Effects of supra-total resection in neurocognitive and oncological outcome of high-grade gliomas comparing asleep and awake surgery

The Case for Neurosurgical Intervention in Cancer Neuroscience

The emerging field of cancer neuroscience reshapes our understanding of the intricate relationship between the nervous system and cancer biology; this new paradigm is likely to fundamentally change and advance neuro-oncological care. The profound interplay between cancers and the nervous system is reciprocal: Cancer growth can be induced and regulated by the nervous system; conversely, tumors can themselves alter the nervous system. Such crosstalk between cancer cells and the nervous system is evident in both the peripheral and central nervous systems. Recent advances have uncovered numerous direct neuron-cancer interactions at glioma-neuronal synapses, paracrine mechanisms within the tumor microenvironment, and indirect neuroimmune interactions. Neurosurgeons have historically played a central role in neuro-oncological care, and as the field of cancer neuroscience is becoming increasingly established, the role of neurosurgical intervention is becoming clearer. Examples include peripheral denervation procedures, delineation of neuron-glioma networks, development of neuroprostheses, neuromodulatory procedures, and advanced local delivery systems. The present review seeks to highlight key cancer neuroscience mechanisms with neurosurgical implications and outline the future role of neurosurgical intervention in cancer neuroscience.

Resting State Functional Networks in Gliomas: Validation With Direct Electric Stimulation of a New Tool for Planning Brain Resections

BACKGROUND AND OBJECTIVES

Precise mapping of functional networks in patients with brain tumor is essential for tailoring personalized treatment strategies. Resting-state functional MRI (rs-fMRI) offers an alternative to task-based fMRI, capable of capturing multiple networks within a single acquisition, without necessitating task engagement. This study demonstrates a strong concordance between preoperative rs-fMRI maps and the gold standard intraoperative direct electric stimulation (DES) mapping during awake surgery.

METHODS

We conducted an analysis involving 28 patients with glioma who underwent awake surgery with DES mapping. A total of 100 DES recordings were collected to map sensorimotor (SMN), language (LANG), visual (VIS), and speech articulation cognitive domains. Preoperative rs-fMRI maps were generated using an updated version of the ReStNeuMap software, specifically designed for rs-fMRI data preprocessing and automatic detection of 7 resting-state networks (SMN, LANG, VIS, speech articulation, default mode, frontoparietal, and visuospatial). To evaluate the agreement between these networks and those mapped with invasive cortical mapping, we computed patient-specific distances between them and intraoperative DES recordings.

RESULTS

Automatically detected preoperative functional networks exhibited excellent agreement with intraoperative DES recordings. When we spatially compared DES points with their corresponding networks, we found that SMN, VIS, and speech articulatory DES points fell within the corresponding network (median distance = 0 mm), whereas for LANG a median distance of 1.6 mm was reported.

CONCLUSION

Our findings show the remarkable consistency between key functional networks mapped noninvasively using presurgical rs-fMRI and invasive cortical mapping. This evidence highlights the utility of rs-fMRI for personalized presurgical planning, particularly in scenarios where awake surgery with DES is not feasible to protect eloquent areas during tumor resection. We have made the updated tool for automated functional network estimation publicly available, facilitating broader utilization of rs-fMRI mapping in various clinical contexts, including presurgical planning, functional reorganization over follow-up periods, and informing future treatments such as radiotherapy.

Intraoperative magnetic resonance imaging in glioma surgery: a single-center experience

PURPOSE

To investigate the effect of intraoperative magnetic resonance imaging (Io MRI) on overall and progression-free survival (OS and PFS), on the extent of resection (EOR) in patients with glioma, and impact of the radiological diagnosis on the decision to continue the surgery when a residual mass was detected on Io MRI.

METHODS

The study comprised 153 glioma patients who received surgical treatment between 2013 and 2023. One-hundred twenty-five of them had Io MRI guidance during surgery. The remainder 28 patients constituted the control group who did not undergo Io MRI. All patients' age at surgery, gender, initial radiological diagnosis, primary tumor localization, EOR, last histopathological diagnosis, and the follow-up periods were recorded.

RESULTS

The rate of tumor recurrence in Io MRI cases was significantly lower compared to the cases in the control group (p < .0001). It was decided to continue the operation in 45 Io MRI applied cases. This raised the gross total resection (GTR) rate from 33.6% to 49.6% in the Io MRI group. The frequency of GTR was significantly higher in patients with an initial radiological diagnosis of low grade glioma than those with high grade glioma. The shortest OS was seen in occipital gliomas.

CONCLUSION

In this study, the convenience provided by the high-field MRI device was explored and proven both in reducing the tumor burden, increasing the PFS, and providing the surgeon with a maximal resection in the first operation.

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.

Supramaximal resection: retrospective study on IDH-wildtype Glioblastomas based on the new RANO-Resect classification

BACKGROUND

The prognostic value of the extent of resection in the management of Glioblastoma is a long-debated topic, recently widened by the 2022 RANO-Resect Classification, which advocates for the resection of the non-enhancing disease surrounding the main core of tumors (supramaximal resection, SUPR) to achieve additional survival benefits. We conducted a retrospective analysis to corroborate the role of SUPR by the RANO-Resect Classification in a single center, homogenous cohort of patients.

METHODS

Records of patients operated for WHO-2021 Glioblastomas at our institution between 2007 and 2018 were retrospectively reviewed; volumetric data of resected lesions were computed and classified by RANO-Resect criteria. Survival and correlation analyses were conducted excluding patients below near-total resection.

RESULTS

117 patients met the inclusion criteria, encompassing 45 near-total resections (NTR), 31 complete resections (CR), and 41 SUPR. Median progression-free and overall survival were 11 and 15 months for NTR, 13 and 17 months or CR, 20 and 24 months for SUPR, respectively (p < 0.001), with inverse correlation observed between survival and FLAIR residual volume (r -0.28). SUPR was not significantly associated with larger preoperative volumes or higher rates of postoperative deficits, although it was less associated with preoperative neurological deficits (OR 3.37, p = 0.003). The impact of SUPR on OS varied between MGMT unmethylated (HR 0.606, p = 0.044) and methylated (HR 0.273, p = 0.002) patient groups.

CONCLUSIONS

Results of the present study support the validity of supramaximal resection by the new RANO-Resect classification, also highlighting a possible surgical difference between tumors with methylated and unmethylated MGMT promoter.

What helps patients to prepare for and cope during awake craniotomy? A prospective qualitative study

There is growing interest in awake craniotomies, but some clinicians are concerned that such procedures are poorly tolerated by patients. Therefore, we conducted a study to assess this phenomenon. In this prospective qualitative study, 68 patients who qualified for awake craniotomy were asked to complete the Hospital Anxiety and Depression Scale (HADS)-two days before the surgery and visual analogue scales (VAS) for pain and stress, two days before the surgery and again about two days after. In addition, after their surgery, they took part in a structured interview about what helped them prepare for and cope with the surgery. Most patients tolerated the awake surgery well, scoring low on stress and pain scales. They reported a lower level of stress during the surgery (when questioned afterwards) than before it. Intensity of stress before the surgery correlated negatively with age, positively with HADS anxiety score and positively with stress subsequently experienced during surgery. The level of stress during surgery was associated with stress experienced before the surgery, pain and HADS anxiety and depression scores. Severity of pain during the surgery was positively correlated with stress during surgery and HADS depression and anxiety scores before the surgery. There was no correlation between stress, pain, anxiety and depression and the location of the lesion. Patients have a high tolerance for awake craniotomy. Various factors have an impact on how well patients cope with the operation. Extensive preoperative preparation should be considered a key part of the procedure.

