Brain tumors in children

Drug repurposing towards targeting cancer stem cells in pediatric brain tumors

In the pediatric population, brain tumors represent the most commonly diagnosed solid neoplasms and the leading cause of cancer-related deaths globally. They include low-grade gliomas (LGGs), medulloblastomas (MBs), and other embryonal, ependymal, and neuroectodermal tumors. The mainstay of treatment for most brain tumors includes surgical intervention, radiation therapy, and chemotherapy. However, resistance to conventional therapy is widespread, which contributes to the high mortality rates reported and lack of improvement in patient survival despite advancement in therapeutic research. This has been attributed to the presence of a subpopulation of cells, known as cancer stem cells (CSCs), which reside within the tumor bulk and maintain self-renewal and recurrence potential of the tumor. An emerging promising approach that enables identifying novel therapeutic strategies to target CSCs and overcome therapy resistance is drug repurposing or repositioning. This is based on using previously approved drugs with known pharmacokinetic and pharmacodynamic characteristics for indications other than their traditional ones, like cancer. In this review, we provide a synopsis of the drug repurposing methodologies that have been used in pediatric brain tumors, and we argue how this selective compilation of approaches, with a focus on CSC targeting, could elevate drug repurposing to the next level.

EPAC2: A new and promising protein for glioma pathogenesis and therapy

Gliomas are prime brain cancers which are initiated by malignant modification of neural stem cells, progenitor cells and differentiated glial cells such as astrocyte, oligodendrocyte as well as ependymal cells. Exchange proteins directly activated by cAMP (EPACs) are crucial cyclic adenosine 3’,5’-monophosphate (cAMP)-determined signaling pathways. Cyclic AMP-intermediated signaling events were utilized to transduce protein kinase A (PKA) leading to the detection of EPACs or cAMP-guanine exchange factors (cAMP-GEFs). EPACs have been detected as crucial proteins associated with the pathogenesis of neurological disorders as well as numerous human diseases. EPAC proteins have two isoforms. These isoforms are EPAC1 and EPAC2. EPAC2 also known as Rap guanine nucleotide exchange factor 4 (RAPGEF4) is generally expression in all neurites. Higher EAPC2 levels was detected in the cortex, hippocampus as well as striatum of adult mouse brain. Activation as well as over-secretion of EPAC2 triggers apoptosis in neurons and EPAC-triggered apoptosis was intermediated via the modulation of Bcl-2 interacting member protein (BIM). EPAC2 secretory levels has proven to be more in low-grade clinical glioma than high-grade clinical glioma. This review therefore explores the effects of EPAC2/RAPGEF4 on the pathogenesis of glioma instead of EPAC1 because EPAC2 and not EPAC1 is predominately expressed in the brain. Therefore, EPAC2 is most likely to modulate glioma pathogenesis rather than EPAC1.

Provider views on perioperative steroid use for patients with newly diagnosed pediatric brain tumors

PURPOSE

Cerebral edema from brain tumors can cause neurological impairment. Steroids treat edema but with possible adverse effects. We surveyed providers regarding steroid use in newly diagnosed patients with brain tumors to determine if practices are standard or markedly variable.

METHODS

An anonymous voluntary online survey was sent to members of neuro-oncology consortiums. Four clinical scenarios were provided and questions regarding initiation of steroids, type, dose, formulation, and duration were asked. Demographic information was collected.

RESULTS

369 providers received the survey, 76 responded (20.6% response rate). The proportion of providers who would start steroids significantly differed among scenarios (scenario 1 vs 2, p < 0.001; 2 vs 3, p < 0.001; 1 vs 3, p < 0.001). 75 (98.7%) providers would start steroids for vasogenic edema (scenario 1) and 55 (72.4%) for obstructive hydrocephalus (scenario 2). 16 (21.1%) would start steroids for vasogenic edema but not obstructive hydrocephalus. The odds of choosing to start steroids in patients with obstructive hydrocephalus were 7.59 times more (95% CI: 2.29, 25.13) if providers felt symptoms would improve within 24 h. All would use dexamethasone. A significant difference was seen between the proportion of providers who would give a loading dose if vasogenic edema with neurological deficits were noted versus vasogenic edema alone (57.9% vs 43.4%; p = 0.002).

CONCLUSIONS

These results suggest that providers recommend dexamethasone for patients with vasogenic edema and obstructive hydrocephalus. Variability remains with dosing schedule. Further studies are needed to identify the most appropriate use of steroids for newly diagnosed CNS tumor patients with the goal to create steroid management guidelines.

Extraordinary case presentations in pediatric pituitary adenoma: report of 6 cases

Pediatric pituitary adenomas (PPAs) are rare neoplasms with a propensity for unusual presentations and an aggressive clinical course. Here, the authors describe 6 highly atypical PPAs to highlight this tendency and discuss unexpected management challenges.A 14-year-old girl presented with acute hemiparesis and aphasia. MRI revealed a pituitary macroadenoma causing internal carotid artery invasion/obliteration without acute apoplexy, which was treated via emergent transsphenoidal resection (TSR). Another 14-year-old girl developed precocious galactorrhea due to macroprolactinoma, which was medically managed. Several years later, she re-presented with acute, severe, bitemporal hemianopia during her third trimester of pregnancy, requiring emergent induction of labor followed by TSR. A 13-year-old boy was incidentally diagnosed with a prolactinoma after routine orthodontic radiographs captured a subtly abnormal sella. An 18-year-old male self-diagnosed pituitary gigantism through a school report on pituitary disease. A 17-year-old boy was diagnosed with Cushing disease by his basketball coach, a former endocrinologist. A 12-year-old girl with growth arrest and weight gain was diagnosed with Cushing disease, which was initially treated via TSR but subsequently recurred and ultimately required 12 operations, 5 radiation treatments involving 3 modalities, bilateral adrenalectomy, and chemotherapy. Despite these efforts, she ultimately died from pituitary carcinoma.

Functional Outcomes of Cerebellar Malformations

The cerebellum is well-established as a primary center for controlling sensorimotor functions. However, recent experiments have demonstrated additional roles for the cerebellum in higher-order cognitive functions such as language, emotion, reward, social behavior, and working memory. Based on the diversity of behaviors that it can influence, it is therefore not surprising that cerebellar dysfunction is linked to motor diseases such as ataxia, dystonia, tremor, and Parkinson's disease as well to non-motor disorders including autism spectrum disorders (ASD), schizophrenia, depression, and anxiety. Regardless of the condition, there is a growing consensus that developmental disturbances of the cerebellum may be a central culprit in triggering a number of distinct pathophysiological processes. Here, we consider how cerebellar malformations and neuronal circuit wiring impact brain function and behavior during development. We use the cerebellum as a model to discuss the expanding view that local integrated brain circuits function within the context of distributed global networks to communicate the computations that drive complex behavior. We highlight growing concerns that neurological and neuropsychiatric diseases with severe behavioral outcomes originate from developmental insults to the cerebellum.

Pediatric Brain Tumors

Pediatric central nervous system (CNS) tumors are the most common solid tumors in children and comprise 15% to 20% of all malignancies in children. Presentation, symptoms, and signs depend on tumor location and age of the patient at the time of diagnosis. This article summarizes the common childhood CNS tumors, presentations, classification, and recent updates in treatment approaches due to the increased understanding of the molecular pathogenesis of pediatric brain tumors.

Intravoxel Incoherent Motion MR Imaging of Pediatric Intracranial Tumors: Correlation with Histology and Diagnostic Utility

BACKGROUND AND PURPOSE

Intravoxel incoherent motion imaging, which simultaneously measures diffusion and perfusion parameters, is promising for brain tumor grading. However, intravoxel incoherent motion imaging has not been tested in children. The purpose of this study was to evaluate the correlation between intravoxel incoherent motion parameters and histology to assess the accuracy of intravoxel incoherent motion imaging for pediatric intracranial tumor grading.

