Search

Introduction: Human Herpes Virus-6 (HHV-6) is a ubiquitous virus but can lead to deleterious clinical manifestations due to its predilection for the pediatric central nervous system. Despite significant literature describing its common clinical course, it is rarely considered as a causative agent in CSF pleocytosis in the setting of craniotomy and external ventricular drainage device. Identification of a primary HHV-6 infection allowed for timely treatment with an antiviral agent along with earlier discontinuation of antibiotic regimen and expedited placement of a ventriculoperitoneal shunt. Case Presentation: A two-year-old girl presented with 3 months of progressive gait disturbance and intranuclear ophthalmoplegia. Following craniotomy for removal of 4th ventricular pilocytic astrocytoma and decompression of hydrocephalus, she suffered a prolonged clinical course due to persistent fevers and worsening CSF leukocytosis despite multiple antibiotic regimens. The patient was admitted to the hospital during the COVID-19 pandemic and isolated with her parents in the intensive care unit with strict infection control measures. FilmArray Meningitis/Encephalitis (FAME) panel ultimately detected HHV-6. Clinical confirmation of HHV-6-induced meningitis was proposed given improvement in CSF leukocytosis and fever reduction following the initiation of antiviral medications. Pathologic analysis of brain tumor tissue failed to show HHV-6 genome positivity, suggesting a primary peripheral etiology of infection. Discussion/Conclusion: Here, we present the first known case of HHV-6 infection detected by FAME following intracranial tumor resection. We propose a modified algorithm for persistent fever of unknown origin which may decrease symptomatic sequelae, minimize additional procedures, and shorten length of ICU stay.

Achondroplasia is the most common of skeletal dysplasias and is caused by a defect in endochondral bone formation. In addition to skeletal deformities, patients with achondroplasia possess significant abnormalities of the axial skeleton, including small skull base with a narrowed foramen magnum and small vertebral bodies with shortened pedicles. Consequently, patients with achondroplasia are at risk of several severe neurologic conditions, such as cervicomedullary compression, spinal stenosis, and hydrocephalus, which frequently require the attention of a neurosurgeon. This article provides an updated review on the neurosurgical evaluation and care of children with Achondroplasia.

Introduction: Arachnoid membranes are well recognized as a cause of cerebrospinal fluid (CSF) flow impairment in disorders such as obstructive hydrocephalus and syringohydromyelia, but can be difficult to detect with standard noninvasive imaging techniques. True fast imaging with steady-state precession (TrueFISP) can exhibit brain pulsations and CSF dynamics with high spatiotemporal resolution. Here, we demonstrate the utility of this technique in the diagnosis and management of arachnoid membranes in the posterior fossa. Case Presentations: Three symptomatic children underwent cine TrueFISP imaging for suspicion of CSF membranous obstruction. Whereas standard imaging failed to or did not clearly visualize the site of an obstructive lesion, preoperative TrueFISP identified a membrane in all 3 cases. The membranes were confirmed intraoperatively, and postoperative TrueFISP helped verify adequate marsupialization and recommunication of CSF flow. Two out of the 3 cases showed a decrease in cerebellar tonsillar pulsatility following surgery. All children showed symptomatic improvement. Conclusion: TrueFISP is able to detect pulsatile arachnoid membranes responsible for CSF outflow obstruction that are otherwise difficult to visualize using standard imaging techniques. We advocate use of this technology in pre- and postsurgical decision-making as it provides a more representative image of posterior fossa pathology and contributes to our understanding of CSF flow dynamics. There is potential to use this technology to establish prognostic biomarkers for disorders of CSF hydrodynamics.

Background: Choroid plexectomy was first performed around 1910. Later, the technique evolved into subtotal choroid plexus cauterization (CPC) but was largely abandoned following the invention of the ventriculoperitoneal shunt. Over time, with improved understanding of the pathophysiology of hydrocephalus and improvement in endoscopic techniques and equipment, the procedure of CPC was reintroduced. However, little is known about the biomolecular consequences of ablation of a significant portion of the choroid plexus on metabolic brain homeostasis, neurogenesis, and neuroimmunology. Summary: The physiological functions of choroid plexus in neurogenesis and neuroimmunology and its role in diseases, such as AD and MS, should alert to possible as yet to be determined consequences. Studies, both in children and in adults, are needed not only on the success in hydrodynamic stabilization of hydrocephalus but also on the long-term outcome, especially premature neurodegeneration and inflammatory changes and on compensatory metabolic mechanisms. Key Messages: The value of CPC for treatment of hydrocephalus in medically underserved areas should be remembered, yet when alternative treatment options are available, we cannot responsibly advocate against or for the use of CPC. Therefore, perhaps a more detailed discussion of risks and benefits of a CPC with parents would be best to include the possible implications in brain development and function.

