Brain Mapping as Helpful Tool in Brain Glioma Surgical Treatment-Toward the "Perfect Surgery"?

An update on tests used for intraoperative monitoring of cognition during awake craniotomy

PURPOSE

Mapping higher-order cognitive functions during awake brain surgery is important for cognitive preservation which is related to postoperative quality of life. A systematic review from 2018 about neuropsychological tests used during awake craniotomy made clear that until 2017 language was most often monitored and that the other cognitive domains were underexposed (Ruis, J Clin Exp Neuropsychol 40(10):1081-1104, 218). The field of awake craniotomy and cognitive monitoring is however developing rapidly. The aim of the current review is therefore, to investigate whether there is a change in the field towards incorporation of new tests and more complete mapping of (higher-order) cognitive functions.

METHODS

We replicated the systematic search of the study from 2018 in PubMed and Embase from February 2017 to November 2023, yielding 5130 potentially relevant articles. We used the artificial machine learning tool ASReview for screening and included 272 papers that gave a detailed description of the neuropsychological tests used during awake craniotomy.

RESULTS

Comparable to the previous study of 2018, the majority of studies (90.4%) reported tests for assessing language functions (Ruis, J Clin Exp Neuropsychol 40(10):1081-1104, 218). Nevertheless, an increasing number of studies now also describe tests for monitoring visuospatial functions, social cognition, and executive functions.

CONCLUSIONS

Language remains the most extensively tested cognitive domain. However, a broader range of tests are now implemented during awake craniotomy and there are (new developed) tests which received more attention. The rapid development in the field is reflected in the included studies in this review. Nevertheless, for some cognitive domains (e.g., executive functions and memory), there is still a need for developing tests that can be used during awake surgery.

Assessment of the Efficacy of Circulating Tumor Cells by Liquid Biopsy in the Diagnosis and Prediction of Tumor Behavior of Gliomas: A Systematic Review

In the realm of glioma management, the ability to accurately diagnose and predict tumor behavior remains a formidable task. Emerging as a beacon of hope, liquid biopsy (LB), with its potential to detect circulating tumor (CT) cells, offers a novel and promising avenue for addressing these challenges. This systematic review delves into the effectiveness of LB in transforming the landscape of glioma analysis as well as prognosis, shedding light on its clinical significance and implications. We conducted a comprehensive literature search from 2015 to 2023, using multiple sources. We assessed titles and abstracts first, followed by full-text review if they met our criteria. We included those studies that fulfill the inclusion criteria of the study. For bias assessment, we used a two-part tool for specific domains and a quality assessment tool for diagnostic accuracy studies. In this review, we incorporated eight studies. A total of 498 patients were identified across eight studies. The average sensitivity was 72.28% in seven of these studies, while the average specificity was 91.52% in the same seven studies. Our review revealed a sensitivity of 72.28% and an impressive specificity of 91.52%. This underscores the potential of LB as a valuable prognostic tool for detecting CT cells. However, the early detection of tumor cells and the prediction of tumor behavior in gliomas continue to be topics of debate, necessitating further research for more precise and reliable outcomes.

Corticocortical Evoked Potentials in Eloquent Brain Tumor Surgery. A Systematic Review

Eloquent brain tumor surgery involves the delicate task of resecting tumors located in regions of the brain responsible for critical functions, such as language, motor control, and sensory perception. Preserving these functions is of paramount importance to maintain the patient's quality of life. Corticocortical evoked potentials (CCEPs) have emerged as a valuable intraoperative monitoring technique that aids in identifying and preserving eloquent cortical areas during surgery. This systematic review aimed to assess the utility of CCEPs in eloquent brain tumor surgery and determine their effectiveness in improving patient outcomes. A comprehensive literature search was conducted using electronic databases, including PubMed/Medline and Scopus. The search strategy identified 11 relevant articles for detailed analysis. The findings of the included studies consistently demonstrated the potential of CCEPs in guiding surgical decision making, minimizing the risk of postoperative neurological deficits, and mapping functional connectivity during surgery. However, further research and standardization are needed to fully establish the clinical benefits and refine the implementation of CCEPs in routine neurosurgical practice.

