Improving advanced intraoperative MRI methods during pediatric neurosurgery

Advanced intraoperative MR images (ioMRI) acquired during the resection of pediatric brain tumors could offer additional physiological information to preserve healthy tissue. With this work, we aimed to develop a protocol for ioMRI with increased sensitivity for arterial spin labeling (ASL) and diffusion MRI (dMRI), optimized for patient positioning regularly used in the pediatric neurosurgery setting. For ethical reasons, ASL images were acquired in healthy adult subjects that were imaged in the prone and supine position. After this, the ASL cerebral blood flow (CBF) was quantified and compared between both positions. To evaluate the impact of the RF coils setups on image quality, we compared different setups (two vs. four RF coils) by looking at T1-weighted (T1w) signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), as well as undertaking a qualitative evaluation of T1w, T2w, ASL, and dMR images. Mean ASL CBF did not differ between the surgical prone and supine positions in any of the investigated regions of interest or the whole brain. T1w SNR (gray matter: p = 0.016, 34% increase; white matter: p = 0.016, 32% increase) and CNR were higher (p = 0.016) in the four versus two RF coils setups (18.0 ± 1.8 vs. 13.9 ± 1.8). Qualitative evaluation of T1w, T2w, ASL, and dMR images resulted in acceptable to good image quality and did not differ statistically significantly between setups. Only the nonweighted diffusion image maps and corticospinal tract reconstructions yielded higher image quality and reduced susceptibility artifacts with four RF coils. Advanced ioMRI metrics were more precise with four RF coils as the standard deviation decreased. Taken together, we have investigated the practical use of advanced ioMRI during pediatric neurosurgery. We conclude that ASL CBF quantification in the surgical prone position is valid and that ASL and dMRI acquisition with two RF coils can be performed adequately for clinical use. With four versus two RF coils, the SNR of the images increases, and the sensitivity to artifacts reduces.

Protocol for investigating data quality and reporting outcomes of pediatric gliomas in population-based cancer registry research

Cancer registry data on pediatric gliomas come with inherent limitations as inclusion criteria and registration practices of these tumors differ between registries due to specific guidelines that are lacking. These limitations can lead to biased estimates in incidence and survival outcomes. Here, we present a protocol to investigate data quality and comparability for retrospective population-based pediatric glioma studies. We describe steps for obtaining institutional permissions, dealing with data quality issues, regrouping tumors, and reporting tumors in a clinically relevant manner. For complete details on the use and execution of this protocol, please refer to Hoogendijk et al.1.

Taenia martis Neurocysticercosis-Like Lesion in Child, Associated with Local Source, the Netherlands

A neurocysticercosis-like lesion in an 11-year-old boy in the Netherlands was determined to be caused by the zoonotic Taenia martis tapeworm. Subsequent testing revealed that 15% of wild martens tested in that region were infected with T. martis tapeworms with 100% genetic similarity; thus, the infection source was most likely local.

Robotic alignment system Cirq (Brainlab) for navigated brain tumor biopsies in children

INTRODUCTION

The Cirq robotic alignment system (Brainlab, Munich, Germany) is a manually adjustable electronic arm with a robotic alignment module on its distal end, enabling the neurosurgeon to automatically and accurately align surgical instruments to a preoperatively planned trajectory. In this study, we share our first experiences and results using Cirq for intracranial tumor biopsy in children.

METHODS

From May 2021 until October 2022, all consecutive patients that underwent a brain tumor biopsy using Cirq were included and compared to a historical cohort of patients biopsied with the non-robotic system Varioguide (Brainlab, Munich, Germany). Patient-related data, tumor-related data, and surgery-related data were collected. Registration accuracy was calculated for different patient-to-image registration methods. Pre- and postoperative images were fused, and entry error, target error, and angulation error were calculated.

RESULTS

Thirty-seven patients, aged 1-19 years, were included (14 with Cirq and 23 with Varioguide). An integrated histopathological and molecular diagnosis was acquired in all cases. Patient-to-image registration was significantly more accurate when based on bone screw fiducials combined with intraoperative CT, as compared to surface matching or skin fiducials. The target error (Euclidian distance) was 5.3 mm for Cirq as compared to 8.3 mm for Varioguide, but this was not statistically significant. Entry error and angulation error were also not significantly different between both groups.

CONCLUSION

Intracranial biopsy with the Cirq robotic system is feasible and safe, and its accuracy does not differ from the Varioguide system.

Treatment and outcome of the Dutch Childhood Craniopharyngioma Cohort study: First results after centralization of care

BACKGROUND

Childhood craniopharyngioma (cCP) has excellent survival, but quality of life may be severely hampered by hypothalamic dysfunction. We aimed to evaluate treatment and hypothalamic outcomes of a Dutch cCP cohort, and evaluate the effect of centralization of care.

METHODS

A retrospective cohort study was performed, including cCP patients diagnosed between 2004 and 2021. Treatment characteristics and hypothalamic outcomes were evaluated and compared before and since centralization of care in May 2018.

RESULTS

We included 87 cCP patients. Cyst drainage/fenestration was performed in 29.9%, limited resection in 27.6%, near-total resection in 16.1%, and gross total resection (GTR) in 25.4%. Radiotherapy was given in 46.0%. After a median follow-up of 6.5 years, hypothalamic obesity (HO) was present in 24.7% and panhypopituitarism with diabetes insipidus in 71.3%. Higher body mass index (BMI) SDS at diagnosis and Muller grade II at last magnetic resonance imaging of follow-up were associated with overweight/obesity. No association was found between extensiveness of resection and overweight/obesity at last follow-up. When comparing before and after centralization of care, rates of GTR remained similar, but BMI outcomes changed; mean ΔBMI SDS 1 year after diagnosis from 1.12 (SD 1.15) to 0.81 (SD 1.24), and HO after 1 year decreased from 33.3% to 12.0% (P = .067), and after 2 years from 28.6% to 6.7% (P = NS).

CONCLUSIONS

In our nationwide cohort, GTR was performed in a relatively low percentage of patients and extensiveness of resection was no longer associated with HO at follow-up. A trend toward improvement of BMI is observed since centralization of care, which needs further exploration.

Ultra-fast deep-learned CNS tumour classification during surgery

Central nervous system tumours represent one of the most lethal cancer types, particularly among children1. Primary treatment includes neurosurgical resection of the tumour, in which a delicate balance must be struck between maximizing the extent of resection and minimizing risk of neurological damage and comorbidity2,3. However, surgeons have limited knowledge of the precise tumour type prior to surgery. Current standard practice relies on preoperative imaging and intraoperative histological analysis, but these are not always conclusive and occasionally wrong. Using rapid nanopore sequencing, a sparse methylation profile can be obtained during surgery4. Here we developed Sturgeon, a patient-agnostic transfer-learned neural network, to enable molecular subclassification of central nervous system tumours based on such sparse profiles. Sturgeon delivered an accurate diagnosis within 40 minutes after starting sequencing in 45 out of 50 retrospectively sequenced samples (abstaining from diagnosis of the other 5 samples). Furthermore, we demonstrated its applicability in real time during 25 surgeries, achieving a diagnostic turnaround time of less than 90 min. Of these, 18 (72%) diagnoses were correct and 7 did not reach the required confidence threshold. We conclude that machine-learned diagnosis based on low-cost intraoperative sequencing can assist neurosurgical decision-making, potentially preventing neurological comorbidity and avoiding additional surgeries.

Safety of Growth Hormone Replacement Therapy in Childhood-Onset Craniopharyngioma: A Systematic Review and Cohort Study

INTRODUCTION

Survival of childhood-onset craniopharyngioma (cCP) is excellent; however, many survivors suffer from hypothalamic-pituitary dysfunction. Growth hormone replacement therapy (GHRT) is of high importance for linear growth and metabolic outcome. Optimal timing for initiation of GHRT in cCP is on debate because of concerns regarding tumor progression or recurrence.

METHODS

A systematic review and cohort studys were performed for the effect and timing of GHRT on overall mortality, tumor progression/recurrence, and secondary tumors in cCP. Within the cohort, cCP receiving GHRT ≤1 year after diagnosis were compared to those receiving GHRT >1 year after diagnosis.

RESULTS

Evidence of 18 included studies, reporting on 6,603 cCP with GHRT, suggests that GHRT does not increase the risk for overall mortality, progression, or recurrent disease. One study evaluated timing of GHRT and progression/recurrence-free survival and found no increased risk with earlier initiation. One study reported a higher than expected prevalence of secondary intracranial tumors compared to a healthy population, possibly confounded by radiotherapy. In our cohort, 75 of 87 cCP (86.2%) received GHRT for median of 4.9 years [0.0-17.1]. No effect of timing of GHRT was found on mortality, progression/recurrence-free survival, or secondary tumors.

CONCLUSION

Although the quality of the evidence is low, the available evidence suggests no effect of GHRT or its timing on mortality, tumor progression/recurrence, or secondary neoplasms in cCP. These results support early initiation of GHRT in cCP aiming to optimize linear growth and metabolic outcome. Prospective studies are needed to increase the level of evidence upon the optimal timing to start GHRT in cCP patients.

