The choroid plexus links innate immunity to CSF dysregulation in hydrocephalus.

The choroid plexus (ChP) is the blood-cerebrospinal fluid (CSF) barrier and the primary source of CSF. Acquired hydrocephalus, caused by brain infection or hemorrhage, lacks drug treatments due to obscure pathobiology. Our integrated, multi-omic investigation of post-infectious hydrocephalus (PIH) and post-hemorrhagic hydrocephalus (PHH) models revealed that lipopolysaccharide and blood breakdown products trigger highly similar TLR4-dependent immune responses at the ChP-CSF interface. The resulting CSF "cytokine storm", elicited from peripherally derived and border-associated ChP macrophages, causes increased CSF production from ChP epithelial cells via phospho-activation of the TNF-receptor-associated kinase SPAK, which serves as a regulatory scaffold of a multi-ion transporter protein complex. Genetic or pharmacological immunomodulation prevents PIH and PHH by antagonizing SPAK-dependent CSF hypersecretion. These results reveal the ChP as a dynamic, cellularly heterogeneous tissue with highly regulated immune-secretory capacity, expand our understanding of ChP immune-epithelial cell cross talk, and reframe PIH and PHH as related neuroimmune disorders vulnerable to small molecule pharmacotherapy.

Response to the BRAF/MEK inhibitors dabrafenib/trametinib in an adolescent with a BRAF V600E mutated anaplastic ganglioglioma intolerant to vemurafenib.

Efficacy of BRAF V600E targeted therapies in brain tumors harboring the mutation has been shown in several case reports and is currently being studied in larger clinical trials. Monotherapy with vemurafenib has been associated with significant side effects, including rashes, papillomas, and squamous cell carcinomas. Here we describe an adolescent female with anaplastic ganglioglioma and significant skin reaction to vemurafenib with subsequent tumor response and tolerance to the BRAF/MEK inhibitor combination of dabrafenib and trametinib without recurrence of previous reaction.

Non-syndromic single-suture craniosynostosis in triplets.

INTRODUCTION: Craniosynostosis is the premature fusion of one or more cranial sutures. The cause of non-syndromic craniosynostosis has been attributed to a complex interaction among genetic, epigenetic, and environmental factors. Increased concordance rates in monozygotic twins support a genetic etiology while a concordance rate less than 100% suggests environmental and/or epigenetic influences. Here, we describe the first reported occurrence of all three children in a triplet set with non-syndromic single-suture craniosynostosis. CASE REPORT: The dichorionic triamniotic triplets were the product of a non-consanguineous marriage delivered at 35 weeks' gestation by a 38-year-old mother and consisted of a monochorionic-diamniotic pair (A and B) and a fraternal triplet (C). Three-dimensional computed tomography scans confirmed sagittal synostosis in A and B and metopic synostosis in C. All patients underwent endoscopic strip craniectomy and were discharged on the second postoperative day with helmet orthoses. Comparative genetic hybridization (CGH) and whole-exome sequencing (WES) failed to identify pathogenic copy number variants or gene mutations, respectively. DISCUSSION AND CONCLUSION: The results of the genetic testing suggest the possibility of a rare variant contributing to the risk of midline craniosynostosis shared among the triplets, with potential modifiers at other genetic loci affecting the phenotype. We speculate mutations at loci within non-coding regions not captured by our genetic analysis may have been involved. Moreover, epigenetic factors as well as environmental factors including, but not limited to, in utero head constraint could have contributed to the observed phenotype.

A Review of Cerebral Shunts, Current Technologies, and Future Endeavors.

Objective. The use of cerebrospinal shunts is the standard of care for hydrocephalus. However, shunts are extremely vulnerable to failure and lack noninvasive methods to monitor their viability. We review current shunt technologies and attempts to improve their function. Methods. A PubMed search was performed to find literature on shunts and shunt function. Company brochures and websites were also used. Results. Fixed and variable pressure valves from four major companies are discussed. Also reviewed are siphon resistive devices, intracranial pressure sensors, and recent attempts on the development of cerebrospinal fluid sensors, including a micromechanical flow sensor we have recently developed. Conclusions. While variable pressure valves and siphon resistive devices have both had considerable success in dealing with variable intracranial pressure, a more sophisticated, continuous monitoring system is needed to ensure shunt viability and patient safety. An integrated flow sensor may provide the ability to track fluid flow and determine shunt functionality.