"Non-Eloquent" brain regions predict neuropsychological outcome in tumor patients undergoing awake craniotomy

Supratotal resection of primary brain tumors is being advocated especially when involving "non-eloquent" tissue. However, there is extensive neuropsychological data implicating functions critical to higher cognition in areas considered "non-eloquent" by most surgeons. The goal of the study was to determine pre-surgical brain regions that would be predictive of cognitive outcome at 4-6 months post-surgery. Cortical reconstruction and volumetric segmentation were performed with the FreeSurfer-v6.0 image analysis suite. Linear regression models were used to regress cortical volumes from both hemispheres, against the total cognitive z-score to determine the relationship between brain structure and broad cognitive functioning while controlling for age, sex, and total segmented brain volume. We identified 62 consecutive patients who underwent planned awake resections of primary (n = 55, 88%) and metastatic at the University of New Mexico Hospital between 2015 and 2019. Of those, 42 (23 males, 25 left hemispheric lesions) had complete pre and post-op neuropsychological data available and were included in this study. Overall, total neuropsychological functioning was somewhat worse (p = 0.09) at post-operative neuropsychological outcome (Mean = -.20) than at baseline (Mean = .00). Patients with radiation following resection (n = 32) performed marginally worse (p = .036). We found that several discrete brain volumes obtained pre-surgery predicted neuropsychological outcome post-resection. For the total sample, these volumes included: left fusiform, right lateral orbital frontal, right post central, and right paracentral regions. Regardless of lesion lateralization, volumes within the right frontal lobe, and specifically right orbitofrontal cortex, predicted neuropsychological difference scores. The current study highlights the gaps in our current understanding of brain eloquence. We hypothesize that the volume of tissue within the right lateral orbital frontal lobe represents important cognitive reserve capacity in patients undergoing tumor surgery. Our data also cautions the neurosurgeon when considering supratotal resections of tumors that do not extend into areas considered "non-eloquent" by current standards.

Cognition, Emotional States and Health-Related Quality of Life in Awake Craniotomy for Glioma: A Case Series

BACKGROUND

Awake craniotomy is an effective procedure for optimizing the onco-functional balance of resections in glioma. However, limited data exists on the cognition, emotional states, and health-related quality of life (HRQoL) of patients with glioma who undergo awake craniotomy. This study aims to describe 1) perioperative cognitive function and emotional states in a multilingual Asian population, 2) associations between perioperative cognitive function and follow-up HRQoL, and 3) associations between preoperative emotional states and follow-up HRQoL.

METHODS

This is a case series of 14 adult glioma patients who underwent awake craniotomy in Singapore. Cognition was assessed with the Montreal Cognitive Assessment and the Repeatable Battery for the Assessment of Neuropsychological Status, emotional states with the Depression, Anxiety and Stress Scale-21 Items, and HRQoL using the EuroQol-5D-5L, the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30, and the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-BN20.

RESULTS

Patients with better preoperative cognitive scores on all domains reported better HRQoL. Better postoperative immediate memory and language scores were associated with better HRQoL. Moderate preoperative depression scores and mild and moderate preoperative stress scores were associated with poorer HRQoL compared to scores within the normal range. Mild preoperative anxiety scores were associated with better HRQoL compared to scores within the normal range.

CONCLUSION

This descriptive case series showed that patients with higher preoperative cognitive scores reported better follow-up HRQoL, while patients who reported more preoperative depressive and stress symptomatology reported worse follow-up HRQoL. Future analytical studies may help to draw conclusions about whether perioperative cognition and emotional states predict HRQoL on follow-up.

The arcuate fasciculus: Combining structure and function into surgical considerations

BACKGROUND

Two Centuries from today, Karl Friedrich Burdach attributed the nomenclature "arcuate fasciculus" to a white matter (WM) pathway connecting the frontal to the temporal cortices by arching around the Sylvian fissure. Although this label remained essentially unvaried, the concepts related to it and the characterization of the structural properties of this bundle evolved along with the methodological progress of the past years. Concurrently, the functional relevance of the arcuate fasciculus (AF) classically restricted to the linguistic domain has extended to further cognitive abilities. These features make it a relevant structure to consider in a large variety of neurosurgical procedures.

OBJECTIVE

Herein, we build on our previous review uncovering the connectivity provided by the Superior Longitudinal System, including the AF, and provide a handy representation of the structural organization of the AF by considering the frequency of defined reports in the literature. By adopting the same approach, we implement an account of which functions are mediated by this WM bundle. We highlight how this information can be transferred to the neurosurgical field by presenting four surgical cases of glioma resection requiring the evaluation of the relationship between the AF and the nearby structures, and the safest approaches to adopt.

CONCLUSIONS

Our cumulative overview reports the most common wiring patterns and functional implications to be expected when approaching the study of the AF, while still considering seldom descriptions as an account of interindividual variability. Given its extension and the variety of cortical territories it reaches, the AF is a pivotal structure for different cognitive functions, and thorough understanding of its structural wiring and the functions it mediates is necessary for preserving the patient's cognitive abilities during glioma resection.

Survival, Functional, and Seizure Control Outcomes After Resection of Perirolandic World Health Organization Grade II and III Gliomas: A Single-Center Retrospective Review

OBJECTIVE

We aimed to assess, in patients with perirolandic gliomas and gliomas originating from other regions, survival, functional outcomes, and seizure control and, in addition, to identify any clinical characteristics predictive of progression-free survival, overall survival, and seizure control.

METHODS

We retrospectively analyzed 87 patients who underwent resection of World Health Organization grade II or III gliomas at a single institution between 2009 and 2021. Tumors were classified by topographic involvement. One-year postoperative functional status was quantified with Karnofsky Performance Status. One-year seizure control was defined by Engel seizure classification. Dichotomous and categorical variables were reported as counts and percentages and compared using Fisher exact test. A Cox regression model was used to identify covariates that affect progression-free survival and overall survival.

RESULTS

Patients with perirolandic gliomas had similar survival and functional outcomes to patients with gliomas from other regions and a low rate of lasting neurologic deficits. Patients with perirolandic gliomas had comparatively worse long-term seizure outcomes (approached statistical significance). Perirolandic involvement (hazard ratio [HR], 0.10; 95% confidence interval [CI], 0.02-0.46; P = 0.005) and preoperative seizures (HR, 0.14; 95% CI, 0.02-0.62; P = 0.017) conferred a lower likelihood of durable seizure control, whereas increased extent of resection (HR, 1.07; 95% CI, 1.03-1.12; P = 0.003) enhanced the likelihood of seizure freedom.

CONCLUSIONS

Despite proximity to or presence in eloquent structures, perirolandic gliomas can largely be resected without incurring worse functional outcomes. Patients with perirolandic gliomas should be considered for maximal safe resection to optimize survival outcomes and improve seizure control.