Atypical teratoid/rhabdoid tumoroids reveal subgroup-specific drug vulnerabilities

Atypical teratoid/rhabdoid tumors (ATRTs) represent a rare, but aggressive pediatric brain tumor entity. They are genetically defined by alterations in the SWI/SNF chromatin remodeling complex members SMARCB1 or SMARCA4. ATRTs can be further classified in different molecular subgroups based on their epigenetic profiles. Although recent studies suggest that the different subgroups have distinct clinical features, subgroup-specific treatment regimens have not been developed thus far. This is hampered by the lack of pre-clinical in vitro models representative of the different molecular subgroups. Here, we describe the establishment of ATRT tumoroid models from the ATRT-MYC and ATRT-SHH subgroups. We demonstrate that ATRT tumoroids retain subgroup-specific epigenetic and gene expression profiles. High throughput drug screens on our ATRT tumoroids revealed distinct drug sensitivities between and within ATRT-MYC and ATRT-SHH subgroups. Whereas ATRT-MYC universally displayed high sensitivity to multi-targeted tyrosine kinase inhibitors, ATRT-SHH showed a more heterogeneous response with a subset showing high sensitivity to NOTCH inhibitors, which corresponded to high expression of NOTCH receptors. Our ATRT tumoroids represent the first pediatric brain tumor organoid model, providing a representative pre-clinical model which enables the development of subgroup-specific therapies.

Radiosensitisation by olaparib through focused ultrasound delivery in a diffuse midline glioma model

BACKGROUND AND PURPOSE

Diffuse midline glioma H3K27-altered (DMG) is an aggressive, inoperable, predominantly paediatric brain tumour. Treatment strategies are limited, resulting in a median survival of only 11 months. Currently, radiotherapy (RT), often combined with temozolomide, is considered the standard of care but remains palliative, highlighting the urgency for new therapies. Radiosensitisation by olaparib, an inhibitor of PARP1 and subsequently PAR-synthesis, is a promising treatment option. We assessed whether PARP1 inhibition enhances radiosensitivity in vitro and in vivo following focused ultrasound mediated blood-brain barrier opening (FUS-BBBO).

METHODS

Effects of PARP1 inhibition were evaluated in vitro using viability, clonogenic, and neurosphere assays. In vivo olaparib extravasation and pharmacokinetic profiling following FUS-BBBO was measured by LC-MS/MS. Survival benefit of FUS-BBBO combined with olaparib and RT was assessed using a patient-derived xenograft (PDX) DMG mouse model.

RESULTS

Treatment with olaparib in combination with radiation delayed tumour cell proliferation in vitro through the reduction of PAR. Prolonged exposure of low olaparib concentration was more efficient in delaying cell growth than short exposure of high concentration. FUS-BBBO increased olaparib bioavailability in the pons by 5.36-fold without observable adverse effects. A Cmax of 54.09 μM in blood and 1.39 μM in the pontine region was achieved following administration of 100 mg/kg olaparib. Although RT combined with FUS-BBBO mediated olaparib extravasation delayed local tumour growth, survival benefits were not observed in an in vivo DMG PDX model.

CONCLUSIONS

Olaparib effectively radiosensitises DMG cells in vitro and reduces primary tumour growth in vivo when combined with RT. Further studies are needed to investigate the therapeutic benefit of olaparib in suitable preclinical PDX models.

Could deep brain stimulation be a possible solution for acquired hypothalamic obesity?

Objective

Hypothalamic dysfunction may result in morbid obesity as a consequence of decreased energy expenditure, decreased feelings of satiety, and increased fat storage. In patients with hypothalamic dysfunction, neurobehavioral dysfunction is also often present. Currently, no effective treatment has been found for hypothalamic obesity (HO). We hypothesize that deep brain stimulation (DBS) may be an effective treatment for patients with hypothalamic dysfunction, aiming to treat HO as well as the neurobehavioral dysfunction.

Methods

A systematic search was conducted in the PubMed, EMBASE and Cochrane Library databases for studies published until May 2022 reporting on DBS for the treatment of HO.

Results

Three studies met the predetermined inclusion criteria, with in total six patients treated with DBS for HO, of which five patients with Prader-Willi syndrome (PWS) and one patient with HO after treatment for craniopharyngioma (CP). Targets of DBS included the lateral hypothalamic area (LHA) and the nucleus accumbens (NAcc). In patients with PWS, LHA-DBS was associated with a mean increase of Body Mass Index (BMI) (+5.8%), with no change in hormonal levels, results of blood workup, sleep, or neuropsychological evaluation. In the patient with CP, NAcc-DBS was associated with a decrease in BMI (-8.7%) and a subjective increase in mental health, energy and willingness to act, and no feeling of increased appetite. No objective measurements on neurobehavioral function were reported. No severe adverse events were reported in these cases. Mild to moderate adverse events included hypomanic symptoms and infection. All patients with a described follow-up period (n = 5) were able to sustain the treatment for at least 6 months with few interruptions.

Conclusion

There is limited research reporting on DBS for HO. The effectiveness differed across studies and the evidence is limited. Although there may be potential for DBS treatment in the severe-refractory condition of HO in patients with CP, more research is needed for target selection and evaluation of effectiveness.

Incisional CSF leakage after intradural cranial surgery in children: incidence, risk factors, and complications

OBJECTIVE

The risk of cerebrospinal fluid (CSF) leakage after cranial surgery and its associated complications in children are unclear because of variable definitions and the lack of multicenter studies. In this study, the authors aimed to establish the incidence of CSF leakage after intradural cranial surgery in the pediatric population. In addition, they evaluated potential risk factors and complications related to CSF leakage in the pediatric population.

METHODS

The authors performed an international multicenter retrospective cohort study in three tertiary neurosurgical referral centers. Included were all patients aged 18 years or younger who had undergone cranial surgery to reach the subdural space during the period between 2015 and 2021. Patients who died or were lost to follow-up within 6 weeks after surgery were excluded. The primary outcome measure was the incidence of CSF leakage, defined as leakage through the skin, within 6 weeks after surgery. Univariable and multivariable logistic regression analyses were performed to identify risk factors for and complications related to CSF leakage.

RESULTS

In total, 759 procedures were identified, performed in 687 individual patients. The incidence of CSF leakage was 7.5% (95% CI 5.7%-9.6%). In the multivariate model, independent risk factors for CSF leakage were hydrocephalus (OR 4.5, 95% CI 2.2-8.9) and craniectomy (OR 7.6, 95% CI 3.0-19.5). Patients with CSF leakage had higher odds of pseudomeningocele (5.7, 95% CI 3.0-10.8), meningitis (21.1, 95% CI 9.5-46.8), and surgical site infection (7.4, 95% CI 2.6-20.8) than patients without leakage.

CONCLUSIONS

CSF leakage risk in children after cranial surgery, which is comparable to the risk reported in adults, is an event of major concern and has a serious clinical impact.

Advanced intraoperative MRI in pediatric brain tumor surgery

Introduction: In the pediatric brain tumor surgery setting, intraoperative MRI (ioMRI) provides "real-time" imaging, allowing for evaluation of the extent of resection and detection of complications. The use of advanced MRI sequences could potentially provide additional physiological information that may aid in the preservation of healthy brain regions. This review aims to determine the added value of advanced imaging in ioMRI for pediatric brain tumor surgery compared to conventional imaging. Methods: Our systematic literature search identified relevant articles on PubMed using keywords associated with pediatrics, ioMRI, and brain tumors. The literature search was extended using the snowball technique to gather more information on advanced MRI techniques, their technical background, their use in adult ioMRI, and their use in routine pediatric brain tumor care. Results: The available literature was sparse and demonstrated that advanced sequences were used to reconstruct fibers to prevent damage to important structures, provide information on relative cerebral blood flow or abnormal metabolites, or to indicate the onset of hemorrhage or ischemic infarcts. The explorative literature search revealed developments within each advanced MRI field, such as multi-shell diffusion MRI, arterial spin labeling, and amide-proton transfer-weighted imaging, that have been studied in adult ioMRI but have not yet been applied in pediatrics. These techniques could have the potential to provide more accurate fiber tractography, information on intraoperative cerebral perfusion, and to match gadolinium-based T1w images without using a contrast agent. Conclusion: The potential added value of advanced MRI in the intraoperative setting for pediatric brain tumors is to prevent damage to important structures, to provide additional physiological or metabolic information, or to indicate the onset of postoperative changes. Current developments within various advanced ioMRI sequences are promising with regard to providing in-depth tissue information.

Implementation of paediatric precision oncology into clinical practice: The Individualized Therapies for Children with cancer program ‘iTHER’

iTHER is a Dutch prospective national precision oncology program aiming to define tumour molecular profiles in children and adolescents with primary very high-risk, relapsed, or refractory paediatric tumours. Between April 2017 and April 2021, 302 samples from 253 patients were included. Comprehensive molecular profiling including low-coverage whole genome sequencing (lcWGS), whole exome sequencing (WES), RNA sequencing (RNA-seq), Affymetrix, and/or 850k methylation profiling was successfully performed for 226 samples with at least 20% tumour content. Germline pathogenic variants were identified in 16% of patients (35/219), of which 22 variants were judged causative for a cancer predisposition syndrome. At least one somatic alteration was detected in 204 (90.3%), and 185 (81.9%) were considered druggable, with clinical priority very high (6.1%), high (21.3%), moderate (26.0%), intermediate (36.1%), and borderline (10.5%) priority. iTHER led to revision or refinement of diagnosis in 8 patients (3.5%). Temporal heterogeneity was observed in paired samples of 15 patients, indicating the value of sequential analyses.

Of 137 patients with follow-up beyond twelve months, 21 molecularly matched treatments were applied in 19 patients (13.9%), with clinical benefit in few. Most relevant barriers to not applying targeted therapies included poor performance status, as well as limited access to drugs within clinical trial.

iTHER demonstrates the feasibility of comprehensive molecular profiling across all ages, tumour types and stages in paediatric cancers, informing of diagnostic, prognostic, and targetable alterations as well as reportable germline variants. Therefore, WES and RNA-seq is nowadays standard clinical care at the Princess Máxima Center for all children with cancer, including patients at primary diagnosis. Improved access to innovative treatments within biology-driven combination trials is required to ultimately improve survival.

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Implementing comprehensive molecular profiling into standard of care is feasible.

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Temporal heterogeneity is observed, indicating the value of sequential analyses.