Study Design Retrospective cohort study Objectives To describe the common types of complications and their risk factors during spine surgery in patients with achondroplasia. Methods A retrospective review was performed of medical records of adult achondroplasia patients who underwent spine surgery at our institution between 2007 and 2021. Inclusion criteria were achondroplasia and age >16 years. Surgical encounters were evaluated for durotomy, postoperative neurologic deficit, wound compromise, medical complications, and return to the operating room. Statistical analysis included evaluation of relationships across complications and fisher exact test applied to bivariate/categorical variables and t-test/ANOVA for continuous variables. Multivariable analysis using logistic regression was performed to account for patient characteristics Results Fifty-five patients with achondroplasia underwent 95 surgeries. Forty-nine percent of the surgeries involved a complication. These included durotomy (33.7%), neurologic deficit (11.6%), wound compromise (6.3%), and other medical complications (6.3%). Thirteen percent of surgeries required return to the operating room. The greatest number of complications occurred in thoracolumbar region (60.0%) compared to cervicothoracic (18.2%) and craniocervical junction (33.3%). Chronologically later surgical encounters had decreased complications and durotomies only occurred in thoracolumbar surgeries (45.7%). Conclusions Adult patients with achondroplasia undergoing surgery chronologically later in this set of consecutive patients were at a decreased risk for complications. Thoracolumbar surgeries were at the greatest risk for durotomies. Male sex was a risk factor for durotomy, while age was a risk factor for neurologic deficit. The potential for adverse surgical events should be considered when evaluating patients with achondroplasia for spine surgery.

Much of the current medical discussion for within centers for skeletal dysplasia and specifically patients with achondroplasia focuses on infancy and early childhood. Most neurosurgical concerns arise due to a defect in the endochondral ossification, resulting on early fusion of the synchondrosis. As patients age, the neurosurgical focus shifts from primarily cranial to spinal concerns. Often pediatric neurosurgeons may continue to follow their patients with skeletal dysplasia. However, general adult neurosurgeons and orthopedic surgeons may see these graduated adults in their practice. This article provides a review of the common neurosurgical concerns for patients with achondroplasia.

Graphical abstract, Neurosurgery as one of the most technologically demanding medical fields rapidly adapts the newest developments from multiple scientific disciplines for treating brain tumors. Despite half a century of clinical trials, survival for brain primary tumors such as glioblastoma (GBM), the most common primary brain cancer, or rare ones including primary central nervous system lymphoma (PCNSL), is dismal. Cancer therapy and research have currently shifted toward targeted approaches, and personalized therapies. The orchestration of novel and effective blood–brain barrier (BBB) drug delivery approaches, targeting of cancer cells and regulating tumor microenvironment including the immune system are the key themes of this review. As the global pandemic due to SARS-CoV-2 virus continues, neurosurgery and neuro-oncology must wrestle with the issues related to treatment-related immune dysfunction. The selection of chemotherapeutic treatments, even rare cases of hypersensitivity reactions (HSRs) that occur among immunocompromised people, and number of vaccinations they have to get are emerging as a new chapter for modern Nano neurosurgery.

INTRODUCTION Gliomas are considered immunologically “cold” tumors that mask themselves from the immune system. Immunotherapy, a breakthrough for cancer treatment, remains inefficient for gliomas. H3K27M mutant diffuse midline glioma has poor survival. Using our innovative mosaic analysis with dual recombinases technology (Cell 2019), we further created a novel murine model of H3K27M glioma with an inducible expression of LAG3 and TGFBR2 to make the tumor recognizable by the immune system. This allows studying molecular mechanisms of “perfect” immunotherapy in pediatric gliomas with histone H3.3 mutations. METHODS To make a novel murine model, H3K27M plasmids with doxycycline-inducible expression for TGFBR2 and LAG3 were designed, sequenced, and replicated. For in vitro validation, murine neuronal stem cells were nucleofected with these plasmids, grown and sorted. Doxycycline was added to the experimental group in vitro to induce expression. The plasmids were then electroporated into neonatal MGMT mice (n=21) of both genders. Control mice were used on a standard diet (n=9) and experimental mice (n=12) were given doxycycline in food to induce TGFBR2 and LAG3 expression in vivo. Mice were followed up for survival. RESULTS Plasmid sequencing validation demonstrated their high purity. In vitro nucleofected neuronal stem cells showed significant increase in TGFBR2 and LAG3 expression by immunofluorescent staining after addition of doxycycline. The mouse survival study showed a significant benefit with treatment group surviving 46% longer (135 ± 41.9 days vs. 92.6 ± 32.7 days in the control group, p=0.030). Conclusion and Future Directions: We have successfully modified H3K27M glioma to have inducible expression of TGFBR2 and LAG3 to simulate “perfect” immunotherapy. The survival study showed a significant survival benefit. The development of organoid transplants for more uniform testing and next-generation sequencing is ongoing. This can lead to the emergence of novel immune therapies and uncover novel mechanisms of tumor response to treatment.

Growth promoting variants in PIK3CA cause a spectrum of developmental disorders, depending on the developmental timing of the mutation and tissues involved. These phenotypically heterogeneous entities have been grouped as PIK3CA-Related Overgrowth Spectrum disorders (PROS). Deep sequencing technologies have facilitated detection of low-level mosaic, often necessitating testing of tissues other than blood. Since clinical management practices vary considerably among healthcare professionals and services across different countries, a consensus on management guidelines is needed. Clinical heterogeneity within this spectrum leads to challenges in establishing management recommendations, which must be based on patient-specific considerations. Moreover, as most of these conditions are rare, affected families may lack access to the medical expertise that is needed to help address the multi-system and often complex medical issues seen with PROS. In March 2019,macrocephaly-capillary malformation (M-CM) patient organizations hosted an expert meeting in Manchester, United Kingdom, to help address these challenges with regards to M-CM syndrome. We have expanded the scope of this project to cover PROS and developed this consensus statement on the preferred approach for managing affected individuals based on our current knowledge.