Primary spinal myxopapillary ependymoma in the pediatric population: a study from the Surveillance, Epidemiology, and End Results (SEER) database.

Primary spinal myxopapillary ependymomas (MPE) in children are extremely rare. We examined the patient demographics, treatment modalities, and the associated outcomes of children with MPE using the Surveillance, Epidemiology, and End Results (SEER) national cancer database to gain a better understanding of these tumors. The SEER database (1973-2012) was used to analyze patients 21 years of age and younger with histologically confirmed MPE localized to the spinal cord or cauda equina. We analyzed patient demographics, extent of surgical resection, and radiation treatment. Overall survival was calculated using the Kaplan-Meier method. Statistical significance was defined as p < 0.05, with all data analyzed in IBM SPSS Statistics 21. 122 pediatric patients met inclusion criteria. The median age was 16 years (range 0-21) with 63 % male and 87 % Caucasian. The mean follow-up time was 4.5 years (95 % CI 3.93-5.07). Overall survival at 5 and 10 years was 97 and 95 %, respectively. We found 37 % underwent gross-total resection (GTR), 36 % subtotal resection (STR), and 27 % biopsy only. Patients who received GTR alone (n = 37) had a statistically significant increase in overall survival compared to those who received STR plus adjuvant radiation (n = 20) (Χ2 = 5.9, p < 0.05). To our knowledge, this is the largest survival analysis of pediatric patients with MPE. Overall survival is excellent at the 5 and 10-year time points; however, GTR should be the goal of treatment when possible. For patients with MPE, future studies should focus on longer follow-up, the role of radiation, and the therapeutic approach at tumor recurrence.

Cerebrospinal fluid hypersecretion in pediatric hydrocephalus.

Hydrocephalus, despite its heterogeneous causes, is ultimately a disease of disordered CSF homeostasis that results in pathological expansion of the cerebral ventricles. Our current understanding of the pathophysiology of hydrocephalus is inadequate but evolving. Over this past century, the majority of hydrocephalus cases has been explained by functional or anatomical obstructions to bulk CSF flow. More recently, hydrodynamic models of hydrocephalus have emphasized the role of abnormal intracranial pulsations in disease pathogenesis. Here, the authors review the molecular mechanisms of CSF secretion by the choroid plexus epithelium, the most efficient and actively secreting epithelium in the human body, and provide experimental and clinical evidence for the role of increased CSF production in hydrocephalus. Although the choroid plexus epithelium might have only an indirect influence on the pathogenesis of many types of pediatric hydrocephalus, the ability to modify CSF secretion with drugs newer than acetazolamide or furosemide would be an invaluable component of future therapies to alleviate permanent shunt dependence. Investigation into the human genetics of developmental hydrocephalus and choroid plexus hyperplasia, and the molecular physiology of the ion channels and transporters responsible for CSF secretion, might yield novel targets that could be exploited for pharmacotherapeutic intervention.

Isolated unilateral alar ligamentous injury: illustrative cases.

BACKGROUND: Isolated unilateral alar ligament injury (IUALI) is a rare and likely underreported occurrence after upper cervical trauma, with only 16 cases documented in the literature to date. Patients generally present with neck pain, and definitive diagnosis is typically made by magnetic resonance imaging (MRI). Unfortunately, likely due in part to its rarity, there are no formal guidelines for the treatment of an IUALI. Furthermore, there is a limited understanding of the long-term consequences associated with its inadequate treatment. OBSERVATIONS: Here, the authors report on three pediatric patients, each found to have an IUALI after significant trauma. All patients presented with neck tenderness, and two of the three had associated pain-limited range of neck motion. Imaging revealed either a laterally deviated odontoid process on cervical radiographs and/or MRI evidence of ligamentous strain or discontinuity. Each patient was placed in a hard cervical collar for 1 to 2 months with excellent resolution of symptoms. A comprehensive review of the literature showed that all patients with IUALI who had undergone external immobilization with either rigid cervical collar or halo fixation had favorable outcomes at follow-up. LESSONS: For patients with IUALI, a moderate course of nonsurgical management with rigid external immobilization appears to be an adequate first-line treatment.