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Molecularly matched treatments are applied in a minority of patients despite clinical benefit.

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Poor performance status & limited access to drugs within trial hamper targeted treatment.

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The multidisciplinary tumour board is crucial in translating findings into clinical decision making.

Ophthalmological Findings in Youths With a Newly Diagnosed Brain Tumor

Importance

Visual impairment is an irreversible adverse effect in individuals who experienced a childhood brain tumor. Ophthalmological evaluation at diagnosis enables early detection of vision loss, decision-making about treatment, and when applicable, the timely use of visual interventions. However, awareness of visual impairment in clinical practice is suboptimal, and adherence to ophthalmological evaluation needs to be improved.

Objective

To assess the prevalence and types of abnormal ophthalmological findings in youths with a newly diagnosed brain tumor.

Design, Setting, and Participants

In this nationwide, prospective cohort study, youths aged 0 to 18 years with a newly diagnosed brain tumor between May 15, 2019, and August 11, 2021, were consecutively enrolled in 4 hospitals in the Netherlands, including the dedicated tertiary referral center for pediatric oncology care.

Exposures

A standardized and comprehensive ophthalmological examination, including orthoptic evaluation, visual acuity testing, visual field examination, and ophthalmoscopy, was performed within 4 weeks from brain tumor diagnosis.

Main Outcomes and Measures

The main outcomes were prevalence and types of visual symptoms and abnormal ophthalmological findings at brain tumor diagnosis.

Results

Of 170 youths included in the study (96 [56.5%] male; median age, 8.3 years [range, 0.2-17.8 years]), 82 (48.2%) had infratentorial tumors; 53 (31.2%), supratentorial midline tumors; and 35 (20.6%), cerebral hemisphere tumors. A total of 161 patients (94.7%) underwent orthoptic evaluation (67 [41.6%] preoperatively; 94 [58.4%] postoperatively); 152 (89.4%), visual acuity testing (63 [41.4%] preoperatively; 89 [58.6%] postoperatively); 121 (71.2%), visual field examination (49 [40.4%] preoperatively; 72 [59.6%] postoperatively); and 164 (96.5%), ophthalmoscopy (82 [50.0%] preoperatively; 82 [50.0%] postoperatively). Overall, 101 youths (59.4%) presented with visual symptoms at diagnosis. Abnormal findings were found in 134 patients (78.8%) during ophthalmological examination. The most common abnormal findings were papilledema in 86 of 164 patients (52.4%) who underwent ophthalmoscopy, gaze deficits in 54 of 161 (33.5%) who underwent orthoptic evaluation, visual field defects in 32 of 114 (28.1%) with reliable visual field examination, nystagmus in 40 (24.8%) and strabismus in 32 (19.9%) of 161 who underwent orthoptic evaluation, and decreased visual acuity in 13 of 152 (8.6%) with reliable visual acuity testing. Forty-five of 69 youths (65.2%) without visual symptoms at diagnosis had ophthalmological abnormalities on examination.

Conclusions and Relevance

The results of this study suggest that there is a high prevalence of abnormal ophthalmological findings in youths at brain tumor diagnosis regardless of the presence of visual symptoms. These findings support the need of standardized ophthalmological examination and the awareness of ophthalmologists and referring oncologists, neurologists, and neurosurgeons for ophthalmological abnormalities in this patient group.

Hypothalamic-Pituitary and Other Endocrine Surveillance Among Childhood Cancer Survivors

Endocrine disorders in survivors of childhood, adolescent, and young adult (CAYA) cancers are associated with substantial adverse physical and psychosocial effects. To improve appropriate and timely endocrine screening and referral to a specialist, the International Late Effects of Childhood Cancer Guideline Harmonization Group (IGHG) aims to develop evidence and expert consensus-based guidelines for healthcare providers that harmonize recommendations for surveillance of endocrine disorders in CAYA cancer survivors. Existing IGHG surveillance recommendations for premature ovarian insufficiency, gonadotoxicity in males, fertility preservation, and thyroid cancer are summarized. For hypothalamic-pituitary (HP) dysfunction, new surveillance recommendations were formulated by a guideline panel consisting of 42 interdisciplinary international experts. A systematic literature search was performed in MEDLINE (through PubMed) for clinically relevant questions concerning HP dysfunction. Literature was screened for eligibility. Recommendations were formulated by drawing conclusions from quality assessment of all evidence, considering the potential benefits of early detection and appropriate management. Healthcare providers should be aware that CAYA cancer survivors have an increased risk for endocrine disorders, including HP dysfunction. Regular surveillance with clinical history, anthropomorphic measures, physical examination, and laboratory measurements is recommended in at-risk survivors. When endocrine disorders are suspected, healthcare providers should proceed with timely referrals to specialized services. These international evidence-based recommendations for surveillance of endocrine disorders in CAYA cancer survivors inform healthcare providers and highlight the need for long-term endocrine follow-up care in subgroups of survivors and elucidate opportunities for further research.

Radiological characteristics of spinal hemangioblastomas in von Hippel Lindau disease as guidance in clinical interventions

Hemangioblastomas in the central nervous system (CNS) are the most common manifestation of Von Hippel-Lindau (VHL) disease. Because the growth rate of hemangioblastomas is unpredictable, regular follow-up is mandatory, focusing on clinical symptoms and imaging of the CNS. However, clinical symptoms may be subtle and non-specific, and data about the relationship between the radiological findings and clinical symptoms are sparse.

AIM OF THE STUDY

This study aims to evaluate if and how findings of magnetic resonance imaging (MRI) regarding spinal hemangioblastomas are associated with symptoms of VHL disease, with special attention to peritumoral edema and spinal cysts.

METHODS

Serial spinal MRI scans of 43 genetically or clinically established VHL patients with at least two years of follow-up were re-evaluated to examine the volume, growth rate, and location of spinal hemangioblastomas and the presence, size, and growth rate of peritumoral edema and cysts. Findings were compared with clinical symptoms using Fisher's exact test.

RESULTS

We observed a total of 77 spinal hemangioblastomas in 28 patients. Eight of the 28 patients showed peritumoral edema and spinal cysts, and one patient showed peritumoral edema without cyst formation; six of these nine patients showed clinical symptoms. Both peritumoral edema and spinal cysts were associated with clinical symptoms (P=0.023 and P=0.011, respectively).

CONCLUSION

The presence of peritumoral edema and/or spinal cysts shown on MRI in VHL-patients with spinal hemangioblastomas is associated with symptoms in more than half of the patients and may alert the clinician to intensify clinical and radiological surveillance.

Chromosomal Instability Characterizes Pediatric Medulloblastoma but Is Not Tolerated in the Developing Cerebellum

Medulloblastoma is a pediatric brain malignancy that consists of four transcriptional subgroups. Structural and numerical aneuploidy are common in all subgroups, although they are particularly profound in Group 3 and Group 4 medulloblastoma and in a subtype of SHH medulloblastoma termed SHHα. This suggests that chromosomal instability (CIN), the process leading to aneuploidy, is an important player in medulloblastoma pathophysiology. However, it is not known if there is ongoing CIN in medulloblastoma or if CIN affects the developing cerebellum and promotes tumor formation. To investigate this, we performed karyotyping of single medulloblastoma cells and demonstrated the presence of distinct tumor cell clones harboring unique copy number alterations, which is suggestive of ongoing CIN. We also found enrichment for processes related to DNA replication, repair, and mitosis in both SHH medulloblastoma and in the highly proliferative compartment of the presumed tumor cell lineage-of-origin, the latter also being sensitive to genotoxic stress. However, when challenging these tumor cells-of-origin with genetic lesions inducing CIN using transgenic mouse modeling, we found no evidence for large chromosomal aberrations in the cerebellum or for medulloblastoma formation. We therefore conclude that without a background of specific genetic mutations, CIN is not tolerated in the developing cerebellum in vivo and, thus, by itself is not sufficient to initiate medulloblastoma.

Resting energy expenditure in children at risk of hypothalamic dysfunction

OBJECTIVE

Children with suprasellar brain damage are at risk of hypothalamic dysfunction (HD). HD may lead to decreased resting energy expenditure (REE). Decreased REE, however, is not present in all children with HD. Our aim was to assess which children suspect for HD have low REE, and its association with clinical severity of HD or radiological hypothalamic damage.

PATIENTS AND METHODS

A retrospective cohort study was performed. Measured REE (mREE) of children at risk of HD was compared to predicted REE (pREE). Low REE was defined as mREE <90% of predicted. The mREE/pREE quotient was associated to a clinical score for HD symptoms and to radiological hypothalamic damage.

RESULTS

In total, 67 children at risk of HD (96% brain tumor diagnosis) with a mean BMI SDS of +2.3 ± 1.0 were included. Of these, 45 (67.2%) had low mREE. Children with severe HD had a significant lower mean mREE/pREE quotient compared to children with no, mild, or moderate HD. Mean mREE/pREE quotient of children with posterior hypothalamic damage was significantly lower compared to children with no or anterior damage. Tumor progression or tumor recurrence, severe clinical HD, and panhypopituitarism with diabetes insipidus (DI) were significant risk factors for reduced REE.

CONCLUSION

REE may be lowered in children with hypothalamic damage and is associated to the degree of clinical HD. REE is, however, not lowered in all children suspect for HD. For children with mild or moderate clinical HD symptoms, REE measurements may be useful to distinguish between those who may benefit from obesity treatment that increases REE from those who would be better helped using other obesity interventions.

