Untangling the web of glioblastoma treatment resistance using a multi-omic and multidisciplinary approach

Glioblastoma (GBM), the most common human brain tumor, has been notoriously resistant to treatment. As a result, the dismal overall survival of GBM patients has not changed over the past three decades. GBM has been stubbornly resistant to checkpoint inhibitor immunotherapies, which have been remarkably effective in the treatment of other tumors. It is clear that GBM resistance to therapy is multifactorial. Although therapeutic transport into brain tumors is inhibited by the blood brain barrier, there is evolving evidence that overcoming this barrier is not the predominant factor. GBMs generally have a low mutation burden, exist in an immunosuppressed environment and they are inherently resistant to immune stimulation, all of which contribute to treatment resistance. In this review, we evaluate the contribution of multi-omic approaches (genomic and metabolomic) along with analyzing immune cell populations and tumor biophysical characteristics to better understand and overcome GBM multifactorial resistance to treatment.

Metabolomic differentiation of tumor core versus edge in glioma

OBJECTIVE

Gliomas exhibit high intratumor and interpatient heterogeneity. Recently, it has been shown that the microenvironment and phenotype differ significantly between the glioma core (inner) and edge (infiltrating) regions. This proof-of-concept study differentiates metabolic signatures associated with these regions, with the potential for prognosis and targeted therapy that could improve surgical outcomes.

METHODS

Paired glioma core and infiltrating edge samples were obtained from 27 patients after craniotomy. Liquid-liquid metabolite extraction was performed on the samples and metabolomic data were obtained via 2D liquid chromatography-mass spectrometry/mass spectrometry. To gauge the potential of metabolomics to identify clinically relevant predictors of survival from tumor core versus edge tissues, a boosted generalized linear machine learning model was used to predict metabolomic profiles associated with O6-methylguanine DNA methyltransferase (MGMT) promoter methylation.

RESULTS

A panel of 66 (of 168) metabolites was found to significantly differ between glioma core and edge regions (p ≤ 0.05). Top metabolites with significantly different relative abundances included DL-alanine, creatine, cystathionine, nicotinamide, and D-pantothenic acid. Significant metabolic pathways identified by quantitative enrichment analysis included glycerophospholipid metabolism; butanoate metabolism; cysteine and methionine metabolism; glycine, serine, alanine, and threonine metabolism; purine metabolism; nicotinate and nicotinamide metabolism; and pantothenate and coenzyme A biosynthesis. The machine learning model using 4 key metabolites each within core and edge tissue specimens predicted MGMT promoter methylation status, with AUROCEdge = 0.960 and AUROCCore = 0.941. Top metabolites associated with MGMT status in the core samples included hydroxyhexanoycarnitine, spermine, succinic anhydride, and pantothenic acid, and in the edge samples metabolites included 5-cytidine monophosphate, pantothenic acid, itaconic acid, and uridine.

CONCLUSIONS

Key metabolic differences are identified between core and edge tissue in glioma and, furthermore, demonstrate the potential for machine learning to provide insight into potential prognostic and therapeutic targets.

Intraoperative MRI use in transsphenoidal surgery for pituitary tumors: Trends and healthcare utilization

BACKGROUND

Intraoperative magnetic resonance imaging (iMRI) use in transsphenoidal approach (TSA) for pituitary tumors (PTs) has been reported to improve the extent of resection (EOR). The aim of this study is to report the trends and the impact of iMRI on healthcare utilization in patients who underwent TSA for PTs.

MATERIALS AND METHODS

MarketScan database were queried using the ICD-9/10 and CPT-4, from 2004 to 2020. We included patients ≥ 18 years of age PTs with > 1 year follow-up. Outcomes were length of stay (LOS), discharge disposition, hospital/emergency room (ER) re-admissions, outpatient services, medication refills and corresponding payments.

RESULTS

A cohort of 10,192 patients were identified from the database, of these 141 patients (1.4%) had iMRI used during the procedure. Use of iMRI for PTs remained stable (2004-2007: 0.85%; 2008-2011: 1.6%; 2012-2015:1.4% and 2016-2019: 1.46%). No differences in LOS (median 3 days each), discharge to home (93% vs. 94%), complication rates (7% vs. 13%) and payments ($34604 vs. $33050) at index hospitalization were noted. Post-discharge payments were not significantly different without and with iMRI use at 6-months ($8315 vs. $ 7577, p = 0.7) and 1-year ($13,654 vs. $ 14,054, p = 0.70), following the index procedure.