Concurrent impact of de novo mutations on cranial and cortical development in nonsyndromic craniosynostosis.

OBJECTIVE: Nonsyndromic craniosynostosis (nsCS), characterized by premature cranial suture fusion, is considered a primary skull disorder in which impact on neurodevelopment, if present, results from the mechanical hindrance of brain growth. Despite surgical repair of the cranial defect, neurocognitive deficits persist in nearly half of affected children. Therefore, the authors performed a functional genomics analysis of nsCS to determine when, where, and in what cell types nsCS-associated genes converge during development. METHODS: The authors integrated whole-exome sequencing data from 291 nsCS proband-parent trios with 29,803 single-cell transcriptomes of the prenatal and postnatal neurocranial complex to inform when, where, and in what cell types nsCS-mutated genes might exert their pathophysiological effects. RESULTS: The authors found that nsCS-mutated genes converged in cranial osteoprogenitors and pial fibroblasts and their transcriptional networks that regulate both skull ossification and cerebral neurogenesis. Nonsyndromic CS-mutated genes also converged in inhibitory neurons and gene coexpression modules that overlapped with autism and other developmental disorders. Ligand-receptor cell-cell communication analysis uncovered crosstalk between suture osteoblasts and neurons via the nsCS-associated BMP, FGF, and noncanonical WNT signaling pathways. CONCLUSIONS: These data implicate a concurrent impact of nsCS-associated de novo mutations on cranial morphogenesis and cortical development via cell- and non-cell-autonomous mechanisms in a developmental nexus of fetal osteoblasts, pial fibroblasts, and neurons. These results suggest that neurodevelopmental outcomes in nsCS patients may be driven more by mutational status than surgical technique.

Decompressive hemicraniectomy for ischemic stroke in the pediatric population.

Adult patients with space-occupying hemispheric infarctions have a poor prognosis, with an associated fatality rate of 80%. Decompressive hemicraniectomy (DH) has been studied as a treatment option for patients with malignant cerebral infarction refractory to maximal medical therapy, with reasonable outcomes demonstrated in the adult population if the patient is decompressed within 48 h. However, there are no randomized controlled trials in the pediatric literature to make the same claims. In this study, we evaluated the current literature in regards to DH following malignant stroke in the pediatric population. We found that excellent recovery, with an acceptable quality of life, is possible, particularly in the pediatric patient. Our cohort suggests that pediatric intervention beyond the 48-h time interval may still lead to positive outcomes, unlike adult patients. Regardless, randomized controlled trials are needed to determine optimal timing of intervention following symptom onset, as well as to identify predictors for positive outcome in the pediatric population.

Management of dynamic cervical kyphosis with dorsal epidural lipomatosis: a Hirayama disease variant? Illustrative case.

BACKGROUND: Hirayama disease, a cervical myelopathy characterized most commonly by a self-limiting atrophic weakness of the upper extremities, is a rare entity, scarcely reported in the literature. Diagnosis is made by spinal magnetic resonance imaging (MRI), which typically shows loss of normal cervical lordosis, anterior displacement of the cord during flexion, and a large epidural cervical fat pad. Treatment options include observation or cervical immobilization by collar or surgical decompression and fusion. OBSERVATIONS: Here, the authors report an unusual case of a Hirayama-like disease in a young White male athlete who presented with rapidly progressive paresthesia in all 4 extremities and no weakness. Imaging showed characteristic findings of Hirayama disease as well as worsened cervical kyphosis and spinal cord compression in cervical neck extension, which has not previously been reported. Two-level anterior cervical discectomy and fusion and posterior spinal fusion improved both cervical kyphosis on extension and symptoms. LESSONS: Given the disease's self-limiting nature, and a lack of current reporting, there remains no consensus on how to manage these patients. Such findings presented here demonstrate the potentially heterogeneous MRI findings that can be observed in Hirayama disease and emphasize the utility of aggressive surgical management in young, active patients whereby a cervical collar may not be tolerated.

