Variables Associated With Shunt Failure in Children With Cerebrospinal Fluid Diverting Shunts.

OBJECTIVES: We sought to identify clinical characteristics that would negatively predict shunt failure, thus potentially obviating the need for further diagnostic workup or extended periods of observation. We hypothesized that viral symptoms and a patient history of epilepsy or chronic headaches would be negative predictors of shunt failure. METHODS: Data were retrospectively collected for children 19 years or younger with a cerebrospinal fluid diverting shunt in their medical history or problem list who underwent neuroimaging during an ED visit from March 2008 to September 2016. Patients were defined as having shunt failure if they required surgical exploration for shunt revision within 7 days of the ED visit. Descriptive statistics were used for patient demographics, current symptoms, and historical features. We conducted a logistic regression analysis to determine which characteristics were associated with the odds of shunt failure and used binary recursive partitioning to determine if there were features or a combination of features that were able to accurately classify patients without shunt failure. RESULTS: There were 606 visits by 277 patients during this interval, 34% of whom were experiencing shunt failure. Variables found to be significantly predictive of shunt failure were revision within the prior 6 months, vomiting, personality changes, family opinion of shunt failure, and cranial nerve palsies. Viral symptoms and a history of epilepsy or chronic headaches were not predictive of shunt failure. Binary recursive partitioning identified family opinion and personality changes as predictive of shunt failure, with a sensitivity of 72.2% (95% confidence interval, 65.5%-78.2%) and specificity of 46.6% (95% confidence interval, 41.7%-51.7%). CONCLUSIONS: Although certain clinical and historical features have modest predictive value in children with shunted hydrocephalus, these factors are insufficiently sensitive to exclude shunt failure, arguing for liberal neuroimaging and extended observation.

Postoperative MR imaging surveillance of pediatric craniopharyngioma: new institutional guidelines.

PURPOSE: To develop postoperative surveillance protocols that yield efficient detection rates of tumor recurrence or progression using fewer imaging studies and less cost. METHOD: This is a retrospective cohort study of all pediatric craniopharyngioma patients who have been diagnosed and treated at Boston Children's Hospital (BCH) between 1990 and 2017. All statistical analyses were performed using Stata. RESULTS: Eighty patients (43 males and 37 females) fulfilled the inclusion criteria. The mean age at time of diagnosis was 8.6 ± 4.4 years. The mean follow-up period was 10.9 ± 6.5 years. Overall 30/80 (37.5%) patients experienced tumor recurrence/progression. The median latency to recurrence/progression was 12.75 months (range 3 to 108 months), with 76.6% of the recurrences/progressions taking place within the first 2 years postoperatively. Given the lack of any clinical symptoms/signs associated with the vast majority of the recurrent/progressed cases, we propose postoperative MR imaging surveillance protocols that are substantially less intensive than the current practice. Therefore, we recommend the following postoperative MR imaging surveillance protocols, stratified by management strategies; 0, 9, 15, 36, 48, and 60 months for patients who underwent GTR, 0, 3, 6,12, 18, and 24 months for patients who underwent STR alone and 0, 3, 12, 72, 96, and 120 months for patients who underwent STR followed by subsequent XRT. CONCLUSION: The proposed postoperative MR imaging surveillance protocols would provide a potential 50% decrement of healthcare costs. It may also minify the psychological burden of frequent MR scanning for these patients and their families.

Moyamoya syndrome associated with Alagille syndrome: outcome after surgical revascularization.

Vasculopathy is well-described in Alagille syndrome (ALGS); however, few data exist regarding neurosurgical interventions. We report 5 children with ALGS with moyamoya who underwent revascularization surgery. Postsurgical complications included 1 stroke and 1 death from thalamic hemorrhage. Global function improved in survivors. Revascularization is reasonably safe in patients with ALGS and may improve neurologic outcomes.

Third-ventricular neurocysticercosis: hydraulic maneuvers facilitating endoscopic resection.

BACKGROUND: Neurocysticercosis, an infection of the central nervous system with the larval cysts of the pork tapeworm, Taenia solium, is the most common parasitic disease of the central nervous system. The disease is a major global cause of acquired epilepsy and may also manifest as intracranial hypertension due to mass effect from large cysts or to cerebrospinal fluid flow obstruction by intraventricular cysts or inflammation of the subarachnoid space. While the condition is endemic in several regions of the world and has been appreciated as a public health problem in such regions for several decades, its emergence in the USA in areas far from the Mexican border is a more recent phenomenon. METHODS: We present a case of surgically corrected acute hydrocephalus in a recent Haitian emigrant child due to a third ventricular neurocysticercal cyst complex. RESULTS: We describe the endoscope-assisted en bloc removal of the complex, together with hydraulic maneuvers facilitating the removal of the intact cyst. CONCLUSIONS: Simple hydraulic maneuvers can facilitate the endoscopic en bloc removal of third ventricular neurocysticercal cysts.

