Surgery of low-grade gliomas: towards a ‘functional neurooncology’

Contact Endoscopy in Neurosurgery: A Feasibility Anatomical Study on Advantages, Limitations, and Clinical Applications

BACKGROUND

Contact endoscopy (CE) is a visualization technique with high magnification power, facilitating the in vivo examination of biological tissue morphology during different endoscopic-assisted procedures. Although its widespread implementation remains limited in neurosurgery, CE has emerged as a novel visualization tool, with several reports in the literature documenting its adoption.

METHODS

The functionality and limitations of CE were investigated using 6 formalin-fixed heads (12 sides) and in 2 patients with both intra- and extra-axial lesions to comprehensively evaluate the effectiveness and potential limitations of CE in real-world clinical scenarios. Furthermore, a standard Karl Storz endoscope, 0°, 4 mm in diameter, and 18 cm in length, was adopted as a mean of comparison.

RESULTS

CE provided a magnified, real-time visualization of targeted areas, facilitating the identification of the interface between pathologic and normal tissue. The recognition of distinctive vascular patterns represented a reproducible benefit of the CE. Despite presenting a steep learning curve and being limited by higher distal tip temperatures, the contact endoscope does not demonstrate significant maneuverability differences from other standard endoscopes.

CONCLUSIONS

The present study serves as a practical "technical guide" for utilizing CE visualization in neurosurgery, providing useful information on optimizing its potential by detailing the specific and complex features of the endoscope itself, including guidance on proper handling and usage techniques in neurosurgery to enhance its effectiveness.

Cognitive Decline in Glioblastoma (GB) Patients with Different Treatment Modalities and Insights on Untreated Cases

BACKGROUND

Cognitive decline is common in patients with Glioblastoma (GB), occurring in both treated and untreated cases. It frequently presents as impairments in memory, attention, language, or other cognitive functions. In addition, these cognitive deficits can affect quality of life, functional independence, and overall survival, and they are associated with psychiatric conditions such as anxiety and depression.

METHODS

This narrative review evaluates cognitive deficits in GB patients, both with and without treatment. It also explores the impact of tumor features such as size, location, and histology, along with patient characteristics such as age and education, and discusses the effects of standard therapies, such as surgery, chemotherapy, and radiotherapy, on cognitive outcomes.

RESULTS

Cognitive impairment in GB is influenced by tumor- and patient-specific factors, as well as treatment modalities. Initially, combination therapies such as surgery, radiotherapy, and chemotherapy may improve cognitive domains by reducing tumor burden, relieving cerebral edema, and reducing mass effects, subsequently bringing indirect effects of improved mental health and mood. While certain treatments like radiotherapy and chemotherapy carry risks of delayed neurotoxicity, studies indicate that, on balance, treated patients generally show better preservation or improvement in cognitive function than those who go untreated. However, excessive treatment aggressiveness and cumulative neurotoxic effects may diminish cognitive benefits.

CONCLUSION

Cognitive function is an independent factor in GB, which could affect survival in GB patients, therefore making routine cognitive assessments essential for prognosis, treatment planning, and rehabilitation. Neuroprotective agents, cognitive rehabilitation, and personalized, multidisciplinary strategies can help optimize both survival and cognitive preservation.

Porto Alegre Line predicts lenticulostriate arteries encasement and extent of resection in insular gliomas. A preliminary study

Object

In insular glioma surgery, lenticulostriate arteries (LSTa) tumoral encasement increases neurological deficits risk despite intensive efforts to preserve the internal capsule's integrity. In this study, we focus on the LSTa relationships with the medial aspect of the insular tumors. We propose a new non-invasive method for LSTa involvement prediction in preoperative MRI (Porto Alegre Line). We compare it with direct intraoperative encased LSTa visualization.

Methods

A retrospective review of our database of 52 patients of insular glioma was performed. In cases with no tumor located medial to Porto Alegre line, our medial resection limit, mainly for the tumor part located next to the limen insula, was the inferior fronto-occipital fasciculus (IFOF), identified through altered speech patterns during electric subcortical stimulation. In cases with no assumed LSTa involvement, the parameter used to stop resection was the confirmation of the corticospinal tract with 10-mA stimulus. The resection limit of tumors placed medially to the Porto Alegre line was intraoperative direct LSTa visualization.

Results

The LSTa involvement was the most critical medial limiting factor in more aggressive tumor resection and an excellent overall survival (P = 0.022). In cases in which there were direct intraoperative LSTa encasement visualization, Porto Alegre Line was employed as an MRI preoperative landmark for prediction of LSTa involvement in those patients with Sensitivity, Specificity, Positive Predictive Values of 1, 0.975 and 0.923, respectively.

Conclusion

We have found that LSTa encasement is a limiting factor to reach a satisfactory extent of resection and that Porto Alegre Line can predict it.

Towards a New Dawn for Neuro-Oncology: Nanomedicine at the Service of Drug Delivery for Primary and Secondary Brain Tumours

(1) Background/Objectives: Primary and secondary brain tumours often hold devastating prognoses and low survival rates despite the application of maximal neurosurgical resection, and state-of-the-art radiotherapy and chemotherapy. One limiting factor in their management is that several antineoplastic agents are unable to cross the blood-brain barrier (BBB) to reach the tumour microenvironment. Nanomedicine could hold the potential to become an effective means of drug delivery to overcome previous hurdles towards effective neuro-oncological treatments. (2) Methods: A scoping review following the PRISMA-ScR guidelines and checklist was conducted using key terms input into PubMed to find articles that reflect emerging trends in the utilisation of nanomedicine in drug delivery for primary and secondary brain tumours. (3) Results: The review highlights various strategies by which different nanoparticles can be exploited to bypass the BBB; we provide a synthesis of the literature on the ongoing contributions to therapeutic protocols based on chemotherapy, immunotherapy, focused ultrasound, radiotherapy/radiosurgery, and radio-immunotherapy. (4) Conclusions: The emerging trends summarised in this scoping review indicate encouraging advantageous properties of nanoparticles as potential effective drug delivery mechanisms; however, there are still nanotoxicity issues that largely remain to be addressed before the translation of these innovations from laboratory to clinical practice.

A Longitudinal Multimodal Imaging Study in Patients with Temporo-Insular Diffuse Low-Grade Tumors: How the Inferior Fronto-Occipital Fasciculus Provides Information on Cognitive Outcomes

BACKGROUND

Tractography allows the in vivo study of subcortical white matter, and it is a potential tool for providing predictive indices on post-operative outcomes. We aim at establishing whether there is a relation between cognitive outcome and the status of the inferior fronto-occipital fasciculus's (IFOF's) microstructure.

METHODS

The longitudinal neuropsychological data of thirty young (median age: 35 years) patients operated on for DLGG in the left temporo-insular cortex along with pre-surgery tractography data were processed.