The role of cervicomedullary decompression (CMD) in the care of hydrocephalic achondroplastic children who present with simultaneous foramen magnum stenosis is not well understood. We sought to determine the percentage of symptomatic achondroplastic children with foramen magnum stenosis who had stabilization or improvement in ventriculomegaly following CMD. The authors retrospectively reviewed the records of pediatric patients at Cedars-Sinai Medical Center with achondroplasia and signs of progressive ventriculomegaly who underwent CMD for symptomatic foramen magnum stenosis between the years 2000 and 2018. Clinical outcomes included changes in fontanelle characteristics, head circumference (HC) percentile, and incidence of ventriculoperitoneal (VP) shunting. Radiographic outcomes measured included changes in Evans ratio. We excluded individuals who were shunted before CMD from our study. Sixteen children presented with symptomatic foramen magnum stenosis and full anterior fontanelle or jump in the HC percentiles. Two children underwent placement of a VP shunt before decompressive surgery and were excluded from further analysis. Of the remaining 14 children who underwent CMD, 13 (93%) showed softening or flattening of their fontanelles post-operatively. Ten of these 14 children had both pre- and post-operative HC percentile records available, with 8 showing increasing HC percentiles before surgery. Seven of those eight children (88%) showed a deceleration or stabilization of HC growth velocity following decompression of the foramen magnum. Among 10 children with available pre- and post-operative brain imaging, ventricular size improved in 5 (50%), stabilized in 2 (20%), and slightly increased in 3 (30%) children after decompression. Two children (14%) required a shunt despite decompression of the foramen magnum. A significant proportion of children with concomitant signs of raised intracranial pressure or findings of progressive ventriculomegaly and foramen magnum stenosis may have improvement or stabilization of these findings following CMD. CMD may decrease the need for VP shunting and its associated complications in the select group of hydrocephalic children with achondroplasia presenting with symptomatic foramen magnum stenosis.

In situ transgenesis methods such as virus and electroporation can create somatic transgenic mice quickly, but they lack the exquisite control over copy number, zygosity, and locus specificity. We have recently established mosaic analysis by dual recombinase-mediated cassette exchange (MADR), which permits stable labeling of mutant cells expressing transgenic elements from precisely-defined chromosomal loci. MADR provides a toolkit of elements for combinatorial labeling, inducible/reversible transgene manipulation, VCre recombinase expression, and genetic manipulation of human cells. Further, we have demonstrated the versatility of MADR by creating glioma models with mixed, reporter-identified zygosity or with “personalized” driver mutations from pediatric glioma. For example, introducing H3f3a mutation variants with MADR regulates the spatiotemporal profile of glioma, and single-cell RNA and ATAC sequencing analysis demonstrates a recapitulation of developmental hierarchy seen in K27M-mutant human glioma. Moreover, we have generated novel models of supratentorial ependymoma using patient-derived oncofusion transgenes. These models display a high degree of fidelity and we now compare these models on a single-cell level with our previous models and human tumor cell transcriptomes. In addition, we now demonstrate the ability to generalize the MADR technology to other non-CNS tissues using local plasmid delivery. Finally, we have engineered human cells to allow for MADR transgenesis and somatic transgenic organoids. These combined approaches will enable researchers to discovery disease mechanisms and test therapeutics in more physiologically relevant cancer models.MADR is extensible to thousands of existing mouse lines and can be adapted to human cells, providing a flexible platform to democratize the generation of somatic transgenic disease models. Citation Format: Gi Bum Kim, David Rincon Fernandez Pacheco, David Saxon, Amy Yang, Sara Sabat, Marina Dutra-Clarke, Rachelle Levy, Ashley Watkins, Hannah Park, Aslam Abbasi Akhtar, Paul W. Linesch, Naomi Kobritz, Swasty S. Shandra, Katie Grausam, Alberto Ayala-Sarmiento, Jessica Molina, Kristyna Sedivakova, Daniel S. Gareau, Mariella G. Filbin, Serguei Bannykh, Jie Tang, Mario L. Suva, Bin Chen, Moise Danielpour, Joshua J. Breunig. MADR: Rapid generation of somatic mosaics to model cancer in mice and human organoids [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr NG01.