Surgical management of Glioma Grade 4: technical update from the neuro-oncology section of the Italian Society of Neurosurgery (SINch®): a systematic review

PURPOSE

The extent of resection (EOR) is an independent prognostic factor for overall survival (OS) in adult patients with Glioma Grade 4 (GG4). The aim of the neuro-oncology section of the Italian Society of Neurosurgery (SINch®) was to provide a general overview of the current trends and technical tools to reach this goal.

METHODS

A systematic review was performed. The results were divided and ordered, by an expert team of surgeons, to assess the Class of Evidence (CE) and Strength of Recommendation (SR) of perioperative drugs management, imaging, surgery, intraoperative imaging, estimation of EOR, surgery at tumor progression and surgery in elderly patients.

RESULTS

A total of 352 studies were identified, including 299 retrospective studies and 53 reviews/meta-analysis. The use of Dexamethasone and the avoidance of prophylaxis with anti-seizure medications reached a CE I and SR A. A preoperative imaging standard protocol was defined with CE II and SR B and usefulness of an early postoperative MRI, with CE II and SR B. The EOR was defined the strongest independent risk factor for both OS and tumor recurrence with CE II and SR B. For intraoperative imaging only the use of 5-ALA reached a CE II and SR B. The estimation of EOR was established to be fundamental in planning postoperative adjuvant treatments with CE II and SR B and the stereotactic image-guided brain biopsy to be the procedure of choice when an extensive surgical resection is not feasible (CE II and SR B).

CONCLUSIONS

A growing number of evidences evidence support the role of maximal safe resection as primary OS predictor in GG4 patients. The ongoing development of intraoperative techniques for a precise real-time identification of peritumoral functional pathways enables surgeons to maximize EOR minimizing the post-operative morbidity.

Oncological and functional neurosurgery: Perspectives for the decade regarding diffuse gliomas

For decades, diffuse glioma (DG) studies mostly focused on oncological considerations, whereas functional outcomes received less attention. Currently, because overall survival has increased in DG, especially in low-grade glioma (overall survival > 15 years), quality of life including neurocognitive and behavioral aspects should be assessed and preserved more systematically, particularly regarding surgery. Indeed, early maximal tumor removal results in greater survival in both high-grade and low-grade gliomas, leading to propose "supra-marginal" resection, with excision of the peritumoral zone in diffuse neoplasms. To minimize functional risks while maximizing the extent of resection, traditional "tumor-mass resection" is replaced by "connectome-guided resection" conducted under awake mapping, taking into account inter-individual brain anatomo-functional variability. A better understanding of the dynamic interplay between DG progression and reactional neuroplastic mechanisms is critical to adapt a personalized multistage therapeutic strategy, with integration of functional neurooncological (re)operation(s) in a multimodal management scheme including repeated medical therapies. Because the therapeutic armamentarium remains limited, the aims of this paradigmatic shift are to predict one/several step(s) ahead glioma behavior, its modifications, and compensatory neural networks reconfiguration over time in order to optimize the onco-functional benefit of each treatment - either in isolation or in combination with others - in human beings bearing a chronic tumoral disease while enjoying an active familial and socio-professional life as close as possible to their expectations. Thus, new ecological endpoints such as return to work should be incorporated into future DG trials. "Preventive neurooncology" might also be envisioned, by proposing a screening policy to discover and treat incidental glioma earlier.

Update for astrocytomas: medical and surgical management considerations

Astrocytomas include a wide range of tumors with unique mutations and varying grades of malignancy. These tumors all originate from the astrocyte, a star-shaped glial cell that plays a major role in supporting functions of the central nervous system (CNS), including blood-brain barrier (BBB) development and maintenance, water and ion regulation, influencing neuronal synaptogenesis, and stimulating the immunological response. In terms of epidemiology, glioblastoma (GB), the most common and malignant astrocytoma, generally occur with higher rates in Australia, Western Europe, and Canada, with the lowest rates in Southeast Asia. Additionally, significantly higher rates of GB are observed in males and non-Hispanic whites. It has been suggested that higher levels of testosterone observed in biological males may account for the increased rates of GB. Hereditary syndromes such as Cowden, Lynch, Turcot, Li-Fraumeni, and neurofibromatosis type 1 have been linked to increased rates of astrocytoma development. While there are a number of specific gene mutations that may influence malignancy or be targeted in astrocytoma treatment, O 6-methylguanine-DNA methyltransferase (MGMT) gene function is an important predictor of astrocytoma response to chemotherapeutic agent temozolomide (TMZ). TMZ for primary and bevacizumab in the setting of recurrent tumor formation are two of the main chemotherapeutic agents currently approved in the treatment of astrocytomas. While stereotactic radiosurgery (SRS) has debatable implications for increased survival in comparison to whole-brain radiotherapy (WBRT), SRS demonstrates increased precision with reduced radiation toxicity. When considering surgical resection of astrocytoma, the extent of resection (EoR) is taken into consideration. Subtotal resection (STR) spares the margins of the T1 enhanced magnetic resonance imaging (MRI) region, gross total resection (GTR) includes the margins, and supramaximal resection (SMR) extends beyond the margin of the T1 and into the T2 region. Surgical resection, radiation, and chemotherapy are integral components of astrocytoma treatment.

Maximal Safe Resection in Glioblastoma Surgery: A Systematic Review of Advanced Intraoperative Image-Guided Techniques

Glioblastoma multiforme (GBM) represents the most common and aggressive central nervous system tumor associated with a poor prognosis. The aim of this study was to depict the role of intraoperative imaging techniques in GBM surgery and how they can ensure the maximal extent of resection (EOR) while preserving the functional outcome. The authors conducted a systematic review following PRISMA guidelines on the PubMed/Medline and Scopus databases. A total of 1747 articles were identified for screening. Studies focusing on GBM-affected patients, and evaluations of EOR and functional outcomes with the aid of advanced image-guided techniques were included. The resulting studies were assessed for methodological quality using the Risk of Bias in Systematic Review tool. Open Science Framework registration DOI 10.17605/OSF.IO/3FDP9. Eighteen studies were eligible for this systematic review. Among the selected studies, eight analyzed Sodium Fluorescein, three analyzed 5-aminolevulinic acid, two evaluated IoMRI imaging, two evaluated IoUS, and three evaluated multiple intraoperative imaging techniques. A total of 1312 patients were assessed. Gross Total Resection was achieved in the 78.6% of the cases. Follow-up time ranged from 1 to 52 months. All studies assessed the functional outcome based on the Karnofsky Performance Status scale, while one used the Neurologic Assessment in Neuro-Oncology score. In 77.7% of the cases, the functional outcome improved or was stable over the pre-operative assessment. Combining multiple intraoperative imaging techniques could provide better results in GBM surgery than a single technique. However, despite good surgical outcomes, patients often present a neurocognitive decline leading to a marked deterioration of the quality of life. Advanced intraoperative image-guided techniques can allow a better understanding of the anatomo-functional relationships between the tumor and the surrounding brain, thus maximizing the EOR while preserving functional outcomes.