RESULTS

A degraded integrity of the left (vs. right) IFOF (lower fractional anisotropy and length, p < 0.001; higher mean and axial diffusivity, p < 0.01) was found, with lower microstructural variables in the infiltration (vs. dislocation) group. Significant decreases immediately post-surgery vs. pre-surgery mainly occurred in lexico-semantics (p < 0.001), with significant improvements at follow-up in all the tests (p < 0.01 to p < 0.001), despite values in the range of 44% to 47.82% of patients with below cut-off scores regarding naming verbs and making visual lexical decisions. The status of left and right IFOFs is predictive of a decrease in immediate post-surgery performance for several tests (p < 0.05); similarly, it is predictive of better recovery in the follow-up performance for naming nouns, naming verbs, making phonological fluency lexical decisions, and the token test (p < -0.05). For the ROC analysis, a significant result was obtained for the verb-naming test, with a cut-off of 79%.

CONCLUSIONS

This study supports the role of the predictive value of pre-operative tractography for assessing the immediate post-operative result and at follow-up the risk of developing a cognitive deficit.

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.

Intraoperative mapping of epileptogenic foci and tumor infiltration in neuro-oncology patients with epilepsy

Background

Epileptogenesis and glioma growth have a bidirectional relationship. We hypothesized people with gliomas can benefit from the removal of epileptic tissue and that tumor-related epileptic activity may signify tumor infiltration in peritumoral regions. We investigated whether intraoperative electrocorticography (ioECoG) could improve seizure outcomes in oncological glioma surgery, and vice versa, what epileptic activity (EA) tells about tumor infiltration.

Methods

We prospectively included patients who underwent (awake) ioECoG-assisted diffuse-glioma resection through the oncological trajectory. The IoECoG-tailoring strategy relied on ictal and interictal EA (spikes and sharp waves). Brain tissue, where EA was recorded, was assigned for histopathological examination separate from the rest of the tumor. Weibull regression was performed to assess how residual EA and extent of resection (EOR) related to the time-to-seizure recurrence, and we investigated which type of EA predicted tumor infiltration.

Results

Fifty-two patients were included. Residual spikes after resection were associated with seizure recurrence in patients with isocitrate dehydrogenase (IDH) mutant astrocytoma or oligodendroglioma (HR = 7.6[1.4-40.0], P-value = .01), independent from the EOR. This was not observed in IDH-wildtype tumors. All tissue samples resected based on interictal spikes were infiltrated by tumor, even if the MRI did not show abnormalities.

Conclusions

Complete resection of epileptogenic foci in ioECoG may promote seizure control in IDH-mutant gliomas. The cohort size of IDH-wildtype tumors was too limited to draw definitive conclusions. Interictal spikes may indicate tumor infiltration even when this area appears normal on MRI. Integrating electrophysiology guidance into oncological tumor surgery could contribute to improved seizure outcomes and precise guidance for radical tumor resection.

Low-Grade Gliomas: Histological Subtypes, Molecular Mechanisms, and Treatment Strategies

Low-Grade Gliomas (LGGs) represent a diverse group of brain tumors originating from glial cells, characterized by their unique histopathological and molecular features. This article offers a comprehensive exploration of LGGs, shedding light on their subtypes, histological and molecular aspects. By delving into the World Health Organization's grading system, 5th edition, various specificities were added due to an in-depth understanding of emerging laboratory techniques, especially genomic analysis. Moreover, treatment modalities are extensively discussed. The degree of surgical resection should always be considered according to postoperative quality of life and cognitive status. Adjuvant therapies focused on chemotherapy and radiotherapy depend on tumor grading and invasiveness. In the current literature, emerging targeted molecular therapies are well discussed due to their succinctly therapeutic effect; in our article, those therapies are summarized based on posttreatment results and possible adverse effects. This review serves as a valuable resource for clinicians, researchers, and medical professionals aiming to deepen their knowledge on LGGs and enhance patient care.

Brain Plasticity Profiling as a Key Support to Therapeutic Decision-Making in Low-Grade Glioma Oncological Strategies

The ability of neural circuits to compensate for damage to the central nervous system is called postlesional plasticity. In diffuse low-grade gliomas (LGGs), a crosstalk between the brain and the tumor activates modulations of plasticity, as well as tumor proliferation and migration, by means of paracrine and electrical intercommunications. Such adaptative mechanisms have a major impact on the benefits and risks of oncological treatments but are still disregarded by current neuro-oncological guidelines. In this review, the authors first aimed to highlight clinical, radiological, and oncological markers that robustly reflect the plasticity potentials and limitations in LGG patients, including the location of the tumor and the degree of critical white matter tract infiltration, the velocity of tumor expansion, and the reactional changes of neuropsychological performances over time. Second, the interactions between the potential/limitations of cerebral plasticity and the efficacy/tolerance of treatment options (i.e., surgery, chemotherapy, and radiotherapy) are reviewed. Finally, a longitudinal and multimodal treatment approach accounting for the evolutive profiles of brain plasticity is proposed. Such an approach integrates personalized predictive models of plasticity potentials with a step-by-step therapeutic decision making and supports onco-functional balanced strategies in patients with LGG, with the ultimate aim of optimizing overall survival and quality of life.

Reorganization and Plasticity of the Language Network in Patients with Cerebral Gliomas

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

Predictors of Seizure Freedom in Pediatric Low-Grade Gliomas

OBJECTIVE

Pediatric low-grade gliomas (LGGs) are found in approximately one to three percent of patients with childhood epilepsy. Epilepsy in these patients is often medically refractory and therefore represents a unique cohort with significant morbidity from concomitant pathology. Similar studies in adult patients with low-grade gliomas have identified predictors of seizure freedom including gross-total resection, preoperative seizure control on antiepileptic medication and duration of seizures of less than one year. This study aims to identify similar predictors of seizure freedom in operatively managed pediatric LGGs.

METHODS

A retrospective chart review was performed for patients diagnosed with World Health Organization (WHO) Grade I and II gliomas in patients ≤18 years old at a single institution (Indiana University School of Medicine at Riley Hospital for Children in Indianapolis, IN) from 2007-2017. Infratentorial and purely intraventricular lesions were excluded. WHO classification and histologic diagnosis were based on surgical pathology. Tumor grade, location, laterality, seizure status at presentation, and AED requirements pre- and post-operatively were recorded. Chi-squared analyses for independence were performed controlling for age at presentation, resection extent, seizure type, and Engel Class for seizure freedom post-operatively.

RESULTS

Forty-two patients met the inclusion criteria. Preoperative seizures were observed in 23 patients (55%). Presentation with preoperative seizures was highly associated with continued seizure burden post-operatively, independent of the extent of surgical resection. Supratentorial location and the administration of prophylactic pre- and post-operative AEDs were associated with Engel Class I seizure freedom. Temporal location was not significantly associated with medically refractory epilepsy compared with extra-temporal locations.

CONCLUSIONS

In our cohort of pediatric LGGs, we find that patients that did not initially present with seizures and those who were treated with prophylactic pre- and post-operative AEDs, were more likely to achieve Engel Class I seizure freedom post-operatively. Tumors located in the temporal location were not significantly associated with a higher seizure burden than other supratentorial, extra-temporal tumors. Neither extent of resection nor electrocorticography-guided resection correlated with improved seizure freedom outcomes during glioma resection.