Forecasting Molecular Features in IDH-Wildtype Gliomas: The State of the Art of Radiomics Applied to Neurosurgery

BACKGROUND

The fifth edition of the WHO Classification of Tumors of the Central Nervous System (CNS), published in 2021, marks a step forward the future diagnostic approach to these neoplasms. Alongside this, radiomics has experienced rapid evolution over the last several years, allowing us to correlate tumor imaging heterogeneity with a wide range of tumor molecular and subcellular features. Radiomics is a translational field focused on decoding conventional imaging data to extrapolate the molecular and prognostic features of tumors such as gliomas. We herein analyze the state-of-the-art of radiomics applied to glioblastoma, with the goal to estimate its current clinical impact and potential perspectives in relation to well-rounded patient management, including the end-of-life stage.

METHODS

A literature review was performed on the PubMed, MEDLINE and Scopus databases using the following search items: "radiomics and glioma", "radiomics and glioblastoma", "radiomics and glioma and IDH", "radiomics and glioma and TERT promoter", "radiomics and glioma and EGFR", "radiomics and glioma and chromosome".

RESULTS

A total of 719 articles were screened. Further quantitative and qualitative analysis allowed us to finally include 11 papers. This analysis shows that radiomics is rapidly evolving towards a reliable tool.

CONCLUSIONS

Further studies are necessary to adjust radiomics' potential to the newest molecular requirements pointed out by the 2021 WHO classification of CNS tumors. At a glance, its application in the clinical routine could be beneficial to achieve a timely diagnosis, especially for those patients not eligible for surgery and/or adjuvant therapies but still deserving palliative and supportive care.

Intraoperative Evaluation of Brain-Tumor Microvascularization through MicroV IOUS: A Protocol for Image Acquisition and Analysis of Radiomic Features

Microvascular Doppler (MicroV) is a new-generation Doppler technique developed by Esaote (Esaote s.p.a., Genova, Italy), which is able to visualize small and low-flow vessels through a suppression of interfering signals. MicroV uses advanced filters that are able to differentiate tissue artifacts from low-speed blood flows; by exploiting the space-time coherence information, these filters can selectively suppress tissue components, preserving the signal coming from the microvascular flow. This technique is clinically applied to the study of the vascularization of parenchymatous lesions, often with better diagnostic accuracy than color/power Doppler techniques. The aim of this paper is to develop a reproducible protocol for the recording and collection of MicroV intraoperative ultrasound images by the use of a capable intraoperative ultrasound machine and post-processing aimed at evaluation of brain-tumor microvascularization through the analysis of radiomic features. The proposed protocol has been internally validated on eight patients and will be firstly applied to patients affected by WHO grade IV astrocytoma (glioblastoma-GBM) candidates for craniotomy and lesion removal. In a further stage, it will be generally applied to patients with primary or metastatic brain tumors. IOUS is performed before durotomy. Tumor microvascularization is evaluated using the MicroV Doppler technique and IOUS images are recorded, stored, and post-processed. IOUS images are remotely stored on the BraTIoUS database, which will promote international cooperation and multicentric analysis. Processed images and texture radiomic features are analyzed post-operatively using ImageJ, a free scientific image-analysis software based on the Sun-Java platform. Post-processing protocol is further described in-depth. The study of tumor microvascularization through advanced IOUS techniques such as MicroV could represent, in the future, a non-invasive and real-time method for intraoperative predictive evaluation of the tumor features. This evaluation could finally result in a deeper knowledge of brain-tumor behavior and in the on-going adaptation of the surgery with the improvement of surgical outcomes.