Preoperative language tract integrity is a limiting factor in recovery from aphasia after glioma surgery

Aphasia can occur in a broad range of pathological conditions that affect cortical or subcortical structures. Here we test the hypothesis that white matter integrity of language pathways assessed by preoperative diffusion tensor imaging (DTI) is associated with language performance and its recovery after glioma resection. 27 patients with preoperative DTI were included. Segmentation of the arcuate fascicle (AF), the inferior fronto-occipital fascicle (IFOF), the inferior longitudinal fascicle (ILF), the superior longitudinal fascicle (SLF), and the uncinate fascicle (UF) was performed with a fully-connected neural network (FCNN, TractSeg). Median fractional anisotropy (FA) was extracted from the resulting volumes as surrogate marker for white matter integrity and tested for correlation with clinical parameters. After correction for demographic data and multiple testing, preoperative white matter integrity of the IFOF, the ILF, and the UF in the left hemisphere were independently and significantly associated with aphasia three months after surgery. Comparison between patients with and without aphasia three months after surgery revealed significant differences in preoperative white matter integrity of the left AF (p = 0.021), left IFOF (p = 0.015), left ILF (p = 0.003), left SLF (p = 0.001, p = 0.021, p = 0.043 for respective sub-bundles 1-3), left UF (p = 0.041) and the right AF (p = 0.027). Preoperative assessment of white matter integrity of the language network by time-efficient MRI protocols and FCNN-driven segmentation may assist in the evaluation of postoperative rehabilitation potential in glioma patients.

A Systematic Review of Amino Acid PET Imaging in Adult-Type High-Grade Glioma Surgery: A Neurosurgeon's Perspective

Amino acid PET imaging has been used for a few years in the clinical and surgical management of gliomas with satisfactory results in diagnosis and grading for surgical and radiotherapy planning and to differentiate recurrences. Biological tumor volume (BTV) provides more meaningful information than standard MR imaging alone and often exceeds the boundary of the contrast-enhanced nodule seen in MRI. Since a gross total resection reflects the resection of the contrast-enhanced nodule and the majority of recurrences are at a tumor's margins, an integration of PET imaging during resection could increase PFS and OS. A systematic review of the literature searching for "PET" [All fields] AND "glioma" [All fields] AND "resection" [All fields] was performed in order to investigate the diffusion of integration of PET imaging in surgical practice. Integration in a neuronavigation system and intraoperative use of PET imaging in the primary diagnosis of adult high-grade gliomas were among the criteria for article selection. Only one study has satisfied the inclusion criteria, and a few more (13) have declared to use multimodal imaging techniques with the integration of PET imaging to intentionally perform a biopsy of the PET uptake area. Despite few pieces of evidence, targeting a biologically active area in addition to other tools, which can help intraoperatively the neurosurgeon to increase the amount of resected tumor, has the potential to provide incremental and complementary information in the management of brain gliomas. Since supramaximal resection based on the extent of MRI FLAIR hyperintensity resulted in an advantage in terms of PFS and OS, PET-based biological tumor volume, avoiding new neurological deficits, deserves further investigation.

Incidence of ischemic complications and technical nuances of arteries preservation for insular gliomas resection

Introduction

Insular gliomas have complex anatomy and microvascular supply that make resection difficult. Furthermore, resection of insular glioma is associated with a significant risk of postoperative ischemic complications. Thus, this study aimed to assess the incidence of ischemic complications related to insular glioma resection, determine its risk factors, and describe a single surgeon's experience of artery-preserving tumor resection.

Methods

We enrolled 75 consecutive patients with insular gliomas who underwent transcortical tumor resection. Preoperative and postoperative demographic, clinical, radiological [including diffusion-weighted imaging (DWI)], intraoperative neurophysiological data, and functional outcomes were analyzed. Motor evoked potentials (MEPs) and radiological characteristics like the relationship between the proximal segment of the lateral lenticulostriate arteries (LLSAs) and the tumor, the flat inner edge sign (the inner edge of the insular glioma is well-defined) or obscure inner edge sign, the distance between the lesion and posterior limb of the internal capsule and the invasion of the superior limiting sulcus by the tumor were analyzed. Strategies such as "residual triangle," "basal ganglia outline reappearance," and "sculpting" technique were used to preserve the LLSAs and the main branches of M2 for maximal tumor resection according to the Berger-Sinai classification.

Results

Postoperative DWI showed acute ischemia in 44 patients (58.7%). Moreover, nine patients (12%) had developed new motor deficits, as determined by the treating neurosurgeons. The flat inner edge sign [odds ratio (OR), 0.144; 95% confidence interval (CI), 0.024-0.876) and MEPs (>50%) (OR, 18.182; 95% CI, 3.311-100.00) were significantly associated with postoperative core ischemia, which affected the posterior limb of the internal capsule or corona radiata.

Conclusions

Insular glioma resection was associated with a high incidence of ischemia, as detected by DWI, as well as new motor deficits that were determined by the treating neurosurgeons. Insular glioma patients with obscure inner edge signs and intraoperative MEPs decline >50% had a higher risk of developing core ischemia. With our strategies, maximal safe resection of insular gliomas may be achieved.

The need to consider return to work as a main outcome in patients undergoing surgery for diffuse low-grade glioma: a systematic review

OBJECTIVE

For a long time, return to work (RTW) has been neglected in patients harboring a diffuse low-grade glioma (LGG). However, a majority of LGG patients worked at time of diagnosis. Moreover, these patients now live longer given current treatment paradigms, especially thanks to early maximal surgery.

METHODS

We systematically searched available medical databases for studies that reported data on RTW in patients who underwent resection for LGG.

RESULTS

A total of 30 studies were selected: 19 considered RTW (especially rate and timing) as an outcome and 11 used scales of health-related quality of life (HRQoL) which included work-related aspects. Series that considered RTW as a main endpoint were composed of 1014 patients, with postoperative RTW rates ranging from 31 to 97.1% (mean 73.1%). Timing to RTW ranged from 15 days to 22 months (mean 6.3 months). Factors related to an increased proportion of RTW were: younger age, better neurologic status, having a white-collar occupation, working pre-operatively, being the sole breadwinner, the use of awake surgery, and greater extent of resection. Female sex, older age, poor neurologic status, pre-operative history of work absences, slow lexical access speed, and postoperative seizures were negatively related to RTW. No studies that used HRQoL scales directly investigated RTW rate or timing.

CONCLUSIONS

RTW was scarcely analyzed in LGG patients who underwent resection. However, because they are usually young, with no or only mild functional deficits and have a longer life expectancy, postoperative RTW should be assessed more systematically and accurately as a main outcome. As majority (61.5-100%) of LGG patients were working at time of surgery, the responsibility of neurosurgeons is to bring these patients back to their previous activities according to his/her wishes. RTW might also be included as a critical endpoint for future prospective studies and randomized control trials on LGGs.

Indication and eligibility of glioma patients for awake surgery: A scoping review by a multidisciplinary perspective

Background

Awake surgery (AS) permits intraoperative mapping of cognitive and motor functions, allowing neurosurgeons to tailor the resection according to patient functional boundaries thus preserving long-term patient integrity and maximizing extent of resection. Given the increased risks of the awake scenario, the growing importance of AS in surgical practice favored the debate about patient selection concerning both indication and eligibility criteria. Nonetheless, a systematic investigation is lacking in the literature.