The Use of Standardized Intraoperative Language Tests in Awake Craniotomies: A Scoping Review

Assessment of speech and language functions is an essential part of awake craniotomies. Although standardized and validated tests have several advantages compared to homemade (or mixed) batteries, in the literature it is unclear how such tests are used or whether they are used at all. In this study, we performed a scoping review in order to locate standardized and validated intraoperative language tests. Our inquiry included two databases (PubMED and MEDLINE), gray literature, and snowball referencing. We discovered 87 studies reporting use of mixed batteries, which consist of homemade tasks and tests borrowed from other settings. The tests we found to meet the validation and standardization criteria we set were ultimately three (n = 3) and each one has its own advantages and disadvantages. We argue that tests with high sensitivity and specificity not only can lead to better outcomes postoperatively, but they can also help us to gain a better understanding of the neuroanatomy of language.

Isocitrate Dehydrogenase Mutant Grade II and III Glial Neoplasms

Mutations in isocitrate dehydrogenase (IDH) 1 or IDH2 occur in most of the adult low-grade gliomas and, less commonly, in cholangiocarcinoma, chondrosarcoma, acute myeloid leukemia, and other human malignancies. Cancer-associated mutations alter the function of the enzyme, resulting in production of R(-)-2-hydroxyglutarate and broad epigenetic dysregulation. Small molecule IDH inhibitors have received regulatory approval for the treatment of IDH mutant (mIDH) leukemia and are under development for the treatment of mIDH solid tumors. This article provides a current view of mIDH adult astrocytic and oligodendroglial tumors, including their clinical presentation and treatment, and discusses novel approaches and challenges toward improving the treatment of these tumors.

Cerebral white matter vasculature: still uncharted?

White matter vasculature plays a major role in the pathophysiology of permanent neurological deficits following a stroke or progressive cognitive alteration related to small vessel disease. Thus, knowledge of the complex vascularization and functional aspects of the deep white matter territories is paramount to comprehend clinical manifestations of brain ischemia. This review provides a structured presentation of the existing knowledge of the vascularization of the human cerebral white matter from seminal historical studies to the current literature. First, we revisit the highlights of prenatal development of the endoparenchymal telencephalic vascular system that are crucial for the understanding of vessel organization in the adult. Second, we reveal the tangled history of debates on the existence, clinical significance, and physiological role of leptomeningeal anastomoses. Then, we present how conceptions on white matter vascularization transitioned from the mixed ventriculopetal/ventriculofugal theory, in which a low-flow area was interposed in between concurrent arterial flows, to the purely ventriculopetal theory. The latter model explains variable white matter sensitivity to ischemia by various organizations of ventriculopetal vessel terminals having different origin/length properties and interconnection patterns. Next, arteries supplying primarily the white matter are described according to their length and overall structure. Furthermore, the known distribution territories, to date, are studied in relation to primary anatomical structures of the human cerebral white matter, emphasizing the sparsity of the "ground-truth" data available in the literature. Finally, the implications for both large vessel occlusion and chronic small vessel disease are discussed, as well as the insights from neuroimaging. All things considered, we identify the need for further research on deep white matter vascularization, especially regarding the arterial supply of white matter fiber tracts.

Gamma Knife radiosurgery as primary treatment of low-grade brainstem gliomas: A systematic review and metanalysis of current evidence and predictive factors

The current standard of care for surgically inaccessible low-grade brainstem gliomas (BS-LLGs) is external-beam radiotherapy (RT). Developments toward more innovative conformal techniques have focused on decreasing morbidity, by limiting radiation to surrounding tissues. Among these Gamma Knife radiosurgery (SRS-GK) has recently gained an increasingly important role in the treatment of these tumors. Although SRS-GK has not yet been compared with conventional RT in patients harboring focal BS-LGGs, clinical practice has been deeply influenced by trials performed on other tumors. This is the first meta-analysis on the topic, systematically reviewing the most relevant available evidence, comparing RT and SRS-GK as primary treatments of BS-LGGs, focusing on survival, clinical outcome, oncological control, and complications. Predictive factors have been systematically evaluated and analyzed according to statistical significance and clinical relevance.

Avoidance and Improvement in Visual Field Defect After Surgery for Metastatic Brain Tumors in the Parietal and the Occipital Lobe

OBJECTIVE

Visual field defects occasionally occur secondary to tumors in the parietal and the occipital lobes. The aim of this study was to analyze the efficacy of improvement in hemianopsia after surgery for metastatic brain tumors involving or adjacent to the optic radiation (OR).

METHODS

The study included 49 patients with brain metastasis in the parietal and occipital lobes in the present study. Preoperative and postoperative neurological assessments included visual field, Mini-Mental State Examination, and Karnofsky performance scale.

RESULTS

Of 49 patients, 33 (67.3%) presented with preoperative homonymous hemianopsia. Of these 33 patients, the visual field was improved postoperatively in 17 patients (51.5%). In all patients regardless of preoperative hemianopsia, postoperative visual fields did not deteriorate. Tractography demonstrated that the OR was split by the tumor (n = 6) and fanning of fibers expanded along the lateral side of the tumor (n = 11). All tumors were removed via surgical access toward the medial side of the tumor. Gross total resection was achieved in most tumors in the group with visual improvement (n = 16/17; 94.1%). Improvement in the visual field was attributed to tumor location in the subcortical white matter, removal rate of the tumor, and higher postoperative Karnofsky performance scale score.

CONCLUSIONS

The OR tended to deviate to the lateral side of the tumor in the parieto-occipital junction. The postoperative visual field improved even in cases of an occipital tumor. Based on the present study, total resection via an appropriate surgical route should be considered to preserve the OR, leading to improvement in the postoperative visual field.

Seizure Outcome After Surgery for Insular High-Grade Glioma

BACKGROUND

The insular cortex is an eloquent island of mesocortex surrounded by vital structures making this region relatively challenging to neurosurgeons. Historically, lesions in this region were considered too high risk to approach given the strong chance of poor surgical outcome. Advances in recent decades have meant that surgeons can more safely access this eloquent region. Seizure outcome after excision of insular low-grade gliomas is well reported, but little is known about seizure outcomes after excision of insular high-grade gliomas.

METHODS

A retrospective analysis was performed of all patients presenting with new-onset seizures during 2015-2019 who underwent excision of an insular high-grade glioma at 3 regional neurosurgical centers in the United Kingdom.

RESULTS

We identified 38 patients with a mean (SD) age of 45.7 (15.3) years with median follow-up of 21 months. At long-term follow-up, of 38 patients, 23 were seizure-free (Engel class I), 2 had improved seizures (Engel class II), 6 had poor seizure control (Engel class III/IV), and 7 died.

CONCLUSIONS

Excision of insular high-grade gliomas is safe and results in excellent postoperative seizure control.

Intraoperative Neuromonitoring During Resection of Gliomas Involving Eloquent Areas

In the case of resection of gliomas involving eloquent areas, equal consideration should be given to maintain maximal extent of resection (EOR) and neurological protection, for which the intraoperative neuromonitoring (IONM) proves an effective and admirable approach. IONM techniques applied in clinical practice currently consist of somatosensory evoked potential (SSEP), direct electrical stimulation (DES), motor evoked potential (MEP), electromyography (EMG), and electrocorticography (ECoG). The combined use of DES and ECoG has been adopted widely. With the development of technology, more effective IONM tactics and programs would be proposed. The ultimate goal would be strengthening the localization of eloquent areas and epilepsy foci, reducing the incidence of postoperative dysfunction and epilepsy improving the life quality of patients.