Molecular profiling of pre- and post-treatment pediatric high-grade astrocytomas reveals acquired increased tumor mutation burden in a subset of recurrences.

Diffuse gliomas are a heterogeneous category of primary central nervous system tumors. Due to their infiltrative growth precluding complete surgical resection, most diffuse high-grade gliomas are treated with adjuvant chemotherapy and radiation. Recurrent/progressive diffuse gliomas may show genetic differences when compared to the primary tumors, giving insight into their molecular evolution and mechanisms of treatment resistance. In adult-type diffuse gliomas with or without isocitrate dehydrogenase gene mutations, tumor recurrence/progression can be associated with mutations in genes encoding DNA mismatch repair proteins, leading to a dramatic increase in tumor mutation burden. This phenomenon is closely linked to treatment with the DNA alkylating agent temozolomide, a mainstay of adult diffuse glioma chemotherapeutic management. Post-treatment mismatch repair deficiency and acquired high tumor mutation burden is relatively unexplored in pediatric patients who have recurrent high-grade gliomas. Here, we report a molecular and histological analysis of an institutional cohort of eleven pediatric patients with paired initial and recurrent high-grade astrocytoma samples with intervening temozolomide treatment. We identified three cases with evidence for increased tumor mutation burden at recurrence, including two cases of diffuse hemispheric glioma H3 G34-mutant (one previously reported). We also show that molecular analysis by next-generation DNA sequencing and DNA methylation-based profiling enabled an integrated diagnosis per 2021 World Health Organization criteria in 10 of 11 cases (91%). Our findings indicate that increased tumor mutation burden at post-treatment recurrence is relevant in pediatric-type diffuse high-grade gliomas. Diffuse hemispheric glioma H3 G34-mutant may be particularly susceptible to this phenomenon.

Positioning Transclival Tumor-Treating Fields for the Treatment of Diffuse Intrinsic Pontine Gliomas.

Diffuse intrinsic pontine glioma (DIPG) carries an extremely poor prognosis, with 2-year survival rates of <10% despite the maximal radiation therapy. DIPG cells have previously been shown to be sensitive to low-intensity electric fields in vitro. Accordingly, we sought to determine if the endoscopic endonasal (EE) implantation of an electrode array in the clivus would be feasible for the application of tumor-treating fields (TTF) in DIPG. Anatomic constraints are the main limitation in pediatric EE approaches. In our Boston Children's Hospital's DIPG cohort, we measured the average intercarotid distance (1.68 ± 0.36 cm), clival width (1.62 ± 0.19 cm), and clival length from the base of the sella (1.43 ± 0.69 cm). Using a linear regression model, we found that only clival length and sphenoid pneumatization were significantly associated with age (R2 = 0.568, p = 0.005 *; R2 = 0.605, p = 0.0002 *). Critically, neither of these parameters represent limitations to the implantation of a device within the dimensions of those currently available. Our findings confirm that the anatomy present within this age group is amenable to the placement of a 2 × 1 cm electrode array in 94% of patients examined. Our work serves to demonstrate the feasibility of implantable transclival devices for the provision of TTFs as a novel adjunctive therapy for DIPG.

H3K27-altered diffuse midline gliomas with MAPK pathway alterations: Prognostic and therapeutic implications.

Large-scale sequencing led to the identification of driver molecular alterations such as FGFR1 and BRAF in occasional diffuse midline gliomas (DMGs) H3K27-mutant but their significance has not been completely explored. We evaluated these associations in our institutional cohorts. We searched our archives for H3K2M7-mutant gliomas and analyzed the co-occurring genetic alterations. The demographics, clinical information, and pathology were reviewed. Oncoplots and Kaplan-Meier survival curves were generated with the maftools R package. We identified 81 patients (age range 2-68, median 26), of which 79 (97%) were DMGs, and 2 were glioneuronal tumors. The 2 glioneuronal tumors (1 with BRAF fusion and 1 BRAF-V600E-mutant) were removed from the outcome analysis. Four cases had BRAF V600E mutation, 12 had FGFR1 hotspot mutations, and one each had KRAS and NRAS pathogenic mutations. The most common correlating anatomic location was the brainstem for the BRAF group and thalamus for the FGFR1group. Follow-up ranged from 0 to 78 months, average 20.4 months. The overall survival in FGFR1- and BRAF V600E-mutant DMGs was not statistically improved when compared with those that were wildtype. However, the possibility of targeted therapy argues for comprehensive sequencing of H3K27-altered gliomas.