MATERIALS AND METHODS

Between April 2013 and September 2015, 17 children (11 boys, 6 girls; 2 months to 15 years of age) with intracranial tumors were included in this retrospective study. Intravoxel incoherent motion parameters were fitted using 13 b-values for a biexponential model. The perfusion-free diffusion coefficient, pseudodiffusion coefficient, and perfusion fraction were measured in high- and low-grade tumors. These intravoxel incoherent motion parameters and the ADC were compared using the unpaired t test. The correlations between the intravoxel incoherent motion parameters and microvessel density or the MIB-1 index were analyzed using the Spearman correlation test. Receiver operating characteristic analysis was used to evaluate diagnostic performance.

RESULTS

The perfusion-free diffusion coefficient and ADC were lower in high-grade than in low-grade tumors (perfusion-free diffusion coefficient, 0.85 ± 0.40 versus 1.53 ± 0.21 × 10^-3 mm²/s, P < .001; ADC, 1.04 ± 0.33 versus 1.60 ± 0.21 × 10^-3 mm²/s, P < .001). The pseudodiffusion coefficient showed no difference between the groups. The perfusion fraction was higher in high-grade than in low-grade tumors (21.7 ± 8.2% versus 7.6 ± 4.3%, P < .001). Receiver operating characteristic analysis found that the combined perfusion-free diffusion coefficient and perfusion fraction had the best diagnostic performance for tumor differentiation (area under the curve = 0.986).

CONCLUSIONS

Intravoxel incoherent motion imaging reflects tumor histology and may be a helpful, noninvasive method for pediatric intracranial tumor grading.

Prone versus sitting position in pediatric low-grade posterior fossa tumors

PURPOSE

The choice between sitting and prone position to access the infratentorial space in a suboccipital craniotomy is still a matter of debate. The comparisons in terms of complications and outcome of both positions are scarce, and the pediatric population is indeed more infrequent in these in scientific reviews. In this paper, we assess intraoperative and postoperative complications and neurological outcome in pediatric patients undergoing posterior cranial fossa surgery for pilocytic astrocytoma in sitting and prone position respectively.

METHODS

We retrospectively analyzed 30 consecutive patients undergoing surgery for cerebellar pilocytic astrocytoma at the two neurosurgical units referring to the University of Padova Medical School from 1999 to 2017. Preoperative, intraoperative, and postoperative data were retrieved from our medical archives.

RESULTS

The statistical analysis did not show any differences between the two groups in terms of preoperative, intraoperative, and postoperative data. The neurological status at last follow-up was similar in both groups of patients.

CONCLUSIONS

Our results suggest that both sitting and prone position can be considered safe in suboccipital craniotomies. Further studies are needed to show if there are possible differences between these positions for other frequent pediatric tumors such as medulloblastomas and ependymomas.

Phase I trial of convection-enhanced delivery of IL13-Pseudomonas toxin in children with diffuse intrinsic pontine glioma

OBJECTIVE In this clinical trial report, the authors analyze safety and infusion distribution of IL13-Pseudomonas exotoxin, an antitumor chimeric molecule, administered via intratumoral convection enhanced delivery (CED) in pediatric patients with diffuse intrinsic pontine glioma (DIPG). METHODS This was a Phase I single-institution, open-label, dose-escalation, safety and tolerability study of IL13-PE38QQR infused via single-catheter CED into 5 pediatric DIPG patients. IL13-PE38QQR was administered to regions of tumor selected by radiographic findings. Two escalating dose levels were evaluated: 0.125 µg/mL in cohort 1 and 0.25 µg/mL in cohort 2. Real-time MRI was performed during intratumoral infusions, and MRI and MR spectroscopy were performed before and after the infusions. Clinical evaluations, including parent-reported quality of life (QOL), were assessed at baseline and 4 weeks post-infusion. RESULTS Direct infusion of brainstem tumor with IL13-PE using the CED technique in patients with DIPG produced temporary arrest of disease progression in 2 of 5 patients, both of whom subsequently received a second infusion. All 5 patients showed signs of disease progression by 12 weeks after initial infusion. Two patients experienced transient cranial nerve deficits and lethargy after infusion, and these deficits resolved with corticosteroid treatment in both cases. No patient had radiographic evidence of acute or long-term treatment toxicity. Parent-reported QOL was consistent with medical outcomes. CONCLUSIONS Even though IL13-PE delivered by CED did not reach the entire MRI-defined tumor volume in any patient, short-term radiographic antitumor effects were observed in 2 of the 5 patients treated. The patients’ performance status did not improve. Drug delivery using multiple catheters may produce improved outcomes. Clinical trial registration no.: NCT00088061 (clinicaltrials.gov) ABBREVIATIONS CED = convection-enhanced delivery; DIPG = diffuse intrinsic pontine glioma; IL-13 = interleukin 13; IL13R = IL-13 receptor; IPI = Impact of Pediatric Illness; KPS = Karnofsky Performance Status; LPS = Lansky Performance Status; MRS = MR spectroscopy; NAA = n-acetyl aspartate; QOL = quality of life; Vd = volume of distribution; Vi = volume of infusion.

Childhood brain tumors: current management, biological insights, and future directions

Brain tumors are the most common solid tumors in children, and, unfortunately, many subtypes continue to have a suboptimal long-term outcome. During the last several years, however, remarkable advances in our understanding of the molecular underpinnings of these tumors have occurred as a result of high-resolution genomic, epigenetic, and transcriptomic profiling, which have provided insights for improved tumor categorization and molecularly directed therapies. While tumors such as medulloblastomas have been historically grouped into standard- and high-risk categories, it is now recognized that these tumors encompass four or more molecular subsets with distinct clinical and molecular characteristics. Likewise, high-grade glioma, which for decades was considered a single high-risk entity, is now known to comprise multiple subsets of tumors that differ in terms of patient age, tumor location, and prognosis. The situation is even more complex for ependymoma, for which at least nine subsets of tumors have been described. Conversely, the majority of pilocytic astrocytomas appear to result from genetic changes that alter a single, therapeutically targetable molecular pathway. Accordingly, the present era is one in which treatment is evolving from the historical standard of radiation and conventional chemotherapy to a more nuanced approach in which these modalities are applied in a risk-adapted framework and molecularly targeted therapies are implemented to augment or, in some cases, replace conventional therapy. Herein, the authors review advances in the categorization and treatment of several of the more common pediatric brain tumors and discuss current and future directions in tumor management that hold significant promise for patients with these challenging tumors.

Arterial spin labelling and diffusion-weighted imaging in paediatric brain tumours

BACKGROUND

Diffusion- and perfusion-weighted MRI are valuable tools for measuring the cellular and vascular properties of brain tumours. This has been well studied in adult patients, however, the biological features of childhood brain tumours are unique, and paediatric-focused studies are less common. We aimed to assess the diagnostic utility of apparent diffusion coefficient (ADC) values derived from diffusion-weighted imaging (DWI) and cerebral blood flow (CBF) values derived from arterial spin labelling (ASL) in paediatric brain tumours.

METHODS

We performed a meta-analysis of published studies reporting ADC and ASL-derived CBF values in paediatric brain tumours. Data were combined using a random effects model in order to define typical parameter ranges for different histological tumour subtypes and WHO grades. New data were also acquired in a 'validation cohort' at our institution, in which ADC and CBF values in treatment naïve paediatric brain tumour patients were measured, in order to test the validity of the findings from the literature in an un-seen cohort. ADC and CBF quantification was performed by two radiologists via manual placement of tumour regions of interest (ROIs), in addition to an automated approach to tumour ROI placement.