Objective

To provide a scoping review of the literature concerning indication and eligibility criteria for AS in patients with gliomas to answer the questions:1) "What are the functions mostly tested during AS protocols?" and 2) "When and why should a patient be excluded from AS?".

Materials and methods

Pertinent studies were retrieved from PubMed, PsycArticles and Cochrane Central Register of Controlled Trials (CENTRAL), published until April 2021 according to the PRISMA Statement Extension for Scoping Reviews. The retrieved abstracts were checked for the following features being clearly stated: 1) the population described as being composed of glioma(LGG or HGG) patients; 2) the paper had to declare which cognitive or sensorimotor function was tested, or 2bis)the decisional process of inclusion/exclusion for AS had to be described from at least one of the following perspectives: neurosurgical, neurophysiological, anesthesiologic and psychological/neuropsychological.

Results

One hundred and seventy-eight studies stated the functions being tested on 8004 patients. Language is the main indication for AS, even if tasks and stimulation techniques changed over the years. It is followed by monitoring of sensorimotor and visuospatial pathways. This review demonstrated an increasing interest in addressing other superior cognitive functions, such as executive functions and emotions. Forty-five studies on 2645 glioma patients stated the inclusion/exclusion criteria for AS eligibility. Inability to cooperate due to psychological disorder(i.e. anxiety),severe language deficits and other medical conditions(i.e.cardiovascular diseases, obesity, etc.)are widely reported as exclusion criteria for AS. However, a very few papers gave scale exact cut-off. Likewise, age and tumor histology are not standardized parameters for patient selection.

Conclusion

Given the broad spectrum of functions that might be safely and effectively monitored via AS, neurosurgeons and their teams should tailor intraoperative testing on patient needs and background as well as on tumor location and features. Whenever the aforementioned exclusion criteria are not fulfilled, AS should be strongly considered for glioma patients.

Segregated circuits for phonemic and semantic fluency: A novel patient-tailored disconnection study

Phonemic and semantic fluency are neuropsychological tests widely used to assess patients' language and executive abilities and are highly sensitive tests in detecting language deficits in glioma patients. However, the networks that are involved in these tasks could be distinct and suggesting either a frontal (phonemic) or temporal (semantic) involvement. 42 right-handed patients (26 male, mean age = 52.5 years, SD=±13.3) were included in this retrospective study. Patients underwent awake (54.8%) or asleep (45.2%) surgery for low-grade (16.7%) or high-grade-glioma (83.3%) in the frontal (64.3%) or temporal lobe (35.7%) of the left (50%) or right (50%) hemisphere. Pre-operative tractography was reconstructed for each patient, with segmentation of the inferior fronto-occipital fasciculus (IFOF), arcuate fasciculus (AF), uncinate fasciculus (UF), inferior longitudinal fasciculus (ILF), third branch of the superior longitudinal fasciculus (SLF-III), frontal aslant tract (FAT), and cortico-spinal tract (CST). Post-operative percentage of damage and disconnection of each tract, based on the patients' surgical cavities, were correlated with verbal fluencies scores at one week and one month after surgery. Analyses of differences between fluency scores at these timepoints (before surgery, one week and one month after surgery) were performed; lesion-symptom mapping was used to identify the correlation between cortical areas and post-operative scores. Immediately after surgery, a transient impairment of verbal fluency was observed, that improved within a month. Left hemisphere lesions were related to a worse verbal fluency performance, being a damage to the left superior frontal or temporal gyri associated with phonemic or semantic fluency deficit, respectively. At a subcortical level, disconnection analyses revealed that fluency scores were associated to the involvement of the left FAT and the left frontal part of the IFOF for phonemic fluency, and the association was still present one month after surgery. For semantic fluency, the correlation between post-surgery performance emerged for the left AF, UF, ILF and the temporal part of the IFOF, but disappeared at the follow-up. This approach based on the patients' pre-operative tractography, allowed to trace for the first time a dissociation between white matter pathways integrity and verbal fluency after surgery for glioma resection. Our results confirm the involvement of a frontal anterior pathway for phonemic fluency and a ventral temporal pathway for semantic fluency. Finally, our longitudinal results suggest that the frontal executive pathway requires a longer interval to recover compared to the semantic one.

Repeated Awake Surgical Resection(s) for Recurrent Diffuse Low-Grade Gliomas: Why, When, and How to Reoperate?

Early maximal surgical resection is the first treatment in diffuse low-grade glioma (DLGG), because the reduction of tumor volume delays malignant transformation and extends survival. Awake surgery with intraoperative mapping and behavioral monitoring enables to preserve quality of life (QoL). However, because of the infiltrative nature of DLGG, relapse is unavoidable, even after (supra)total resection. Therefore, besides chemotherapy and radiotherapy, the question of reoperation(s) is increasingly raised, especially because patients with DLGG usually enjoy a normal life with long-lasting projects. Here, the purpose is to review the literature in the emerging field of iterative surgeries in DLGG. First, long-term follow-up results showed that patients with DLGG who underwent multiple surgeries had an increased survival (above 17 years) with preservation of QoL. Second, the criteria guiding the decision to reoperate and defining the optimal timing are discussed, mainly based on the dynamic intercommunication between the glioma relapse (including its kinetics and pattern of regrowth) and the reactional cerebral reorganization—i.e., mechanisms underpinning reconfiguration within and across neural networks to enable functional compensation. Third, how to adapt medico-surgical strategy to this individual spatiotemporal brain tumor interplay is detailed, by considering the perpetual changes in connectome. These data support early reoperation in recurrent DLGG, before the onset of symptoms and before malignant transformation. Repeat awake resection(s) should be integrated in a global management including (neo)adjuvant medical treatments, to enhance long-lasting functional and oncological outcomes. The prediction of potential and limitation of neuroplasticity at each step of the disease must be improved to anticipate personalized multistage therapeutic attitudes.

Personal space regulation is affected by unilateral temporal lesions beyond the amygdala

We constantly face situations involving interactions with others that require us to automatically adjust our physical distances to avoid discomfort or anxiety. A previous case study has demonstrated that the integrity of both amygdalae is essential to regulate interpersonal distances. Despite unilateral lesion to the amygdala, as to other sectors of the medial temporal cortex, are known to also affect social behavior, their role in the regulation of interpersonal distances has never been investigated. Here, we sought to fill this gap by testing three patients with unilateral temporal lesions following surgical resections, including one patient with a lesion mainly centered on the amygdala and two with lesions to adjacent medial temporal cortex, on two versions of the stop distance paradigm (i.e. in a virtual reality environment and in a real setting). Our results showed that all three patients set shorter interpersonal distances compared to neurotypical controls. In addition, compared to controls, none of the patients adjusted such physical distances depending on facial emotional expressions, despite they preserved ability to categorize them. Finally, patients' heart rate responses differed from controls when viewing approaching faces. Our findings bring compelling evidence that unilateral lesions within the medial temporal cortex, not necessarily restricted to the amygdala, are sufficient to alter interpersonal distance, thus shedding new light on the neural circuitry regulating distance in social interactions.