In situ transgenesis methods such as virus and electroporation can create somatic transgenic mice quickly, but they lack the exquisite control over copy number, zygosity, and locus specificity. We have recently established mosaic analysis by dual recombinase-mediated cassette exchange (MADR), which permits stable labeling of mutant cells expressing transgenic elements from precisely defined chromosomal loci. MADR provides a toolkit of elements for combinatorial labeling, inducible/reversible transgene manipulation, VCre recombinase expression, and genetic manipulation of human cells. Further, we have demonstrated the versatility of MADR by creating glioma models with mixed, reporter-identified zygosity or with “personalized” driver mutations from pediatric glioma. For example, introducing H3f3a mutation variants with MADR regulates the spatiotemporal profile of glioma, and single-cell RNA and ATAC sequencing analysis demonstrates a recapitulation of developmental hierarchy seen in K27M mutant human glioma. Moreover, we have generated novel models of supratentorial ependymoma using patient-derived oncofusion transgenes. These models display a high degree of fidelity, and we now compare these models on a single-cell level with our previous models and human tumor cell transcriptomes. In addition, we now demonstrate the ability to generalize the MADR technology to other non-CNS tissues using local plasmid delivery. Finally, we have engineered human cells to allow for MADR transgenesis and somatic transgenic organoids. These combined approaches will enable researchers to discover disease mechanisms and test therapeutics in more physiologically relevant cancer models. MADR is extensible to thousands of existing mouse lines and can be adapted to human cells, providing a flexible platform to democratize the generation of somatic transgenic disease models. This abstract is also being presented as Poster B46. Citation Format: Gi Bum Kim, David Rincon Fernandez Pacheco, David Saxon, Amy Yang, Sara Sabet, Marina Dutra-Clarke, Rachelle Levy, Ashley Watkins, Hannah Park, Aslam Abbasi Akhtar, Paul W. Linesch, Naomi Kobritz, Swasty S. Chandra, Katie Grausam, Alberto Ayala- Sarmiento, Jessica Molina, Kristyna Sedivakova, Daniel S. Gareau, Mariella G. Filbin, Serguei Bannykh, Jie Tang, Mario Suva, Bin Chen, Moise Danielpour, Joshua J. Breunig. MADR: Rapid generation of somatic mosaics with locus-specific, stably integrated transgenic elements for generation of “personalized” mouse models and human organoid tumor models [abstract]. In: Proceedings of the AACR Special Conference on the Evolving Landscape of Cancer Modeling; 2020 Mar 2-5; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2020;80(11 Suppl):Abstract nr PR11.

Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00401-018-1883-2) contains supplementary material, which is available to authorized users.

Summary Precise methods for transgene regulation are important to study signaling pathways and cell lineages in biological systems where gene function is often recycled within and across lineages. We engineered a genetic toolset for flexible transgene regulation in these diverse cellular contexts. Specifically, we created an optimized piggyBac transposon-based system, allowing for the facile generation of stably transduced cell lineages in vivo and in vitro. The system, termed pB-Tet-GOI (piggyBac-transposable tetracycline transactivator-mediated flexible expression of a genetic element of interest), incorporates the latest generation of tetracycline (Tet) transactivator and reverse Tet transactivator variants—along with engineered mutants—in order to provide regulated transgene expression upon addition or removal of doxycycline (dox). Altogether, the flexibility of the system allows for dox-induced, dox-suppressed, dox-resistant (i.e., constitutive), and dox-induced/constitutive regulation of transgenes. This versatile strategy provides reversible temporal regulation of transgenes with robust inducibility and minimal leakiness., Graphical Abstract, Highlights • pB-Tet-GOI features the latest generation of Tet transactivators (tTAs) and variants • piggyBac transposition allows for genomic insertion of pb-Tet-GOI • pb-Tet-GOI provides flexible control of transgenes in vitro and in vivo • tTA variants permit reversible, constitutive, or induced constitutive expression, In this article, Breunig and colleagues describe a stable, flexible genetic system for inducible and reversible gene expression. The doxycycline-mediated system, termed pB-Tet-GOI, is non-leaky, robust, and allows for “On→Off→On,” “Off→On→Off” and inducible-constitutive temporal control (“Off→permanently On”) of transgenes in vivo and in vitro, as well as a dox-resistant variant for strong, constitutive expression of transgenes.

Tuberous sclerosis complex (TSC) predisposes to the development of benign lesions within multiple organ systems, including the brain, kidneys, heart, lungs, and skin. Disease mortality is due to space-occupying subependymal giant cell astrocytomas and hemorrhage-prone renal angiomyolipomas. The recent use of mTORC1 inhibitors, such as everolimus, has allowed for direct targeting of TSC-associated mass lesions without apparent effect on surrounding tissues. Because of the mechanism of these drugs, there is reason to believe that these effects are not durable and that there may be need for continued long-term maintenance therapy.We present a case of TSC-associated mass lesions that were ill-suited for definitive surgical therapy. The patient was started on everolimus, however due to a complex social situation treatment was discontinued and ultimately resumed many months later. Radiologic studies acquired before and after each period of therapeutic onset/cessation reveal the dramatic but impermanent effects of mTORC1 inhibition.While everolimus provides a non-invasive way to treat TSC-associated lesions, patients may require lifelong therapy. When termination of therapy is considered, the patient should be made aware of the expectation of potentially dramatic increases in lesion size. If consideration is to be given to definitive surgical therapy, it should be pursued while the patient is still on the medication, or at least soon after treatment is halted.