Spinal Tractography as a Potential Prognostic Tool in Spinal Cord Injury: A Systematic Review

Magnetic resonance imaging is considered the most accurate examination to study the spinal cord. Nevertheless, the use of diffusion tensor imaging (DTI) can demonstrate additional key details about spinal cord lesions. We examined the literature to investigate and discuss the role, limitations, and possible evolution as a prognostic tool of DTI in spinal cord injury (SCI). For this systematic literature review, a detailed search was performed using PubMed (2005-2021), Cochrane Database of Systematic Reviews (2016-2021), and Cochrane Central Register of Controlled Trials (2016-2021). To be included, studies had to report the use of DTI in SCIs, its clinical relevance, and its use as a prognostic tool. We identified 17 studies comprising 299 patients. The mean age of patients was 41.22 ± 10.62 years. There was a prevalence of males (70.9%) compared with females (29.1%). The main spinal cord tract involved and studied in SCIs was the cervical tract (57.5%), followed by conus terminalis (15.4%) and dorsal tract (13.7%). In all studies based on American Spine Injury Association impairment scale score for neurological assessment, a correlation was found between FA values and American Spine Injury Association impairment scale: patients with complete SCI had a statistically significative lower FA value at the injured site compared with patients with incomplete SCI. Published clinical studies showed promising results for the utility of DTI parameters as noninvasive biomarkers in SCI grade evaluation, remaining an evolving area of further investigation.

Preliminary Study on the Therapeutic Effect of Doxorubicin-Loaded Targeting Nanoparticles on Glioma

Doxorubicin (DOX) is an anthracycline anticancer drug, which is often associated with drug resistance and cytotoxicity. More unfortunately, the biological barrier in the human environment can weaken the efficacy of DOX, such as the blood-brain barrier (BBB). This work attempts to make efforts to solve this problem. We used polyethylene glycol distearoylphosphatidylethanolamine (PEG-DSPE) as a nanocarrier and DOX as a model drug to construct a composite nanodrug (TF-PEG-DSPE/DOX NPs) by coupling transferrin (TF). The results of glioma experiments show that the nanodrug can effectively penetrate BBB to achieve an antitumor effect.

Liquid Biopsy in Diagnosis and Prognosis of High-Grade Gliomas; State-of-the-Art and Literature Review

Gliomas, particularly high-grade gliomas, represent the most common and aggressive tumors of the CNS and are still burdened by high mortality and a very poor prognosis, regardless of the type of therapy. Their diagnosis and monitoring rely on imaging techniques and direct biopsy of the pathological tissue; however, both procedures have inherent limitations. To address these limitations, liquid biopsies have been proposed in this field. They could represent an innovative tool that could help clinicians in the early diagnosis, monitoring, and prognosis of these tumors. Furthermore, the rapid development of next-generation sequencing (NGS) technologies has led to a significant reduction in sequencing cost, with improved accuracy, providing a molecular profile of cancer and leading to better survival results and less disease burden. This paper focuses on the current clinical application of liquid biopsy in the early diagnosis and prognosis of cancer, introduces NGS-related methods, reviews recent progress, and summarizes challenges and future perspectives.

Intraoperative Ultrasound: Emerging Technology and Novel Applications in Brain Tumor Surgery

Intraoperative ultrasound (IOUS) is becoming progressively more common during brain tumor surgery. We present data from our case series of brain tumor surgery performed with the aid of IOUS in order to identify IOUS advantages and crucial aspects that may improve the management of neurosurgical procedures for brain tumors. From January 2021 to September 2021, 17 patients with different brain tumors underwent brain tumor surgery aided by the use of IOUS. During surgery, the procedure was supported by the use of multiples ultrasonographic modalities in addition to standard B-mode: Doppler, color Doppler, elastosonography, and contrast-enhanced intraoperative ultrasound (CEUS). In selected cases, the use of IOUS during surgical procedure was combined with neuronavigation and the use of intraoperative fluorescence by the use of 5-aminolevulinic acid (5-ALA). In one patient, a preoperative ultrasound evaluation was performed through a former iatrogenic skull defect. This study confirms the role of IOUS in maximizing the EOR, which is strictly associated with postoperative outcome, overall survival (OS), and patient’s quality of life (QoL). The combination of ultrasound advanced techniques such as Doppler, color Doppler, elastosonography, and contrast-enhanced intraoperative ultrasound (CEUS) is crucial to improve surgical effectiveness and patient’s safety while expanding surgeon’s view.