Management, functional outcomes and survival in a French multicentric series of 118 adult patients with cerebellar glioblastoma

PURPOSE

To analyze the outcomes and predictors in a large series of cerebellar glioblastomas in order to guide patient management.

METHODS

The French brain tumor database and the Club de Neuro-Oncologie of the Société Française de Neurochirurgie retrospectively identified adult patients with cerebellar glioblastoma diagnosed between 2003 and 2017. Diagnosis was confirmed by a centralized neuropathological review.

RESULTS

Data from 118 cerebellar glioblastoma patients were analyzed (mean age 55.9 years, 55.1% males). The clinical presentation associated raised intracranial pressure (50.8%), static cerebellar syndrome (68.6%), kinetic cerebellar syndrome (49.2%) and/or cranial nerve disorders (17.8%). Glioblastomas were hemispheric (55.9%), vermian (14.4%) or both (29.7%). Hydrocephalus was present in 49 patients (41.5%). Histologically, tumors corresponded either to IDH-wild-type or to K27-mutant glioblastomas. Surgery consisted of total (12.7%), subtotal (35.6%), partial resection (33.9%) or biopsy (17.8%). The postoperative Karnofsky performance status was improved, stable and worsened in 22.4%, 43.9% and 33.7% of patients, respectively. Progression-free and overall survivals reached 5.1 months and 9.1 months, respectively. Compared to other surgical strategies, total or subtotal resection improved the Karnofsky performance status (33.3% vs 12.5%, p < 0.001), prolonged progression-free and overall survivals (6.5 vs 4.3 months, p = 0.015 and 16.7 vs 6.2 months, p < 0.001, respectively) and had a comparable complication rate (40.4% vs 31.1%, p = 0.29). After total or subtotal resection, the functional outcomes were correlated with age (p = 0.004) and cerebellar hemispheric tumor location (p < 0.001) but not brainstem infiltration (p = 0.16).

CONCLUSION

In selected patients, maximal resection of cerebellar glioblastoma is associated with improved onco-functional outcomes, compared with less invasive procedures.

What do we know about pre- and postoperative plasticity in patients with glioma? A review of neuroimaging and intraoperative mapping studies

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Brain reorganization can take place before and after surgery of low- and high-grade gliomas.

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Plasticity is observed for low-grade but also for high-grade gliomas.

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The contralesional hemisphere can be vital for successful compensation.

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There is evidence of plasticity for both the language system and the sensorimotor system.

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Partial compensation can also occur at the white-matter level.

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Subcortical connectivity is crucial for brain reorganization.

Brain plasticity potential is a central theme in neuro-oncology and is currently receiving increased attention. Advances in treatment have prolonged life expectancy in neuro-oncological patients and the long-term preservation of their quality of life is, therefore, a new challenge. To this end, a better understanding of brain plasticity mechanisms is vital as it can help prevent permanent deficits following neurosurgery.

Indeed, reorganization processes can be fundamental to prevent or recover neurological and cognitive deficits by reallocating brain functions outside the lesioned areas. According to more recent studies in the literature, brain reorganization taking place following neurosurgery is associated with good neurofunctioning at follow-up. Interestingly, in the last few years, the number of reports on plasticity has notably increased.

Aim of the current review was to provide a comprehensive overview of pre- and postoperative neuroplasticity patterns. Within this framework, we aimed to shed light on some tricky issues, including i) involvement of the contralateral healthy hemisphere, ii) role and potential changes of white matter and connectivity patterns, and iii) reorganization in low- versus high-grade gliomas.

We finally discussed the practical implications of these aspects and role of additional potentially relevant factors to be explored. Final purpose was to provide a guideline helpful in promoting increase in the extent of tumor resection while preserving the patients’ neurological and cognitive functioning.

Diffuse low grade glioma and pregnancy: Practical considerations and clinical tips

OBJECTIVE

The interaction between pregnancy and diffuse low-grade glioma (DLGG) is poorly investigated. The goal of this study was to provide further insights into the relationship between pregnancy and DLGG.

METHODS

A total of 12 patients were selected from a shared database of DLGGs, according to the following inclusion criteria: DLGG diagnosis in post-partum, DLGG recurrence after pregnancy in patients previously operated for DLGG. The extent of surgical resection (EOR) at first surgery were evaluated. All cases were assessed based on the 2016 WHO classification. The tumor growing patter, expresses by preoperative ΔT2T1 MRI index was evaluated.

RESULTS

In four cases newly diagnosed DLGG were detected patients in post-partum. Seven women, previously operated for DLGG, experienced pregnancy during the natural history of glioma, and were affected by tumor recurrence after pregnancy. One singular had an incidental LGG not surgically treated, who presented an important tumor growth after pregnancy. Radiological and surgical data were discussed according to literature.

CONCLUSIONS

Pregnancy does not seem to have an impact on the survival of women with DLGG. The potential role of pregnancy as risk factor in tumor recurrence is described, however, not proven. In this regard, the association between pregnancy and Tumor recurrence is extremely doubtful, and currently attributable to the simple coincidence. Further multicenter molecular investigations are required to better understand the mechanisms by which the pregnancy, in patients with a pervious surgery for DLGG, may influence tumor regrowth in comparison with the natural history of the disease.

Awake Craniotomy with Functional Mapping for Glioma Resection in a Limited-Resource-Setting: Preliminary Experience from a Lower-Middle Income Country

BACKGROUND

Awake craniotomy with brain mapping aims to maximize resection of gliomas located within eloquent regions while minimizing the risk of postoperative deficits. This technique is common practice in the developed world but has yet to be implemented in most low- and middle-income countries (LMICs). We assessed the feasibility, safety, and efficiency of functional-based glioma resection using minimal facilities in a limited-resource institution.

METHODS

This is a retrospective review of patients harboring gliomas within eloquent regions who underwent awake craniotomy and tumor resection guided by cortico-subcortical mapping at a tertiary hospital of an LMIC. Patient characteristics, surgical results, and functional outcomes were studied.

RESULTS

Twenty consecutive patients with a mean age of 37 years were enrolled in the study. Seizure, present in 70% of patients, was the major presenting symptom. Eighteen patients had diffuse low-grade gliomas and 2 patients had high-grade gliomas. Intraoperative events were dominated by seizures, occurring in 5 patients (25%). The average extent of tumor removal was 89.5% and the rate of total and subtotal removal was 85%. New postoperative deficits were observed in 5 patients (25%), and permanent deficits were found in 1 patient (5%). The main hurdles encountered were the difficulties in investigating patients and human resource availability.

CONCLUSIONS

Awake craniotomy with brain mapping for functional-based resection of gliomas can be safely achieved in a limited-resource institution with good functional and oncologic results.

