Pediatric Posterior Fossa Tumors Research Articles

Measuring the impact of treatment on memory functions in pediatric posterior fossa tumor survivors using diffusion tensor imaging

Background and purposeThe aim of the present prospective exploratory study was to investigate the long-term impact of treatment on brain structure integrity and memory functions in pediatric posterior fossa tumor (PFT) survivors using diffusion tensor imaging (DTI), to determine whether the latter could provide useful biomarkers of memory impairment. Material and MethodsSixty participants were included in this study, divided into three groups: 22 irradiated PFT, 17 non-irradiated PFT, and 21 healthy controls. All underwent memory tests and multimodal MRI, including a DTI sequence. Mean diffusivity and fractional anisotropy values were extracted for bilateral brain structures involved in memory, in order to carry out between-group comparisons and calculate correlations with memory test scores and radiotherapy doses. Statistical tests were two-sided, and p values < 0.05 were considered statistically significant. ResultsDTI metrics were significantly higher for irradiated PFT survivors than in non-irradiated PFT survivors and controls (p < 0.05). Memory test scores were significantly lower for PFT survivors, particularly irradiated patients (p < 0.02), and were correlated with DTI metrics.(−0.27 < r < -0.62, p < 0.04). DTI metrics were correlated with either total or maximum dose for some structures. ConclusionPreliminary results of this study point to microstructural damage in memory-related brain areas in PFT survivors, particularly in irradiated patients, and identify DTI metrics as potential biomarkers of memory deficit.

Clinical, Histologic, and Therapeutic Pattern of Posterior Fossa Tumors in Children in Cameroon: A Cross-sectional Study.

Posterior fossa tumors are significant in pediatric neurooncological populations due to their frequency and morbimortality. We convey a 10-year experience managing pediatric posterior fossa tumors at two reference centers in Cameroon. We conducted a cross-sectional study with data collected retrospectively in the Neurosurgery Department of the Central and General Hospitals of Yaounde from January 2010 to December 2019. Included in the study were all patients aged 0-15 years who underwent surgery for posterior fossa tumors. We retained 43 pediatric posterior fossa tumor files, representing 47.89% of pediatric brain tumors. The male/female sex ratio was 0.86, with a mean age of 6.93 ± 4.345 years. The predominant clinical presentations were headaches + vomiting (97.7%), visual impairment (67.4%), and altered consciousness (14%). The vermis was the most frequent site affected (46.5%). Hydrocephalus was found to be associated with the tumor in 30 patients (69.8%). Tumor excision was total in 90.7% of cases, with cerebrospinal fluid diversion performed within the surgery in 83% of cases. Pilocytic astrocytomas represented 37.2%, medulloblastomas 30.25%, ependymomas 6.9%, and brainstem gliomas 4.6%. The postoperatory mortality rate was 20.9%. The survival rate at 5 years for medulloblastomas was 43%. Pediatric posterior fossa tumors are frequent. Pilocytic astrocytomas are the most common histologic type, followed by medulloblastomas. Radical surgery is the leading standard of care. Adjuvant treatment remains limited.

Predicting cerebellar mutism syndrome in children using lesion map combined with clinical features.

This study aimed to develop a predictive model for cerebellar mutism syndrome (CMS) in pediatric patients with posterior fossa tumors, integrating lesion-symptom mapping (LSM) data with clinical factors, and to assess the model's performance. A cohort of pediatric patients diagnosed with posterior fossa tumors and undergoing surgery at Beijing Children's Hospital from July 2013 to December 2023 was analyzed. Clinical variables gender, age at surgery, tumor characteristics, hydrocephalus, surgical route and pathology were collected. LSM was used to link tumor locations with CMS outcomes. Lasso regression and logistic regression were employed for feature selection and model construction, respectively. Model performance was assessed using area under the curve (AUC) and accuracy metrics. The study included 197 patients in total, with CMS rates consistent across training, validation, and prospective groups. Significant associations were found between CMS and gender, tumor type, hydrocephalus, paraventricular edema, surgical route, and pathology. A predictive model combining voxel location data from LSM with clinical factors achieved high predictive performance (C-index: training 0.956, validation 0.933, prospective 0.892). Gender, pathology, and voxel location were identified as key predictors for CMS. The study established an effective predictive model for CMS in pediatric posterior fossa tumor patients, leveraging LSM data and clinical factors. The model's accuracy and robustness suggest its potential utility in clinical practice for early CMS risk assessment and intervention planning.