IMMU-05. Integrative transcriptomic analysis of pilocytic astrocytomas reveals CNS region-associated characteristics

BACKGROUND: Recent insights highlight how the initiation and growth of gliomas is governed by interactions between glioma stem-like cells and stromal and immune cells in the tumor microenvironment. For pilocytic astrocytomas, the most common pediatric CNS tumor, this relationship is so far less explored. To this end, we used transcriptomic methods to investigate inter-patient heterogeneity, and the stromal and immune microenvironment of pilocytic astrocytomas. MATERIALS AND METHODS: In this study, we collected clinical data and tissue of 90 pre-treatment pilocytic astrocytomas from different CNS compartments: posterior fossa (n=57), supratentorial (n=23), and spinal (n=10). The median age at primary resection was 8 (0-16) years, and 66% (n=59) of our cohort was male. From 10 of these patients, we collected post-treatment samples after re-growth of the tumor as well. We characterized all samples by bulk RNA-sequencing and DNA methylation profiling, and selected a subset (n=10) samples for single-nucleus RNA-sequencing. RESULTS: Principal component analysis and unsupervised clustering of bulk sequencing data revealed gene expression patterns correlating to the CNS location of the tumor, consistent with prior reports. Using differential expression and functional pathway analysis, we found CNS region-associated enrichment of cell-cycle, developmental, and inflammatory-related pathways. With respect to the glioma immune microenvironment, supratentorial tumors were enriched in gene-sets related to T-cell activation and cytotoxicity, while spinal tumors had lowest expression of immune-related genes. Moreover, spinal tumors were enriched in pathways related to cell division, nucleotide synthesis, and neurodevelopment. To resolve cell-type expression programs of glioma and immune cells in the microenvironment, we collected and analyzed snRNA-seq data of 10 pilocytic astrocytomas, as well as harmonized our findings with a pre-existing dataset from Vladoiu, 2019. CONCLUSION: Our integrative transcriptomic analysis of pilocytic astrocytomas highlights CNS region-associated differences in expression programs of the glioma cells and in the immune cell composition of the tumor microenvironment.

MODL-16. Generation of immunocompetent syngeneic allograft mouse models for pediatric diffuse midline glioma

Diffuse midline gliomas (DMG) are highly aggressive pediatric brain tumors with a grim prognosis. A lack of effective treatment options highlights the critical need to investigate new therapeutic strategies. This includes the use of immunotherapy, which has shown promise in other hard-to-treat tumors. To facilitate immunotherapeutic research in this field, and to complement the existing immunodeficient patient-derived DMG models, we developed three distinct immunocompetent mouse models representing different DMG subtypes, i.e., histone 3 wildtype and histone 3 K27M mutant DMG (H3.3K27M or H3.1K27M), that can be used for preclinical testing of new therapies. We first established primary tumor cell cultures from murine DMG tumors that were generated by brainstem-targeted intra-uterine electroporation (IUE). This method enabled the introduction of DMG-associated mutations within the intact developing brainstem, thereby generating DMG tumors in a spatially and temporally defined manner, while maintaining a genetically identical (isogenic) background. We then created allograft DMG mouse models by orthotopically implanting the established primary cell cultures into syngeneic (C57BL/6) mice. Herewith, we provide an allograft tool that is better suitable for large-scale therapeutic studies and more accessible to the scientific community. Importantly, we demonstrated that these allograft models recapitulate the histopathologic phenotype of human DMG, including their diffuse infiltrative growth and expression of DMG-associated antigens. Furthermore, CyTOF mass cytometry analysis indicated that these murine pontine tumors exhibit a tumor immune microenvironment (TIME) similar to human DMG, characterized by considerable myeloid cell infiltration and a paucity of T-lymphocytes and NK cells. As such, we provide a representative model to further delineate the immune landscape in DMG and to preclinically investigate novel (immuno)therapies. Currently, we are using these immunocompetent models to study the interaction between DMG cells and microglia, and we are investigating how we can modify the immune microenvironment to improve checkpoint inhibition in DMG.

RONC-04. Relationship between proton therapy and the development of the limbic system in pediatric posterior fossa tumors

BACKGROUND: Pediatric brain tumor survivors may develop neuropsychological impairments after treatment. The first months after treatment could be a crucial time-window where the development of the brain may be affected by different types of treatments. For example, deficits in memory and learning related to hippocampal damage have resulted in radiotherapy dose constraints to the hippocampus. However, other limbic system substructures, important for cognition or behavior, may suffer from collateral doses. Therefore, we investigated the early effect of treatment on limbic structure volume. We hypothesized that radiotherapy (vs. no radiotherapy) would contribute to a decrease in volume of the limbic structures. METHODS AND MATERIALS: Thirty-eight patients with a tumor in the posterior fossa region (medulloblastoma n=12; pilocytic astrocytoma n=24; other=2) who were diagnosed between June 2018 and September 2020 and were alive ≥1 year diagnosis were included. Patients receiving neurosurgery only (n=26) were compared to patients treated with neurosurgery, proton therapy and chemotherapy (n=12). Limbic structures were automatically segmented in 111 MRI scans. These structures were amygdala, hippocampus (CA1+CA2/3), subiculum, dentate gyrus, parahippocampal gyrus, fornix, mammillary bodies, nucleus accumbens and thalamo-anteroventral nucleus of thalamus. RESULTS: Analyses revealed a significant negative effect of time on the amygdala (p<0.01), hippocampus (CA1) (p<0.001), and dentate gyrus (p<0.01). This indicates that these structures decreased in volume within the first year after diagnosis, independent of radiation treatment. Furthermore, an interaction effect was found between time and radiation in the subiculum (p=0.02) and fornix (p=0.052). CONCLUSION: These results indicate that the volumetric decline were stronger for the patients that received proton radiation. Future comparisons will test how results relate to the volumes in healthy children of the same age. Also, we will investigate whether this abnormal development is associated to the radiation dose and how it relates to the neuropsychological outcomes of the child over time.

Generation of Immunocompetent Syngeneic Allograft Mouse Models for Pediatric Diffuse Midline Glioma

Background

Diffuse midline gliomas (DMG) are highly malignant incurable pediatric brain tumors. A lack of effective treatment options highlights the need to investigate novel therapeutic strategies. This includes the use of immunotherapy, which has shown promise in other hard-to-treat tumors. To facilitate preclinical immunotherapeutic research, immunocompetent mouse models that accurately reflect the unique genetic, anatomical, and histological features of DMG patients are warranted.

Methods

We established cell cultures from primary DMG mouse models (C57BL/6) that were generated by brainstem targeted intra-uterine electroporation (IUE). We subsequently created allograft DMG mouse models by orthotopically implanting these tumor cells into syngeneic mice. Immunohistochemistry and -fluorescence, mass cytometry, and cell-viability assays were then used to verify that these murine tumors recapitulated human DMG.

Results

We generated three genetically distinct allograft models representing histone 3 wildtype (H3 WT) and K27M-mutant DMG (H3.3 K27M and H3.1 K27M). These allograft models recapitulated the histopathologic phenotype of their human counterparts, including their diffuse infiltrative growth and expression of DMG-associated antigens. These murine pontine tumors also exhibited an immune microenvironment similar to human DMG, characterized by considerable myeloid cell infiltration and a paucity of T-lymphocytes and NK cells. Finally, we show that these murine DMG cells display similar sensitivity to histone deacetylase (HDAC) inhibition as patient-derived DMG cells.

Conclusions

We created and validated an accessible method to generate immunocompetent allograft models reflecting different subtypes of DMG. These models adequately recapitulated the histopathology, immune microenvironment, and therapeutic response of human DMG, providing useful tools for future preclinical studies.

The developmental stage of the medulloblastoma cell-of-origin restricts Hedgehog pathway usage and drug sensitivity

Sonic hedgehog (SHH) medulloblastoma originates from the cerebellar granule neuron progenitor (CGNP) lineage, which depends on Hedgehog signaling for its perinatal expansion. Whereas SHH tumors exhibit overall deregulation of this pathway, they also show patient age-specific aberrations. To investigate whether the developmental stage of the CGNP can account for these age-specific lesions, we analyzed developing murine CGNP transcriptomes and observed highly dynamic gene expression as a function of age. Cross-species comparison with human SHH medulloblastoma showed partial maintenance of these expression patterns, and highlighted low primary cilium expression as hallmark of infant medulloblastoma and early embryonic CGNPs. This coincided with reduced responsiveness to upstream SHH pathway component Smoothened, whereas sensitivity to downstream components SUFU and GLI family proteins was retained. Together, these findings can explain the preference for SUFU mutations in infant medulloblastoma and suggest that drugs targeting the downstream SHH pathway will be most appropriate for infant patients.

Summary: There is a relationship between the age of the medulloblastoma patient and the developmental age of the tumor cell-of-origin, and this influences the SHH pathway signaling route used by the tumor.

Ophthalmological Evaluation in Children Presenting With a Primary Brain Tumor

BACKGROUND

Children with a brain tumor are prone to develop visual impairment, which to date is often underestimated and unrecognized. Our aim was to assess the prevalence of ophthalmological evaluation and abnormal ophthalmological findings, and investigate whether demographic and tumor-related characteristics are associated with abnormal ophthalmological findings in children presenting with a primary brain tumor.

METHODS

Medical records of all 90 children diagnosed with a primary brain tumor between June 2018 and May 2019 and treated at the Princess Máxima Center for Pediatric Oncology, a tertiary referral center in the Netherlands, were retrospectively reviewed. Univariate regression analysis was used to investigate associations between demographic, tumor-related and clinical characteristics, and abnormal ophthalmological findings.