The role of the default mode network in longitudinal functional brain reorganization of brain gliomas

The study of patients after glioma resection offers a unique opportunity to investigate brain reorganization. It is currently unknown how the whole-brain connectomic profile evolves longitudinally after surgical resection of a glioma and how this may be associated with tumor characteristics and cognitive outcome. In this longitudinal study, we investigate the impact of tumor lateralization and grade on functional connectivity (FC) in highly connected networks, or hubs, and cognitive performance. Twenty-eight patients (17 high-grade, 11 low-grade gliomas) underwent longitudinal pre/post-surgery resting-state fMRI scans and neuropsychological assessments (73 total measures). FC matrices were constructed considering as functional hubs the default mode (DMN) and fronto-parietal networks. No-hubs included primary sensory functional networks and any other no-hubs nodes. Both tumor hemisphere and grade affected brain reorganization post-resection. In right-hemisphere tumor patients, regardless of grade and relative to left-hemisphere gliomas, FC increased longitudinally after the intervention, both in terms of FC within hubs (p_hubs = 0.0004) and FC between hubs and no-hubs (p_hubs-no-hubs = 0.005). Regardless of tumor side, only lower-grade gliomas showed longitudinal FC increases relative to high-grade tumors within a precise hub network, the DMN. The neurocognitive profile was longitudinally associated with spatial features of the connectome, mainly within the DMN. We provide evidence that clinical glioma features, such as lateralization and grade, affect post-surgical longitudinal functional reorganization and cognitive recovery. The data suggest a possible role of the DMN in supporting cognition, providing useful information for prognostic prediction and surgical planning.

The death of localizationism: The concepts of functional connectome and neuroplasticity deciphered by awake mapping, and their implications for best care of brain-damaged patients

Although clinical neurology was mainly erected on the dogma of localizationism, numerous reports have described functional recovery after lesions involving presumed non-compensable areas in an inflexible view of brain processing. Here, the purpose is to review new insights into the functional connectome and the mechanisms underpinning neural plasticity, gained from intraoperative direct electrostimulation mapping and real-time behavioral monitoring in awake patients, combined with perioperative neuropsychological and neuroimaging data. Such longitudinal anatomo-functional correlations resulted in the reappraisal of classical models of cognition, especially by highlighting the dynamic interplay within and between neural circuits, leading to the concept of meta-network (network of networks), as well as by emphasizing that subcortical connectivity is the main limitation of neuroplastic potential. Beyond their contribution to basic neurosciences, these findings might also be helpful for an optimization of care for brain-damaged patients, such as in resective oncological or epilepsy neurosurgery in structures traditionally deemed inoperable (e.g., in Broca's area) as well as for elaborating new programs of functional rehabilitation, eventually combined with transcranial brain stimulation, aiming to change the connectivity patterns in order to enhance cognitive competences following cerebral injury.

Feasibility, Safety and Impact on Overall Survival of Awake Resection for Newly Diagnosed Supratentorial IDH-Wildtype Glioblastomas in Adults

Simple Summary

A few studies have suggested the benefits of awake surgery by maximizing the extent of resection while preserving neurological function and improving survival in high-grade glioma patients. However, the histomolecular heterogeneity in these series, mixing grade 3 with grade 4, and IDH-mutated with IDH-wildtype gliomas, represents a major selection bias that may influence survival analyses. For the first time, in a large homogeneous single-institution cohort of newly diagnosed supratentorial IDH-wildtype glioblastoma in adult patients, we assessed feasibility, safety and efficacy of awake surgery using univariate, multivariate and case-matched analysis. Awake surgery was associated with higher resection rates, lower residual tumor rates, and more supratotal resections than asleep resections, allowed standard radiochemotherapy to be performed systematically within a short time between surgery and radiotherapy, and was an independent predictor of progression-free survival and overall survival in the whole series, together with the extent of resection, MGMT promoter methylation status, and standard.

Abstract

Background: Although awake resection using intraoperative cortico-subcortical functional brain mapping is the benchmark technique for diffuse gliomas within eloquent brain areas, it is still rarely proposed for IDH-wildtype glioblastomas. We have assessed the feasibility, safety, and efficacy of awake resection for IDH-wildtype glioblastomas. Methods: Observational single-institution cohort (2012–2018) of 453 adult patients harboring supratentorial IDH-wildtype glioblastomas who benefited from awake resection, from asleep resection, or from a biopsy. Case matching (1:1) criteria between the awake group and asleep group: gender, age, RTOG-RPA class, tumor side, location and volume and neurosurgeon experience. Results: In patients in the awake resection subgroup (n = 42), supratotal resections were more frequent (21.4% vs. 3.1%, p < 0.0001) while partial resections were less frequent (21.4% vs. 40.1%, p < 0.0001) compared to the asleep (n = 222) resection subgroup. In multivariable analyses, postoperative standard radiochemistry (aHR = 0.04, p < 0.0001), supratotal resection (aHR = 0.27, p = 0.0021), total resection (aHR = 0.43, p < 0.0001), KPS score > 70 (HR = 0.66, p = 0.0013), MGMT promoter methylation (HR = 0.55, p = 0.0031), and awake surgery (HR = 0.54, p = 0.0156) were independent predictors of overall survival. After case matching, a longer overall survival was found for awake resection (HR = 0.47, p = 0.0103). Conclusions: Awake resection is safe, allows larger resections than asleep surgery, and positively impacts overall survival of IDH-wildtype glioblastoma in selected adult patients.

Awake craniotomy in brain tumors - Technique systematization and the state of the art

The anesthesia for awake craniotomy (AC) is a consecrated anesthetic technique that has been perfected over the years. Initially used to map epileptic foci, it later became the standard technique for the removal of glial neoplasms in eloquent brain areas. We present an AC anesthesia technique consisting of three primordial times, called awake-asleep-awake, and their respective particularities, as well as delve into the anesthetic medications used. Its use in patients with low and high-grade gliomas was favorable for the resection of tumors within the functional boundaries of patients, with shorter hospital stay and lower direct costs. The present study aims to systematize the technique based on the experience of the largest philanthropic hospital in Latin America and discusses the most relevant aspects that have consolidated this technique as the most appropriate in the surgery of gliomas in eloquent areas.

Evidence-based recommendations on categories for extent of resection in diffuse glioma

Surgical resection represents the standard of care in diffuse glioma, and more extensive tumour resection appears to be associated with favourable outcome. Up to now, terminology to describe extent of resection has been inconsistently applied across clinical trials which hampers comparative analysis of cohorts between different studies. Based on a comprehensive literature review, we developed evidence-based expert recommendations on categories for extent of resection. Recommendations are formulated for the categories 'biopsy', 'partial resection', 'subtotal resection', 'near total resection', 'complete resection' and 'supramaximal resection'. Definitions rest on reduction of contrast- and non-contrast-enhancing tumour in glioblastoma, and on reduction of T2/FLAIR-hyperintense tumour in gliomas WHO grade 2 or 3. Both relative reduction of tumour volume (in percentage) as a measurement of surgical efficacy and absolute residual tumour volume (in cm³) as a measurement of remaining tumour burden are incorporated into the categories for extent of resection. Class of evidence for the proposed categories ranges from class IIB to IV. Limitations of the suggested categories are discussed. The proposed categories on extent of resection offer a framework to standardize nomenclature based on previous studies, and will need to be evaluated in prospective, molecularly well-defined cohorts. Our categories may eventually help as a stratification factor for future clinical trials.