Coplanar Indirect-Navigated Intraoperative Ultrasound: Matching Un-navigated Probes With Neuronavigation During Neurosurgical Procedures. How We Do It

BACKGROUND

Intraoperative ultrasound (IOUS) is becoming more and more adopted in neurosurgery, since it has been associated to greater extent of resection (EOR) and to gross total resection (GTR) during brain tumor surgery. IOUS main limitations are spatial resolution, width and orientation of the field of view and scan quality, which are operator-dependent. Furthermore, most neurosurgeons are not confident with this technique, which needs a long learning curve in order to identify and interpret anatomic structures.

OBJECTIVE

To describe an effective procedure to take advantages of both IOUS and neuronavigation in case of lack of a navigated ultrasound system.

METHODS

We propose a reliable "indirect-navigated" technique which is based on the optical tracking of un-navigated IOUS probe by the use of a multipurpose passive tracker and a proper configuration of common neuronavigation system.

RESULTS

Navigated IOUS is not available in all neurosurgical operating rooms but ultrasound systems are common tools in many hospital facilities and neuronavigation systems are common in almost all the neurosurgical operating rooms. The proposed indirect-navigated technique shows some paramount advantages: since almost all the neurosurgical operating rooms are provided with a neuronavigation system, the only tool needed is the ultrasonography. Therefore, this procedure is largely accessible and costless, reliable, and may improve the neurosurgeon's ability in ultrasonographic anatomy.

CONCLUSION

This technique is based on the coplanar and coupled use of both un-navigated IOUS probe and standard optical neuronavigation, in order to allow the intraoperative navigation of IOUS images when a navigated ultrasound system is not available.

Correlation between intraoperative mapping and monitoring and functional outcomes following supratentorial glioma surgery

OBJECTIVES

Intraoperative neurophysiological monitoring (IONM) has long been regarded as the "gold standard" when resecting a supratentorial glioma, as it facilitates the goals of maximal tumor resection and preservation of sensorimotor function. The purpose of the present study was to evaluate the ability of motor evoked potentials (MEPs) monitoring or subcortical mapping (SCM), alone or in combination, to predict postoperative functional outcomes in glioma surgery.

MATERIALS AND METHODS

We retrospectively reviewed patients with supratentorial glioma that underwent craniotomy for tumor removal with IONM. Statistical analyses were used to evaluate whether the following criteria correlated with postoperative functional outcomes: Reduced amplitude (>50% reduction) or disappearance of MEPs (criterion 1), SCM with a stimulation intensity threshold less than 3 mA (criterion 2), the presence of both two phenomena (criterion 3), or either one of the two phenomena (criterion 4).

RESULTS

Ninety-two patients were included in this study, of whom 15 sustained new postoperative deficits, 4 experienced improved functional status, and 73 were unchanged. Postoperative functional status correlated significantly with all four criteria, and especially with criterion 3 (r = 0.647, P = 0.000). Sensitivity of IONM was better if using criteria 2 and 4, but specificity was better if using criteria 1 and 3. Criterion 3 had the most favorable overall results.

CONCLUSION

Using statistical methodology, our study indicates that concomitant interpretation of MEPs and SCM is the most accurate predictor of functional outcomes following supratentorial glioma surgery. However, accurate interpretations of the monitoring results by experienced neurophysiologists are essential.

68Ga-DOTATOC PET/CT Follow Up after Single or Hypofractionated Gamma Knife ICON Radiosurgery for Meningioma Patients