Impact of insurance status on healthcare resource utilization and outcomes in adolescent patients presenting with spinal cord injuries.

OBJECTIVE: Insurance disparities have been suggested to influence the medical and surgical outcomes of adult patients with spinal cord injury (SCI), with a paucity of studies demonstrating their impact on the outcomes of pediatric and adolescent SCI patients. The aim of this study was to assess the impact of insurance status on healthcare utilization and outcomes in adolescent patients presenting with SCI. METHODS: An administrative database study was performed using the 2017 admission year from 753 facilities using the National Trauma Data Bank. Adolescent patients (11-17 years old) with cervical/thoracic SCIs were identified using International Classification of Diseases, Tenth Revision, Clinical Modification coding. Patients were categorized by governmental insurance versus private insurance/self-pay. Patient demographics, comorbidities, imaging, procedures, hospital adverse events (AEs), and length of stay (LOS) data were collected. Multivariate regression analyses were used to determine the effect of insurance status on LOS, any imaging or procedure, or any AE. RESULTS: Of the 488 patients identified, 220 (45.1%) held governmental insurance while 268 (54.9%) were privately insured. Age was similar between the cohorts (p = 0.616), with the governmental insurance cohort (GI cohort) having a significantly lower proportion of non-Hispanic White patients than the private insurance cohort (PI cohort) (GI: 43.2% vs PI: 72.4%, p < 0.001). While transportation accident was the most common mechanism of injury for both cohorts, assault was significantly greater in the GI cohort (GI: 21.8% vs PI: 3.0%, p < 0.001). A significantly greater proportion of patients in the PI cohort received any imaging (GI: 65.9% vs PI: 75.0%, p = 0.028), while there were no significant differences in procedures performed (p = 0.069) or hospital AEs (p = 0.386) between the cohorts. The median (IQR) LOS (p = 0.186) and discharge disposition (p = 0.302) were similar between the cohorts. On multivariate analysis, with respect to governmental insurance, private insurance was not independently associated with obtaining any imaging (OR 1.38, p = 0.139), undergoing any procedure (OR 1.09, p = 0.721), hospital AEs (OR 1.11, p = 0.709), or LOS (adjusted risk ratio -2.56, p = 0.203). CONCLUSIONS: This study suggests that insurance status may not independently influence healthcare resource utilization and outcomes in adolescent patients presenting with SCIs. Further studies are needed to corroborate these findings.

Multiomic analyses implicate a neurodevelopmental program in the pathogenesis of cerebral arachnoid cysts.

Cerebral arachnoid cysts (ACs) are one of the most common and poorly understood types of developmental brain lesion. To begin to elucidate AC pathogenesis, we performed an integrated analysis of 617 patient-parent (trio) exomes, 152,898 human brain and mouse meningeal single-cell RNA sequencing transcriptomes and natural language processing data of patient medical records. We found that damaging de novo variants (DNVs) were highly enriched in patients with ACs compared with healthy individuals (P = 1.57 × 10-33). Seven genes harbored an exome-wide significant DNV burden. AC-associated genes were enriched for chromatin modifiers and converged in midgestational transcription networks essential for neural and meningeal development. Unsupervised clustering of patient phenotypes identified four AC subtypes and clinical severity correlated with the presence of a damaging DNV. These data provide insights into the coordinated regulation of brain and meningeal development and implicate epigenomic dysregulation due to DNVs in AC pathogenesis. Our results provide a preliminary indication that, in the appropriate clinical context, ACs may be considered radiographic harbingers of neurodevelopmental pathology warranting genetic testing and neurobehavioral follow-up. These data highlight the utility of a systems-level, multiomics approach to elucidate sporadic structural brain disease.

Simulated fronto-orbital advancement achieves reproducible results in metopic synostosis.