Surgical treatment of drug-resistant epilepsy caused by gliomas in eloquent areas: experience report

INTRODUCTION

Drug-resistant epilepsy associated with central nervous system tumors is generally caused by low grade gliomas. This group of tumors is usually found in brain eloquent areas, such as the insular lobe, rolandic cortex and supplementary motor area and, historically, possess a greater risk of postoperative deficits.

OBJECTIVE

The aim of this investigation was to present our surgical experience on patients with drug-resistant epilepsy caused by gliomas in eloquent areas. We retrospectively investigated variables that impact seizure control, such as tumor location, extent of resection, invasion into the lenticulostriate arteries in the patient, especially those with insular gliomas.

METHODS

Out of 67 patients with eloquent area brain tumors operated on in our service between 2007 and 2016, 14 patients had symptoms of drug-resistant epilepsy. Volumetric analysis, extent of resection (EOR), type of approach and mapping, among other factors were correlated with the 12-month postoperative seizure outcome.

RESULTS

Univariate analysis showed that the factors showing statistical relevance with seizure control were preoperative volume (p = 0.005), EOR (p = 0.028) and postoperative volume (p = 0.030).

CONCLUSION

There was a statistically significant association between the EOR and the Engel score for epilepsy control: an EOR < 70 was associated with Engel II, III, IV and an EOR > 90 was associated with Engel I. Eloquent area gliomas can safely be resected when surgeons use not only microsurgical anatomy concepts but also brain mapping.

ReStNeuMap: a tool for automatic extraction of resting-state functional MRI networks in neurosurgical practice

OBJECTIVE

Resting-state functional MRI (rs-fMRI) represents a promising and cost-effective alternative to task-based fMRI for presurgical mapping. However, the lack of clinically streamlined and reliable rs-fMRI analysis tools has prevented wide adoption of this technique. In this work, the authors introduce an rs-fMRI processing pipeline (ReStNeuMap) for automatic single-patient rs-fMRI network analysis.

METHODS

The authors provide a description of the rs-fMRI network analysis steps implemented in ReStNeuMap and report their initial experience with this tool after performing presurgical mapping in 6 patients. They verified the spatial agreement between rs-fMRI networks derived by ReStNeuMap and localization of activation with intraoperative direct electrical stimulation (DES).

RESULTS

The authors automatically extracted rs-fMRI networks including eloquent cortex in spatial proximity with the resected lesion in all patients. The distance between DES points and corresponding rs-fMRI networks was less than 1 cm in 78% of cases for motor, 100% of cases for visual, 87.5% of cases for language, and 100% of cases for speech articulation mapping.

CONCLUSIONS

The authors' initial experience with ReStNeuMap showed good spatial agreement between presurgical rs-fMRI predictions and DES findings during awake surgery. The availability of the rs-fMRI analysis tools for clinicians aiming to perform noninvasive mapping of brain functional networks may extend its application beyond surgical practice.

Optimization of high-grade glioma resection using 5-ALA fluorescence-guided surgery: A literature review and practical recommendations from the neuro-oncology club of the French society of neurosurgery

BACKGROUND

When feasible, the surgical resection is the standard first step of the management of high-grade gliomas. 5-ALA fluorescence-guided-surgery (5-ALA-FGS) was developed to ease the intra-operative delineation of tumor borders in order to maximize the extent of resection.

METHODS

A Medline electronic database search was conducted. English language studies from January 1998 until July 2018 were included, following the PRISMA guidelines.

RESULTS

5-ALA can be considered as a specific tool for the detection of tumor remnant but has a weaker sensibility (level 2). 5-ALA-FGS is associated with a significant increase in the rate of gross total resection reaching more than 90% in some series (level 1). Consistently, 5-ALAFGS improves progression-free survival (level 1). However, the gain in overall survival is more debated. The use of 5-ALA-FGS in eloquent areas is feasible but requires simultaneous intraoperative electrophysiologic functional brain monitoring to precisely locate and preserve eloquent areas (level 2). 5-ALA is usable during the first resection of a glioma but also at recurrence (level 2). From a practical standpoint, 5-ALA is orally administered 3 hours before the induction of anesthesia, the recommended dose being 20 mg/kg. Intra-operatively, the procedure is performed as usually with a central debulking and a peripheral dissection during which the surgeon switches from white to blue light. Provided that some precautions are observed, the technique does not expose the patient to particular complications.

CONCLUSION

Although 5-ALA-FGS contributes to improve gliomas management, there are still some limitations. Future methods will be developed to improve the sensibility of 5-ALA-FGS.

Clinical characteristics associated with postoperative seizure control in adult low-grade gliomas: a systematic review and meta-analysis

Background

Epilepsy is the most common symptom in patients with supratentorial low-grade gliomas (LGGs), which adversely affects the patient's quality of life. Poor seizure control with anti-epileptic therapy is an indication for surgery in these patients. Recent studies have sought to identify predictors of postoperative seizure control after surgical resection of LGG; gross total resection was shown to be a significant predictor in this respect. However, the prognostic value of other factors is not clear.

Methods

We performed a systematic review and meta-analysis of 23 studies with a combined study population of 2641 patients with LGG, in order to identify potential factors associated with favorable postoperative seizure control. Data were extracted on age and sex of patient, tumor location, tumor histology, type of seizure, seizure duration, extent of resection, and imaging characteristics.

Results

Patients ≥45 years of age achieved better postoperative seizure control (risk ratio [RR], 0.89; 95% CI, 0.81-0.99). Focal seizures were associated with poor seizure control (RR, 1.32; 95% CI, 1.18-1.49) compared with generalized seizures (RR, 0.77; 95% CI, 0.68-0.87). Prolonged history of seizures (≥1 y) had a negative impact on postoperative seizure control (RR, 1.22; 95% CI, 1.10-1.34). Gross total resection was superior to subtotal resection with respect to postoperative seizure control (RR, 0.68; 95% CI, 0.63-0.73).

Conclusions

This systematic review and meta-analysis identified predictors of postoperative seizure control in patients undergoing surgical resection of LGGs. Our results provide a reference for clinical treatment of LGG-related epilepsy.

Insular glioma surgery: an evolution of thought and practice

OBJECTIVEThe goal of this article is to review the history of surgery for low- and high-grade gliomas located within the insula with particular focus on microsurgical technique, anatomical considerations, survival, and postoperative morbidity.METHODSThe authors reviewed the literature for published reports focused on insular region anatomy, neurophysiology, surgical approaches, and outcomes for adults with World Health Organization grade II-IV gliomas.RESULTSWhile originally considered to pose too great a risk, insular glioma surgery can be performed safely due to the collective efforts of many individuals. Similar to resection of gliomas located within other cortical regions, maximal resection of gliomas within the insula offers patients greater survival time and superior seizure control for both newly diagnosed and recurrent tumors in this region. The identification and the preservation of M2 perforating and lateral lenticulostriate arteries are critical steps to preventing internal capsule stroke and hemiparesis. The transcortical approach and intraoperative mapping are useful tools to maximize safety.CONCLUSIONSThe insula's proximity to middle cerebral and lenticulostriate arteries, primary motor areas, and perisylvian language areas makes accessing and resecting gliomas in this region challenging. Maximal safe resection of insular gliomas not only is possible but also is associated with excellent outcomes and should be considered for all patients with low- and high-grade gliomas in this area.