Feasibility study of computed high b-value diffusion-weighted magnetic resonance imaging for pediatric posterior fossa tumors.

To evaluate the diagnostic efficacy of computed diffusion-weighted imaging (DWI) in pediatric posterior fossa tumors generated using high b-values. We retrospectively performed our study on 32 pediatric patients who had undergone brain magnetic resonance imaging for a posterior fossa tumor between January 2016 and January 2022. The DWIs were evaluated for each patient by two blinded radiologists. The computed DWI (cDWI) was mathematically derived using a mono-exponential model from images with b = 0 and 1,000 s/mm2 and high b-values of 1,500, 2,000, 3,000, and 5,000 s/mm2. The posterior fossa tumors were divided into two groups, low grade and high grade, and the tumor/thalamus signal intensity (SI) ratios were compared. The Mann-Whitney U test and receiver operating characteristic (ROC) curves were used to compare the diagnostic performance of the acquired DWI (DWI1000), apparent diffusion coefficient (ADC)1000 maps, and cDWI (cDWI1500, cDWI2000, cDWI3000, and cDWI5000). The comparison of the two tumor groups revealed that the tumor/thalamus SI ratio on the DWI1000 and cDWI (cDWI1500, cDWI2000, cDWI3000, and cDWI5000) was statistically significantly higher in high-grade tumors (P < 0.001). In the ROC curve analysis, higher sensitivity and specificity were detected in the cDWI1500, cDWI2000, cDWI3000, and ADC1000 maps (100%, 90.90%) compared with the DWI1000 (80%, 81.80%). cDWI3000 had the highest area under the curve (AUC) value compared with other parameters (AUC: 0.976). cDWI generated using high b-values was successful in differentiating between low-grade and high-grade posterior fossa tumors without increasing imaging time. cDWI created using high b-values can provide additional information about tumor grade in pediatric posterior fossa tumors without requiring additional imaging time.

Machine Learning Analysis in Diffusion Kurtosis Imaging for Discriminating Pediatric Posterior Fossa Tumors: A Repeatability and Accuracy Pilot Study.

Background and purpose: Differentiating pediatric posterior fossa (PF) tumors such as medulloblastoma (MB), ependymoma (EP), and pilocytic astrocytoma (PA) remains relevant, because of important treatment and prognostic implications. Diffusion kurtosis imaging (DKI) has not yet been investigated for discrimination of pediatric PF tumors. Estimating diffusion values from whole-tumor-based (VOI) segmentations may improve diffusion measurement repeatability compared to conventional region-of-interest (ROI) approaches. Our purpose was to compare repeatability between ROI and VOI DKI-derived diffusion measurements and assess DKI accuracy in discriminating among pediatric PF tumors. Materials and methods: We retrospectively analyzed 34 children (M, F, mean age 7.48 years) with PF tumors who underwent preoperative examination on a 3 Tesla magnet, including DKI. For each patient, two neuroradiologists independently segmented the whole solid tumor, the ROI of the area of maximum tumor diameter, and a small 5 mm ROI. The automated analysis pipeline included inter-observer variability, statistical, and machine learning (ML) analyses. We evaluated inter-observer variability with coefficient of variation (COV) and Bland-Altman plots. We estimated DKI metrics accuracy in discriminating among tumor histology with MANOVA analysis. In order to account for class imbalances, we applied SMOTE to balance the dataset. Finally, we performed a Random Forest (RF) machine learning classification analysis based on all DKI metrics from the SMOTE dataset by partitioning 70/30 the training and testing cohort. Results: Tumor histology included medulloblastoma (15), pilocytic astrocytoma (14), and ependymoma (5). VOI-based measurements presented lower variability than ROI-based measurements across all DKI metrics and were used for the analysis. DKI-derived metrics could accurately discriminate between tumor subtypes (Pillai's trace: p < 0.001). SMOTE generated 11 synthetic observations (10 EP and 1 PA), resulting in a balanced dataset with 45 instances (34 original and 11 synthetic). ML analysis yielded an accuracy of 0.928, which correctly predicted all but one lesion in the testing set. Conclusions: VOI-based measurements presented improved repeatability compared to ROI-based measurements across all diffusion metrics. An ML classification algorithm resulted accurate in discriminating PF tumors on a SMOTE-generated dataset. ML techniques based on DKI-derived metrics are useful for the discrimination of pediatric PF tumors.