BACKGROUND: Metopic synostosis results in trigonocephaly with bitemporal narrowing. Treatment involves differential fronto-orbital advancement, widening of the bitemporal region, and rounding the forehead. The purpose of this article was to implement three-dimensional surgical planning to treat metopic synostosis, including use of intraoperative templates, and to test the accuracy of the results. METHODS: This is a prospectively analyzed series of retrospective patients with metopic synostosis. Consecutive cases treated by the authors involving a simulated computer-aided planning session were reviewed. Demographic data were tabulated, and three-dimensional quantitative data reviewed. Measurements obtained included bifrontal angle, temporal advancement, and bitemporal distance and widening. Preoperative, simulated, and actual results were compared and analyzed using the t test. RESULTS: Five infants with metopic synostosis treated by this method were included (3 boys, 2 girls). The endocranial bifrontal anglechanged from 111.25° preoperatively to 148.58° postoperatively (P = 0.0001) and simulated 145.62° (compared with actual 148.58) (P = 0.5099). The bitemporal distance preoperative averaged 73.72mm, compared with actual of 89.78mm (P = 0.019), and was simulated to 89.28mm (vs actual 89.78) (P = 0.8815). The surgically planned advancement and expansion were similar compared with actual (P = 0.591, 0.806, and 0.806), respectively. CONCLUSIONS: The results show that simulated surgical planning can accurately and reproducibly be translated to actual surgical outcome during fronto-orbital advancement for trigonocephaly. The treatment goals for metopic synostosis are conserved and effectively achieved, including lateral orbital advancement, widening of the endocranial bifrontal angle, bitemporal expansion, and rounding of the forehead.

Use of droxidopa for blood pressure augmentation after acute spinal cord injury: case reports.

Hypotension secondary to autonomic dysfunction is a common complication of acute spinal cord injury (SCI) that may worsen neurologic outcomes. Midodrine, an enteral α-1 agonist, is often used to facilitate weaning intravenous (IV) vasopressors, but its use can be limited by reflex bradycardia. Alternative enteral agents to facilitate this wean in the acute post-SCI setting have not been described. We aim to describe novel application of droxidopa, an enteral precursor of norepinephrine that is approved to treat neurogenic orthostatic hypotension, in the acute post-SCI setting. Droxidopa may be an alternative enteral therapy for those intolerant of midodrine due to reflex bradycardia. We describe two patients suffering traumatic cervical SCI who were successfully weaned off IV vasopressors with droxidopa after failing with midodrine. The first patient was a 64-year-old male who underwent C3-6 laminectomies and fusion after a ten-foot fall resulting in quadriparesis. Post-operatively, the addition of midodrine in an attempt to wean off IV vasopressors resulted in significant reflexive bradycardia. Treatment with droxidopa facilitated rapidly weaning IV vasopressors and transfer to a lower level of care within 72 hours of treatment initiation. The second patient was a 73-year-old male who underwent C3-5 laminectomies and fusion for a traumatic hyperflexion injury causing paraplegia. The addition of midodrine resulted in severe bradycardia, prompting consideration of pacemaker placement. However, with the addition of droxidopa, this was avoided, and the patient was weaned off IV vasopressors on dual oral therapy with midodrine and droxidopa. Droxidopa may be a viable enteral therapy to treat hypotension in patients after acute SCI who are otherwise not tolerating midodrine in order to wean off IV vasopressors. This strategy may avoid pacemaker placement and facilitate shorter stays in the intensive care unit, particularly for patients who are stable but require continued intensive care unit admission for IV vasopressors, which can be cost ineffective and human resource depleting.

Hypermutated phenotype in gliosarcoma of the spinal cord.