RESULTS

A total of 14 studies met the inclusion criteria for the meta-analysis, constituting data acquired in 542 paediatric patients. Parameters of interest were based on measurements from ROIs placed within the tumour, including mean and minimum ADC values (ADC_ROI-mean, ADC_ROI-min) and the maximum CBF value normalised to grey matter (nCBF_ROI-max). After combination of the literature data, a number of histological tumour subtype groups showed significant differences in ADC values, which were confirmed, where possible, in our validation cohort of 32 patients. In both the meta-analysis and our cohort, diffuse midline glioma was found to be an outlier among high-grade tumour subtypes, with ADC and CBF values more similar to the low-grade tumours. After grouping patients by WHO grade, significant differences in grade groups were found in ADC_ROI-mean, ADC_ROI-min, and nCBF_ROI-max, in both the meta-analysis and our validation cohort. After excluding diffuse midline glioma, optimum thresholds (derived from ROC analysis) for separating low/high-grade tumours were 0.95 × 10^-3 mm²/s (ADC_ROI-mean), 0.82 × 10^-3 mm²/s (ADC_ROI-min) and 1.45 (nCBF_ROI-max). These thresholds were able to identify low/high-grade tumours with 96%, 83%, and 83% accuracy respectively in our validation cohort, and agreed well with the results from the meta-analysis. Diagnostic power was improved by combining ADC and CBF measurements from the same tumour, after which 100% of tumours in our cohort were correctly classified as either low- or high-grade (excluding diffuse midline glioma).

CONCLUSION

ADC and CBF values are useful for differentiating certain histological subtypes, and separating low- and high-grade paediatric brain tumours. The threshold values presented here are in agreement with previously published studies, as well as a new patient cohort. If ADC and CBF values acquired in the same tumour are combined, the diagnostic accuracy is optimised.

Differential diagnosis of posterior fossa tumours in children: new insights

Central nervous system neoplasms are the most common solid tumours that develop in children, with the greatest proportion located in the infratentorium. The 2016 World Health Organization Central Nervous System tumour classification evolved from the 2007 edition with the integration of molecular and genetic profiling into the diagnosis, the addition of new entities and the removal of others. Radiology can assist with the subtyping of tumours from certain characteristics described below to provide prognostic information and guide further management. The latest insights into the radiologic characteristics of these posterior fossa tumours are presented below: medulloblastoma, ependymoma, pilocytic astrocytoma, embryonal tumours with multilayered rosettes, atypical teratoid rhabdoid tumours, diffuse midline glioma and the new entity of diffuse leptomeningeal glioneuronal tumours.

Early changes in white matter predict intellectual outcome in children treated for posterior fossa tumors

Purpose

Prospective and longitudinal neuroimaging studies of posterior fossa tumors are scarce. Here we evaluate the early changes in white matter and intellectual outcome up to 3 years after diagnosis.

Patients and methods

Twenty-two children with posterior fossa tumors and 24 similarly-aged healthy children participated. Patients included: (a) 12 individuals who received surgery, cranial-spinal radiation (CSR), and focal radiation to the tumor bed (CSR group) and (b) 10 individuals who received local therapy, either surgery only or surgery and focal radiation to the tumor bed (Local group). Diffusion tensor imaging (DTI) and intelligence measures were obtained an average of 3 months after diagnosis and then at 12, 24, and 36 months later. DTI tractography and voxel-wise approaches were employed. The Neurological Predictor Scale was used to summarize the type and amount of treatment for PF tumor patients. Linear mixed modelling was used to evaluate group differences at baseline and changes over time in DTI metrics for both the specific white matter tracts and voxel-wise, as well as for intelligence measures.

Results

Based on tractography, patients treated with CSR had significantly higher Axial and Mean diffusivity in the cortical-spinal tracts (CST) 3 month after diagnosis – particularly on the right side, p < .003, compared to healthy children. Mean diffusivity in right CST decreased over time in this group of patients, p = .001. No differences compared to controls were evident in specific tracts for the Local group, p > .10. Voxel-wise analyses revealed multiple areas of white matter compromise in both patients groups. Notably, both patient groups had lower scores on intelligence measures compared to the Control group: The CSR group displayed lower performance 3 months following diagnosis, ps < 0.001, and their performance remained stable over time ps > 0.10, whereas the Local group displayed no differences at 3 months, ps> 0.10, but their performance declined over time, ps < 0.01. At baseline, higher MD in right CST predicted lower Perceptual Reasoning scores across all participants, p = .001. Furthermore, lower FA in left IFOF at baseline predicted decline in Processing Speed over time, p = .001. In patients, more aggressive treatment protocols and presence of mutism were related to lower performance on intelligence measures at baseline, ps < 0.04.

Conclusions

Children treated with CSR displayed diffuse white matter compromise and poor intellectual outcome shortly after radiation treatment. There was evidence of subsequent growth of white matter structure, but stable intellectual insult. Conversely, in children treated with either surgery only or surgery and focal radiation to the tumor bed we observed less compromise of white matter early following treatment and no intellectual insult compared to healthy children. However, declines in intellectual function were evident for these children, though their performance remained within the average normative range. Overall, results suggest that early intervention is necessary to circumvent these deficits.

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There are early deficits to intellect and white matter shortly after treatment

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Early deficits were observed only after cranial-spinal radiation

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Intellectual deficits are generally stable over time

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White matter indices, mutism, and treatment predicted intellectual outcome

The 100 Most-Cited Reports About Craniopharyngioma

OBJECTIVE

Our objective was to identify the 100 most-cited research reports on craniopharyngiomas.

METHODS

The Thomson Reuters Web of Science service was queried for the years 1900 to 2017 without language restrictions. The articles were sorted in descending order of the number of times they had been cited by other studies, and all titles and abstracts were screened to identify the research areas of the top 100 reports. The number of citations per year was calculated.

RESULTS

We identified the 100 most-cited articles on craniopharyngioma, which, collectively, had been cited 20,994 times at the time of our report. The top cited report had been cited 718 times, with an average of 144 citations annually since publication. The oldest article had been published in 1969 and the most recent in 2013; the most prolific decade was the 2000s, with 38 of the included articles published during that period. Thirty-two unique journals contributed to the 100 articles, with the Journal of Neurosurgery contributing most of the articles (n = 31). The most common country of article origin was the United States (n = 49), followed by United Kingdom (n = 12), Germany (n = 10), and Italy (n = 6).

CONCLUSIONS

The present study identified the 100 most-cited research articles in craniopharyngioma. These results highlight the multidisciplinary and multimodal nature of craniopharyngioma management. Recognition of important historical contributions to this field could guide future investigations.

Clinically Integrated Sequencing Alters Therapy in Children and Young Adults With High-Risk Glial Brain Tumors

Purpose

Brain tumors have become the leading cause of cancer-related mortality in young patients. Novel effective therapies on the basis of the unique biology of each tumor are urgently needed. The goal of this study was to evaluate the feasibility, utility, and clinical impact of integrative clinical sequencing and genetic counseling in children and young adults with high-risk brain tumors.

Patients and Methods

Fifty-two children and young adults with brain tumors designated by the treating neuro-oncologist to be high risk (> 25% chance for treatment failure; mean age, 10.2 years; range, 0 to 39 years) were enrolled in a prospective, observational, consecutive case series, in which participants underwent integrative clinical exome (tumor and germline DNA) and transcriptome (tumor RNA) sequencing and genetic counseling. Results were discussed in a multi-institutional brain tumor precision medicine teleconference.