Object Achondroplasia may be associated with compression at the cervicomedullary junction. Determining which patients are at greatest risk for neurological complications of cervicomedullary compression can be difficult. In the current study the authors reviewed their records to determine the incidence and clinical significance of dynamic cervicomedullary stenosis and obstruction of CSF flow along with surgical outcomes following posterior fossa decompression. Methods The authors reviewed 34 consecutive cases involving symptomatic children with achondroplasia undergoing cervicomedullary decompression performed by a single surgeon over 11 years. Of these patients, 29 had undergone preoperative dynamic MRI of the cervicomedullary junction with cine (cinema) CSF flow studies; 13 of these patients underwent postoperative dynamic MRI studies. Clinical outcomes included changes in polysomnography, head circumference percentile, and fontanel characteristics. Radiographic outcomes included changes in dynamic spinal cord diameter, improvement in CSF flow at the foramen magnum, and change in the Evans ratio. Results Patients were predominantly female, with a mean age at presentation of 6.6 years and mean follow-up of 3.7 years (range 1–10 years). All patients had moderate to excellent improvement in postoperative polysomnography, slight decrease in average head circumference percentile (from 46.9th percentile to 45.7th percentile), and no subjective worsening of fontanel characteristics. The Evans ratio decreased by 2%, spinal cord diameter increased an average of 3.1 mm, 5.2 mm, and 0.2 mm in the neutral, flexed, and extended positions, respectively, and CSF flow improved qualitatively in all 3 positions. There were no postoperative infections, CSF leaks, or other major complications. None of the patients undergoing initial foramen magnum decompression performed at our medical center required reoperation. Conclusions Patients with achondroplasia and symptomatic cervicomedullary compression have increased risk of dynamic stenosis at the foramen magnum evident upon dynamic cine MRI. Operative decompression may be offered with low risk of complications or need for reoperation.

We have developed a simple and generalizable in vivo method for brain tumor modeling, mosaic analysis by dual recombinase-mediated cassette exchange (MADR). MADR allows for stable labeling of mutant cells expressing transgenic elements from a precisely-defined chromosomal locus. We have demonstrated the power and versatility of MADR by creating novel glioma models with mixed, reporter-defined zygosity, or with “personalized” H3. 3-containing driver mutation signatures from pediatric glioma--each manipulation altering the spatiotemporal profile of resulting tumors. Further we have generated ependymoma models by employing patient-derived fusion driver mutations. Notably, each model displays divergent spatiotemporal tumor expansion profiles and cellular phenotypes. Now, we use single-cell RNA-seq to compare these models to their cells of mutation and to human datasets to elucidate the fundamental transcriptional programs and markers within and across these tumor types. This investigation will assess and credential these models against their clinical counterparts by scrutinizing the resulting datasets and validating their clinical relevance as pre-clinical models for therapeutic discovery and testing.

Viral vectors and electroporation (EP)-mediated gene transfers are efficient means of inducing somatic mosaicism in mice, but they lack the exquisite control over transgene copy number, gene zygosity, and genomic-locus specificity that genetically engineered mouse models (GEMMs) provide. Here, we develop and demonstrate a simple and generalizable in vivo method, mosaic analysis by dual recombinase-mediated cassette ex-change (MADR). MADR allows for stable labeling of mutant cells express transgenic elements from a precisely-defined chromosomal locus. To test our method, we generated reporter-labeled lineages from stem and progenitor cells in a well-defined Rosa26mTmG mouse. We demonstrate the power and versatility MADR by creating novel glioma models with mixed, reporter-defined zygosity or with personalized driver mutations from pediatric glioma-with each manipulation altering the profile of resulting tumors. Thus, MADR provides a high-throughput genetic platform for the dissection of development and disease, and this rapid method can be ap-plied to the thousands of existing gene-trap mice.

Bent Bone Dysplasia-FGFR2 type is a relatively recently described bent bone phenotype with diagnostic clinical, radiographic, and molecular characteristics. Here we report on 11 individuals, including the original four patients plus seven new individuals with three longer-term survivors. The prenatal phenotype included stillbirth, bending of the femora, and a high incidence of polyhydramnios, prematurity, and perinatal death in three of 11 patients in the series. The survivors presented with characteristic radiographic findings that were observed among those with lethality, including bent bones, distinctive (moustache-shaped) small clavicles, angel-shaped metacarpals and phalanges, poor mineralization of the calvarium, and craniosynostosis. Craniofacial abnormalities, hirsutism, hepatic abnormalities, and genitourinary abnormalities were noted as well. Longer-term survivors all needed ventilator support. Heterozygosity for mutations in the gene that encodes Fibroblast Growth Factor Receptor 2 (FGFR2) was identified in the nine individuals with available DNA. Description of these patients expands the prenatal and postnatal findings of Bent Bone Dysplasia-FGFR2 type and adds to the phenotypic spectrum among all FGFR2 disorders. © 2016 Wiley Periodicals, Inc.

We have developed a simple and generalizable in vivo method for brain tumor modeling, mosaic analysis by dual recombinase-mediated cassette exchange (MADR). MADR allows for stable labeling of mutant cells expressing transgenic elements from a precisely-defined chromosomal locus. We have demonstrated the power and versatility of MADR by creating novel glioma models with mixed, reporter-defined zygosity, or with “personalized” H3.3-containing driver mutation signatures from pediatric glioma--each manipulation altering the spatiotemporal profile of resulting tumors. Further we have generated ependymoma models by employing patient-derived fusion driver mutations. Notably, each model displays divergent spatiotemporal tumor expansion profiles and cellular phenotypes. Now, we use single-cell RNA-seq to compare these models to their cells of mutation and to human datasets to elucidate the fundamental transcriptional programs and markers within and across these tumor types. This investigation will assess and credential these models against their clinical counterparts by scrutinizing the resulting datasets and validating their clinical relevance as pre-clinical models for therapeutic discovery and testing.

Bacillus cereus meningitis is a rare disease with a very high mortality rate in neonates. The authors present the rare case of a premature infant with B. cereus bacteremia and subsequent intracranial abscesses. In addition to aggressive medical therapy, surgical drainage was performed via a left frontal mini-craniotomy. At 15 months of age, the patient had mild developmental delay, cortical blindness, and sensorineural hearing loss. The clinical case is described and difficulties in the management of B. cereus meningoencephalitis in infants are discussed.