Gliosarcoma is a variant of glioblastoma with equally poor prognosis and characterized by mixed glial and mesenchymal pathology. Metastasis is not uncommon but the involvement of the spinal cord is rare, and comprehensive genetic characterization of spinal gliosarcoma is lacking. We describe a patient initially diagnosed with a low-grade brain glioma via biopsy, followed by adjuvant radiation and temozolomide treatment. Nearly 2 years after diagnosis, she developed neurological deficits from an intradural, extramedullary tumor anterior to the spinal cord at T4, which was resected and diagnosed as gliosarcoma. Whole-exome sequencing (WES) of this tumor revealed a hypermutated phenotype, characterized by somatic mutations in key DNA mismatch repair (MMR) pathway genes, an abundance of C>T transitions within the identified somatic single nucleotide variations, and microsatellite stability, together consistent with temozolomide-mediated hypermutagenesis. This is the first report of a hypermutator phenotype in gliosarcoma, which may represent a novel genomic mechanism of progression from lower grade glioma.

DIAPH1 Variants in Non-East Asian Patients With Sporadic Moyamoya Disease.

Importance: Moyamoya disease (MMD), a progressive vasculopathy leading to narrowing and ultimate occlusion of the intracranial internal carotid arteries, is a cause of childhood stroke. The cause of MMD is poorly understood, but genetic factors play a role. Several familial forms of MMD have been identified, but the cause of most cases remains elusive, especially among non-East Asian individuals. Objective: To assess whether ultrarare de novo and rare, damaging transmitted variants with large effect sizes are associated with MMD risk. Design, Setting, and Participants: A genetic association study was conducted using whole-exome sequencing case-parent MMD trios in a small discovery cohort collected over 3.5 years (2016-2019); data were analyzed in 2020. Medical records from US hospitals spanning a range of 1 month to 1.5 years were reviewed for phenotyping. Exomes from a larger validation cohort were analyzed to identify additional rare, large-effect variants in the top candidate gene. Participants included patients with MMD and, when available, their parents. All participants who met criteria and were presented with the option to join the study agreed to do so; none were excluded. Twenty-four probands (22 trios and 2 singletons) composed the discovery cohort, and 84 probands (29 trios and 55 singletons) composed the validation cohort. Main Outcomes and Measures: Gene variants were identified and filtered using stringent criteria. Enrichment and case-control tests assessed gene-level variant burden. In silico modeling estimated the probability of variant association with protein structure. Integrative genomics assessed expression patterns of MMD risk genes derived from single-cell RNA sequencing data of human and mouse brain tissue. Results: Of the 24 patients in the discovery cohort, 14 (58.3%) were men and 18 (75.0%) were of European ancestry. Three of 24 discovery cohort probands contained 2 do novo (1-tailed Poisson P = 1.1 × 10-6) and 1 rare, transmitted damaging variant (12.5% of cases) in DIAPH1 (mammalian diaphanous-1), a key regulator of actin remodeling in vascular cells and platelets. Four additional ultrarare damaging heterozygous DIAPH1 variants (3 unphased) were identified in 3 other patients in an 84-proband validation cohort (73.8% female, 77.4% European). All 6 patients were non-East Asian. Compound heterozygous variants were identified in ena/vasodilator-stimulated phosphoproteinlike protein EVL, a mammalian diaphanous-1 interactor that regulates actin polymerization. DIAPH1 and EVL mutant probands had severe, bilateral MMD associated with transfusion-dependent thrombocytopenia. DIAPH1 and other MMD risk genes are enriched in mural cells of midgestational human brain. The DIAPH1 coexpression network converges in vascular cell actin cytoskeleton regulatory pathways. Conclusions and Relevance: These findings provide the largest collection to date of non-East Asian individuals with sporadic MMD harboring pathogenic variants in the same gene. The results suggest that DIAPH1 is a novel MMD risk gene and impaired vascular cell actin remodeling in MMD pathogenesis, with diagnostic and therapeutic ramifications.

Novel VLDLR microdeletion identified in two Turkish siblings with pachygyria and pontocerebellar atrophy.