Results

Sequencing revealed a potentially actionable germline or tumor alteration in 25 (63%) of 40 tumors with adequate tissue, of which 21 (53%) resulted in an impact on treatment or change of diagnosis. Platelet-derived growth factor receptor or fibroblast growth factor receptor pathway alterations were seen in nine of 20 (45%) glial tumors. Eight (20%) sequenced tumors harbored an oncogenic fusion isolated on RNA sequencing. Seventeen of 20 patients (85%) with glial tumors were found to have a potentially actionable result, which resulted in change of therapy in 14 (70%) patients. Patients with recurrent brain tumors receiving targeted therapy had a median progression-free survival (from time on therapy) of 4 months.

Conclusion

Selection of personalized agents for children and young adults with highrisk brain tumors on the basis of integrative clinical sequencing is feasible and resulted in a change in therapy in more than two thirds of children and young adults with high-risk glial tumors.

Probing the neuroanatomy of the cerebellum using tractography

Diffusion tensor imaging (DTI) is a noninvasive neuroimaging tool assessing the organization of white-matter tracts and brain microstructure in vivo. The technique takes into account the three-dimensional (3D) direction of diffusion of water in space, the brownian movements of water being constrained by the brain microstructure. The main direction of diffusion in the brain is extracted to obtain the principal direction of axonal projection within a given voxel. Overall, the diffusion tensor is a mathematic analysis of the magnitude/directionality (anisotropy) of the movement of water molecules in 3D space. Tracts running in the white matter are subsequently reconstructed graphically with fiber tractography. Tractography can be applied to myelinated and unmyelinated fibers or axonopathy. Decreased fractional anisotropy in white-matter tracts occurs in cases of injury with disorganized or disrupted myelin sheaths. Furthermore, high angular resolution methods enable detection of fiber crossings or convergence. DTI is a modern tool which complements conventional magnetic resonance techniques and is particularly relevant to assess the organization of cerebellar tracts. Indeed, both the afferent and efferent pathways of the cerebellar circuitry passing through the inferior, middle, and superior cerebellar peduncles can be visualized in vivo, including in children. The microanatomy of the cerebellar cortex and cerebellar nuclei is also emerging as a future assessment. Applications in the field of cerebellar disorders are multiple, ranging from developmental disorders to adult-onset cerebellar ataxias.

Correlation between arterial spin-labeling perfusion and histopathological vascular density of pediatric intracranial tumors

Traditional MRI methods for estimation of blood flow in brain tumors require high-flow injection of contrast agents through large-bore intravenous access, which limits their pediatric utility. In contrast, arterial spin-labeling (ASL) can be used without contrast media. This study aimed to evaluate the relationship between tumor blood flow (TBF) measured by ASL and histopathological vascular density in pediatric brain tumors. Nineteen consecutive children were evaluated (10 boys, 9 girls; median age: 6 years; 8 high-grade and 11 low-grade tumors). ASL was performed with a pseudocontinuous labeling time of 1650 ms and post-labeling delay of 1525 ms. The maximal absolute (aTBF) and relative (rTBF) tumor blood flows were measured. To evaluate the relative vascular area (%Vessel), the total stained vascular area was divided by the whole tissue area. Spearman's rank-order correlation, the Mann-Whitney U test, and receiver operating characteristic analysis were used for statistical analysis. The absolute and relative TBF rates were 4.9-92.9 mL/100 g/min and 0.17-3.59 mL/100 g/min, respectively. The %Vessel was 0.6-30.2%. The %Vessel showed a significant positive correlation with TBF (aTBF: r = 0.87, P < 0.0001; rTBF: r = 0.89, P < 0.0001). The TBF rate of high-grade tumors was significantly higher than that of low-grade tumors (aTBF: P = 0.0050, rTBF: P = 0.0036). The rTBF had the best diagnostic performance (area under the curve: 0.89). ASL perfusion imaging without contrast material can be used for accurate evaluation of histopathological vascular density and may be helpful for tumor grading in children.

Mining the glioma susceptibility genes in children from gene expression profiles and a methylation database

Glioma is the most common type of primary brain tumor, which is associated with a poor prognosis due to its aggressive growth behavior and highly invasive nature. Research regarding glioma pathogenesis is expected to provide novel methods of adjuvant therapy for the treatment of glioma. The use of bioinformatics to identify candidate genes is commonly used to understand the genetic basis of disease. The present study used bioinformatics to mine the disease-related genes using gene expression profiles (GSE50021) and dual-channel DNA methylation data (GSE50022). The results identified 17 methylation sites located on 33 transcription factor binding sites, which may be responsible for downregulation of 17 target genes. glutamate metabotropic receptor 2 was one of the 17 downregulated target genes. Furthermore, inositol-trisphosphate 3-kinase A (ITPKA) was revealed to be the gene most associated with the risk of glioma in children. The protein coded by the ITPKA gene appeared in all risk sub-pathways, thus suggesting that ITPKA was the gene most associated with the risk of glioma, and inositol phosphate metabolism may be a key pathway associated with glioma in children. The identification of specific genes helps to determine the pathogenesis and possible therapeutic targets for the treatment of glioma in children.

Neuronal correlates of cognitive function in patients with childhood cerebellar tumor lesions

While it has been shown that cerebellar tumor lesions have an impact on cognitive functions, the extent to which they shape distant neuronal pathways is still largely undescribed. Thus, the present neuroimaging study was designed to investigate different aspects of cognitive function and their neuronal correlates in patients after childhood cerebellar tumor surgery. An alertness task, a working memory task and an incompatibility task were performed by 11 patients after childhood cerebellar tumor surgery and 17 healthy controls. Neuronal correlates as reflected by alterations in functional networks during tasks were assessed using group independent component analysis. We were able to identify eight networks involved during task performance: default mode network, precuneus, anterior salience network, executive control network, visual network, auditory and sensorimotor network and a cerebellar network. For the most ‘basic’ cognitive tasks, a weaker task-modulation of default mode network, left executive control network and the cerebellar network was observed in patients compared to controls. Results for higher-order tasks are in line with a partial restoration of networks responsible for higher-order task execution. Our results provide tentative evidence that the synchronicity of brain activity in patients was at least partially restored in the course of neuroplastic reorganization, particularly for networks related to higher-order cognitive processes. The complex activation patterns underline the importance of testing several cognitive functions to assess the specificity of cognitive deficits and neuronal reorganization processes after brain lesions.

Pediatric high-grade glioma: current molecular landscape and therapeutic approaches

High-grade pediatric central nervous system glial tumors are comprised primarily of anaplastic astrocytomas (AA, WHO grade III) and glioblastomas (GBM, WHO grade IV). High-grade gliomas are most commonly diagnosed in the primary setting in children, but as in adults, they can also arise as a result of transformation of a low-grade malignancy, though with limited frequency in the pediatric population. The molecular genetics of high-grade gliomas in the pediatric population are distinct from their adult counterparts. In contrast to the adult population, high-grade gliomas in children are relatively infrequent, representing less than 20% of cases.

Seizures caused by brain tumors in children

PURPOSE

To review the epidemiology, clinical features, and treatment of seizures secondary to pediatric brain tumors.

METHOD

Literature review.