Doing more with less: surgical results of pediatric posterior fossa tumors from a single center in Latin America.

We aim to report the epidemiology, surgical outcomes, and survival rates of pediatric patients with posterior fossa tumors in a large single-center case series. A retrospective analysis was conducted on pediatric patients who underwent surgical treatment for posterior fossa tumors between January 2011 and January 2019. A total of 135 pediatric patients, with an average age of 7.5years at diagnosis and a mean follow-up of 35.7months, were included in the study. Most tumors were located within the midline, with ventriculomegaly observed in 71.4% of the patients. Pilocytic astrocytomas encompassed the majority of tumors (34.1%), followed by medulloblastomas (27.4%) and ependymomas (11.8%). Gross total resection (GTR) was achieved in 71.8% of the patients, with a recurrence rate of 20%. Surgical complications were observed in 25.9% of the patients. GTR significantly impacted 5-year overall survival (OS) and 4-year progression-free survival (PFS) in patients with posterior fossa tumors. Patients who underwent GTR had a 5-year OS of 89.7%, compared to 72.7% for near-total resection and 70.8% for subtotal resection. The 4-year PFS for patients who underwent GTR was 82.5%, whereas it was 63.6% for patients who underwent near-total resection and 54.2% for patients who underwent subtotal resection. Surgical resection remains the main treatment for pediatric posterior fossa tumors, and higher resection rates are linked to better survival outcomes. Despite limited resources for molecular diagnosis, our institution has demonstrated that a specialized neurooncological center with a high surgical volume can still achieve favorable survival outcomes for these patients.

Exploring Memory Systems After Pediatric Posterior Fossa Tumor: From Memory Profile Comparisons in Nonirradiated Versus Irradiated Patients to Episodic Memory Tests Capable of Detecting Radiation-induced Hippocampal Damage

AimsPediatric posterior fossa tumor (PFT) survivors experience long-term cognitive sequelae, including memory disorders, for which irradiation is one of the main risk factors. The aims of the present study were to (1) explore the profile of impairment in episodic, semantic, working and procedural memory systems in irradiated versus nonirradiated PFT survivors, and (2) test whether an autobiographical questionnaire and a two-phase ecological test (Epireal) assessing episodic memory are more sensitive to radiation-induced hippocampal damage than commonly used tests. Materials and methodsA total of 60 participants (22 irradiated PFT survivors, 17 nonirradiated PFT survivors, and 21 controls) were included in the prospective IMPALA study. They all underwent a broad battery of tests assessing the different memory systems in two 2-day sessions 3 weeks apart. We performed between-groups comparisons and analyzed impairment profiles, using -1.65 SDs as a cut-off. For irradiated patients, correlations were calculated between mean radiation doses to key brain structures involved in memory (hippocampus, cerebellum, and striatum) and corresponding memory scores. ResultsPBT survivors performed significantly more poorly than controls (p < 0.001) on conventional tests of episodic, semantic and working memory: 64% of irradiated patients and 35% of nonirradiated patients had a deficit in at least two memory systems, with episodic memory impairment being more specific to the irradiated group. Epireal had a larger effect size than the other episodic memory tests, allowing us to detect deficits in a further 18% of irradiated patients. These deficits were correlated with the mean radiation dose to the left hippocampus. ConclusionMemory impairment is a frequent long-term cognitive sequela in PFT survivors, especially after radiation therapy. New ecological tests of episodic memory that are more sensitive to radiation-induced deficits than conventional tests could yield specific markers of the toxicity of medial temporal lobe irradiation.