Endoscopic third ventriculostomy with choroid plexus cauterization: predictors of long-term success and comparison with shunt placement for primary treatment of infant hydrocephalus.

OBJECTIVE: Endoscopic third ventriculostomy (ETV) with choroid plexus cauterization (CPC) can avoid ventriculoperitoneal shunt (VPS) dependence in very young hydrocephalic children, although long-term success as a primary treatment in North America has not been previously reported. Moreover, optimal age at surgery, impact of preoperative ventriculomegaly, and relationship to prior cerebrospinal fluid (CSF) diversion remain poorly defined. The authors compared ETV/CPC and VPS placement for averting reoperation, and they evaluated preoperative predictors for reoperation and shunt placement after ETV/CPC. METHODS: All patients under 12 months of age who underwent initial hydrocephalus treatment via ETV/CPC or VPS placement at Boston Children's Hospital between December 2008 and August 2021 were reviewed. Analyses included Cox regression for independent outcome predictors, and both Kaplan-Meier and log-rank rank tests for time-to-event outcomes. Cutoff values for age and preoperative frontal and occipital horn ratio (FOHR) were determined with receiver operating characteristic curve analysis and Youden's J index. RESULTS: In total, 348 children (150 females) were included with principal etiologies of posthemorrhagic hydrocephalus (26.7%), myelomeningocele (20.1%), and aqueduct stenosis (17.0%). Of these, 266 (76.4%) underwent ETV/CPC and 82 (23.6%) underwent VPS placement. Treatment choice largely reflected surgeon preferences before practice shifted toward endoscopy, with endoscopy not considered for > 70% of initial VPS cases. ETV/CPC patients trended toward fewer reoperations, and Kaplan-Meier analysis estimated that 59% of patients would achieve long-term shunt freedom through 11 years (median 42 months of actual follow-up). Among all patients, corrected age < 2.5 months (p < 0.001), prior temporizing CSF diversion (p = 0.003), and excess intraoperative bleeding (p < 0.001) independently predicted reoperation. Among ETV/CPC patients, corrected age < 2.5 months (p = 0.031), prior CSF diversion (p = 0.001), preoperative FOHR > 0.613 (p = 0.011), and excessive intraoperative bleeding (p = 0.001) independently predicted ultimate conversion to VPS. The actual VPS insertion rates remained low in patients who were ≥ 2.5 months old at ETV/CPC either with prior CSF diversion (2/10 [20.0%]) or without prior CSF diversion (24/123 [19.5%]); however, the actual VPS insertion rates increased in patients who were < 2.5 months old at ETV/CPC with prior CSF diversion (19/26 [73.1%]) or without prior CSF diversion (44/107 [41.1%]). CONCLUSIONS: ETV/CPC successfully treated hydrocephalus in most patients younger than 1 year irrespective of etiology, averting observed shunt dependence in 80% of patients ≥ 2.5 months of age regardless of prior CSF diversion and in 59% of those < 2.5 months of age without prior CSF diversion. For infants aged < 2.5 months with prior CSF diversion, particularly those with severe ventriculomegaly, ETV/CPC was unlikely to succeed unless safely delayed.

Craniofacial reconstruction as a treatment for elevated intracranial pressure.