RESULTS

Sixty children (34 male [56.7%]; median [range] age, 9.3 [0-16.9] years) underwent ophthalmological evaluation within 6 weeks before or after diagnosis, 11 children (5 male [45.5%]; median [range] age, 5.7 [0.1-17.2] years) were seen more than 6 weeks before or after diagnosis, and 19 children (7 male [36.8%]; median [range] age, 7.2 [1.9-16.6] years) did not receive ophthalmological evaluation within at least 6 months from diagnosis. A total of 19 children (21.1%) presented with visual symptoms as first sign leading to the diagnosis of a brain tumor. Children who presented with visual symptoms (odds ratio [OR], 22.52; 95% confidence interval [CI], 4.90-103.60) and/or hydrocephalus (OR, 3.60; 95% CI, 1.38-9.36) at diagnosis were more often seen for ophthalmological evaluation. The most common abnormal ophthalmological findings were eye movement disorders (66.0%), papilledema (44.1%), and visual field defects (58.1%). Eye movement disorders occurred more frequently in patients with an infratentorial tumor (OR, 4.71; 95% CI, 1.03-21.65). The risk of papilledema was associated with older age (OR, 1.19; 95% CI, 1.05-1.34), hydrocephalus (OR, 9.63; 95% CI, 2.68-34.61), and infratentorial (OR, 9.11; 95% CI, 1.77-46.78) and supratentorial (OR, 13.13; 95% CI, 1.92-89.52) tumors.

CONCLUSIONS

In this study, most children with a primary brain tumor underwent ophthalmological evaluation around diagnosis, 21% of the children were not evaluated. The high prevalence of abnormal ophthalmological findings stresses the importance of early standardized ophthalmological evaluation to detect visual impairment and provide timely treatment to potentially prevent permanent visual loss.

Transition From Diencephalic Syndrome to Hypothalamic Obesity in Children With Suprasellar Low Grade Glioma: A Case Series

BACKGROUND

Children with suprasellar low grade glioma (LGG) frequently develop problems to maintain their body weight within the normal range, due to hypothalamic dysfunction. Hypothalamic damage may result in the diencephalic syndrome (DS), characterized by underweight or failure to thrive, but also in hypothalamic obesity (HO). Children with LGG presenting with DS at young age often develop HO later in life. The underlying pathophysiology for this change in body mass index (BMI) is not understood. Previous hypotheses have focused on the tumor or its treatment as the underlying cause. To better understand its etiology, we aimed to relate changes in BMI over time in children with suprasellar LGG presenting with DS to age, tumor progression, treatment, and endocrine function. We hypothesize that the development of HO in children with LGG presenting with DS is related to maturation status of the hypothalamus at time of injury and thus age.

METHODS

In this retrospective case series, all cases diagnosed in the Netherlands with suprasellar located LGG, currently treated or followed, with a history of DS developing into HO were included.

RESULTS

In total, 10 children were included. Median age at LGG diagnosis was 1.5 years (range 0.4-5.5), median BMI SDS was -2.64. The children developed overweight at a median age of 4.5 years (2.2-9.8). The median total difference in BMI SDS between underweight and obesity was +5.75 SDS (4.5-8.7). No association could be found between transition of DS to HO and onset of a pituitary disorder (present in 70.0%), surgery, chemotherapy, or tumor behavior. Two had developed central precocious puberty (CPP), both while having underweight or normal weight.

CONCLUSION

The shift from DS to HO in children with hypothalamic LGG may be associated with age and not to tumor behavior, treatment characteristics or pituitary function. The development of CPP in these children seems not to be related to obesity. Our findings may indicate that the clinical picture of hypothalamic dysfunction reflects the maturation state of the hypothalamus at time of lesioning. Future prospective studies are needed to better understand underlying causative mechanisms of the morbid changes in body weight.

Pediatric high-grade gliomas and the WHO CNS Tumor Classification—Perspectives of pediatric neuro-oncologists and neuropathologists in light of recent updates

Background

The WHO Classification of Tumors of the Central Nervous System has undergone major restructuring. Molecularly defined diagnostic criteria were introduced in 2016 (revised 4th edition) and expanded in 2021 (5th edition) to incorporate further essential diagnostic molecular parameters. We investigated potential differences between specialists in perception of these molecularly defined subtypes for pediatric high-grade gliomas (pedHGG).

Methods

We designed a 22-question survey studying the impact of the revised 4th edition of the WHO classification on pedHGG. Data were collected and statistically analyzed to examine the spectrum of viewpoints and possible differences between neuro-oncologists and neuropathologists.

Results

465 participants from 53 countries were included; 187 pediatric neuro-oncologists (40%), 160 neuropathologists (34%), and 118 additional experts (26%). Neuro-oncologists reported issues with the introduction of molecularly defined tumor types, as well as the abolishment or renaming of established tumor entities, while neuropathologists did not to the same extent. Both groups indicated less relevant or insufficient diagnostic definitions were available in 2016. Reported issues were classified and assessed in the 2021 WHO classification and a substantial improvement was perceived. However, issues of high clinical relevance remain to be addressed, including the definition of clinical phenotypes for diffuse intrinsic pontine glioma and gliomatosis cerebri.

Conclusions

Within the WHO classification of pediatric brain tumors, such as pedHGG, rapid changes in molecular characterization have been introduced. This study highlights the ongoing need for cross talk between pathologist and oncologist to advance the classification of pedHGG subtypes and ensure biological relevance and clinical impact.

Cerebrospinal fluid leakage costs after craniotomy and health economic assessment of incidence reduction from a hospital perspective in the Netherlands

OBJECTIVES

We aim to quantify the cost difference between patients with incisional cerebrospinal fluid (iCSF) leakage and those without after intradural cranial surgery. Second, the potential cost savings per patient when a decrease in iCSF leakage rate would be achieved with and without added costs for preventative measures of various price and efficacy are modelled.

DESIGN

Health economic assessment from a hospital perspective based on a retrospective cohort study.

SETTING

Dutch tertiary referral centre.

PARTICIPANTS

We included 616 consecutive patients who underwent intradural cranial surgery between 1 September 2017 and 1 September 2018. Patients undergoing burr hole surgery or transsphenoidal surgery, or who died within 1 month after surgery or were lost to follow-up were excluded.

PRIMARY AND SECONDARY OUTCOME MEASURES

Outcomes of the cost analysis include a detailed breakdown of mean costs per patient for patients with postoperative iCSF leakage and patients without, and the mean cost difference. For the scenario analyses the outcomes are the potential cost savings per 1000 patients when a decrease in iCSF leakage would be achieved.

RESULTS

Mean cost difference between patients with and without iCSF leakage was €9665 (95%CI, €5125 to €14 205). The main cost driver was hospital stay with a difference of 8.5 days. A 25% incidence reduction would result in a mean cost saving of -€94 039 (95% CI, -€218 258 to -€7077) per 1000 patients. A maximum cost reduction of -€653 025 (95% CI, -€1 204 243 to -€169 120) per 1000 patients could be achieved if iCSF leakage would be reduced with 75% in all patients, with 72 cases of iCSF leakage avoided.

CONCLUSIONS

Postoperative iCSF leakage after intradural cranial surgery increases healthcare costs significantly and substantially. From a health economic perspective preventative measures to avoid iCSF leakage should be pursued.

Transitioning to molecular diagnostics in pediatric high-grade glioma: experiences with the 2016 WHO classification of CNS tumors

Background

Pediatric neuro-oncology was profoundly changed in the wake of the 2016 revision of the WHO Classification of Tumors of the Central Nervous System. Practitioners were challenged to quickly adapt to a system of tumor classification redefined by molecular diagnostics.

Methods

We designed a 22-question survey studying the impact of the revised WHO classification on pediatric high-grade glioma. The survey collected basic demographics, general attitudes, issues encountered, and opinions on pediatric subtypes. Participant answers were analyzed along socioeconomic lines utilizing the human development index (HDI) of the United Nations and membership in the group of seven (G7) world economic forum.

Results

Four hundred and sixty-five participants from 53 countries were included, 187 pediatric neurooncologists (40%), 160 neuropathologists (34%), and 118 other experts (26%). When asked about pediatric high-grade glioma entities, participants from very high development countries preferred treating a patient based on genetic findings. Participants from high and medium development countries indicated using traditional histology and tumor location as mainstays for therapeutic decisions. Non-G7 countries tended to regard the introduction of molecularly characterized tumor entities as a problem for daily routine due to lack of resources.

Conclusions

Our findings demonstrate an overall greater reliance and favorability to molecular diagnostics among very high development countries. A disparity in resources and access to molecular diagnostics has left some centers unable to classify pediatric high-grade glioma per the WHO classification. The forthcoming edition should strain to abate disparities in molecular diagnostic availability and work toward universal adaptation.

Cerebrospinal Fluid Leak after Transsphenoidal Surgery: A Systematic Review and Meta-analysis

Background Cerebrospinal fluid (CSF) leak is widely recognized as a challenging and commonly occurring postoperative complication of transsphenoidal surgery (TSS).

The primary objective of this study is to benchmark the current prevalence of CSF leak after TSS in the adult population.

Methods The authors followed the PRISMA guidelines. The PubMed, Embase, and Cochrane Library databases were searched for articles reporting CSF leak after TSS in the adult population. Meta-analysis was performed using the Untransformed Proportion metric in OpenMetaAnalyst. For two between-group comparisons a generalized linear mixed model was applied.

Results We identified 2,408 articles through the database search, of which 70, published since 2015, were included in this systematic review. These studies yielded 24,979 patients who underwent a total of 25,034 transsphenoidal surgeries. The overall prevalence of postoperative CSF leak was 3.4% (95% confidence interval or CI 2.8–4.0%). The prevalence of CSF leak found in patients undergoing pituitary adenoma resection was 3.2% (95% CI 2.5–4.2%), whereas patients who underwent TSS for another indication had a CSF leak prevalence rate of 7.1% (95% CI 3.0–15.7%) (odds ratio [OR] 2.3, 95% CI 0.9–5.7). Patients with cavernous sinus invasion (OR 3.0, 95% CI 1.1–8.7) and intraoperative CSF leak (OR 5.9, 95% CI 3.8–9.0) have increased risk of postoperative CSF leak. Previous TSS and microscopic surgery are not significantly associated with postoperative CSF leak.