Brain connectomics applied to oncological neuroscience: from a traditional surgical strategy focusing on glioma topography to a meta-network approach

The classical way for surgical selection and planning in cerebral glioma mainly focused on tumor topography. The emerging science of connectomics, which aims of mapping brain connectivity, resulted in a paradigmatic shift from a modular account of cerebral organization to a meta-network perspective. Adaptive behavior is actually mediated by constant changes in interactions within and across large-scale delocalized neural systems underlying conation, cognition, and emotion. Here, to optimize the onco-functional balance of glioma surgery, the purpose is to switch toward a connectome-based resection taking account of both relationships between the tumor and critical distributed circuits (especially subcortical pathways) as well as the perpetual instability of the meta-network. Such dynamic in the neural spatiotemporal integration permits functional reallocation leading to neurological recovery after massive resection in structures traditionally thought as "inoperable." This better understanding of connectome increases benefit/risk ratio of surgery (i) by selecting resection in areas deemed "eloquent" according to a localizationist dogma; (ii), conversely, by refining intraoperative awake cognitive mapping and monitoring in so-called non-eloquent areas; (iii) by improving preoperative information, enabling an optimal selection of intrasurgical tasks tailored to the patient's wishes; (iv) by developing an "oncological disconnection surgery"; (v) by defining a personalized multistep surgical strategy adapted to individual brain reshaping potential; and (vi) ultimately by preserving environmentally and socially appropriate behavior, including return to work, while increasing the extent of (possibly repeated) resection(s). Such a holistic vision of neural processing can enhance reliability of connectomal surgery in oncological neuroscience and may also be applied to restorative neurosurgery.

Updated perspectives on awake neurosurgery with cognitive and emotional assessment for patients with low-grade gliomas

Introduction: Thanks to early extensive surgical resection combined with medical oncological therapies, life expectancy dramatically increased in low-grade glioma (LGG), with an overall survival currently over 15 years. Therefore, patients should be able to maintain valuable family and socio-professional activities.Areas covered: For many decades, cognitive and emotional aspects were neglected by surgical and medical neurooncologists. The goal of surgery was to avoid hemiplegia and/or aphasia, with no considerations regarding behavior. However, because LGG patients live longer, they must be cognitively and affectively able to make long-term projects. Preservation of higher-order functions should be considered systematically in LGG surgery by means of awake cognitive/emotional mapping and monitoring.Expert opinion: The aim is to incorporate recent advances in neurosciences, which proposed revisited models of cerebral processing relying on a meta-network perspective, into the pre-, intra- and postoperative procedure. In this connectomal approach, brain functions result from complex interactions within and between neural networks. This improved understanding of a constant instability of the neural system allows a better cognitive/emotional assessment before and after each treatment over years, in order to preserve personality and adaptive behavior for each LGG patient, based on his/her own definition of quality of life. It is time to create oncological neurosciences.

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.

Scale-Free Analysis of Intraoperative ECoG During Awake Craniotomy for Glioma

BACKGROUND

Electrocorticography (ECoG) has been utilized in many epilepsy cases however, the use of this technique for evaluating electrophysiological changes within tumoral zones is spare. Nonetheless, epileptic activities seem to arise from the neocortex surrounding the gliomas suggesting a link between epileptogenesis and glioma cell infiltration in the peritumoral area. The purpose of this study was to implement novel scale-free measures to assess how cortical physiology is altered by the presence of an invasive brain tumor.

METHODS

Twelve patients undergoing an awake craniotomy for resection of a supratentorial glioma were included. ECoG data over the main tumor and the exposed surroundings was acquired intra-operatively just prior to tumor resection. Six of the patients presented with seizures and had data acquired both in the awake and anesthetic state. The corresponding anatomical location of each electrode in relation to the macroscopically-detectable tumor was recorded using the neuronavigation system based on structural anatomical images obtained pre-operatively. The electrodes were classified into tumoral, healthy or peritumoral based on the macroscopically detectable tumoral tissue from the pre-operative structural MRI.

RESULTS

The electrodes overlying the tumoral tissue revealed higher power law exponent (PLE) values across tumoral area compared to the surrounding tissues. The difference between the awake and anesthetic states was significant in the tumoral and healthy tissue (p < 0.05) but not in the peritumoral tissue. The absence of a significant PLE reduction in the peritumoral tissue from the anesthetic to the awake state could be considered as an index of the presence or absence of infiltration of tumor cells into the peritumoral tissue.

CONCLUSIONS

The current study portrays for the first time distinct power law exponent features in the tumoral tissue, which could provide a potential novel electrophysiological marker in the future. The distinct features seen in the peritumoral tissue of gliomas seem to indicate the area where both the onset of epileptiform activity and the tumor infiltration take place.

Planning Brain Tumor Resection Using a Probabilistic Atlas of Cortical and Subcortical Structures Critical for Functional Processing: A Proof of Concept

BACKGROUND

Functional preoperative planning for resection of intrinsic brain tumors in eloquent areas is still a challenge. Predicting subcortical functional framework is especially difficult. Direct electrical stimulation (DES) is the recommended technique for resection of these lesions. A reliable probabilistic atlas of the critical cortical epicenters and subcortical framework based on DES data was recently published.

OBJECTIVE

To propose a pipeline for the automated alignment of the corticosubcortical maps of this atlas with T1-weighted MRI.

METHODS

To test the alignment, we selected 10 patients who underwent resection of brain lesions by using DES. We aligned different cortical and subcortical functional maps to preoperative volumetric T1 MRIs (with/without gadolinium). For each patient we quantified the quality of the alignment, and we calculated the match between the location of the functional sites found at DES and the functional maps of the atlas.

RESULTS

We found an accurate brain extraction and alignment of the functional maps with both the T1 MRIs of each patient. The matching analysis between functional maps and functional responses collected during surgeries was 88% at cortical and, importantly, 100% at subcortical level, providing a further proof of the correct alignment.

CONCLUSION

We demonstrated quantitatively and qualitatively the reliability of this tool that may be used for presurgical planning, providing further functional information at the cortical level and a unique probabilistic prevision of distribution of the critical subcortical structures. Finally, this tool offers the chance for multimodal planning through integrating this functional information with other neuroradiological and neurophysiological techniques.

Seizure outcome in temporal glioblastoma surgery: lobectomy as a supratotal resection regime outclasses conventional gross-total resection

Introduction

The postoperative seizure freedom represents an important secondary outcome measure in glioblastoma surgery. Recently, supra-total glioblastoma resection in terms of anterior temporal lobectomy (ATL) has gained growing attention with regard to superior long-term disease control for temporal-located glioblastoma compared to conventional gross-total resections (GTR). However, the impact of ATL on seizure outcome in these patients is unknown. We therefore analyzed ATL and GTR as differing extents of resection in regard of postoperative seizure control in patients with temporal glioblastoma and preoperative symptomatic seizures.