Pediatric Posterior Fossa Tumors Classification and Explanation-Driven with Explainable Artificial Intelligence Models

The use of deep learning for identifying defects in medical images has rapidly emerged as a significant area of interest across various medical diagnostic applications. The automated recognition of Posterior Fossa Tumors (PFT) in Magnetic Resonance Imaging (MRI) plays a vital role, as it furnishes essential data about irregular tissue, essential for treatment planning. Human examination has traditionally been the standard approach for identifying defects in brain MRI. This technique is unsuitable for a massive quantity of data. Therefore, automated PFT detection techniques are being established to minimize radiologist's time. In this paper, the posterior fossa tumor is detected and classified in brain MRI using Convolutional Neural Network (CNN) algorithms, and the model result and accuracy obtained from each algorithm are explained. A dataset collection made up of 3,00,000 images with an average of 500 patients from the Children's Cancer Hospital Egypt (CCHE) was used. The CNN algorithms investigated to classify the PFT were VGG19, VGG16, and ResNet50. Moreover, explanations for the behavior of networks were investigated using three different techniques: LIME, SHAP, and ICE. Overall, the results showed that the best model was VGG16 compared with other CNN-used models with accuracy rate values of 95.33%, 93.25%, and 87.4%, respectively.

Clinical practice in European centres treating paediatric posterior fossa tumours with pencil beam scanning proton therapy

Background and purposeAs no guidelines for pencil beam scanning (PBS) proton therapy (PT) of paediatric posterior fossa (PF) tumours exist to date, this study investigated planning techniques across European PT centres, with special considerations for brainstem and spinal cord sparing. Materials and methodsA survey and a treatment planning comparison were initiated across nineteen European PBS-PT centres treating paediatric patients. The survey assessed all aspects of the treatment chain, including but not limited to delineations, dose constraints and treatment planning. Each centre planned two PF tumour cases for focal irradiation, according to their own clinical practice but based on common delineations. The prescription dose was 54 Gy(RBE) for Case 1 and 59.4 Gy(RBE) for Case 2. For both cases, planning strategies and relevant dose metrics were compared. ResultsSeventeen (89 %) centres answered the survey, and sixteen (80 %) participated in the treatment planning comparison. In the survey, thirteen (68 %) centres reported using the European Particle Therapy Network definition for brainstem delineation. In the treatment planning study, while most centres used three beam directions, their configurations varied widely across centres. Large variations were also seen in brainstem doses, with a brainstem near maximum dose (D2%) ranging from 52.7 Gy(RBE) to 55.7 Gy(RBE) (Case 1), and from 56.8 Gy(RBE) to 60.9 Gy(RBE) (Case 2). ConclusionThis study assessed the European PBS-PT planning of paediatric PF tumours. Agreement was achieved in e.g. delineation-practice, while wider variations were observed in planning approach and consequently dose to organs at risk. Collaboration between centres is still ongoing, striving towards common guidelines.