Conclusion The overall recent prevalence of CSF leak after TSS in adults is 3.4%. Intraoperative CSF leak and cavernous sinus invasion appear to be significant risk factors for postoperative CSF leak.

Fully automatic brain tumor segmentation for 3D evaluation in augmented reality

OBJECTIVE

For currently available augmented reality workflows, 3D models need to be created with manual or semiautomatic segmentation, which is a time-consuming process. The authors created an automatic segmentation algorithm that generates 3D models of skin, brain, ventricles, and contrast-enhancing tumor from a single T1-weighted MR sequence and embedded this model into an automatic workflow for 3D evaluation of anatomical structures with augmented reality in a cloud environment. In this study, the authors validate the accuracy and efficiency of this automatic segmentation algorithm for brain tumors and compared it with a manually segmented ground truth set.

METHODS

Fifty contrast-enhanced T1-weighted sequences of patients with contrast-enhancing lesions measuring at least 5 cm3 were included. All slices of the ground truth set were manually segmented. The same scans were subsequently run in the cloud environment for automatic segmentation. Segmentation times were recorded. The accuracy of the algorithm was compared with that of manual segmentation and evaluated in terms of Sørensen-Dice similarity coefficient (DSC), average symmetric surface distance (ASSD), and 95th percentile of Hausdorff distance (HD95).

RESULTS

The mean ± SD computation time of the automatic segmentation algorithm was 753 ± 128 seconds. The mean ± SD DSC was 0.868 ± 0.07, ASSD was 1.31 ± 0.63 mm, and HD95 was 4.80 ± 3.18 mm. Meningioma (mean 0.89 and median 0.92) showed greater DSC than metastasis (mean 0.84 and median 0.85). Automatic segmentation had greater accuracy for measuring DSC (mean 0.86 and median 0.87) and HD95 (mean 3.62 mm and median 3.11 mm) of supratentorial metastasis than those of infratentorial metastasis (mean 0.82 and median 0.81 for DSC; mean 5.26 mm and median 4.72 mm for HD95).

CONCLUSIONS

The automatic cloud-based segmentation algorithm is reliable, accurate, and fast enough to aid neurosurgeons in everyday clinical practice by providing 3D augmented reality visualization of contrast-enhancing intracranial lesions measuring at least 5 cm3. The next steps involve incorporation of other sequences and improving accuracy with 3D fine-tuning in order to expand the scope of augmented reality workflow.

Hypothalamic-Pituitary Outcome after Treatment for Childhood Craniopharyngioma

Although childhood-onset craniopharyngioma is a low-grade intracranial tumor with excellent prognosis in terms of overall survival, survivors may suffer from devastating consequences caused by hypothalamic damage. Disease- or treatment-related hypothalamic damage leads to disturbed hunger-satiety and thirst feelings, decreased energy expenditure, behavioral problems, disturbances of circadian rhythm, temperature dysregulation, and pituitary dysfunction. These children are at great risk for developing the metabolic syndrome and comorbidities leading to premature mortality. In this chapter, we shall discuss hypothalamic-pituitary morbidity and outcome of childhood-onset craniopharyngioma patients and future perspectives for improvement.

Holographic patient tracking after bed movement for augmented reality neuronavigation using a head-mounted display

BACKGROUND

Holographic neuronavigation has several potential advantages compared to conventional neuronavigation systems. We present the first report of a holographic neuronavigation system with patient-to-image registration and patient tracking with a reference array using an augmented reality head-mounted display (AR-HMD).

METHODS

Three patients undergoing an intracranial neurosurgical procedure were included in this pilot study. The relevant anatomy was first segmented in 3D and then uploaded as holographic scene in our custom neuronavigation software. Registration was performed using point-based matching using anatomical landmarks. We measured the fiducial registration error (FRE) as the outcome measure for registration accuracy. A custom-made reference array with QR codes was integrated in the neurosurgical setup and used for patient tracking after bed movement.

RESULTS

Six registrations were performed with a mean FRE of 8.5 mm. Patient tracking was achieved with no visual difference between the registration before and after movement.

CONCLUSIONS

This first report shows a proof of principle of intraoperative patient tracking using a standalone holographic neuronavigation system. The navigation accuracy should be further optimized to be clinically applicable. However, it is likely that this technology will be incorporated in future neurosurgical workflows because the system improves spatial anatomical understanding for the surgeon.

Somatic mutations and single-cell transcriptomes reveal the root of malignant rhabdoid tumours

Malignant rhabdoid tumour (MRT) is an often lethal childhood cancer that, like many paediatric tumours, is thought to arise from aberrant fetal development. The embryonic root and differentiation pathways underpinning MRT are not firmly established. Here, we study the origin of MRT by combining phylogenetic analyses and single-cell mRNA studies in patient-derived organoids. Comparison of somatic mutations shared between cancer and surrounding normal tissues places MRT in a lineage with neural crest-derived Schwann cells. Single-cell mRNA readouts of MRT differentiation, which we examine by reverting the genetic driver mutation underpinning MRT, SMARCB1 loss, suggest that cells are blocked en route to differentiating into mesenchyme. Quantitative transcriptional predictions indicate that combined HDAC and mTOR inhibition mimic MRT differentiation, which we confirm experimentally. Our study defines the developmental block of MRT and reveals potential differentiation therapies.

Cerebrospinal fluid leakage after cranial surgery in the pediatric population-a systematic review and meta-analysis

BACKGROUND

Cerebrospinal fluid (CSF) leakage is a common complication after neurosurgical intervention. It is associated with substantial morbidity and increased healthcare costs. The current systematic review and meta-analysis aim to quantify the incidence of cerebrospinal fluid leakage in the pediatric population and identify its risk factors.

METHODS

The authors followed the PRISMA guidelines. The Embase, PubMed, and Cochrane database were searched for studies reporting CSF leakage after intradural cranial surgery in patients up to 18 years old. Meta-analysis of incidences was performed using a generalized linear mixed model.

RESULTS

Twenty-six articles were included in this systematic review. Data were retrieved of 2929 patients who underwent a total of 3034 intradural cranial surgeries. Surprisingly, only four of the included articles reported their definition of CSF leakage. The overall CSF leakage rate was 4.4% (95% CI 2.6 to 7.3%). The odds of CSF leakage were significantly greater for craniectomy as opposed to craniotomy (OR 4.7, 95% CI 1.7 to 13.4) and infratentorial as opposed to supratentorial surgery (OR 5.9, 95% CI 1.7 to 20.6). The odds of CSF leakage were significantly lower for duraplasty use versus no duraplasty (OR 0.41 95% CI 0.2 to 0.9).

CONCLUSION

The overall CSF leakage rate after intradural cranial surgery in the pediatric population is 4.4%. Risk factors are craniectomy and infratentorial surgery. Duraplasty use is negatively associated with CSF leak. We suggest defining a CSF leak as "leakage of CSF through the skin," as an unambiguous definition is fundamental for future research.

Current Accuracy of Augmented Reality Neuronavigation Systems: Systematic Review and Meta-Analysis

BACKGROUND

Augmented reality neuronavigation (ARN) systems can overlay three-dimensional anatomy and disease without the need for a two-dimensional external monitor. Accuracy is crucial for their clinical applicability. We performed a systematic review regarding the reported accuracy of ARN systems and compared them with the accuracy of conventional infrared neuronavigation (CIN).

METHODS

PubMed and Embase were searched for ARN and CIN systems. For ARN, type of system, method of patient-to-image registration, accuracy method, and accuracy of the system were noted. For CIN, navigation accuracy, expressed as target registration error (TRE), was noted. A meta-analysis was performed comparing the TRE of ARN and CIN systems.

RESULTS

Thirty-five studies were included, 12 for ARN and 23 for CIN. ARN systems could be divided into head-mounted display and heads-up display. In ARN, 4 methods were encountered for patient-to-image registration, of which point-pair matching was the one most frequently used. Five methods for assessing accuracy were described. Ninety-four TRE measurements of ARN systems were compared with 9058 TRE measurements of CIN systems. Mean TRE was 2.5 mm (95% confidence interval, 0.7-4.4) for ARN systems and 2.6 mm (95% confidence interval, 2.1-3.1) for CIN systems.

CONCLUSIONS

In ARN, there seems to be lack of agreement regarding the best method to assess accuracy. Nevertheless, ARN systems seem able to achieve an accuracy comparable to CIN systems. Future studies should be prospective and compare TREs, which should be measured in a standardized fashion.

Surgical intervention for hydrocephalus in infancy; etiology, age and treatment data in a Dutch cohort

PURPOSE

To gain insight into the patient characteristics of surgically treated hydrocephalus in the Netherlands, we report the first data from the Dutch Quality Registry NeuroSurgery (QNRS) database for infants with hydrocephalus requiring surgical intervention.

METHODS

We used the prospectively gathered database concerning infants ≤ 2 years of age surgically treated for hydrocephalus. We report data from start of registry, concerning etiology, age, and treatment of patients registered. We compared data with the Hydrocephalus Clinical Research Network (HCRN), a multicenter network of pediatric neurosurgical institutions in North America.

RESULTS

A total of 359 operated infants was registered in the period from 2010 to 2017. A drop in patients registered was seen in 2015, possibly due to revisions of the database. Most infants were operated on between 1 and 6 months of age. Cause of hydrocephalus was predominantly intracranial hemorrhage, followed by congenital causes. The proportion of infants with aqueduct stenosis and myelomeningocele as cause of hydrocephalus stayed relatively stable during this period of registration. Initial shunting was performed in 40% and reservoir/ETV as initial treatment was done in 60%. In both groups, 50% needed revision surgery.