Central nervous system medulloepitheliomas are extremely rare and malignant (World Health Organization Grade IV) primitive neuroectodermal tumors (PNETs) that arise in childhood. Unlike other PNETs, medulloepitheliomas have a dismal prognosis, with only 2 reported cases in the literature in which the patient survived beyond 5 years after treatment. The authors report on the third known case of a child who survived longer than 5 years. A review of all the published cases of medulloepithelioma is also presented, and alternative treatment strategies for PNET tumors, including high-dose chemotherapy with stem-cell rescue, are discussed.

SummaryAs the list of putative driver mutations in glioma grows, we are just beginning to elucidate the effects of dysregulated developmental signaling pathways on the transformation of neural cells. We have employed a postnatal, mosaic, autochthonous glioma model that captures the first hours and days of gliomagenesis in more resolution than conventional genetically engineered mouse models of cancer. We provide evidence that disruption of the Nf1-Ras pathway in the ventricular zone at multiple signaling nodes uniformly results in rapid neural stem cell depletion, progenitor hyperproliferation, and gliogenic lineage restriction. Abolishing Ets subfamily activity, which is upregulated downstream of Ras, rescues these phenotypes and blocks glioma initiation. Thus, the Nf1-Ras-Ets axis might be one of the select molecular pathways that are perturbed for initiation and maintenance in glioma.

✓The authors report on three patients with a congenital brain overgrowth syndrome, macrocephaly–cutis marmorata telangiectatica congenita (M-CMTC), who experienced neurological sequelae associated with herniation of the cerebellar tonsils through the foramen magnum. In two of these patients, the authors document postnatal brain overgrowth that contributed to recurrent descent of the cerebellar tonsils and complicated the surgical treatment in one of the patients. The authors address the neurosurgical concerns related to this syndrome with special attention to acquired tonsillar ectopia and postulate that some patients may be at risk for progressive tonsillar herniation and consequent neurological symptoms due to cerebellar overgrowth. Ectopic cerebellar tonsils have been reported previously in cases of M-CMTC, and this phenomenon may be a secondary event associated with brain overgrowth rather than due to a congenitally small posterior fossa.

The past decade has seen the identification of several mutations associated with low grade pediatric glioma—notably those to the v-raf murine sarcoma viral oncogene homolog B1 (BRAF). Further, next generation sequencing has recently led to the discovery of a wide variety of recurrent somatic mutations associated with low grade gliomas as well as elucidating the landscape of genetic alterations in low and high grade glioma. We have employed a novel methodology, postnatal electroporation coupled with piggyBac transposition in order to rapidly interrogate the causality of these mutations in tumorigenesis. Introduction of somatic mutation to tumor cells lining the ventricular zone led to a characteristic hyperplasia denoted by dramatic overgrowth of mutant cells. However, the cells rapidly senesced. In the minority of cases, tumors transition into invasive high grade glioblastoma. Co-introduction of additional tumor suppressor targeting elements (shRNA against p16/p19, Trp53 shRNA) increased tumor grade. Here, we discuss findings from our functional investigations of these putative low grade driver mutations.

We have created a novel method for studying glioma initiation, progression, and recurrence with in vivo-postnatal electroporation combined with piggyBac transposition. Electroporation allows for rapid addition of transgenes, simply by the inclusion of plasmid DNA in the initial injection. Thus, we have created a toolkit for interrogating the resulting tumor cells in vivo. Specifically, we have created piggyBac plasmids expressing a spectrum of transgenes or elements for modeling recently discovered and previously identified pediatric driver mutations, including H3.3, Atrx, Trp53, Nf1, and Pdgfra . Here we detail the use of these elements with additional transgenes for non-invasive imaging and inducible cell ablation. Further, we are investigating the use of novel methods for genetically labeling quiescent and recurrent cells, including inducible and reversible transgenic systems. Here we discuss these methodologies and their use in the context of our novel pediatric glioma models with a focus on emergent properties from different driver gene combinations.

A 4-year-old girl with history of polydactyly and imperforate anus surgeries presented with short stature. Brain MRI revealed a large hypothalamic hamartoma (figure). Pallister-Hall syndrome (PHS) was diagnosed. Biopsy was not indicated given stable and typical tumoral appearance. Annual evaluations, hormonal replacement, and medical genetics consult were recommended. Compared to sporadic hypothalamic hamartoma, patients with PHS tend to be less symptomatic and have minimal tumor growth.1 The etiology is an autosomal dominant or de novo GLI3 gene mutation.2 Neurologists and neuroradiologists should be familiar with PHS characteristics, surveillance, and symptomatic therapy as neurosurgery is not usually recommended.