IMG-15. A STRATEGIC FLOWCHART FOR PREOPERATIVE IMAGING IN PEDIATRIC POSTERIOR FOSSA TUMORS

Abstract BACKGROUND This comprehensive study delves into pediatric posterior fossa tumors (PFTs), focusing on both common and rare types, including pseudoneoplasms. The aim is to understand the diagnostic challenges of these less typical tumors, enhancing knowledge beyond usual pathologies. A detailed flow chart has been created to aid in accurate preoperative diagnoses. METHODS The study examines neuroimaging data, primarily from MRI and CT scans, collected from various clinical studies and case reports. It concentrates on identifying unique imaging characteristics of rare PFTs and pseudoneoplasms. The flow chart considers lesion location in various anatomical areas of the posterior fossa and factors such as lesion localization, MRI details (including DWI), and patient age. It also emphasizes the identification of cells in the posterior fossa that can lead to tumors, including osseous tissue cells, dura mater cells, arachnoid cells, pia mater cells, various glial cells, neurons, and choroid plexus cells. RESULTS The study reveals distinct imaging features of less common PFTs and pseudoneoplasms, critical for differentiating them from more common tumors. Advanced imaging techniques are highlighted as essential for improving diagnostic accuracy, impacting clinical management and treatment decisions. The review also discusses the varied presentation of tumors and the challenges this poses to standard diagnostic methods. CONCLUSIONS Understanding the imaging characteristics of rare PFTs and pseudoneoplasms, especially in children, is vital. This thorough analysis enhances diagnostic accuracy and influences treatment approaches, potentially improving patient outcomes. The study underscores the necessity of combining clinical observations with advanced imaging for precise diagnoses in atypical cases. This approach is crucial for healthcare professionals managing pediatric PFTs, leading to better clinical decisions and advancing pediatric neuro-oncology.

Expert-level diagnosis of pediatric posterior fossa tumors via consistency calibration

Accurate diagnosis of pediatric posterior fossa tumors (PFTs) is critical for saving lives; however, the limited number of specialists makes accurate diagnostics scarce. To make the diagnosis of PFTs accurate, automatic, and noninvasive, scholars have proposed employing deep neural networks (DNNs) to predict tumor types using magnetic resonance imaging data. Advanced methods primarily focus on fine-tuning DNNs pre-trained on large-scale datasets of natural images, e.g., ImageNet. However, the existing methods overlook the priors of human experts. Human experts typically recheck whether images predicted as a particular class are similar to those predicted as the same class to ensure prediction consistency. Therefore, the predicted results of an intelligent system should be consistent. Inspired by the rechecking process, we propose a novel learning paradigm called Consistency calibration (Coca). Within the Coca framework, the output predicted by DNNs is guided by two objective functions: (i) the task-specific objective of making the predicted results the same as the groundtruth, and (ii) an auxiliary objective of rechecking the prediction consistency. Coca is developed by defining the inconsistency for each sample by inconsistent risks: the auxiliary risk is small (large), but the task-specific risk is large (small). Building on the inconsistency definition, Coca identifies inconsistencies for each sample using an adversarial attack. Subsequently, these inconsistencies are leveraged to tune DNNs in an adversarial training manner for consistency calibration. To verify the efficacy of Coca, we conduct comprehensive experiments using a large-scale PBT dataset, and the results show that Coca significantly outperforms state-of-the-art methods. Moreover, Coca has improved performance over human experts as demonstrated by expert-level diagnostic performance in real-world PBT scenarios for the first time.

Pediatric Posterior Fossa Tumor Treatment Affects Thalamic Volume, Memory, and Processing Speed (S27.004)

Pediatric Posterior Fossa Tumor Treatment Affects Thalamic Volume, Memory, and Processing Speed (S27.004)

What is Under the Tent? Posterior Fossa Tumors in Children, the Usual Suspects—Part 1

Pediatric posterior fossa tumors are a major cause of morbidity and mortality in children. In this 2-part series, we discuss the spectrum of posterior fossa tumors and their clinical and molecular characteristics. In Part 1, the authors discuss the 5 primary differential diagnoses of posterior fossa tumors: medulloblastoma, pilocytic astrocytoma, ependymoma, diffuse midline glioma, H3K27-altered, and atypical teratoid/rhabdoid tumors. Each posterior fossa tumor is clinically and histologically defined. Additionally, relevant epidemiology data, current genetics/molecular classification according to the fifth edition of the World Health Organization Classification of Tumors of the Central Nervous System, and imaging findings are reviewed. The new version of the international standard for the classification of central nervous system tumors introduces major changes that advance the role of molecular diagnostics in the pediatric central nervous system tumor classification, particularly in posterior fossa tumors, which may impact management and outcomes.Learning Objective: To recognize the imaging appearance of the most common posterior fossa tumors in children.