⁶⁸Ga-DOTATOC represents a useful tool in tumor contouring for radiosurgery planning. We present a case series of patients affected by meningiomas on who we performed ⁶⁸Ga-DOTATOC positron emission tomography (PET)/CT pre-operatively, a subgroup of which also underwent a post-operative ⁶⁸Ga-DOTATOC PET/CT to evaluate the standardized uptake value (SUV) modification after Gamma Knife ICON treatment in single or hypofractionated fractions. Twenty patients were enrolled/included in this study: ten females and ten males. The median age was 52 years (range 33-80). The median tumor diameter was 3.68 cm (range 0.12-22.26 cm), and the median pre-radiotherapy maximum SUV value was 11 (range 2.3-92). The average of the relative percentage changes between SUVs at baseline and follow up was -6%, ranging from -41% to 56%. The SUV was reduced in seven out of 12 patients (58%), stable in two out of 12 (17%), and increased in three out of 12 (25%), suggesting a biological response of the tumor to the Gamma Knife treatment in most of the cases. ⁶⁸Ga-DOTATOC-PET represents a valuable tool in assessing the meningioma diagnosis for primary radiosurgery; it is also promising for follow-up assessment.

A rare diagnosis of an extraventricular neurocytoma

Background:

Extraventricular neurocytoma (EVN) is an extremely rare neoplasm of the central nervous system. As reported, it arises in a variety of locations, but mainly within the cerebral hemispheres. Despite its histological similarity with central neurocytoma (CN), EVN occurs outside the ventricular system and, in 2007, was recognized by the World Health Organization as a separate entity.

Case Description:

A 39-year-old man, with a ventriculoperitoneal shunt inserted for communicating hydrocephalus, was admitted at our Unit of Neurosurgery with a 1-month history of gait disturbance, postural instability, speech disorders, and occasional incontinence. Computed tomography scan and magnetic resonance imaging showed a mixed-density neoplasm in the left frontotemporal area, with anterior cerebral falx shift, and perilesional edema. The patient underwent surgical procedure; microsurgical excision of the lesion was performed through left pterional approach. Histopathological and immunohistochemical examination revealed monomorphic round cells of the neuronal lineage, with a percentage of Ki-67 positive nuclei <5% and no evidence of mitosis or necrotic areas. According to radiologic features, this pattern was compatible with the diagnosis of EVN. Patient had a favorable recovery and he is still in follow-up.

Conclusion:

Because of their rarity, clinical, radiologic, and histopathological characteristics of EVNs are not yet well defined, as well as the optimal therapeutic management. Whereas EVNs are rarely described in literature, we aimed to share and discuss our experience along with a review of the published literature.

Navigated Transcranial Magnetic Stimulation Motor Mapping Usefulness in the Surgical Management of Patients Affected by Brain Tumors in Eloquent Areas: A Systematic Review and Meta-Analysis

Background: The surgical strategy for brain glioma has changed, shifting from tumor debulking to a more careful tumor dissection with the aim of a gross-total resection, extended beyond the contrast-enhancement MRI, including the hyperintensity on FLAIR MR images and defined as supratotal resection. It is possible to pursue this goal thanks to the refinement of several technological tools for pre and intraoperative planning including intraoperative neurophysiological monitoring (IONM), cortico-subcortical mapping, functional MRI (fMRI), navigated transcranial magnetic stimulation (nTMS), intraoperative CT or MRI (iCT, iMR), and intraoperative contrast-enhanced ultrasound. This systematic review provides an overview of the state of the art techniques in the application of nTMS and nTMS-based DTI-FT during brain tumor surgery.

Materials and Methods: A systematic literature review was performed according to the PRISMA statement. The authors searched the PubMed and Scopus databases until July 2020 for published articles with the following Mesh terms: (Brain surgery OR surgery OR craniotomy) AND (brain mapping OR functional planning) AND (TMS OR transcranial magnetic stimulation OR rTMS OR repetitive transcranial stimulation). We only included studies regarding motor mapping in craniotomy for brain tumors, which reported data about CTS sparing.

Results: A total of 335 published studies were identified through the PubMed and Scopus databases. After a detailed examination of these studies, 325 were excluded from our review because of a lack of data object in this search. TMS reported an accuracy range of 0.4–14.8 mm between the APB hotspot (n1/4 8) in nTMS and DES from the DES spot; nTMS influenced the surgical indications in 34.3–68.5%.

Conclusion: We found that nTMS can be defined as a safe and non-invasive technique and in association with DES, fMRI, and IONM, improves brain mapping and the extent of resection favoring a better postoperative outcome.