CONCLUSIONS

The first data concerning surgically treated pediatric hydrocephalus from a prospectively collected Dutch register are presented, showing similar results when comparing to the HCRN database.

Variations in screening and management practices for subsequent asymptomatic meningiomas in childhood, adolescent and young adult cancer survivors

INTRODUCTION

Childhood, adolescent and young adult (CAYA) cancer survivors treated with cranial radiotherapy are at risk for developing subsequent meningiomas. There is insufficient evidence concerning the benefits and harms of screening for subsequent meningiomas, and uncertainty about the most appropriate clinical management of asymptomatic meningiomas. Data describing current clinical decision-making is essential to formulate surveillance recommendations.

METHODS

We created an online survey to identify the current international clinical practice regarding screening for and management of subsequent asymptomatic meningiomas among CAYA cancer survivors. Fifty-nine physicians from North America and Europe with expertise relevant to meningiomas were invited to participate.

RESULTS

Thirty-four physicians (58%) completed the survey. The reported number of CAYA cancer survivors that physicians are willing to screen to detect one meningioma varied widely from 0 to 750 (median 50). Physicians expressed concerns regarding harms from MRI screening, including risks of unnecessary interventions (n = 25, 73%) and overdiagnosis (n = 19, 56%). Growth pattern (n = 33, 97%), location (n = 31, 91%) and size (n = 29, 85%) were endorsed as the most important factors influencing the decision to treat asymptomatic meningiomas. A challenging location (n = 14, 52%), indolent tumor growth pattern (n = 13, 48%), and absence of symptoms (n = 12, 44%) were endorsed as the main reasons to monitor without intervention.

CONCLUSIONS

There is international variation in opinions and clinical practice regarding screening for subsequent asymptomatic meningiomas among at risk CAYA cancer survivors. Decision-making regarding interventions of asymptomatic meningiomas are largely driven by clinical characteristics. These valuable insights into current clinical practice will inform surveillance guidelines for CAYA cancer survivors.

Experiences with Glucagon-Like Peptide-1 Receptor Agonist in Children with Acquired Hypothalamic Obesity

OBJECTIVE

Hypothalamic obesity (HO) in children after treatment for a tumor in the suprasellar region has severe implications. Previous studies have shown various effects of glucagon-like peptide-1 (GLP-1) receptor agonist in acquired HO, but in adults only. We present our experience of GLP-1 receptor agonist (exenatide) treatment during a 1-year period on body mass index (BMI) in children with acquired HO.

PATIENTS AND METHODS

Children with severe weight gain after treatment for suprasellar tumor were given 2 mg exenatide weekly for a 12-month period. All had undergone previous dietary intervention. BMI standard deviation score (SDS), weight change, and adverse effects were assessed.

RESULTS

Five children with a mean age of 15.4 years (range 13-18) and a mean follow-up time of 8.4 years (mean age of 7.0 years at the time of brain tumor diagnosis) were treated with GLP-1 receptor agonist. After 1 year, BMI SDS or absolute weight had not changed significantly compared to the period without treatment (BMI SDS change +0.005, 95% CI -0.07 to 0.08, p = 0.89, and absolute weight change +1.5 kg, 95% CI -0.08 to 3.1, p = 0.061). Only 1 patient experienced weight loss after 1 year (-5.4 kg, BMI SDS -0.33). All patients experienced mild side effects, such as injection pain or nausea, and 2 patients stopped treatment upon their own request after 8 and 11 months, respectively.

CONCLUSIONS

In this small cohort, we found little effect of GLP-1 receptor agonist in the treatment for acquired HO. Future research should focus on the prevention of HO or, if prevention is not possible, on alternative, individualized interventions.

Identification of Two Protein-Signaling States Delineating Transcriptionally Heterogeneous Human Medulloblastoma

The brain cancer medulloblastoma consists of different transcriptional subgroups. To characterize medulloblastoma at the phosphoprotein-signaling level, we performed high-throughput peptide phosphorylation profiling on a large cohort of SHH (Sonic Hedgehog), group 3, and group 4 medulloblastomas. We identified two major protein-signaling profiles. One profile was associated with rapid death post-recurrence and resembled MYC-like signaling for which MYC lesions are sufficient but not necessary. The second profile showed enrichment for DNA damage, as well as apoptotic and neuronal signaling. Integrative analysis demonstrated that heterogeneous transcriptional input converges on these protein-signaling profiles: all SHH and a subset of group 3 patients exhibited the MYC-like protein-signaling profile; the majority of the other group 3 subset and group 4 patients displayed the DNA damage/apoptotic/neuronal signaling profile. Functional analysis of enriched pathways highlighted cell-cycle progression and protein synthesis as therapeutic targets for MYC-like medulloblastoma.

Validity Evidence for the Neuro-Endoscopic Ventriculostomy Assessment Tool (NEVAT)

BACKGROUND

Growing demand for transparent and standardized methods for evaluating surgical competence prompted the construction of the Neuro-Endoscopic Ventriculostomy Assessment Tool (NEVAT).

OBJECTIVE

To provide validity evidence of the NEVAT by reporting on the tool's internal structure and its relationship with surgical expertise during simulation-based training.

METHODS

The NEVAT was used to assess performance of trainees and faculty at an international neuroendoscopy workshop. All participants performed an endoscopic third ventriculostomy (ETV) on a synthetic simulator. Participants were simultaneously scored by 2 raters using the NEVAT procedural checklist and global rating scale (GRS). Evidence of internal structure was collected by calculating interrater reliability and internal consistency of raters' scores. Evidence of relationships with other variables was collected by comparing the ETV performance of experts, experienced trainees, and novices using Jonckheere's test (evidence of construct validity).

RESULTS

Thirteen experts, 11 experienced trainees, and 10 novices participated. The interrater reliability by the intraclass correlation coefficient for the checklist and GRS was 0.82 and 0.94, respectively. Internal consistency (Cronbach's α) for the checklist and the GRS was 0.74 and 0.97, respectively. Median scores with interquartile range on the checklist and GRS for novices, experienced trainees, and experts were 0.69 (0.58-0.86), 0.85 (0.63-0.89), and 0.85 (0.81-0.91) and 3.1 (2.5-3.8), 3.7 (2.2-4.3) and 4.6 (4.4-4.9), respectively. Jonckheere's test showed that the median checklist and GRS score increased with performer expertise ( P = .04 and .002, respectively).

CONCLUSION

This study provides validity evidence for the NEVAT to support its use as a standardized method of evaluating neuroendoscopic competence during simulation-based training.

Management and consequences of postoperative fluctuations in plasma sodium concentration after pediatric brain tumor surgery in the sellar region: a national cohort analysis

PURPOSE

Severe fluctuations in plasma sodium concentration and plasma osmolarity, including central diabetes insipidus (CDI), may have significant influence on postoperative morbidity and mortality after pediatric brain tumor surgery.The aim of this study was to describe the frequency, severity and neurological consequences of these fluctuations in pediatric brain tumor survivors.

METHODS

A retrospective, multi-institutional chart review was conducted among all children who underwent brain tumor surgery in the sellar or suprasellar region in seven university hospitals in the Netherlands between January 2004 and December 2013.

RESULTS

Postoperative CDI was observed in 67.5% of 120 included children. Fluctuations of plasma sodium concentration ≥ 10 mmol/L/24 h during the first ten postoperative days were seen in 75.3% of patients with CDI, with a maximum delta of 46 mmol/L/24 h. When compared to patients without CDI, altered mental status occurred more frequently in patients with postoperative CDI (5.1 vs. 23.5% respectively, p = 0.009). Low plasma sodium concentration was related to altered mental status and the occurrence of seizures. Frequency and severity of fluctuations in plasma sodium concentration during the first ten postoperative days were significantly higher in patients with permanent CDI at last follow-up than in patients with transient CDI or without CDI (p = 0.007).

CONCLUSION

Postoperative CDI is a common complication after pediatric brain tumor surgery in the sellar or suprasellar region. Extreme plasma sodium concentrations and large intra-day fluctuations still occur and seem to influence the postoperative neurological course. These results illustrate the need for intensive monitoring in a highly experienced center.

Endoscopic third ventriculostomy and repeat endoscopic third ventriculostomy in pediatric patients: the Dutch experience

OBJECTIVE After endoscopic third ventriculostomy (ETV), some patients develop recurrent symptoms of hydrocephalus. The optimal treatment for these patients is not clear: repeat ETV (re-ETV) or CSF shunting. The goals of the study were to assess the effectiveness of re-ETV relative to initial ETV in pediatric patients and validate the ETV success score (ETVSS) for re-ETV. METHODS Retrospective data of 624 ETV and 93 re-ETV procedures were collected from 6 neurosurgical centers in the Netherlands (1998-2015). Multivariable Cox proportional hazards modeling was used to provide an adjusted estimate of the hazard ratio for re-ETV failure relative to ETV failure. The correlation coefficient between ETVSS and the chance of re-ETV success was calculated using Kendall's tau coefficient. Model discrimination was quantified using the c-statistic. The effects of intraoperative findings and management on re-ETV success were also analyzed. RESULTS The hazard ratio for re-ETV failure relative to ETV failure was 1.23 (95% CI 0.90-1.69; p = 0.20). At 6 months, the success rates for both ETV and re-ETV were 68%. ETVSS was significantly related to the chances of re-ETV success (τ = 0.37; 95% bias corrected and accelerated CI 0.21-0.52; p < 0.001). The c-statistic was 0.74 (95% CI 0.64-0.85). The presence of prepontine arachnoid membranes and use of an external ventricular drain (EVD) were negatively associated with treatment success, with ORs of 4.0 (95% CI 1.5-10.5) and 9.7 (95% CI 3.4-27.8), respectively. CONCLUSIONS Re-ETV seems to be as safe and effective as initial ETV. ETVSS adequately predicts the chance of successful re-ETV. The presence of prepontine arachnoid membranes and the use of EVD negatively influence the chance of success.