Methods

Between 2012 and 2018, 33 patients with preoperative seizures underwent GTR or ATL for temporal glioblastoma at the authors’ institution. Seizure outcome was assessed postoperatively and 6 months after tumor resection according to the International League Against Epilepsy (ILAE) classification and stratified into favorable (ILAE class 1) versus unfavorable (ILAE class 2–6).

Results

Overall, 23 out of 33 patients (70%) with preoperative seizures achieved favorable seizure outcome following resection of temporal located glioblastoma. For the ATL group, postoperative seizure freedom was present in 13 out of 13 patients (100%). In comparison, respective rates for the GTR group were 10 out of 20 patients (50%) (p = 0.002; OR 27; 95% CI 1.4–515.9).

Conclusions

ATL in terms of a supra-total resection strategy was associated with superior favorable seizure outcome following temporal glioblastoma resection compared to GTR. Regarding above mentioned survival benefit following ATL compared to GTR, ATL as an aggressive supra-total resection regime might constitute the surgical modality of choice for temporal-located glioblastoma.

Peritumoral Microenvironment in High-Grade Gliomas: From FLAIRectomy to Microglia-Glioma Cross-Talk

Cellular composition and molecular signatures of the glioma core compared with infiltrative margins are different, and it is well known that the tumor edge is enriched in microglia. In this review of the literature, we summarize the role of the peritumoral area in high-grade gliomas (HGGs) from surgical and biological points of view. There is evidence on the dual role of microglia in HGGs-a scavenger-tumoricidal role when microglia are activated in an M1 phenotype and a role favoring tumor growth and infiltration/migration when microglia are activated in an M2 phenotype. Microglia polarization is mediated by complex pathways involving cross-talk with glioma cells. In this scenario, extracellular vesicles and their miRNA cargo seem to play a central role. The switch to a specific phenotype correlates with prognosis and the pathological assessment of a specific microglial setting can predict a patient's outcome. Some authors have designed an engineered microglial cell as a biologically active vehicle for the delivery of intraoperative near-infrared fluorescent dye with the aim of helping surgeons detect peritumoral infiltrated areas during resection. Furthermore, the pharmacological modulation of microglia-glioma cross-talk paves the way to more effective therapies.

Awake surgery for right frontal lobe glioma can preserve visuospatial cognition and spatial working memory

PURPOSE

Awake surgery is the standard treatment to preserve motor and language functions. This longitudinal study aimed to evaluate the resection rate and preservation of neurocognitive functions in patients with right frontal lobe glioma who underwent awake surgery.

METHODS

Thirty-three patients (mean age, 48.0 years) with right frontal lobe glioma who underwent awake surgery at our hospital between 2013 and 2019 were included. Fourteen, thirteen, and six cases had WHO classification grades of II, III, and IV, respectively. We evaluated visuospatial cognition (VSC) and spatial working memory (SWM) before and three months after surgery. Relevant brain areas for VSC and SWM were intraoperatively mapped, whenever the task was successfully accomplished. Therefore, patients were divided into an intraoperative evaluation group and a non-evaluation group for each function, and the resection rate and functional outcomes were compared.

RESULTS

The removal rate in the evaluation group for VSC and SWM were similar to that in the non-evaluation group. Chronic impairment rate of VSC was significantly lower in the evaluation than in the non-evaluation group (5.6% vs. 33.3%, p = 0.034). No patient showed postoperative SWM impairment in the evaluation group as opposed to the non-evaluation group (16.7%, p = 0.049). The probability of resection of the deeper posterior part of the middle frontal gyrus, the relevant area of VSC, was higher in the non-evaluation group than in the evaluation group.

CONCLUSIONS

We statistically verified that awake surgery for right frontal lobe glioma results in successful preservation of VSC and SWM with satisfying resection rates.

Personalized Multimodal Demarcation of Peritumoral Tissue in Glioma

PURPOSE

Gliomas are life-threatening brain tumors, and the extent of surgical resection is one of the strongest influences on survival rate. However, the proper distinction of infiltrated tissue remains elusive. The aim of this study was to use multimodal analyses to demarcate peritumoral tissue (PT) from tumoral (TT) and healthy tissue (HT).

METHODS

A total of 40 patients with histologically confirmed glioma were recruited. We analyzed resting-state functional magnetic resonance imaging (rs-fMRI) using the voxel-based mean blood-oxygen-level-dependent (BOLD) signal and the corresponding structural MRI (s-MRI) alongside RNA sequencing, whole-exome sequencing, and histology results of biopsy samples obtained from PT, HT, and TT.

RESULTS

We demarcated a functionally defined PT area where the mean BOLD signal gradually decreased near the edge of the tumor and extended beyond the TT borders (as defined by s-MRI), which was confirmed on a case-by-case basis. Correspondingly, genetic analyses showed a gene expression pattern and mutational landscape of the PT that were distinct from that seen in HT and TT. The genetic characterization of PT relative to HT and TT converged with the MRI-defined PT zones. This was confirmed in three individual cases after additional histologic analysis. A wider PT was associated with a longer progression-free survival, which suggests PT might act as an intermediate area between TT and HT.

CONCLUSION

Combined multimodal imaging and genetic analyses can allow for an objective demarcation of the PT in glioma and a robust classification of the degree of infiltration of the PT. These findings could help improve both neurosurgical resection and radio-oncologic therapy.

Functional Mapping before and after Low-Grade Glioma Surgery: A New Way to Decipher Various Spatiotemporal Patterns of Individual Neuroplastic Potential in Brain Tumor Patients

Intraoperative direct electrostimulation mapping (DEM) is currently the gold-standard for glioma surgery, since functional-based resection allows an optimization of the onco-functional balance (increased resection with preserved quality of life). Besides intrasurgical awake mapping of conation, cognition, and behavior, preoperative mapping by means of functional neuroimaging (FNI) and transcranial magnetic stimulation (TMS) has increasingly been utilized for surgical selection and planning. However, because these techniques suffer from several limitations, particularly for direct functional mapping of subcortical white matter pathways, DEM remains crucial to map neural connectivity. On the other hand, non-invasive FNI and TMS can be repeated before and after surgical resection(s), enabling longitudinal investigation of brain reorganization, especially in slow-growing tumors like low-grade gliomas. Indeed, these neoplasms generate neuroplastic phenomena in patients with usually no or only slight neurological deficits at diagnosis, despite gliomas involving the so-called "eloquent" structures. Here, data gained from perioperative FNI/TMS mapping methods are reviewed, in order to decipher mechanisms underpinning functional cerebral reshaping induced by the tumor and its possible relapse, (re)operation(s), and postoperative rehabilitation. Heterogeneous spatiotemporal patterns of rearrangement across patients and in a single patient over time have been evidenced, with structural changes as well as modifications of intra-hemispheric (in the ipsi-lesional and/or contra-lesional hemisphere) and inter-hemispheric functional connectivity. Such various fingerprints of neural reconfiguration were correlated to different levels of cognitive compensation. Serial multimodal studies exploring neuroplasticity might lead to new management strategies based upon multistage therapeutic approaches adapted to the individual profile of functional reallocation.