Gold Nanoparticles for Brain Tumor Imaging: A Systematic Review

Background

Demarcation of malignant brain tumor boundaries is critical to achieve complete resection and to improve patient survival. Contrast-enhanced brain magnetic resonance imaging (MRI) is the gold standard for diagnosis and pre-surgical planning, despite limitations of gadolinium (Gd)-based contrast agents to depict tumor margins. Recently, solid metal-based nanoparticles (NPs) have shown potential as diagnostic probes for brain tumors. Gold nanoparticles (GNPs) emerged among those, because of their unique physical and chemical properties and biocompatibility. The aim of the present study is to review the application of GNPs for in vitro and in vivo brain tumor diagnosis.

Methods

We performed a PubMed search of reports exploring the application of GNPs in the diagnosis of brain tumors in biological models including cells, animals, primates, and humans. The search words were "gold" AND "NP" AND "brain tumor." Two reviewers performed eligibility assessment independently in an unblinded standardized manner. The following data were extracted from each paper: first author, year of publication, animal/cellular model, GNP geometry, GNP size, GNP coating [i.e., polyethylene glycol (PEG) and Gd], blood-brain barrier (BBB) crossing aids, imaging modalities, and therapeutic agents conjugated to the GNPs.

Results

The PubMed search provided 100 items. A total of 16 studies, published between the 2011 and 2017, were included in our review. No studies on humans were found. Thirteen studies were conducted in vivo on rodent models. The most common shape was a nanosphere (12 studies). The size of GNPs ranged between 20 and 120 nm. In eight studies, the GNPs were covered in PEG. The BBB penetration was increased by surface molecules (nine studies) or by means of external energy sources (in two studies). The most commonly used imaging modalities were MRI (four studies), surface-enhanced Raman scattering (three studies), and fluorescent microscopy (three studies). In two studies, the GNPs were conjugated with therapeutic agents.

Conclusion

Experimental studies demonstrated that GNPs might be versatile, persistent, and safe contrast agents for multimodality imaging, thus enhancing the tumor edges pre-, intra-, and post-operatively improving microscopic precision. The diagnostic GNPs might also be used for multiple therapeutic approaches, namely as "theranostic" NPs.

Data-Driven Predictive Models of Diffuse Low-Grade Gliomas Under Chemotherapy

Diffuse low-grade gliomas (DLGG) are brain tumors of young adults. They affect the quality of life of the inflicted patients and, if untreated, they evolve into higher grade tumors where the patient's life is at risk. Therapeutic management of DLGGs includes chemotherapy, and tumor diameter is particularly important for the follow-up of DLGG evolution. In fact, the main clinical basis for deciding whether to continue chemotherapy is tumor diameter growth rate. In order to reliably assist the doctors in selecting the most appropriate time to stop treatment, we propose a novel clinical decision support system. Based on two mathematical models, one linear and one exponential, we are able to predict the evolution of tumor diameter under Temozolomide chemotherapy as a first treatment and thus offer a prognosis on when to end it. We present the results of an implementation of these models on a database of 42 patients from Nancy and Montpellier University Hospitals. In this database, 38 patients followed the linear model and four patients followed the exponential model. From a training data set of a minimal size of five, we are able to predict the next tumor diameter with high accuracy. Thanks to the corresponding prediction interval, it is possible to check if the new observation corresponds to the predicted diameter. If the observed diameter is within the prediction interval, the clinician is notified that the trend is within a normal range. Otherwise, the practitioner is alerted of a significant change in tumor diameter.

Three-Dimensional Printed Modeling of Diffuse Low-Grade Gliomas and Associated White Matter Tract Anatomy

BACKGROUND

Diffuse low-grade gliomas (DLGGs) represent several pathological entities that infiltrate and invade cortical and subcortical structures in the brain.

OBJECTIVE

To describe methods for rapid prototyping of DLGGs and surgically relevant anatomy.

METHODS

Using high-definition imaging data and rapid prototyping technologies, we were able to generate 3 patient DLGGs to scale and represent the associated white matter tracts in 3 dimensions using advanced diffusion tensor imaging techniques.

RESULTS

This report represents a novel application of 3-dimensional (3-D) printing in neurosurgery and a means to model individualized tumors in 3-D space with respect to subcortical white matter tract anatomy. Faculty and resident evaluations of this technology were favorable at our institution.

CONCLUSION

Developing an understanding of the anatomic relationships existing within individuals is fundamental to successful neurosurgical therapy. Imaging-based rapid prototyping may improve on our ability to plan for and treat complex neuro-oncologic pathology.

Differential Effects of Awake Glioma Surgery in "Critical" Language Areas on Cognition: 4 Case Studies

Awake surgery with electrocorticosubcortical stimulation is the golden standard treatment for gliomas in eloquent areas. Preoperatively, mostly mild cognitive disturbances are observed with postoperative deterioration. We describe pre- and postoperative profiles of 4 patients (P1–P4) with gliomas in “critical” language areas (“Broca,” “Wernicke,” and the arcuate fasciculus) undergoing awake surgery to get insight into the underlying mechanism of neuroplasticity. Neuropsychological examination was carried out preoperatively (at T1) and postoperatively (at T2, T3). At T1, cognition of P1 was intact and remained stable. P2 had impairments in all cognitive domains at T1 with further deterioration at T2 and T3. At T1, P3 had impairments in memory and executive functions followed by stable recovery. P4 was intact at T1, followed by a decline in a language test at T2 and recovery at T3. Intraoperatively, in all patients language positive sites were identified. Patients with gliomas in “critical” language areas do not necessarily present cognitive disturbances. Surgery can either improve or deteriorate (existing) cognitive impairments. Several factors may underlie the plastic potential of the brain, for example, corticosubcortical networks and tumor histopathology. Our findings illustrate the complexity of the underlying mechanism of neural plasticity and provide further support for a “hodotopical” viewpoint.

Insular gliomas: a surgical reappraisal based on a systematic review of the literature

INTRODUCTION

Insular gliomas are heterogeneous lesions whose management presents multiple challenges for their tendency to affect young patients in good neurological and cognitive conditions, their deep anatomic location and proximity with critical functional and vascular structures. The appropriate management of insular gliomas requires a multidisciplinary evidence-centred teamwork grounded on the best anatomic, neurophysiological and oncological knowledge. The present study provides a reappraisal of the management of insular gliomas based on a systematic review of the literature with the aim of guiding clinicians in the management of such tumors.

EVIDENCE ACQUISITION

A systematic review of the literature from the Medline, Embase and Cochrane Central databases was performed. From 2006 to 2016, all articles meeting specific inclusion criteria were included.

EVIDENCE SYNTHESIS

The present work summarizes the most relevant evidence about insular gliomas management. The anatomy and physiology of the insula, the new WHO 2016 classification and clinico-radiological presentation of insular gliomas are reviewed. Surgical pearls of insular gliomas resection as well as oncologic and functional outcomes after insular gliomas treatment are discussed.