INTRODUCTION: Craniofacial procedures may be needed to address symptomatic intracranial hypertension. The authors review their institutional experience in the treatment of children with symptomatic increased intracranial pressure (ICP) utilizing craniofacial reconstructive procedures. METHODS: The senior authors' (HSM, SRC) craniofacial experience of 222 patients over a 7-year period from 2000 to 2007 at a single institution (Rady Children's Hospital, San Diego) is reviewed. Seventeen patients were identified who were felt to be candidates for craniofacial surgery with symptomatic increased ICP. RESULTS: Patient diagnoses included single-suture craniosynostosis, craniofacial dysostoses, shunt-induced craniostenosis, and shunt-associated intracranial hypertension (slit-ventricle syndrome). Seventeen patients underwent 21 craniofacial procedures. Age at surgery ranged from 3 months to 13 years with a mean of 5 years. Preoperative symptoms and signs included headaches, unexplained irritability, seizures, papilledema, and visual loss. All patients had diagnostic neuroimaging. Seven patients had preoperative invasive ICP measurements. Surgery was deferred on three of these patients based on these measurements. The mean total operative (including anesthetic preparation) and surgical times were 3 h 12 min and 2 h 20 min, respectively. Percentage operative blood loss averaged 11.3%. In six procedures, no transfusions were required. Average hospital stay was 4 days. There was no perioperative mortality or significant surgery associated morbidity. All patients have had postoperative clinical improvement in signs and symptoms of increased ICP. CONCLUSIONS: Using modern diagnostic and surgical techniques, including invasive ICP monitoring, increased intracranial pressure can be successfully managed by an experienced, multidisciplinary, craniofacial team. Our treatment paradigm and operative management scheme is discussed.

Optic nerve compression in craniopharyngioma by taut anterior cerebral arteries visualized in frontal and transsphenoidal exposures: illustrative cases.

BACKGROUND: During initial exposure and removal of craniopharyngioma in pediatric patients with severe visual field deficits, the authors have encountered severe deformation of the optic apparatus by taut anterior cerebral arteries as seen during both frontal craniotomy and transsphenoidal exposures. OBSERVATIONS: The authors report two pediatric patients with craniopharyngioma whose severe preoperative visual deficits were associated not only with large suprasellar masses but also with severe optic nerve and chiasm compression by taut anterior cerebral arteries. In each patient, the optic nerves were partially cleft by these vessels' indenting them. LESSONS: The role of a taut anterior cerebral artery complex in compression of the optic apparatus in patients with suprasellar tumors has been reported previously, but the intraoperative images in these two cases dramatically reveal this phenomenon.

Pediatric Cranial Dog Bite Injuries: More than Meets the Eye.

CASE PRESENTATION: A six-month-old female presented to a community hospital with small lacerations to the scalp, face, and left eyelid from a dog bite injury. Computed tomography imaging revealed an impacted right frontal bone fracture and left superior orbital fracture, prompting transfer, neurosurgical repair, and infectious disease management of the injury. DISCUSSION: This report highlights the importance of having a high level of suspicion for deeper injury in pediatric and especially infant craniofacial dog bites, obtaining radiographic imaging, and initiating appropriate multidisciplinary triage to prevent life-threatening infection and complications.

Machine Learning in the Classification of Pediatric Posterior Fossa Tumors: A Systematic Review.

Background: Posterior fossa tumors (PFTs) are a morbid group of central nervous system tumors that most often present in childhood. While early diagnosis is critical to drive appropriate treatment, definitive diagnosis is currently only achievable through invasive tissue collection and histopathological analyses. Machine learning has been investigated as an alternative means of diagnosis. In this systematic review and meta-analysis, we evaluated the primary literature to identify all machine learning algorithms developed to classify and diagnose pediatric PFTs using imaging or molecular data. Methods: Of the 433 primary papers identified in PubMed, EMBASE, and Web of Science, 25 ultimately met the inclusion criteria. The included papers were extracted for algorithm architecture, study parameters, performance, strengths, and limitations. Results: The algorithms exhibited variable performance based on sample size, classifier(s) used, and individual tumor types being investigated. Ependymoma, medulloblastoma, and pilocytic astrocytoma were the most studied tumors with algorithm accuracies ranging from 37.5% to 94.5%. A minority of studies compared the developed algorithm to a trained neuroradiologist, with three imaging-based algorithms yielding superior performance. Common algorithm and study limitations included small sample sizes, uneven representation of individual tumor types, inconsistent performance reporting, and a lack of application in the clinical environment. Conclusions: Artificial intelligence has the potential to improve the speed and accuracy of diagnosis in this field if the right algorithm is applied to the right scenario. Work is needed to standardize outcome reporting and facilitate additional trials to allow for clinical uptake.

Immunotherapy approaches for the treatment of diffuse midline gliomas.