CONCLUSION

iMRI use during TSA for PTs remained stable with no impact on LOS, complications, discharge disposition and index payments. Also, there was no difference in combined index payments at 6-months, and 1-year after the index procedure in patients with and without iMRI use for PTs.

Trends and Impact of Treatment modalities (Surgery and Radiation Therapy) on Health Care utilization in patients with Glomus Jugulare Tumors (GJTs): An Inverse Probability of Treatment Weight Analysis

OBJECTIVES

The trend of practice pattern and impact on healthcare utilization for surgery and radiation therapy (RT) in patients with glomus Jugulare tumors (GJTs) is not well defined.

MATERIALS AND METHODS

MarketScan database was queried using the ICD-9/10 and CPT 4^th edition, 2000-2020. We included patients ≥ 18 years of age who underwent either surgery or RT with at-least 1-year follow-up. We compared the health care utilization at 3-month, 6-month and 1-year follow up using the inverse probability of treatment weight (IPTW) technique.

RESULTS

A cohort of 333 patients was identified. Of these, 72.7% (n=242) underwent RT and 27.3% (n=91) underwent surgery. RT use increased from 2002-2004 (50%) to 2017-2019 (91%). Patients in the surgery cohort were younger (median age 49 vs. 56 years, p<0.0001) and had a higher 3+ comorbidity index (34% vs. 30%, p=0.43) compared to patients in the RT cohort. Patient who underwent surgery had higher complications at index hospitalization (22% vs. 6%, p<0.0001) and at 30 days (14% vs. 5%, p=0.0042). No difference in combined index and 6- or 12-months payments were noted (6-months: surgery, $66108, RT: $43509, p=0.1034; 12-months: surgery, $73259, RT: $51576, p=0.1817). Only 4% of patients who had initial RT underwent RT and none underwent surgery at 12 months, whereas 6% of patients who had initial surgery underwent RT and 2% underwent surgery at 12 months.

CONCLUSION

RT plays an increasingly important role in the treatment for patients with GJTs, with less complications and a comparable health care utilization at 1 year.

Demographic variations and time to initiation of adjunct treatment following surgical resection of anaplastic astrocytoma in the United States: a National Cancer Database analysis

BACKGROUND AND AIMS

The aim of this study was to analyze the trends, demographic differences in the type and time to initiation (TTI) of adjunct treatment AT following surgery for anaplastic astrocytoma (AA).

MATERIAL AND METHODS

The National Cancer Database (NCDB) was queried for patients diagnosed with AA from 2004 to 2016. Cox proportional hazards and modeling was used to determine factors influencing survival, including the impact of time to initiation (TTI) of adjuvant therapy.

RESULTS

Overall, 5890 patients were identified from the database. The use of combined RT + CT temporally increased from 66.3% (2004-2007) to 79% (2014-2016), p < 0001. Patients more likely to receive no treatment following surgical resection included elderly (> 60 years old), hispanic patients, those with either no or government insurance, those living > 20 miles from the cancer facility, those treated at low volume centers (< 2 cases/year). AT was received following surgical resection within 0-4 weeks, 4.1-8 weeks, and > 8 weeks in 41%, 48%, and 3%, respectively. Compared to patients who received RT + CT, patients were likely to receive RT only as AT either at 4-8 weeks or > 8 weeks after the surgical procedure. Patients who received AT within 0-4 weeks had the 3-year OS of 46% compared to 56.7% for patients who received treatment at 4.1-8 weeks.

CONCLUSION

We found significant variation in the type and timing of adjunct treatment following surgical resection of AA in the United States. A considerable number of patients (15%) received no AT following surgery.

Feasibility of Transcranial Motor Evoked Potentials and Electromyography during MRI-Guided Laser Interstitial Thermal Therapy for Glioblastoma

BACKGROUND

Intraoperative neuromonitoring (IONM) is routinely used during neurosurgical procedures. Magnetic resonance imaging (MRI)-guided laser interstitial thermal therapy (LITT) is increasingly being used in patients with various brain lesions. Use of IONM (transcranial motor evoked potential [TcMEP] and electromyography [EMG]) during LITT of a brain lesion has not been described previously.