CONCLUSIONS

Management of insular gliomas remains challenging despite improvement in surgical and oncological techniques. However, the literature review supports a growing evidence that recent developments in the multidisciplinary care account for constant improvements of survival and quality of life.

Preoperative prediction of language function by diffusion tensor imaging

For surgery of eloquent tumors in language areas, the accepted gold standard is functional mapping through direct cortical stimulation (DCS) in awake patients. Ever since, neuroscientists are searching for reliable noninvasive detection of function in the human brain, with variable success. The potential of diffusion tensor imaging (DTI) in combination with computational cortical parcellation to predict functional areas in language eloquent tumors has not been assessed so far. We present a proof-of-concept report involving awake surgery for a temporodorsal tumor. Postoperatively, the imaging was extensively studied and a predictive value of multimodal MR imaging for the possible extent of resection was analyzed. After resection using DCS, the extent of resection and functional outcome were correlated with the processed imaging. Preoperative imaging of our patient was taken to compute the lesion volume as a seed for tractography (DTI) and combined with a tractography of the entire hemisphere. For better spatial resolution, an elastic image fusion was performed to correct the distortion of DTI data. After subtotal resection and imaging analysis, the status of the superior part of the lesion could be identified and predicted as functional cortex. There was a strong correlation between the tumor remnant during surgery and the imaging parameters of DTI connectivity of the eloquent tissue. A combination of complex DTI processing may be able to predict function in a patient suffering eloquent brain tumors and thus allow estimation of extent of resection.

Surgery guided with intraoperative electrocorticography in patients with low-grade glioma and refractory seizures

OBJECTIVE Using intraoperative electrocorticography (ECoG) to identify epileptogenic areas and improve postoperative seizure control in patients with low-grade gliomas (LGGs) remains inconclusive. In this study the authors retrospectively report on a surgery strategy that is based on intraoperative ECoG monitoring. METHODS A total of 108 patients with LGGs presenting at the onset of refractory seizures were included. Patients were divided into 2 groups. In Group I, all patients underwent gross-total resection (GTR) combined with resection of epilepsy areas guided by intraoperative ECoG, while patients in Group II underwent only GTR. Tumor location, tumor side, tumor size, seizure-onset features, seizure frequency, seizure duration, preoperative antiepileptic drug therapy, intraoperative electrophysiological monitoring, postoperative Engel class, and histological tumor type were compared between the 2 groups. RESULTS Univariate analysis demonstrated that tumor location and intraoperative ECoG monitoring correlated with seizure control. There were 30 temporal lobe tumors, 22 frontal lobe tumors, and 2 parietal lobe tumors in Group I, with 18, 24, and 12 tumors in those same lobes, respectively, in Group II (p < 0.05). In Group I, 74.07% of patients were completely seizure free (Engel Class I), while 38.89% in Group II (p < 0.05). In Group I, 96.30% of the patients achieved satisfactory postoperative seizure control (Engel Class I or II), compared with 77.78% in Group II (p < 0.05). Intraoperative ECoG monitoring indicated that in patients with temporal lobe tumors, most of the epileptic discharges (86.7%) were detected at the anterior part of the temporal lobe. In these patients with epilepsy discharges located at the anterior part of the temporal lobe, satisfactory postoperative seizure control (93.3%) was achieved after resection of the tumor and the anterior part of the temporal lobe. CONCLUSIONS Intraoperative ECoG monitoring provided the exact location of epileptogenic areas and significantly improved postoperative seizure control of LGGs. In patients with temporal lobe LGGs, resection of the anterior temporal lobe with epileptic discharges was sufficient to control seizures.

Malignant transformation of low-grade gliomas in patients undergoing adjuvant therapy

Low-grade gliomas (LGG) comprise nearly 15-20 % of all central nervous system glial tumors. Several factors have been recognized as playing role in LGG malignant transformation (MT). A breakthrough analysis of a multidisciplinary group pointed that temozolomide may play a role in MT of LGGs. We analyzed the prevalence of MT in LGG patients submitted to adjuvant therapy (AT). We analyzed the medical charts of 43 patients with LGG submitted to surgery or biopsy and attending at Hospital do Servidor Público Estadual de São Paulo (São Paulo, Brazil), consecutively diagnosed from 1995 to 2013. 43 patients (24 women and 19 men) were evaluated, with mean age of 45.3 years. According to histology, 30 were astrocytomas (70 %), 12 (27 %) were oligodendrogliomas, and 1 (3 %) were mixed glioma. Mean follow-up time was 4.2 years with the standard deviation of 2.1. Twenty-eight patients did not receive adjuvant therapy and 15 received adjuvant therapy. From 43 patients with complete follow-up, 21 (48 %) experienced malignant transformation. Among such patients, nine were users of AT. Forty-eight percent of patients presented MT, being 60 % in the AT group and 42.8 % without AT. Our analysis revealed a high prevalence of MT in patients undergoing AT, higher than in patients without AT.

Gamma Knife Radiosurgery for Low-Grade Gliomas: Clinical Results at Long-Term Follow-Up of Tumor Control and Patients' Quality of Life

OBJECTIVE

First-line therapy for low-grade gliomas (LGGs) is surgery, in some cases followed by radiotherapy and chemotherapy. Gamma Knife radiosurgery (GKRS) has gained more relevance in the management of these tumors. The aim of this study was to assess efficacy and safety of GKRS for treatment of LGGs.

METHODS

Between 2001 and 2014, 42 treatments were performed on 39 patients harboring LGGs; 48% of patients underwent previous surgery, and 20.5% underwent previous radiotherapy. Mean tumor volume was 2.7 cm³, and median margin dose was 15 Gy.

RESULTS

Mean follow-up was 60.5 months (range, 6-164 months). Actuarial progression-free survival was 74.9%, 52.8%, and 39.1% at 1 year, 5 years, and 10 years; actuarial overall survival was 97.4%, 94.6%, and 91.8% at 9 months, 1 year, and 5 years. Solid tumor control was achieved in 69.2% of patients, whereas cystic enlargement was recorded in 12.9% of cases. At last follow-up, volume reduction was recorded in 57.7% of cases, and median volume decreased by 33.3%. Clinical improvement was observed in 52.4% of patients. Karnofsky performance scale score was improved in 15 patients (45.5%), unchanged in 17 patients (51.5%), and worsened in 1 patient (3%). Mean posttreatment scores of 36-item short form health survey domains did not significantly differ from scores in a healthy Italian population.

CONCLUSIONS

This study confirms safety and effectiveness of GKRS for LGGs in controlling tumor growth, relevantly improving patients' overall and progression-free survival. GKRS improved patients' functional performance and quality of life, optimizing social functioning and minimizing disease-related psychological impact.