RESULTS

Pediatric brain tumors are the most common solid pediatric tumor and the most common cause of death in pediatric cancer. Seizures are one of the most common symptoms of pediatric brain tumors. Factors associated with increased risk of seizures include supratentorial location, gray matter involvement, low-grade, and certain histological features-especially dysembryoplastic neuroepithelial tumor, ganglioglioma, and oligodendroglioma. Leukemic infiltration of the brain, brain metastases of solid tumors, and brain injury secondary to chemotherapy or radiotherapy can also cause seizures. Mechanisms by which brain tumors cause seizures include metabolic, and neurotransmitter changes in peritumoral brain, morphologic changes - including malformation of cortical development - in peritumoral brain, and presence of peritumoral blood products, gliosis, and necrosis. As there is a high degree of uncertainty on how effective different antiepileptic drugs are for seizures caused by brain tumors, choices are often driven by the interaction and side effect profile. Classic antiepileptic drugs - phenobarbital, phenytoin, or carbamazepine - should be avoided as they may alter the metabolism of chemotherapeutic agents. Newer drugs - valproate, lamotrigine, topiramate, zonisamide, and levetiracetam - may be the preferred option in patients with tumors because of their very limited interaction with chemotherapy.

CONCLUSION

Seizures are a common presentation of pediatric brain tumors, especially in supratentorial tumors with gray matter involvement. Antiepileptic drug therapy is usually driven by the interaction and side effect profile and newer drugs with few interactions are generally preferred.

PET and SPECT studies in children with hemispheric low-grade gliomas

Molecular imaging is playing an increasing role in the pretreatment evaluation of low-grade gliomas. While glucose positron emission tomography (PET) can be helpful to differentiate low-grade from high-grade tumors, PET imaging with amino acid radiotracers has several advantages, such as better differentiation between tumors and non-tumorous lesions, optimized biopsy targeting, and improved detection of tumor recurrence. This review provides a brief overview of single-photon emission computed tomography (SPECT) studies followed by a more detailed review of the clinical applications of glucose and amino acid PET imaging in low-grade hemispheric gliomas. We discuss key differences in the performance of the most commonly utilized PET radiotracers and highlight the advantage of PET/MRI fusion to obtain optimal information about tumor extent, heterogeneity, and metabolism. Recent data also suggest that simultaneous acquisition of PET/MR images and the combination of advanced MRI techniques with quantitative PET can further improve the pretreatment and post-treatment evaluation of pediatric brain tumors.

High Precision Imaging of Microscopic Spread of Glioblastoma with a Targeted Ultrasensitive SERRS Molecular Imaging Probe

The dismal prognosis of patients with malignant brain tumors such as glioblastoma multiforme (GBM) is attributed mostly to their diffuse growth pattern and early microscopic tumor spread to distant regions of the brain. Because the microscopic tumor foci cannot be visualized with current imaging modalities, it remains impossible to direct treatments optimally. Here we explored the ability of integrin-targeted surface-enhanced resonance Raman spectroscopy (SERRS) nanoparticles to depict the true tumor extent in a GBM mouse model that closely mimics the pathology in humans. The recently developed SERRS-nanoparticles have a sensitivity of detection in the femtomolar range. An RGD-peptide-conjugated version for integrin-targeting (RGD-SERRS) was compared directly to its non-targeted RAD-SERRS control in the same mice via Raman multiplexing. Pre-blocking with RGD peptide before injection of RGD-SERRS nanoparticles was used to verify the specificity of integrin-targeting. In contrast to the current belief that the enhanced permeability and retention (EPR) effect results in a baseline uptake of nanoparticles regardless of their surface chemistry, integrin-targeting was shown to be highly specific, with markedly lower accumulation after pre-blocking. While the non-targeted SERRS particles enabled delineation of the main tumor, the RGD-SERRS nanoparticles afforded a major improvement in visualization of the true extent and the diffuse margins of the main tumor. This included the detection of unexpected tumor areas distant to the main tumor, tracks of migrating cells of 2-3 cells in diameter, and even isolated distant tumor cell clusters of less than 5 cells. This Raman spectroscopy-based nanoparticle-imaging technology holds promise to allow high precision visualization of the true extent of malignant brain tumors.

Immune responses and outcome after vaccination with glioma-associated antigen peptides and poly-ICLC in a pilot study for pediatric recurrent low-grade gliomas

BACKGROUND

Low-grade gliomas (LGGs) are the most common brain tumors of childhood. Although surgical resection is curative for well-circumscribed superficial lesions, tumors that are infiltrative or arise from deep structures are therapeutically challenging, and new treatment approaches are needed. Having identified a panel of glioma-associated antigens (GAAs) overexpressed in these tumors, we initiated a pilot trial of vaccinations with peptides for GAA epitopes in human leukocyte antigen-A2+ children with recurrent LGG that had progressed after at least 2 prior regimens.

METHODS

Peptide epitopes for 3 GAAs (EphA2, IL-13Rα2, and survivin) were emulsified in Montanide-ISA-51 and administered subcutaneously adjacent to intramuscular injections of polyinosinic-polycytidylic acid stabilized by lysine and carboxymethylcellulose every 3 weeks for 8 courses, followed by booster vaccines every 6 weeks. Primary endpoints were safety and T-lymphocyte responses against GAA epitopes. Treatment response was evaluated clinically and by MRI.

RESULTS

Fourteen children were enrolled. Other than grade 3 urticaria in one child, no regimen-limiting toxicity was encountered. Vaccination induced immunoreactivity to at least one vaccine-targeted GAA in all 12 evaluable patients: to IL-13Rα2 in 3, EphA2 in 11, and survivin in 3. One child with a metastatic LGG had asymptomatic pseudoprogression noted 6 weeks after starting vaccination, followed by dramatic disease regression with >75% shrinkage of primary tumor and regression of metastatic disease, persisting >57 months. Three other children had sustained partial responses, lasting >10, >31, and >45 months, and one had a transient response.

CONCLUSIONS

GAA peptide vaccination in children with recurrent LGGs is generally well tolerated, with preliminary evidence of immunological and clinical activity.

Risk factors for intraoperative allogeneic blood transfusion during craniotomy for brain tumor removal in children

BACKGROUND

Several clinical and surgical factors can influence the occurrence of allogeneic blood transfusion (ABT) during oncologic neurosurgery.

OBJECTIVES

To identify the potential predictive factors of ABT during craniotomy for the removal of brain tumors in children and the potential impact of intraoperative ABT on early postoperative outcome.

METHODS

A retrospective study was performed in all pediatric patients younger than 18 years who underwent craniotomy for brain tumor removal from December 2009 to December 2012 in our institution. Pre-, intra-, and postoperative data were collected from medical and stored electronic anesthesia records. The predictors of intraoperative ABT were determined using multivariate logistic regression.

RESULTS

A total of 110 patients were included. Twenty-seven patients (25%) received intraoperative ABT with a volume of 16 ± 8 ml·kg(-1) . On multivariate analysis, an age <4 years, a duration of surgery >270 min, and a preoperative hemoglobin <12.2 g·dl(-1) were independently associated with the need for intraoperative ABT. We did not show any significant difference concerning postoperative early outcome and length of stay between the transfused and non-transfused patients except for the duration of postoperative mechanical ventilation that was significantly higher in the transfused group (P = 0.04).

CONCLUSION

In children, craniotomy for brain tumor removal is at risk of intraoperative ABT. An age <4 years, a duration of surgery >270 min, and a preoperative hemoglobin <12.2 g·dl(-1) are the main factors associated with intraoperative ABT during this surgery.

CNS and spinal tumors

Primary CNS tumors consist of a diverse group of neoplasms originating from various cell types in the CNS. Brain tumors are the most common solid malignancy in children under the age of 15 years and the second leading cause of cancer death after leukemia. The most common brain neoplasms in children differ consistently from those in older age groups. Pediatric brain tumors demonstrate distinct patterns of occurrence and biologic behavior according to sex, age, and race. This chapter highlights the imaging features of the most common tumors that affect the child's CNS (brain and spinal cord).