Objectives FG syndrome is an X-linked recessive mental retardation syndrome with ano-rectal anomalies, constipation, and occasional urinary incontinence. Because tethered spinal cord syndrome (TCS) has similar symptoms, we evaluated imaging for TCS in patients with FG syndrome. Study design Patients were recruited from the International FG Syndrome Support Group, and an FG Syndrome Consensus Group reviewed clinical histories, medical records, and photographs of each responding patient. Results of cranial and spinal imaging studies were available for 12 patients. Results Of 12 boys with FG syndrome, 6 had hypoplasia of the corpus callosum, and 3 of these had TCS (all with constipation and urinary symptoms). The other 9 did not have urinary symptoms. After surgical untethering, bowel and bladder symptoms improved. Conclusions Tethered spinal cord syndrome occurred in 25% of patients with FG syndrome associated with hypoplasia of the corpus callosum and causing bowel and bladder incontinence. A high index of suspicion is necessary for early diagnosis, and timely intervention results in significant improvement in symptomatology.

Background: Progressive post-hemorrhagic hydrocephalus in preterm infants strongly predicts abnormal neurologic development, and often accompanies cystic periventricular leukomalacia (cPVL). Transforming growth factor-β1 (TGF-β1), associated with hydrocephalus, can upregulate the chondroitin sulfate proteoglycan (CSPG) synthesis. To date, CSPG and their nitrated metabolites (NT-CSPG) have not been evaluated in hydrocephalus. Objectives: We hypothesized that TGF-β1, TGF-β2, CSPG, and NT-CSPG would accumulate in cerebrospinal fluid (CSF) in preterm hydrocephalus, and their concentrations would correlate with poor long-term outcomes. Methods: TGF-β1, TGF-β2, CSPG, and NT-CSPG concentrations in CSF were measured prospectively by ELISA in 29 preterm newborns with (n = 22) or without (n = 34) progressive post-hemorrhagic hydrocephalus, and correlated with progressive neonatal hydrocephalus and neurologic outcome. Only concentrations from each patient’s initial CSF sample were used for statistical analysis. Results: Compared to neonates without hydrocephalus, CSF [TGF-β1], [TGF-β2], [CSPG] and [NT-CSPG] were significantly greater by >3-, >35-, >8-, and >3-fold, respectively. Unlike CSF [TGF-β2] and [CSPG], [TGF-β1] correlated with CSF [total protein]. Only CSF [NT-CSPG] correlated with cPVL. Unlike [TGF-β2] or [CSPG], [NT-CSPG] correlation with preterm progressive post-hemorrhagic hydrocephalus (PPHH) was explained entirely by the presence of cPVL among these patients. [TGF-β2] was >20-fold greater in preterm survivors who required a ventriculoperitoneal shunt for PPHH (n = 9), as compared to survivors who did not require a shunt (n = 2), or those without hydrocephalus (n = 12). [TGF-β2] and [NT-CSPG] correlated inversely with Bayley Index Scores (15.0 months median adjusted age). Conclusions: This is the first report that [TGF-β2], [CSPG], and [NT-CSPG], measured well before term, accumulate abnormally in preterm progressive post-hemorrhagic hydrocephalus CSF, and correlate with adverse neurologic outcome.

Viral vectors and electroporation (EP)-mediated gene transfers are efficient means of inducing somatic mosaicism in mice, but they lack the exquisite control over transgene copy number, gene zygosity, and genomic-locus speci-ficity that genetically engineered mouse models (GEMMs) provide. Here, we develop and demonstrate a simple and generalizable in vivo method, mosaic analysis by dual recombinase-mediated cassette exchange (MADR). MADR allows for stable labeling of mutant cells express transgenic elements from a precisely-defined chromosomal locus. To test our method, we generated reporter-labeled lineages from stem and progenitor cells in a well-defined Rosa26mTmG mouse. We demonstrate the power and versatility of MADR by creating novel glioma models with mixed, reporter-defined zygosity or with “personalized,” H3.3-containing driver mutation signatures from pediatric glioma-each manipulation altering the profile of resulting tumors. Thus, MADR provides a high-throughput genetic platform for the dissection of development and disease, and this rapid method can be applied to the thousands of existing gene-trap mice.

Pediatric gliomas, a type of brain tumor which arises from uncontrolled growth of glial cells, are the most common type of CNS tumor in children. As the list of putative driver mutations in glioma grows, we are just beginning to elucidate the combined effects of unhinged signaling pathways on the transformation of CNS cells. While the oncogenic role of ETV5 in various cancers is well-established, its role in high-grade pediatric gliomas has yet to be elucidated. We have created a mosaic, autochthonous, glioma model that captures the first hours and days of gliomagenesis in more resolution than conventional mouse models of cancer. Our various models of pediatric glioma have indicated a fundamental role for Etv5 in tumor cells. We show that ETV5 is highly expressed in our glioma models and primary pediatric glioma cells. We are currently pursuing an omics approach to identifying the mechanisms regulating ETV5 in high-grade glioma. Additionally, we are employing a novel single-site conditional system to identify ETV5 genomic targets in patient tumors and to explore the results of ETV5 manipulation on cell fate. Taken together, we provide evidence that Etv5 is necessary for tumor initiation and regulates the exuberant gliogenesis observed in these tumors.

We present the case of a child in whom acute hydrocephalus developed secondary to obstruction of the foramen of Monro by a choroid plexus cyst. The patient was seen in the emergency department with fevers, acute onset of headaches, and lethargy. Computed tomography demonstrated dilated lateral and third ventricles with a relatively normal-sized fourth ventricle. An external ventricular drain was placed. Despite decompression of the lateral ventricles, follow-up magnetic resonance imaging demonstrated a dilated third ventricle with a possible thin-walled mass extending from the foramen of Monro into the posterior portion of the third ventricle. The patient subsequently underwent endoscopic fenestration of the cyst with endoscopic third ventriculostomy. Although two other cases of symptomatic choroid plexus cysts of the third ventricle have been previously reported in children, our paper highlights the possibility of endoscopic cyst fenestration together with a third ventriculostomy as a treatment option in cases where the cyst extends into the posterior third ventricle. Despite adequate decompression, we were concerned that due to CSF pulsations the remnant cyst wall could result in acute aqueduct obstruction and subsequent hydrocephalus.