Functional Magnetic Resonance Imaging (fMRI), Pre-intraoperative Tractography in Neurosurgery: The Experience of Sant' Andrea Rome University Hospital

BACKGROUND

The goal of neurosurgery for cerebral intraparenchymal neoplasms of the eloquent areas is maximal resection with the preservation of normal functions, and minimizing operative risk and postoperative morbidity. Currently, modern technological advances in neuroradiological tools, neuronavigation, and intraoperative magnetic resonance imaging (MRI) have produced great improvements in postoperative morbidity after the surgery of cerebral eloquent areas. The integration of preoperative functional MRI (fMRI), intraoperative MRI (volumetric and diffusion tensor imaging [DTI]), and neuronavigation, defined as "functional neuronavigation" has improved the intraoperative detection of the eloquent areas.

METHODS

We reviewed 142 patients operated between 2004 and 2010 for intraparenchymal neoplasms involving or close to one or more major white matter tracts (corticospinal tract [CST], arcuate fasciculus [AF], optic radiation). All the patients underwent neurosurgery in a BrainSUITE equipped with a 1.5 T MR scanner and were preoperatively studied with fMRI and DTI for tractography for surgical planning. The patients underwent MRI and DTI during surgery after dural opening, after the gross total resection close to the white matter tracts, and at the end of the procedure. We evaluated the impact of fMRI on surgical planning and on the selection of the entry point on the cortical surface. We also evaluated the impact of preoperative and intraoperative DTI, in order to modify the surgical approach, to define the borders of resection, and to correlate this modality with subcortical neurophysiological monitoring. We evaluated the impact of the preoperative fMRI by intraoperative neurophysiological monitoring, performing "neuronavigational" brain mapping, following its data to localize the previously elicited areas after brain shift correction by intraoperative MRI.

RESULTS

The mean age of the 142 patients (89 M/53 F) was 59.1 years and the lesion involved the CST in 66 patients (57 %), the language pathways in 24 (21 %), and the optic radiations in 25 (22 %). The integration of tractographic data into the volumetric dataset for neuronavigation was technically possible in all cases. In all patients intraoperative DTI demonstrated a shift of the bundle position caused by the surgical procedure; its dislocation was both outward and inward in the range of +6 mm and -2 mm.

CONCLUSION

We found a high concordance between fMRI/DTI and intraoperative brain mapping; their combination improves the sensitivity of each technique, reducing pitfalls and so defining "functional neuronavigation", increasing the definition of eloquent areas and also reducing the time of surgery.

The etiopathogenesis of diffuse low-grade gliomas

The origins of diffuse low-grade gliomas (DLGG) are unknown. Beyond some limited data on their temporal and cellular origins, the mechanisms and risk factors involved are poorly known. First, based on strong relationships between DLGG development and the eloquence of brain regions frequently invaded by these tumors, we propose a "functional theory" to explain the origin of DLGG. Second, the biological pathways involved in DLGG genesis may differ according to tumor location (anatomo-molecular correlations). The cellular and molecular mechanisms of such "molecular theory" will be reviewed. Third, the geographical distribution of diffuse WHO grade II-III gliomas within populations is heterogeneous, suggesting possible environmental risk factors. We will discuss this "environmental theory". Finally, we will summarize the current knowledge on genetic susceptibility in gliomas ("genetic predisposition theory"). These crucial issues illustrate the close relationships between the pathophysiology of gliomagenesis, the anatomo-functional organization of the brain, and personalized management of DLGG patients.

Awake surgery for hemispheric low-grade gliomas: oncological, functional and methodological differences between pediatric and adult populations

INTRODUCTION

Brain mapping through a direct cortical and subcortical electrical stimulation during an awake craniotomy has gained an increasing popularity as a powerful tool to prevent neurological deficit while increasing extent of resection of hemispheric diffuse low-grade gliomas in adults. However, few case reports or very limited series of awake surgery in children are currently available in the literature.

METHODS

In this paper, we review the oncological and functional differences between pediatric and adult populations, and the methodological specificities that may limit the use of awake mapping in pediatric low-grade glioma surgery.

RESULTS

This could be explained by the fact that pediatric low-grade gliomas have a different epidemiology and biologic behavior in comparison to adults, with pilocytic astrocytomas (WHO grade I glioma) as the most frequent histotype, and with WHO grade II gliomas less prone to anaplastic transformation than their adult counterparts. In addition, aside from the issue of poor collaboration of younger children under 10 years of age, some anatomical and functional peculiarities of children developing brain (cortical and subcortical myelination, maturation of neural networks and of specialized cortical areas) can influence direct electrical stimulation methodology and sensitivity, limiting its use in children.

CONCLUSIONS

Therefore, even though awake procedure with cortical and axonal stimulation mapping can be adapted in a specific subgroup of children with a diffuse glioma from the age of 10 years, only few pediatric patients are nonetheless candidates for awake brain surgery.

CGCG clinical practice guidelines for the management of adult diffuse gliomas

The Chinese Glioma Cooperative Group (CGCG) Guideline Panel for adult diffuse gliomas provided recommendations for diagnostic and therapeutic procedures. The Panel covered all fields of expertise in neuro-oncology, i.e. neurosurgeons, neurologists, neuropathologists, neuroradiologists, radiation and medical oncologists and clinical trial experts. The task made clearer and more transparent choices about outcomes considered most relevant through searching the references considered most relevant and evaluating their value. The scientific evidence of papers collected from the literature was evaluated and graded based on the Oxford Centre for Evidence-based Medicine Levels of Evidence and recommendations were given accordingly. The recommendations will provide a framework and assurance for the strategy of diagnostic and therapeutic measures to reduce complications from unnecessary treatment and cost. The guideline should serve as an application for all professionals involved in the management of patients with adult diffuse glioma and also as a source of knowledge for insurance companies and other institutions involved in the cost regulation of cancer care in China.

Extension of diffuse low-grade gliomas beyond radiological borders as shown by the coregistration of histopathological and magnetic resonance imaging data

OBJECTIVE Magnetic resonance imaging tends to underestimate the extent of diffuse low-grade gliomas (DLGGs). With the aim of studying the presence of tumor cells outside the radiological border, the authors developed a method of correlating MRI findings with histological data in patients with suspected DLGGs in whom en bloc resections were performed. METHODS Five patients with suspected DLGG suitable for en bloc resection were recruited from an ongoing prospective study. Sections of the entire tumor were immunostained with antibodies against mutated IDH1 protein (IDH1-R132H). Magnetic resonance images were coregistered with corresponding IDH1 images. The growth pattern of tumor cells in white and gray matter was assessed in comparison with signal changes on corresponding MRI slices. RESULTS Neuropathological assessment revealed DLGG in 4 patients and progression to WHO Grade III glioma in 1 patient. The tumor core consisted of a high density of IDH1-R132H-positive tumor cells and was located in both gray and white matter. Tumor cells infiltrated along the peripheral fibers of the white matter tracts. In all cases, tumor cells were found outside the radiological tumor border delineated on T2-FLAIR MRI sequences. CONCLUSIONS The authors present a new method for the coregistration of histological and radiological characteristics of en bloc-removed infiltrative brain tumors that discloses tumor invasion at the radiological tumor borders. This technique can be applied to evaluate the sensitivity of alternative imaging methods to detect scattered tumor cells at tumor borders. Accurate methods for detection of infiltrative tumor cells will improve the possibility of performing radical tumor resection. In future studies, the method could also be used for in vivo studies of tumor invasion.