Clinicopathological Analysis of Pediatric Posterior Fossa Tumors: Insights from a National Neurosurgical Center

BACKGROUNDː Pediatric posterior fossa tumors are the significant cause of morbidity and mortality in children and adolescents. This study aimed to investigate the characteristics of the patient population and report the experience in managing and treating children with these tumors, as well as their survival outcomes in Kazakhstan.&lt;br /&gt; METHODSː This retrospective study analysed data from the archives of the Pediatric Neurosurgery Department and included 214 pediatric patients with PFT in the period from January 2015 to December 2020.&lt;br /&gt; RESULTSː The study included 214 patients with a mean age of 7.29 ± 4.26 years. The most common tumor pathology observed in this study was medulloblastoma (33.18%). Grade I tumors showed a notable median survival of 56.64 months (95% CI, 53.93-59.35), surpassing Grade II tumors at 50.38 months (95% CI, 40.57-60.2). Grade III and IV tumors had median survivals of 38.64 months (95% CI, 31.11-46.17) and 38.76 months (95% CI, 33.96-43.56). Multivariate analysis using Cox regression model revealed significant predictors of overall survival. Grade III-IV tumors (RR = 0.577, 95% CI 0.462-0.720, p = 0.000), delayed resection (RR = 0.950, 95% CI 0.717-1.104, p = 0.000), and brainstem tumors (RR = 2.454, 95% CI 1.791-5.751, p = 0.000) had poorer survival. Tumor volume, age, and adjuvant chemotherapy were not significant predictors of 5-year survival (p &amp;gt; 0.05).&lt;br /&gt; CONCLUSIONSː The study found similar death rates in children with pilocytic astrocytoma compared to other population studies. Regrettably, the 5-year survival rate for medulloblastoma and ependymoma indicates a poorer outcome compared to previous reports.

Duraplasty with autologous cervical fascia in pediatric posterior fossa tumor surgery: a single-center experience with 214 cases.

Posterior fossa surgeries for pediatric tumors pose challenges in achieving optimal dural repair and duraplasty is usually required. Autografts, allografts, xenografts, and synthetic substitutes can be used for duraplasty. Autologous cervical fascia can be a safe and reliable graft option for duraplasty after posterior fossa surgeries. This study aims to investigate the outcomes of duraplasty with autologous cervical fascial graft in children after posterior fossa surgery for pediatric brain tumors. Pediatric patients with posterior fossa tumor who underwent surgery between March 2001 and August 2022 were retrospectively reviewed. Data on demographics, preoperative symptoms, diagnosis, tumor characteristics, hydrocephalus history, and postoperative complications, including cerebrospinal fluid (CSF) leakage, pseudomeningocele, and meningitis were collected. Logistic regression analysis was performed to explore risk factors for postoperative complications. Patient cohort included 214 patients. Autologous cervical fascia was used in all patients for duraplasty. Mean age was 7.9 ± 5.3years. Fifty-seven patients (26.6%) had preoperative hydrocephalus and 14 patients (6.5%) received VPS or EVD perioperatively. Postoperative hydrocephalus was present in 31 patients (14.5%). Rates of CSF leak, pseudomeningocele, and meningitis were 4.2%, 2.8%, and 4.2% respectively. Logistic regression analysis revealed that postoperative EVD and VPS placement were the factors associated with postoperative complications. Autologous cervical fascia is a safe and reliable option for duraplasty with minimal risk of postoperative complications. The straightforward surgical technique and with no additional cost for harvesting the graft renders autologous cervical fascia a favorable alternative for resource-limited countries or surgical settings.

Effects of cognitive-motor intervention for pediatric posterior fossa tumor survivors: results of a pilot study.