Cucurbitacin-I inhibits Aurora kinase A, Aurora kinase B and survivin, induces defects in cell cycle progression and promotes ABT-737-induced cell death in a caspase-independent manner in malignant human glioma cells

Because STAT signaling is commonly activated in malignant gliomas as a result of constitutive EGFR activation, strategies for inhibiting the EGFR/JAK/STAT cascade are of significant interest. We, therefore, treated a panel of established glioma cell lines, including EGFR overexpressors, and primary cultures derived from patients diagnosed with glioblastoma with the JAK/STAT inhibitor cucurbitacin-I. Treatment with cucurbitacin-I depleted p-STAT3, p-STAT5, p-JAK1 and p-JAK2 levels, inhibited cell proliferation, and induced G2/M accumulation, DNA endoreduplication, and multipolar mitotic spindles. Longer exposure to cucurbitacin-I significantly reduced the number of viable cells and this decrease in viability was associated with cell death, as confirmed by an increase in the subG1 fraction. Our data also demonstrated that cucurbitacin-I strikingly downregulated Aurora kinase A, Aurora kinase B and survivin. We then searched for agents that exhibited a synergistic effect on cell death in combination with cucurbitacin-I. We found that cotreatment with cucurbitacin-I significantly increased Bcl(-)2/Bcl(-)xL family member antagonist ABT-737-induced cell death regardless of EGFR/PTEN/p53 status of malignant human glioma cell lines. Although >50% of the cucurbitacin-I plus ABT-737 treated cells were annexin V and propidium iodide positive, PARP cleavage or caspase activation was not observed. Pretreatment of z-VAD-fmk, a pan caspase inhibitor did not inhibit cell death, suggesting a caspase-independent mechanism of cell death. Genetic inhibition of Aurora kinase A or Aurora kinase B or survivin by RNA interference also sensitized glioma cells to ABT-737, suggesting a link between STAT activation and Aurora kinases in malignant gliomas.

Acquired nystagmus as the initial presenting sign of chiasmal glioma in young children

BACKGROUND/PURPOSE

The aim of the study was to investigate the incidence of nystagmus at diagnosis in children with optic pathway glioma involving the chiasm and hypothalamus.

METHODS

Twenty-two patients with a measurable optic pathway/hypothalamic glioma (without neurofibromatosis-1) were followed in our center from 2001 to 2013. The medical files were retrospectively reviewed for demographic and clinical findings, and the imaging scans, for tumor characteristics.

RESULTS

There were 9 boys and 13 girls of mean age 3.5 ± 4.4 years at diagnosis; 15 were aged <2 years. Tumor size ranged from 10 × 6 mm to 62 × 29 mm. Mean duration of follow-up was 8.3 ± 5.4 years. Nystagmus was detected at diagnosis in 10 children (45%), all <2 years old (66.6% of the younger group); no child older than 2 years presented with nystagmus. Nystagmus, once present, did not resolve and continued throughout follow-up. There were no cases of new onset of nystagmus during follow-up in the children in whom it was not detected at diagnosis. Treatment consisted of partial resection/biopsy with/without shunting (n = 13) and chemotherapy (n = 19) with (n = 2) or without adjuvant radiation. Of the 22 children, 6 had a radiographic response to treatment, 8 remained stable, and 8 (all of whom received chemotherapy) showed disease progression despite treatment.

CONCLUSION

In conclusion, monocular nystagmus is a more common presenting sign of optic pathway/hypothalamic glioma in children <2 years old than previously estimated. Although subtle, nystagmus has a very narrow differential diagnosis, and its presence should raise suspicions of a chiasmal tumor with prompt referral for imaging. The visual prognosis is moderate to poor.

Functional and neuropsychological late outcomes in posterior fossa tumors in children

Tumors of the posterior fossa (PF) account for up to 60 % of all childhood intracranial tumors. Over the last decades, the mortality rate of children with posterior fossa tumors has gradually decreased. While survival has been the primary objective in most reports, quality of survival increasingly appears to be an important indicator of a successful outcome. Children with a PF tumor can sustain damage to the cerebellum and other brain structures from the tumor itself, concomitant hydrocephalus, the consequences of treatment (surgery, chemotherapy, radiotherapy), or a combination of these factors. Together, these contribute to long-term sequelae in physical functioning, neuropsychological late outcomes (including academic outcome, working memory, perception and estimation of time, and selective attention, long-term neuromotor speech deficits, and executive functioning). Long-term quality of life can also be affected by endocrinological complication or the occurrence of secondary tumors. A significant proportion of survivors of PF tumors require long-term special education services and have reduced rates of high school graduation and employment. Interventions to improve neuropsychological functioning in childhood PF tumor survivors include (1) pharmacological interventions (such as methylphenidate, modafinil, or donepezil), (2) cognitive remediation, and (3) home-based computerized cognitive training. In order to achieve the best possible outcome for survivors, and ultimately minimize long-term complications, new interventions must be developed to prevent and ameliorate the neuro-toxic effects experienced by these children.

Histogram Analysis of Diffusion Tensor Imaging Parameters in Pediatric Cerebellar Tumors

BACKGROUND AND PURPOSE

Apparent diffusion coefficient (ADC) values have been shown to assist in differentiating cerebellar pilocytic astrocytomas and medulloblastomas. Previous studies have applied only ADC measurements and calculated the mean/median values. Here we investigated the value of diffusion tensor imaging (DTI) histogram characteristics of the entire tumor for differentiation of cerebellar pilocytic astrocytomas and medulloblastomas.

METHODS

Presurgical DTI data were analyzed with a region of interest (ROI) approach to include the entire tumor. For each tumor, histogram-derived metrics including the 25th percentile, 75th percentile, and skewness were calculated for fractional anisotropy (FA) and mean (MD), axial (AD), and radial (RD) diffusivity. The histogram metrics were used as primary predictors of interest in a logistic regression model. Statistical significance levels were set at p < .01.

RESULTS

The study population included 17 children with pilocytic astrocytoma and 16 with medulloblastoma (mean age, 9.21 ± 5.18 years and 7.66 ± 4.97 years, respectively). Compared to children with medulloblastoma, children with pilocytic astrocytoma showed higher MD (P = .003 and P = .008), AD (P = .004 and P = .007), and RD (P = .003 and P = .009) values for the 25th and 75th percentile. In addition, histogram skewness showed statistically significant differences for MD between low- and high-grade tumors (P = .008).

CONCLUSIONS

The 25th percentile for MD yields the best results for the presurgical differentiation between pediatric cerebellar pilocytic astrocytomas and medulloblastomas. The analysis of other DTI metrics does not provide additional diagnostic value. Our study confirms the diagnostic value of the quantitative histogram analysis of DTI data in pediatric neuro-oncology.

The impact of age and race on longevity in pediatric astrocytic tumors: A population-based study

OBJECTIVE

Despite improvements in pediatric brain tumor outcomes, the survivors of childhood brain tumor are burdened by multiple comorbidities. This work reports on the relative survival ratios and excess mortality rate in children with astrocytic tumors over the past four decades.

METHODS

Survival analysis was conducted using flexible parametric model to estimate relative survival and excess mortality rate for non-white and white children (0-19 years old) using the Surveillance, Epidemiology & End Results (SEER) database. We incorporated age group and year of diagnosis into the model to estimate these indices for the period of 1973-2010.

RESULTS

Progressive decline in relative survival ratios was noted over time. Non-white children had lower survival rates than white children, and these survival patterns persisted over the four-decade span of the study. Fifty percent of non-white survivors were deceased 30 years post diagnosis, compared to 35 years in white survivors.