METHODS

In this report, we describe a 70-year-old man who presented with motor weakness in whom imaging revealed a left thalamic lesion. Due to the difficulty in accessing the lesion and proximity to the motor tracts, patient was offered MRI-guided LITT using TcMEP and EMG.

RESULTS

The patient underwent satisfactory ablation of the lesion with successful recording of the TcMEP and EMG. Technical nuances related to the set-up and procedure is discussed in this report. No procedure-related complications were encountered.

CONCLUSIONS

We describe the first report of safety and feasibility of TcMEP and EMG during MRI-guided LITT for left thalamic glioblasatoma. This report paves the way for further prospective investigations regarding the utility of this technique for eloquent brain tumors.

Impact of Management Strategies on New-Onset Mental Health Disorders and Associated Health Care Utilization in Patients with Vestibular Schwannoma

OBJECTIVE

To compare the impact of different management strategies on diagnosis of new-onset mental health disorders (MHDs) in patients with vestibular schwannoma (VS) and health care utilization at 1-year follow-up.

METHODS

MarketScan databases were queried using the International Classification of Diseases, Ninth Revision and Tenth Revision and Current Procedural Terminology, Fourth Edition, 2000-2020. We included patients ≥18 years old with a diagnosis of VS who underwent clinical observation, surgery, or stereotactic radiosurgery (SRS) with at least 1 year of follow-up. We looked at health care outcomes and MHDs at 3-month, 6-month, and 1-year follow-up.

RESULTS

The database search identified 23,376 patients. Of these, 94.2% (n = 22,041) were managed conservatively with clinical observation at the initial diagnosis, and 2% (n = 466) underwent surgery. The surgery cohort had the highest incidence of new-onset MHDs followed by SRS and clinical observation cohorts at 3 months (surgery: 17%; SRS: 12%; clinical observation: 7%), 6 months (surgery: 20%; SRS: 16%; clinical observation: 10%), and 12 months (surgery: 27%; SRS: 23%; clinical observation: 16%) (P < 0.0001). The median difference in combined payments between patients with and without MHDs was highest in the surgery cohort followed by SRS and clinical observation cohorts at all time points (12 months: surgery: $14,469; SRS: $10,557; clinical observation: $6439; P = 0.0002).

CONCLUSIONS

Compared with clinical observation only, patients who underwent surgery for VS were 2 times more likely and patients who underwent SRS were 1.5 times more likely to develop MHDs with corresponding increase in health care utilization at 1-year follow-up.

The CNS-penetrating taxane drug TPI 287 potentiates antiglioma activity of the AURKA inhibitor alisertib in vivo

INTRODUCTION

Glioblastoma (GBM) has a very poor prognosis despite current treatment. We previously found cytotoxic synergy between the AURKA inhibitor alisertib and the CNS-penetrating taxane TPI 287 against GBM tumor cells in vitro.

METHODS

We used an orthotopic human GBM xenograft mouse model to test if TPI 287 potentiates alisertib in vivo. Western blotting, immunohistochemistry, siRNA knockdown, annexin V binding, and 3-dimensional Matrigel invasion assays were used to investigate potential mechanisms of alisertib and TPI 287 treatment interactions.

RESULTS

Alisertib + TPI 287 combination therapy significantly prolonged animal survival compared to vehicle (p = 0.011), but only marginally compared to alisertib alone. Alisertib, TPI 287, and combined alisertib + TPI 287 reduced animal tumor volume compared to vehicle-treated controls. This was statistically significant for the combination therapy at 4 weeks (p < 0.0001). Alisertib + TPI 287 treatment decreased anti-apoptotic Bcl-2 protein levels in vivo and in vitro. Expression of the pro-apoptotic protein Bak was significantly increased by combination treatment (p < 0.0001). Pro-apoptotic Bim and Bak knockdown by siRNA decreased apoptosis by alisertib + TPI 287 in GB9, GB30, and U87 cells (p = 0.0005 to 0.0381). Although alisertib and TPI 287 significantly reduced GBM cell invasion (p < 0.0001), their combination was no more effective than TPI 287 alone.

CONCLUSIONS

Results suggest that apoptosis is the dominant mechanism of potentiation of GBM growth inhibition by alisertib + TPI 287, in part through effects on Bcl-2 family proteins, providing a rationale for further laboratory testing of an AURKA inhibitor plus TPI 287 as a potential therapy against GBM.