Cancer cell secretion of TGF-β is a potent mechanism for immune evasion. However, little is known about how central nervous system tumors guard against immune eradication. We sought to determine the impact of T-cell TGF-β signaling blockade on progression of medulloblastoma (MB), the most common pediatric brain tumor. Genetic abrogation of T-cell TGF-β signaling mitigated tumor progression in the smoothened A1 (SmoA1) transgenic MB mouse. T regulatory cells were nearly abolished and antitumor immunity was mediated by CD8 cytotoxic T lymphocytes. To define the CD8 T-cell subpopulation responsible, primed CD8 T cells were adoptively transferred into tumor-bearing immunocompromised SmoA1 recipients. This led to generation of CD8(+)/killer cell lectin-like receptor G1 high (KLRG1(hi))/IL-7R(lo) short-lived effector cells that expressed granzyme B at the tumor. These results identify a cellular immune mechanism whereby TGF-β signaling blockade licenses the T-cell repertoire to kill pediatric brain tumor cells.

Over the past several years the pial surface has been identified as a germinal niche of importance during embryonic, perinatal and adult neuro- and gliogenesis, including after injury. However, methods for genetically interrogating these progenitor populations and tracking their lineages had been limited owing to a lack of specificity or time consuming production of viruses. Thus, progress in this region has been relatively slow with only a handful of investigations of this location. Electroporation has been used for over a decade to study neural stem cell properties in the embryo, and more recently in the postnatal brain. Here we describe an efficient, rapid, and simple technique for the genetic manipulation of pial surface progenitors based on an adapted electroporation approach. Pial surface electroporation allows for facile genetic labeling and manipulation of these progenitors, thus representing a time-saving and economical approach for studying these cells.

✓In this report the authors describe the clinical features of a rare neonatal anaplastic astrocytoma in the setting of in vitro fertilization (IVF). The infant had been conceived using IVF and was born full term to a 29-year-old prima gravida mother. At birth, the baby boy was irritable and demonstrated poor feeding. Cranial ultrasonography and magnetic resonance imaging revealed an echogenic mass in the left hemisphere with midline shift and hydrocephalus. Gross-total resection of an anaplastic astrocytoma was followed by chemotherapy with temozolomide and vincristine. Previous cases of neonatal brain tumors occurring in the setting of assisted reproduction are reviewed. A possible association between IVF and congenital neuroepithelial tumors is highlighted.

Endolymphatic sac tumors (ELSTs) are rare, low-grade, histologically benign tumors arising from the epithelial lining of the endolymphatic duct or sac. They are slow growing but locally invasive and can be associated with von Hippel-Lindau disease. While there are cases in the medical literature documenting this type of tumor in adults, reports of ELSTs in the pediatric population are limited. The authors report the fifth reported case of a pediatric ELST in the English literature. A 14-year-old Jehovah’s Witness presented with a progressive two-year history of right-sided hearing loss, balance problems, gait difficulty, and bleeding behind the right tympanic membrane. Computed topography (CT) and magnetic resonance imaging (MRI) of the brain and temporal bone revealed a large lesion eroding into the petrous and mastoid bones with extension abutting the brain stem and invading the right transverse sinus. Due to the size and hypervascularity of the tumor, as well as the refusal of the patient and family to receive possible intra-operative blood transfusion, pre-operative tumor embolization and staged surgical resection were used for excision. Histopathological staining and electron microscopy confirmed the diagnosis of ELST. Immediate post-operative imaging did not reveal any residual tumor. Post-operative examination revealed persistence of the right-sided hearing loss that was present pre-operatively. A new facial nerve paralysis was noted post-operatively and remained unchanged at 21 months post-resection follow-up. MRI imaging at 21 months follow-up revealed recurrent tumor. The imaging workup for von Hippel-Lindau disease has been negative. We conclude that it is possible to have reasonable functional outcomes for children with ELSTs using staged resection techniques, though such approaches do not preclude delayed recurrence.

Background Recent findings have indicated the presence of a progenitor domain at the marginal zone/layer 1 of the cerebral cortex, and it has been suggested that these progenitors have neurogenic and gliogenic potential. However, their contribution to the histogenesis of the cortex remains poorly understood due to difficulties associated with genetically manipulating these unique cells in a population-specific manner. Results We have adapted the electroporation technique to target pial surface cells for rapid genetic manipulation at postnatal day 2. In vivo data show that most of these cells proliferate and progressively differentiate into both neuronal and glial subtypes. Furthermore, these cells localize to the superficial layers of the optic tectum and cerebral cortex prior to migration away from the surface. Conclusions We provide a foundation upon which future studies can begin to elucidate the molecular controls governing neural progenitor fate, migration, differentiation, and contribution to cortical and tectal histogenesis. Furthermore, specific genetic targeting of such neural progenitor populations will likely be of future clinical interest.