CONCLUSIONS

Survivors of childhood brain tumors have progressively lower survival rates as they get older, and this is higher in non-white when compared to white children. Future research efforts need to focus on understanding the factors mediating the effect of the tumor or its treatment on survival in these patients, and the ethnic variations that derive these survival trends.

Clinical outcome and molecular characterization of pediatric glioblastoma treated with postoperative radiotherapy with concurrent and adjuvant temozolomide: a single institutional study of 66 children

Background

Glioblastoma (GBM) in children is rare. Pediatric GBM have a distinct molecular profile as compared to adult GBM. There are relatively few studies of pediatric GBMs and no standard of care on adjuvant therapy. We aimed to evaluate the clinical outcome and molecular profile of pediatric GBM.

Methods and Materials

Between 2004 and 2013, 66 consecutive children with histologically proven GBM were identified from our database. The majority of the children underwent maximal safe resection followed by focal radiotherapy with concurrent and adjuvant temozolomide. Immunohistochemical staining was performed for p53, MIB-1 labeling index, MGMT overexpression, and EGFR amplification and isocitrate dehydrogenase (IDH1) R132H point mutation. Survival and impact of possible prognostic factors on outcomes were analyzed.

Result

Median survival was 15 months. The overall survival rate at 1 year was 62%, at 2 years was 30%, and at 3 years was 27%. Patients with thalamic tumors (P < .001), incompletely resected tumors (P < .00001), and tumors with MIB-1 labeling index >25% (P < .002) had poor overall survival rates. p53 was overexpressed in 74% of patients, MGMT promoter methylation was seen in 37% of patients, IDH1 mutation was seen in 4% of patients, and no patients had EGFR amplification. MGMT methylation and p53 overexpression did not impact survival.

Conclusions

Clinical outcome of pediatric GBM is similar to that reported for adult GBM. The frequency of p53 overexpression is higher than in adult GBM, while MGMT methylation, IDH1 mutations and EGFR amplification is lower than in adult GBM. MGMT methylation and p53 expression status do not have any prognostic significance.

Cerebral white matter fractional anisotropy and tract volume as measured by MR imaging are associated with impaired cognitive and motor function in pediatric posterior fossa tumor survivors

BACKGROUND

Disease and therapy cause brain damage and subsequent functional loss in pediatric patients with posterior fossa tumors. Treatment-related toxicity factors are resection in patients with pilocytic astrocytoma (PA) and, additionally, cranio-spinal irradiation together with chemotherapy in patients with medulloblastoma (MB). We tested whether damage to white matter (WM) as revealed by diffusion tensor MR imaging (DTI) correlated with specific cognitive and motor impairments in survivors of pediatric posterior fossa tumors.

PROCEDURES

Eighteen MB (mean age ± SD, 15.2 ± 4.9 y) and 14 PA (12.6 ± 5.0 y) survivors were investigated with DTI on a 3-Tesla-MR system. We identified fractional anisotropy (FA) of WM, the volume ratio of WM to gray matter and cerebrospinal fluid (WM/GM + CSF), and volume of specific frontocerebellar tracts. Ataxia was assessed using the International Cooperative Ataxia Rating Scale (ICARS), while the Wechsler Intelligence Scale for Children determined full-scale intelligence quotients (FSIQ). Amsterdam Neuropsychological Tasks (ANT) was used to assess processing speed. Handwriting automation was analyzed using a digitizing graphic tablet.

RESULTS

The WM/GM + CSF ratio correlated significantly with cognitive measures (IQ, P = 0.002; ANT baseline speed, P = 0.04; ANT shifting attention, P = 0.004). FA of skeletonized tracts correlated significantly with FSIQ (P = 0.008), ANT baseline speed (P = 0.028) and ANT shifting attention (P = 0.045). Moreover, frontocerebellar tract volumes correlated with both the FSIQ (P = 0.011) and ICARS (P = 0.007).

CONCLUSION

DTI provides a method for quantification of WM damage by tumor and by therapy-associated effects in survivors of pediatric posterior fossa tumors. DTI-derived WM integrity may be a representative marker for cognitive and motor deterioration.

Profile of a Malignant Brain Tumour in Jamaica: An Eight-year Review, 2005 to 2012

OBJECTIVE

Glioblastoma multiforme (GBM) is the most malignant and most common primary brain tumour worldwide. This study was undertaken to investigate the demographics of this tumour in Jamaica as there is to date no such published data. Data from the recently started Intracranial Tumour Registry (ITR) at the University Hospital of the West Indies was used.

METHODS

All cases of GBM entered into the ITR between 2005 and 2012 were gathered. Of these, only patients with pathologically proven diagnoses were entered into the study. Demographic data, including age and gender, were recorded. The distribution of the tumours by anatomic location was also documented.

RESULTS

Of the 602 patients entered into the ITR up to that time, 42 were found to have histologically proven GBM with a male to female ratio of 2.2:1. There was an age range of 8-92 years with a mean age of diagnosis of 48 years. The majority of the tumours (66.7%) occurred in the left cerebral hemisphere with the most common lobe being the temporal lobe. Two patients (4.8%) had lesions spanning both hemispheres.

CONCLUSIONS

This preliminary study reveals that there is a similar gender distribution of GBM within our population compared with the rest of the world. It, however, revealed that the mean age of diagnosis in our population (48 years) is lower than that quoted in the worldwide literature (53 to 64 years). One possible explanation for this is the possibility that many of our GBMs are actually secondary tumours which are thought to arise from less malignant, undiagnosed precursors. The percentage of GBMs occurring in the paediatric population was similar to the rest of the world.

Anesthesia for intracranial surgery in infants and children

PURPOSE OF REVIEW

Age-related differences in the surgical lesions, anatomy and physiological responses to surgery and anesthesia underlie the clinically relevant differences between pediatric patients and their adult counterparts. Anesthesiologists need to be aware of the unique challenges in the anesthetic management of the pediatric neurosurgical patient.

RECENT FINDINGS

Neurosurgeons with subspecialty training in pediatrics have driven advances in intracranial surgery in infants and children. Subspecialization in pediatric neurosurgery and critical care has resulted in more favorable outcomes. Innovations in tumor, epilepsy and endoscopic and cerebrovascular neurosurgery are constantly being adapted to the pediatric patient. The highly specialized nature of these and other pediatric neurosurgical procedures prompt calls for similarly trained anesthesiologists for management of these infants and children.

SUMMARY

The aim of this review is to highlight the impact of these techniques on the intraoperative management of the pediatric neurosurgical patient. These issues are essential in minimizing perioperative morbidity and mortality.

A pilot study using carboplatin, vincristine, and temozolomide in children with progressive/symptomatic low-grade glioma: a Children's Oncology Group study†

BACKGROUND

This study was initiated to test the feasibility and toxicity of a regimen that alternates the administration of weekly carboplatin and vincristine with temozolomide in the management of children with progressive and/or symptomatic low-grade glioma.

METHODS

Eligible children received a 10-week induction regimen followed by six 10-week cycles of maintenance chemotherapy. Feasibility was evaluated with short-term and long-term endpoints. Short-term feasibility was evaluated by the ability to complete induction and 1 maintenance cycle in 24 weeks without >25% reduction in either carboplatin or temozolomide. Long-term feasibility was evaluated by the ability to administer induction and 4 maintenance cycles within 60 weeks without >25% reduction in either carboplatin or temozolomide. Efficacy was assessed by response to initial chemotherapy and 5-year event-free survival. Initial pathology was reviewed centrally.