The purpose of this prospective pilot study was to evaluate the feasibility and effects of cognitive-motor intervention on the cognitive and motor abilities of pediatric survivors of posterior fossa tumors. The study involved patients aged 7 to 18 years with cognitive deficits who had completed primary treatment for posterior fossa tumors. 25 participants (Mage=11.3 ± 2.93, 64% male; 17 medulloblastoma, 1 ependymoma, 1 desmoplastic medulloblastoma, 6 piloid astrocytoma; 22 in remission (Mmonths =45), 3 in stabilization (Mmonths=49)) were recruited from the Research Institute for Brain Development and Peak Performance. The intervention consisted of two phases with a 3-month break for home training, and a total duration of 6 months. Each phase lasted 7 weeks and included two assessment procedures (pre- and post-intervention) and 10 training sessions over a period of 5 weeks (two 3-hour sessions per week). At baseline and pre- and post-intervention, all participants underwent a battery of cognitive and motor tests. Each training session included gross motor training (GMT), graphomotor training (GT), and cognitive-motor training (CMT). Statistical analysis was performed using the Friedman test for repeated measures and post-hoc Durbin-Conover test. The results indicated significant improvements in visuospatial working memory, visual attention, eye-hand coordination, semantic verbal fluency, auditory-motor synchronization, reaction time, and a decrease in the rate of ataxia. These improvements remained stable even in the absence of direct intervention. The findings demonstrate positive effects and feasibility of the intervention and suggest the need for further research in this area including randomized controlled feasibility studies with a larger sample.

Evaluation of the ETV Success Score to Improve Decision Making on the Management of Hydrocephalus Secondary to Pediatric Posterior Fossa Tumors

Introduction: Children with posterior fossa tumors (PFT) often have hydrocephalus, which can be treated via endoscopic third ventriculostomy (ETV) before the tumor is removed, thereby improving surgical outcomes. Additionally, a scoring system that forecasts ETV success can help with this procedure's decision-making. The purpose of the research is to assess the effectiveness of electrotherapy (ETV) in treating PFT-related hydrocephalus and the predictive validity of the ETV effectiveness score. Materials and Methods: A retrospective analysis was conducted on patients aged &lt; 18 years who received ETV prior to PFT resection between 2022 and 2023. For every patient, the ETV success score was acquired retroactively, and its ability to forecast success contrasted with the actual success was noted. Results: In the first six months after ETV, a worldwide success rate of 61.7% was observed in 40 surgical patients. For patients who were reviewed a year after surgery, this percentage decreased to 52.8%. The histological level of the tumor and the age of the victim did not correlate with the recovery rate. At both time periods, the ETV effectiveness score showed adequate accuracy (AUC = 0.671 at six months, AUC = 0.649 at one year). Conclusion: In summary, ETV has been shown to be a safe treatment that may effectively cure hydrocephalus in individuals with PFT. In addition, the ETV efficacy score can be a valuable tool for predicting the likelihood of successful endoscopic surgery.

National multicentered retrospective review of clinical and intraoperative factors associated with the development of cerebellar mutism after pediatric posterior fossa tumor resection.

Cerebellar mutism (CM) is characterized by a significant loss of speech in children following posterior fossa (PF) surgery. The biological origin of CM remains unclear and is the subject of ongoing debate. Significant recovery from CM is less likely than previously described despite rigorous multidisciplinary neuro-rehabilitational efforts. A national multi-centered retrospective review of all children undergoing PF resection in four midsized Canadian academic pediatric institutions was undertaken. Patient, tumor and surgical factors associated with the post-operative development of CM were reviewed. Retrospective identification of PF surgery patients including those developing and those that did not (internal control). The study identified 258 patients across the 4 centers between 2010 and 2020 (mean age 6.73years; 42.2% female). Overall, CM was experienced in 19.5% of patients (N = 50). Amongst children who developed CM histopathology included medulloblastoma (35.7%), pilocytic astrocytoma (32.6%) and ependymoma (17.1%). Intraoperative impression of adherence to the floor of the 4th ventricle was positive in 36.8%. Intraoperative abrupt changes in blood pressure and/or heart rate were identified in 19.4% and 17.8% of cases. The clinical resolution of CM was rated to be complete, significant resolution, slight improvement, no improvement and deterioration in 56.0%, 8.0%, 20.0%, 14.0% and 2.0%, respectively. In the cohort of children who experienced post-operative CM as compared to their no-CM counterpart, proportionally more tumors were felt to be adherent to the floor of the 4th ventricle (56.0% vs 49.5%), intraoperative extent of resection was a GTR (74% vs 68.8%) and changes in heart rate were noted (≥ 20% from baseline) (26.0% vs 15.9%). However, a multiple regression analysis identified only abrupt changes in HR (OR 5.97, CI (1.53, 23.1), p = 0.01) to be significantly associated with the development of post-operative CM. As a devastating surgical complication after posterior fossa tumor surgery with variable clinical course, identifying and understanding the operative cues and revising intraoperative plans that optimizes the child's neurooncological and clinical outcome are essential.