Diffuse midline gliomas (DMG) are a highly aggressive and universally fatal subgroup of pediatric tumors responsible for the majority of childhood brain tumor deaths. Median overall survival is less than 12 months with a 90% mortality rate at 2 years from diagnosis. Research into the underlying tumor biology and numerous clinical trials have done little to change the invariably poor prognosis. Continued development of novel, efficacious therapeutic options for DMGs remains a critically important area of active investigation. Given that DMGs are not amenable to surgical resection, have only limited response to radiation, and are refractory to traditional chemotherapy, immunotherapy has emerged as a promising alternative treatment modality. This review summarizes the various immunotherapy-based treatments for DMG as well as their specific limitations. We explore the use of cell-based therapies, oncolytic virotherapy or immunovirotherapy, immune checkpoint inhibition, and immunomodulatory vaccination strategies, and highlight the recent clinical success of anti-GD2 CAR-T therapy in diffuse intrinsic pontine glioma (DIPG) patients. Finally, we address the challenges faced in translating preclinical and early phase clinical trial data into effective standardized treatment for DMG patients.

Discovery of asymptomatic moyamoya arteriopathy in pediatric syndromic populations: radiographic and clinical progression.

OBJECT: Limited data exist to guide management of incidentally discovered pediatric moyamoya. Best exemplified in the setting of unilateral moyamoya, in which the unaffected side is monitored, this phenomenon also occurs in populations undergoing routine surveillance of the cerebral vasculature for other conditions, such as sickle cell disease (SCD) or neurofibromatosis Type 1 (NF1). The authors present their experience with specific syndromic moyamoya populations to better characterize the natural history of radiographic and clinical progression in patients with asymptomatic moyamoya. METHODS: The authors performed a retrospective review of the clinical database of the neurosurgery department at Children's Hospital Boston, including both nonoperative referrals and a consecutive series of 418 patients who underwent surgical revascularization for moyamoya disease between 1988 and 2010. RESULTS: Within the period of time studied, 83 patients were asymptomatic at the time of radiographic diagnosis of moyamoya, while also having either unilateral moyamoya or moyamoya in association with either SCD or NF1. The mean age at presentation was 9.1 years (range 1-21 years), and there were 49 female (59%) and 34 male (41%) patients. The mean follow-up duration was 5.4 ± 3.8 years (mean ± SD), with 45 patients (54%) demonstrating radiographic progression and 37 (45%) becoming symptomatic within this period. Patients with SCD had the highest incidence of both radiographic (15 patients [75%]) and clinical (13 patients [65%]) progression, followed by NF1 (20 patients [59%] with radiographic progression and 15 patients [44%] with clinical progression) and patients with unilateral moyamoya (10 patients [35%] with radiographic progression and 9 patients [31%] with clinical progression). CONCLUSIONS: Radiographic progression occurred in the majority of asymptomatic patients and generally heralded subsequent clinical symptoms. These data demonstrate that moyamoya is a progressive disorder, even in asymptomatic populations, and support the rationale of early surgical intervention to minimize morbidity from stroke.

Management strategies for recurrent pediatric craniopharyngioma: new recommendations.

OBJECTIVE: The goal of this study was to identify the independent risk factors for recurrence or progression of pediatric craniopharyngioma and to establish predictors of the appropriate timing of intervention and best management strategy in the setting of recurrence/progression, with the aim of optimizing tumor control. METHODS: This is a retrospective cohort study of all pediatric patients with craniopharyngioma who were diagnosed and treated at Boston Children's Hospital between 1990 and 2017. This study was approved by the institutional review board at Boston Children's Hospital. All statistical analyses were performed using Stata software. RESULTS: Eighty patients (43 males and 37 females) fulfilled the inclusion criteria. The mean age at the time of diagnosis was 8.6 ± 4.4 years (range 1.2-19.7 years). The mean follow-up was 10.9 ± 6.5 years (range 1.3-24.6 years). Overall, 30/80 (37.5%) patients developed recurrence/progression. The median latency to recurrence/progression was 12.75 months (range 3-108 months). Subtotal resection with no adjuvant radiotherapy (p < 0.001) and fine calcifications (p = 0.008) are independent risk factors for recurrence/progression. An increase (%) in the maximum dimension of the tumor at the time of recurrence/progression was considered a statistically significant predictor of the appropriate timing of intervention. CONCLUSIONS: Based on the identified independent risk factors for tumor recurrence/progression and the predictors of appropriate timing of intervention in the setting of recurrence/progression, the authors propose an algorithm for optimal management of recurrent pediatric craniopharyngioma to increase the likelihood of tumor control.

Occipital-Cervical Fusion and Ventral Decompression in the Surgical Management of Chiari-1 Malformation and Syringomyelia: Analysis of Data From the Park-Reeves Syringomyelia Research Consortium.