Congenital ataxia with cerebellar hypoplasia is a heterogeneous group of disorders that presents with motor disability, hypotonia, incoordination, and impaired motor development. Among these, disequilibrium syndrome describes a constellation of findings including non-progressive cerebellar ataxia, mental retardation, and cerebellar hypoplasia following an autosomal recessive pattern of inheritance and can be caused by mutations in the Very Low Density Lipoprotein Receptor (VLDLR). Interestingly, while the majority of patients with VLDL-associated cerebellar hypoplasia in the literature use bipedal gait, the previously reported patients of Turkish decent have demonstrated similar neurological sequelae, but rely on quadrupedal gait. We present a consanguinous Turkish family with two siblings with cerebellar atrophy, predominantly frontal pachygyria and ataxic bipedal gait, who were found to have a novel homozygous deletion in the VLDLR gene identified by using high-density single nucleotide polymorphism microarrays for homozygosity mapping and identification of CNVs within these regions. Discovery of disease causing homozygous deletions in the present Turkish family capable of maintaining bipedal movement exemplifies the phenotypic heterogeneity of VLDLR-associated cerebellar hypoplasia and ataxia.

Persistent STAG2 mutation despite multimodal therapy in recurrent pediatric glioblastoma.

Similar to their adult counterparts, the prognosis for pediatric patients with high-grade gliomas remains poor. At time of recurrence, treatment options are limited and remain without consensus. This report describes the genetic findings, obtained from whole-exome sequencing of a pediatric patient with glioblastoma who underwent multiple surgical resections and treatment with standard chemoradiation, as well as a novel recombinant poliovirus vaccine therapy. Strikingly, despite the variety of treatments, there was persistence of a tumor clone, characterized by a deleterious STAG2 mutation, whose deficiency in preclinical studies can cause aneuploidy and aberrant mitotic progression, but remains understudied in the clinical setting. There was near elimination of an EGFR mutated and amplified tumor clone after gross total resection, standard chemoradiation, and poliovirus therapy, followed by the emergence of a persistently STAG2 mutated clone, with rare mutations in PTPN11 and BRAF, the latter composed of a novel deleterious mutation previously not reported in pediatric glioblastoma (p.D594G). This was accompanied by a mutation signature shift towards one characterized by increased DNA damage repair defects, consistent with the known underlying STAG2 deficiency. As such, this case represents a novel report following the clinical and genetic progression of a STAG2 mutated glioblastoma, including treatment with a novel and emerging immunotherapy. Although STAG2 deficiency comprises only a small subset of gliomas, this case adds clinical evidence to existing preclinical data supporting a role for STAG2 mutations in gliomagenesis and resistance to standard therapies.

COL4A1 mutation in preterm intraventricular hemorrhage.

Intraventricular hemorrhage is a common complication of preterm infants. Mutations in the type IV procollagen gene, COL4A1, are associated with cerebral small vessel disease with hemorrhage in adults and fetuses. We report a rare variant in COL4A1 associated with intraventricular hemorrhage in dizygotic preterm twins. These results expand the spectrum of diseases attributable to mutations in type IV procollagens.

Primary, non-exophytic, optic nerve germ cell tumors.

Tumors of the optic chiasm are relatively uncommon and usually associated with phakomatoses such as neurofibromatosis. Even more rare is the presentation of a primary, non-exophytic, isolated optic chiasm germ cell tumor (GCT). These tumors have imaging characteristics nearly indistinguishable from optic chiasmatic gliomas (OCGs). Herein we describe two cases of young men who presented with similar findings of progressive, painless visual loss and hypothalamic-pituitary-adrenal axis dysfunction including diabetes insipidus. Brain imaging was non-diagnostic and suggestive of an OCG. Pathology demonstrated GCTs in each case highlighting the importance of biopsy confirmation of the diagnosis. Both patients underwent a pterional craniotomy and sub-frontal approach to the optic chiasm. The chiasm was diffusely enlarged and discolored in each case without evidence of sellar, suprasellar or perichiasmatic pathology. Pathology demonstrated a malignant mixed GCT in the first patient and a germinoma in the second. This case series highlights the importance of tissue biopsy for patients with progressive symptoms from optic chiasm tumors. Furthermore, this is the first report of a primary, non-exophytic malignant mixed GCT. As the treatment regimens differ widely between optic chiasm GCTs and chiasm gliomas, tissue diagnosis is important.