furthermore, SSIs are associated with a longer hospital stay for the patient, which is particularly detrimental in glioblastoma patients due to their limited life expectancy. Risk factors for SSIs have already been described for craniotomies in general. However, there is limited data available for glioblastoma patients. As postoperative radiation influences wound healing, very early radiation is suspected to be a risk factor for SSI. Nevertheless, there are no data on the optimal timing of radiotherapy. To define risk factors for these patients, we analyzed our collective. We performed a retrospective analysis of all operations with histological evidence of a glioblastoma between 2012 and 2021. Open biopsy and tumor removal (gross total resection, subtotal resection) were included. Stereotactic biopsies were excluded. Demographic data such as age and gender, as well as duration of surgery, diameter of the trepanation, postoperative radiation with interval, postoperative chemotherapy, highest blood glucose level, previous surgery, ASA score, foreign material introduced, subgaleal suction drainage, ventricle opening and length of hospital stay, were recorded. The need for surgical revision due to infection was registered as an SSI. A total of 177 patients were included, of which 14 patients (7.9%) suffered an SSI. These occurred after a median of 45 days. The group with SSIs tended to include more men (57.1%, p = 0.163) and more pre-operated patients (50%, p = 0.125). In addition, foreign material and subgaleal suction drains had been implanted more frequently and the ventricles had been opened more frequently, without reaching statistical significance. Surprisingly, significantly more patients without SSIs had been irradiated (80.3%, p = 0.03). The results enable a better risk assessment of SSIs in glioblastoma patients. Patients with previous surgery, introduced foreign material, subgaleal suction drain and opening of the ventricle may have a slightly higher for SSIs. However, because none of these factors were significant, we should not call them risk factors. A less radical approach to surgery potentially involving these factors is not justified. The postulated negative role of irradiation was not confirmed, hence a rapid chemoradiation should be induced to achieve the best possible oncologic outcome.