BACKGROUND: Occipital-cervical fusion (OCF) and ventral decompression (VD) may be used in the treatment of pediatric Chiari-1 malformation (CM-1) with syringomyelia (SM) as adjuncts to posterior fossa decompression (PFD) for complex craniovertebral junction pathology. OBJECTIVE: To examine factors influencing the use of OCF and OCF/VD in a multicenter cohort of pediatric CM-1 and SM subjects treated with PFD. METHODS: The Park-Reeves Syringomyelia Research Consortium registry was used to examine 637 subjects with cerebellar tonsillar ectopia ≥ 5 mm, syrinx diameter ≥ 3 mm, and at least 1 yr of follow-up after their index PFD. Comparisons were made between subjects who received PFD alone and those with PFD + OCF or PFD + OCF/VD. RESULTS: All 637 patients underwent PFD, 505 (79.2%) with and 132 (20.8%) without duraplasty. A total of 12 subjects went on to have OCF at some point in their management (PFD + OCF), whereas 4 had OCF and VD (PFD + OCF/VD). Of those with complete data, a history of platybasia (3/10, P = .011), Klippel-Feil (2/10, P = .015), and basilar invagination (3/12, P < .001) were increased within the OCF group, whereas only basilar invagination (1/4, P < .001) was increased in the OCF/VD group. Clivo-axial angle (CXA) was significantly lower for both OCF (128.8 ± 15.3°, P = .008) and OCF/VD (115.0 ± 11.6°, P = .025) groups when compared to PFD-only group (145.3 ± 12.7°). pB-C2 did not differ among groups. CONCLUSION: Although PFD alone is adequate for treating the vast majority of CM-1/SM patients, OCF or OCF/VD may be occasionally utilized. Cranial base and spine pathologies and CXA may provide insight into the need for OCF and/or OCF/VD.

Extradural decompression versus duraplasty in Chiari malformation type I with syrinx: outcomes on scoliosis from the Park-Reeves Syringomyelia Research Consortium.

OBJECTIVE: Scoliosis is common in patients with Chiari malformation type I (CM-I)-associated syringomyelia. While it is known that treatment with posterior fossa decompression (PFD) may reduce the progression of scoliosis, it is unknown if decompression with duraplasty is superior to extradural decompression. METHODS: A large multicenter retrospective and prospective registry of 1257 pediatric patients with CM-I (tonsils ≥ 5 mm below the foramen magnum) and syrinx (≥ 3 mm in axial width) was reviewed for patients with scoliosis who underwent PFD with or without duraplasty. RESULTS: In total, 422 patients who underwent PFD had a clinical diagnosis of scoliosis. Of these patients, 346 underwent duraplasty, 51 received extradural decompression alone, and 25 were excluded because no data were available on the type of PFD. The mean clinical follow-up was 2.6 years. Overall, there was no difference in subsequent occurrence of fusion or proportion of patients with curve progression between those with and those without a duraplasty. However, after controlling for age, sex, preoperative curve magnitude, syrinx length, syrinx width, and holocord syrinx, extradural decompression was associated with curve progression > 10°, but not increased occurrence of fusion. Older age at PFD and larger preoperative curve magnitude were independently associated with subsequent occurrence of fusion. Greater syrinx reduction after PFD of either type was associated with decreased occurrence of fusion. CONCLUSIONS: In patients with CM-I, syrinx, and scoliosis undergoing PFD, there was no difference in subsequent occurrence of surgical correction of scoliosis between those receiving a duraplasty and those with an extradural decompression. However, after controlling for preoperative factors including age, syrinx characteristics, and curve magnitude, patients treated with duraplasty were less likely to have curve progression than patients treated with extradural decompression. Further study is needed to evaluate the role of duraplasty in curve stabilization after PFD.

The tumor microenvironment.

Recent advances in stem cell and developmental neurobiology have uncovered new perspectives from which we investigate various forms of cancer. Specifically, the hypothesis at tumors are comprised of a subpopulation of malignant cells similar to stem cells is of great interest to scientists and clinicians and has been dubbed the cancer stem cell hypothesis. The region where this is most relevant is within the brain. Cancer stem cells have been isolated from brain tumors that exhibit characteristics of differentiation and proliferation normally seen only in neural stem cells. These cancer stem cells may be responsible for tumor origin, survival and proliferation. Furthermore, these cells must be considered within their immediate microenvironment when investigating mechanisms of tumorgenesis. Evidence of brain tumor stem cells will be reviewed along with the role of tumor environment as the context within which these cells should be understood.