Development of the Endoscopic Endonasal Sinus and Skull Base Surgery Questionnaire

BACKGROUND

The patients' perspective of health outcomes has become important input for assessing treatment effects. However, existing endoscopic endonasal surgery (EES) instruments are not fully aligned with the concept of health-related quality of life (HRQoL). A prospective cohort study was therefore conducted to develop a suitable quality-of-life tool to assess nasal morbidity after EES: the Endoscopic Endonasal Sinus and Skull Base Surgery Questionnaire (EES-Q).

METHODS

The study included 300 patients: 207 with sinus pathology and 93 with anterior skull base pathology. The EES-Q was administered prior to surgery and postoperatively (2 weeks, 3 months, and 1 year). Psychometric instrument properties were tested and relevant health domains were formulated. Seventy-two items were generated by the conventional psychometric approach. An exploratory factor analysis was used to test construct validity. The optimal number of factors to retain was determined by using the eigenvalues-greater-than-1 rule and scree plot. Orthogonal varimax rotation was used to enhance interpretability. Internal consistency was assessed using the Cronbach α.

RESULTS

The factor analysis yielded a 3-factor solution, representing physical, psychological, and social functioning. The final version of the instrument consisted of 30 items with a high internal consistency (>0.80) for all 3 HRQoL domains.

CONCLUSIONS

The EES-Q is a comprehensive, multidimensional, disease-specific instrument. A distinguishing characteristic is that, apart from the physical and psychological domains, the EES-Q also encompasses a social domain. Understanding different HRQoL aspects in patients undergoing EES may help caregivers restore, improve, or preserve the patient's health through individualized care, which depends on identifying their specific needs.

Abstract 5826: Essential role for cyclic-AMP responsive element binding protein 1 (CREB1) phosphorylation in the survival of medulloblastoma patients

Prognosis for recurrent medulloblastoma patients is extremely poor, with a median survival of 26.8 months. Treatment options for recurrent medulloblastoma patients are limited and ineffective due to resistance to chemotherapeutic agents and radiotherapy. Therefore, more research is required to address the high mortality of medulloblastoma patients that have therapy-resistant medulloblastoma. In a previous, study, we showed that cyclic-AMP responsive element binding protein (CREB1) was highly phosphorylated in primary medulloblastoma specimens. CREB is an important transcription factor involved in cerebellar cell proliferation and survival. In various cancers types, the expression of CREB is associated with prognosis. Untill now, CREB expression and its relation with overall survival has not been studied in medulloblastoma patients. In this study, we determined CREB phosphorylation levels and mRNA levels of CREB and its transcriptional co-activators CREBBP and EP300 using peptide phosphorylation and gene expression arrays in a cohort of 50 pediatric medulloblastoma patients. Furthermore, we performed shRNA-mediated knockdown of CREB, CREBBP and EP300 mRNA levels in medulloblastoma cell line DAOY. Knockdown was confirmed by means of qRT-PCR and western blotting. Next, cell viability assays were used to investigate the effect of chemotherapeutic reagents (etoposide and/or cisplatin) on cell viability in CREB, CREBBP or EP300 knockdown cells or in combination with a small molecule CREB inhibitor (KG-501).Low CREB phosphorylation levels in combination with low CREBBP and EP300 mRNA levels was significantly associated with poor overall survival (p=0.0001) with a median survival of 11.7 months in medulloblastoma patients. High CREB phosphorylation in combination with high CREBBP and EP300 mRNA levels was associated with a favourable prognosis (5 year-overall survival: 91%). Supervised clustering of gene expression data based upon low versus high CREB phosphorylation and CREBBP/EP300 mRNA levels and subsequent gene ontology analysis showed significant enrichment of genes associated with cerebellar and neuronal differentiation and development. Furthermore, knockdown with shCREB.3, shCBP.1-2 or shEP300A completely rescued DAOY cells from the etoposide-induced decrease in cell viability that was observed in the scrambled control. Similarly, addition of the CREB inhibitor KG-501 (2μM) completely rescued DAOY cells from the etoposide-induced decrease in cell viability and partially rescued DAOY cells from the cisplatin-induced decrease in cell viability.Together, these findings support an important role for CREB in neuronal differentiation, chemosensitivity and in the overall survival of pediatric medulloblastoma patients.

Citation Format: Walderik W. Zomerman, Sabine L. Plasschaert, Frank J. Scherpen, Harm Jan J. Lourens, Geesina C. Huizinga, Eelco W. Hoving, Wilfred F. den Dunnen, Sophia Bruggeman, Eveline S.J.M. de Bont. Essential role for cyclic-AMP responsive element binding protein 1 (CREB1) phosphorylation in the survival of medulloblastoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5826. doi:10.1158/1538-7445.AM2017-5826

Neurofibromatosis type 1 associated low grade gliomas: A comparison with sporadic low grade gliomas

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder, associated with a variable clinical phenotype including café-au-lait spots, intertriginous freckling, Lisch nodules, neurofibromas, optic pathway gliomas and distinctive bony lesions. NF1 is caused by a mutation in the NF1 gene, which codes for neurofibromin, a large protein involved in the MAPK- and the mTOR-pathway through RAS-RAF signalling. NF1 is a known tumour predisposition syndrome, associated with different tumours of the nervous system including low grade gliomas (LGGs) in the paediatric population. The focus of this review is on grade I pilocytic astrocytomas (PAs), the most commonly observed histologic subtype of low grade gliomas in NF1. Clinically, these PAs have a better prognosis and show different localisation patterns than their sporadic counterparts, which are most commonly associated with a KIAA1549:BRAF fusion. In this review, possible mechanisms of tumourigenesis in LGGs with and without NF1 will be discussed, including the contribution of different signalling pathways and tumour microenvironment. Furthermore we will discuss how increased understanding of tumourigenesis may lead to new potential targets for treatment.

Functional outcome at school age of neonatal post-hemorrhagic ventricular dilatation

BACKGROUND

Specific knowledge about the functional outcome of preterm born children with post-hemorrhagic ventricular dilatation (PHVD) is lacking.

OBJECTIVES

To determine functional outcome at school age in children with post-hemorrhagic ventricular dilatation and to identify whether PHVD characteristics increased the risk for deficits.

METHODS

Single-center case-control study. Included were preterm children born between 1996 and 2003 who had PHVD in their neonatal period. The controls were children matched for gestation, gender, and year of birth. At school age, using standardized tests and questionnaires, we assessed intelligence, attention, verbal memory, executive functioning, visual perception, visuomotor integration, motor skills, and behavior.

RESULTS

Of 34 children with PHVD 28 survived, three of whom could not be tested at school age (one child's parents declined and two were lost to follow-up). At a mean age of 10years (6-14years) the total and verbal IQs of the remaining 25 children (17 boys, 8 girls) were significantly lower compared to controls (difference in total IQ-14 points, verbal IQ-9 points, P=0.001and P=0.009, respectively). After adjustment for possible confounders, the performance of the PHVD group was poorer on visual perception and attention tests. Selective attention showed a trend toward risk of borderline and abnormal scores (OR 4.03, 95%-CI 0.84-19.2). Within the PHVD group, total IQ was significantly lower (P=0.048) in those who had undergone surgical intervention (n=12).

CONCLUSION

At school age, intelligence, attention, and visual perception were more affected in the PHVD group than in the matched controls. Surgical intervention was associated with lower IQ scores.

A heritable form of SMARCE1-related meningiomas with important implications for follow-up and family screening

Childhood meningiomas are rare. Recently, a new hereditary tumor predisposition syndrome has been discovered, resulting in an increased risk for spinal and intracranial clear cell meningiomas (CCMs) in young patients. Heterozygous loss-of-function germline mutations in the SMARCE1 gene are causative, giving rise to an autosomal dominant inheritance pattern. We report on an extended family with a pediatric CCM patient and an adult CCM patient and several asymptomatic relatives carrying a germline SMARCE1 mutation, and discuss difficulties in genetic counseling for this heritable condition. Because of the few reported cases so far, the lifetime risk of developing meningiomas for SMARCE1 mutation carriers is unclear and the complete tumor spectrum is unknown. There is no surveillance guideline for asymptomatic carriers nor a long-term follow-up recommendation for SMARCE1-related CCM patients as yet. Until more information is available about the penetrance and tumor spectrum of the condition, we propose the following screening advice for asymptomatic SMARCE1 mutation carriers: neurological examination and MRI of the brain and spine, yearly from diagnosis until the age of 18 and once every 3 years thereafter, or in between if there are clinical symptoms. This advice can also be used for long-term patient follow-up. More data is needed to optimize this proposed screening advice.

A novel technique to treat acquired Chiari I malformation after supratentorial shunting

PURPOSE

The acquired Chiari I malformation with abnormal cranial vault thickening is a rare late complication of supratentorial shunting. It poses a difficult clinical problem, and there is debate about the optimal surgical strategy. Some authors advocate supratentorial skull enlarging procedures while others prefer a normal Chiari decompression consisting of a suboccipital craniectomy, with or without C1 laminectomy and dural patch grafting.

METHODS

We illustrate three cases of symptomatic acquired Chiari I malformation due to inward cranial vault thickening.

RESULTS

We describe a new surgical approach that appears to be effective in these patients. This approach includes the standard Chiari decompression combined with posterior fossa augmentation by thinning the occipital planum.

CONCLUSION

Internal volume re-expansion of the posterior fossa by thinning the occipital planum appears to be an effective novel surgical strategy in conjunction with the standard surgical therapy of Chiari decompression.