RESULTS

Sixty-six patients were enrolled on the study. It was feasible to deliver the regimen, and toxicity was acceptable. The only significant toxicities were hematologic. Both the short-term and long-term feasibility endpoints were met. The short-term feasibility success rate was 87% (95% CI: 77%-96%) and the long-term feasibility success rate was 79% (95% CI: 68%-90%). The 5-year event-free survival was 46% (95% CI: 33%-58%) and the 5-year survival was 87% (95% CI: 75%-93%).

CONCLUSION

It was feasible to deliver the combination of weekly carboplatin and vincristine alternating with temozolomide to children with progressive/symptomatic low-grade glioma with acceptable toxicities. This combination appears to be effective in delaying progression. Further trials are needed to establish the relative efficacy of this regimen compared with other regimens in use.

Overexpression of N-myc downstream-regulated gene 1 inhibits human glioma proliferation and invasion via phosphoinositide 3-kinase/AKT pathways

N-myc downstream-regulated gene 1 (NDRG1) was previously shown to exhibit low expression in glioma tissue as compared with that in normal brain tissue; however, the role of NDRG1 in human glioma cells has remained to be elucidated. The present study used the U87 MG and SHG-44 human glioma cell lines as well as the normal human astrocyte cell line 1800, which are known to have differential NDRG1 expression. Small interfering (si)RNA targeting NDRG1, and NDRG1 overexpression vectors were transfected into the SHG-44 and U87 MG glioma cells, respectively. Cell proliferation, invasion, apoptosis and cell cycle arrest were subsequently examined by MTT assay, transwell chamber assay, flow cytometry and western blot analysis, respectively. Furthermore, a subcutaneous tumor mouse model was used to investigate the effects of NDRG1 on the growth of glioma cells in vivo. Overexpression of NDRG1 was shown to inhibit cell proliferation and invasion, and induce apoptosis in the U87 MG glioma cells, whereas NDRG1 downregulation increased proliferation, suppressed apoptosis and promoted invasion of the SHG-44 glioma cells. In addition, in the subcutaneous tumor mouse model, overexpression of NDRG1 in U-87 MG cells suppressed tumorigenicity in vivo. The findings of the present study indicated that NDRG1 is required for the inhibition of gliomagenesis; therefore, targeting NDRG1 and its downstream targets may represent novel therapies for the treatment of glioma.

Tumor volumetric measurements in surgically inaccessible pediatric low-grade glioma

Tumor measurement is important in unresectable pediatric low-grade gliomas (pLGGs) to determine either the need for treatment or assess response. Standard methods measure the product of the largest 2 lengths from transverse, anterior-posterior, and cranio-caudal dimensions (SM, cm). This single-institution study evaluated tumor volume measurements (VM, cm) in such pLGGs. Of 50 patients treated with chemotherapy for surgically inaccessible pLGG, 8 met the inclusion criteria of having 2 or more sequential MRI studies of T1-weighted Fast-Spoiled Gradient Recalled acquisition. SM and VM were performed by 2 independent neuroradiologists. Associations of measurement methods with defined therapeutic response criteria and patient clinical status were assessed. The mean tumor size at the first MRI scan was 20 cm and 398 cm according to SM and VM, respectively. VM results did not differ significantly from SM-derived spherical volume calculations (Pearson correlation, P<0.0001) with a high interrater reliability. Both methods were concordant in defining the tumor response according to the current criteria, although radiologic progressive disease was not associated with clinical status (SM: P=0.491, VM: P=0.208). In this limited experience, volumetric analysis of unresectable pLGGs did not seem superior to the standard linear measurements for defining tumor response.

Pituitary Adenomas: Presentations and Outcomes in a South Asian Country

Objective:

: The purpose of this retrospective review of all operated cases of pituitary adenomas in the last decade, is to define the demographic patterns and characteristics of such tumors and to assess surgical outcomes with regards to safety and efficacy of trans–sphenoidal tumor removal in our institution.

Methods:

Surgically treated pituitary adenomas presenting from 1995 till 2005 were reviewed for different variables. Results were expressed as mean, standard deviation and median for continuous and number with percentage for categorical data. Chi square test was applied to measure differences and significance was taken at p value < 0.05.

Results:

One hundred and twenty–five patients were operated for pituitary adenoma. Sixty–three percent were male and mean age was 37 years. Sixty percent of the patients presented with headache and/or visual symptoms. Twelve percent presented with pituitary apoplexy and 28% presented with symptoms due to pituitary hyperfunction. Fifty–five percent of patients had functioning and 44% had nonfunctioning adenomas. Mean pre operative tumor diameter from 86 pre op MRI scans was 26.76 mm (3–78 mm). Eighty–four percent of patients underwent trans–sphenoidal tumor resection and three percent had craniotomy. Mean size of post op residual tumor as calculated from 76 available post operative scans was 5.3 mm (range 0–31 mm). 17.6% of the patients required hormone replacement beyond three months and 10% were re–operated. Overall mortality was 1.6%.

Conclusion:

In Pakistan, patients are more likely to present either with apoplexy or with a giant pituitary adenoma than patients reported from developed countries. Overall, our results have been satisfactory and comparable with the literature.

Postoperative Surveillance Magnetic Resonance Imaging for Cerebellar Astrocytoma

Introduction:

Patients with low grade astrocytomas generally have good prognosis when total resection can be achieved, but surveillance neuroimaging is commonly performed to detect recurrence or progression. This study evaluated the utility and yield of such strategy for pilocytic and non-pilocytic cerebellar astrocytomas.

Methods:

A 20-year retrospective review was performed of patients undergoing resection of cerebellar astrocytoma at a single institution. A negative MRI string (NMS) ratio was computed as the fraction of total follow-up period over which surveillance neuroimaging was negative for recurrence or progression. Chi-squared analysis differentiated NMS ratio by resection extent and lesion histopathology.

Results:

Twenty-eight patients with pilocytic (n=15) and non-pilocytic (n=13) astrocytoma underwent 34 craniotomies, with total resection in 19 cases. Surveillance MRIs (n=167) among total resection patients were uniformly negative for recurrent disease at average seven years follow-up (NMS ratio = 1.0). The 43 surveillance MRIs among subtotal resection patients revealed disease progression in two patients within six months of operation (NMS ratio = 0.78, p<0.05). No differences in NMS ratio were observed between pilocytic and non-pilocytic astrocytoma subtypes.

Discussion:

This study illustrates pediatric patients with low-grade cerebellar astrocytomas undergoing total resection may not benefit from routine surveillance neuroimaging, primarily because of low recurrence likelihood. Patients with subtotal resection may benefit from surveillance of residual disease, with further work aimed at exploring the schedule of such follow-up.

Guiding brain tumor resection using surface-enhanced Raman scattering nanoparticles and a hand-held Raman scanner

The current difficulty in visualizing the true extent of malignant brain tumors during surgical resection represents one of the major reasons for the poor prognosis of brain tumor patients. Here, we evaluated the ability of a hand-held Raman scanner, guided by surface-enhanced Raman scattering (SERS) nanoparticles, to identify the microscopic tumor extent in a genetically engineered RCAS/tv-a glioblastoma mouse model. In a simulated intraoperative scenario, we tested both a static Raman imaging device and a mobile, hand-held Raman scanner. We show that SERS image-guided resection is more accurate than resection using white light visualization alone. Both methods complemented each other, and correlation with histology showed that SERS nanoparticles accurately outlined the extent of the tumors. Importantly, the hand-held Raman probe not only allowed near real-time scanning, but also detected additional microscopic foci of cancer in the resection bed that were not seen on static SERS images and would otherwise have been missed. This technology has a strong potential for clinical translation because it uses inert gold-silica SERS nanoparticles and a hand-held Raman scanner that can guide brain tumor resection in the operating room.