Brain Mapping-Aided SupraTotal Resection (SpTR) of Brain Tumors: The Role of Brain Connectivity

Brain gliomas require a deep knowledge of their effects on brain connectivity. Understanding the complex relationship between tumor and functional brain is the preliminary and fundamental step for the subsequent surgery. The extent of resection (EOR) is an independent variable of surgical effectiveness and it correlates with the overall survival. Until now, great efforts have been made to achieve gross total resection (GTR) as the standard of care of brain tumor patients. However, high and low-grade gliomas have an infiltrative behavior and peritumoral white matter is often infiltrated by tumoral cells. According to these evidences, many efforts have been made to push the boundary of the resection beyond the contrast-enhanced lesion core on T1w MRI, in the so called supratotal resection (SpTR). SpTR is aimed to maximize the extent of resection and thus the overall survival. SpTR of primary brain tumors is a feasible technique and its safety is improved by intraoperative neuromonitoring and advanced neuroimaging. Only transient cognitive impairments have been reported in SpTR patients compared to GTR patients. Moreover, SpTR is related to a longer overall and progression-free survival along with preserving neuro-cognitive functions and quality of life.

Comprehensive analysis of a long non-coding RNA-associated competing endogenous RNA network in glioma

Long non-coding RNAs (lncRNAs) can act as competing endogenous RNAs (ceRNAs), interacting with microRNAs (miRNAs) and playing an important role in tumor progression. However, the role of lncRNA-mediated ceRNAs in glioma remains largely unknown. The present study aimed to identify novel lncRNAs and their associated function in glioma. RNA sequencing and corresponding clinical data from patients with glioma were obtained from The Cancer Genome Atlas. A total of 598 glioma tissues and 5 normal brain tissues were analyzed in the present study. The differentially expressed (DE) lncRNAs, mRNAs and miRNAs were identified using R packages and were used to construct a ceRNA network. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to investigate the biological functions of the DEmRNAs. Kaplan-Meier curve analysis was performed to investigate the association between DElncRNA expression and patient outcome. A total of 752 DElncRNAs, 2,079 DEmRNAs and 113 DEmiRNAs were identified between glioma and normal tissues. A lncRNA-miRNA-mRNA ceRNA network consisting of 61 lncRNAs, 12 miRNAs and 92 mRNAs was constructed. Survival analysis indicated that 36 DElncRNAs, 72 DEmRNAs and 3 DEmiRNAs were associated with overall survival in patients with glioma. The present study identified novel lncRNAs associated with survival prognosis and may facilitate further investigation of lncRNA-mediated ceRNA regulatory mechanisms in glioma.

LncRNA CCAT2 promotes angiogenesis in glioma through activation of VEGFA signalling by sponging miR-424

Glioma is characterized by high morbidity, high mortality and poor prognosis. Recent studies exhibited that lncRNA CCAT2 is overexpressed in glioma and promotes glioma progression, but the specific molecular biological mechanism remains to be determined. We performed qRT-PCR to evaluate the expression of related genes, Western blotting analysis to measure protein levels, colony formation assay to detect the proliferative ability of glioma cells, flow cytometry to measure cell apoptosis, bioinformatics analysis and dual luciferase assay to verify the binding sites and the targeted regulatory relationship in A172 and U251 cell lines and tube formation assay to determine endothelial angiogenesis. LncRNA CCAT2 and VEGFA were highly expressed, while miR-424 was expressed at low levels in NHA cells. Furthermore, knockdown of lncRNA CCAT2 decreased cell proliferation, increased cell apoptosis and inhibited endothelial angiogenesis in glioma. Moreover, lncRNA CCAT2 shared a complementary sequence with miR-424 which in turn directly bound to the 3'-UTR of VEGFA. Further investigation indicated that lncRNA CCAT2 promoted cell proliferation and endothelial angiogenesis by inducing the PI3K/AKT signalling pathway in glioma. The oncogenic lncRNA CCAT2 is highly associated with the development of glioma and exerts its function by upregulating VEGFA via miR-424.