Multimodal imaging with magnetization transfer and diffusion tensor imaging reveals evidence of myelin damage in children and youth treated for a brain tumor.

The microstructural damage underlying compromise of white matter following treatment for pediatric brain tumors is unclear. We use multimodal imaging employing advanced diffusion tensor imaging (DTI) and magnetization transfer imaging (MTI) MRI methods to examine chronic microstructural damage to white matter in children and adolescents treated for pediatric brain tumor. Notably, MTI may be more sensitive to macromolecular content, including myelin, than DTI. Fifty patients treated for brain tumors (18 treated with surgery ± chemotherapy and 32 treated with surgery followed by cranial-spinal radiation; time from diagnosis to scan ~6 years) and 45 matched healthy children completed both MTI and DTI scans. Voxelwise and region-of-interest approaches were employed to compare white matter microstructure metrics (magnetization transfer ratio (MTR); DTI- fractional anisotropy [FA], radial diffusivity [RD], axial diffusivity [AD], mean diffusivity [MD]) between patients and healthy controls. MTR was decreased across multiple white matter tracts in patients when compared to healthy children, P < .001. These differences were observed for both patients treated with radiation and those treated with only surgery, P < .001. We also found that children and adolescents treated for brain tumors exhibit decreased FA and increased RD/AD/MD compared to their healthy counterparts in several white matter regions, Ps < .02. Finally, we observed that MTR and DTI metrics were related to multiple white matter tracts in patients, Ps < .01, but not healthy control children. Our findings provide evidence that the white matter damage observed in patients years after treatment of pediatric posterior fossa tumors, likely reflects myelin disruption.

The long-term impact of irradiation on functional connectivity in brain circuits involved in memory processes after pediatric posterior fossa tumor

PurposeMemory is one of the main specific cognitive domains impaired with attention and processing speed after a pediatric brain tumor. This work explored the long-term impact of radiotherapy in children with posterior fossa tumor (PFT) on brain connectivity in neural circuits involved in memory using resting-state functional magnetic resonance imaging (rs-fMRI). MethodsA total of 20 irradiated and 15 non-irradiated PFT survivors, and 21 healthy controls, prospectively included in the IMPALA study (NCT04324450), performed memory tests assessing episodic, procedural, and working memories and were subjected to an rs-fMRI. We manually contoured main structures involved in memory to explore connectivity at rest in a seed-to-voxel analysis. The groups were compared and differences in connectivity were correlated with behavioral scores and irradiation doses. ResultsThe performance of all mnesic tasks was lower in PFT survivors with a greater alteration in working and episodic memory in irradiated patients. Irradiated survivors had atypical connectivities in all memory circuits compared to controls and in cortico-caudate and cortico-cerebellar circuits compared to non-irradiated survivors. Non-irradiated survivors had only atypical connectivities in the cortico-cerebellar circuits compared to controls. In irradiated survivors, atypical connectivities in cortico-hippocampal circuits were linked with episodic memory scores and dose of irradiation to the left hippocampus and in cortico-striatal circuits with procedural memory scores and dose of irradiation to the striatum. ConclusionThe results of this study highlight that irradiation has a long-term impact on brain connectivity in brain circuits involved in memory after pediatric PFT with a specific radiation-dose effect in supratentorial structures.