Hemorrhage and Recurrence of Obliterated Brain Arteriovenous Malformations Treated With Stereotactic Radiosurgery

BACKGROUND

Although complete nidal obliteration of brain arteriovenous malformations (AVM) is generally presumed to represent durable cure, postobliteration hemorrhage, and AVM recurrence have become increasingly recognized phenomena. The goal of the study was to define hemorrhage and nidal recurrence risks of obliterated AVMs treated with stereotactic radiosurgery (SRS).

METHODS

This is a retrospective cohort study from the International Radiosurgery Research Foundation comprising AVM patients treated between 1987 and 2020. Patients with AVM obliteration on digital subtraction angiography (DSA) were included. Outcomes were (1) hemorrhage and (2) AVM recurrence. Follow-up duration began at the time of AVM obliteration and was censored at subsequent hemorrhage, AVM recurrence, additional AVM treatment, or loss to follow-up. Annualized risk and survival analyses were performed. A sensitivity analysis comprising patients with AVM obliteration on magnetic resonance imaging or DSA was also performed for postobliteration hemorrhage.

RESULTS

The study cohort comprised 1632 SRS-treated patients with AVM obliteration on DSA. Pediatric patients comprised 15% of the cohort, and 42% of AVMs were previously ruptured. The mean imaging follow-up after AVM obliteration was 22 months. Among 1607 patients with DSA-confirmed AVM obliteration, 16 hemorrhages (1.0%) occurred over 2223 patient-years of follow-up (0.72%/y). Of the 1543 patients with DSA-confirmed AVM obliteration, 5 AVM recurrences (0.32%) occurred over 2071 patient-years of follow-up (0.24%/y). Of the 16 patients with postobliteration hemorrhage, AVM recurrence was identified in 2 (12.5%). In the sensitivity analysis comprising 1939 patients with post-SRS AVM obliteration on magnetic resonance imaging or DSA, 16 hemorrhages (0.83%) occurred over 2560 patient-years of follow-up (0.63%/y).

CONCLUSIONS

Intracranial hemorrhage and recurrent arteriovenous shunting after complete nidal obliteration are rare in AVM patients treated with SRS, and each phenomenon harbors an annual risk of <1%. Although routine postobliteration DSA cannot be recommended to SRS-treated AVM patients, long-term neuroimaging may be advisable in these patients.

Astroblastomas exhibit radial glia stem cell lineages and differential expression of imprinted and X-inactivation escape genes

Astroblastomas (ABs) are rare brain tumors of unknown origin. We performed an integrative genetic and epigenetic analysis of AB-like tumors. Here, we show that tumors traceable to neural stem/progenitor cells (radial glia) that emerge during early to later brain development occur in children and young adults, respectively. Tumors with MN1-BEND2 fusion appear to present exclusively in females and exhibit overexpression of genes expressed prior to 25 post-conception weeks (pcw), including genes enriched in early ventricular zone radial glia and ependymal tumors. Other, histologically classic ABs overexpress or harbor mutations of mitogen-activated protein kinase pathway genes, outer and truncated radial glia genes, and genes expressed after 25 pcw, including neuronal and astrocyte markers. Findings support that AB-like tumors arise in the context of epigenetic and genetic changes in neural progenitors. Selective gene fusion, variable imprinting and/or chromosome X-inactivation escape resulting in biallelic overexpression may contribute to female predominance of AB molecular subtypes.

Malignant melanotic nerve sheath tumor with PRKAR1A, KMT2C, and GNAQ mutations

Malignant melanotic nerve sheath tumor (MMNST) is a rare and potentially aggressive lesion defined in the 2021 WHO Classification of Tumors of the Central Nervous System. MMNST demonstrate overlapping histologic and clinical features of schwannoma and melanoma. MMNST often harbor PRKAR1A mutations, especially within the Carney Complex. We present a case of aggressive MMNST of the sacral region in a 48-year-old woman. The tumor contained PRKAR1A frameshift pR352Hfs*89, KMT2C splice site c.7443-1G>T and GNAQ p.R183L missense mutations, as well as BRAF and MYC gains. Genomic DNA methylation analysis using the Illumina 850K EpicBead chip revealed that the lesion did not match an established methylation class; however, uniform manifold approximation and projection (UMAP) placed the tumor very near schwannomas. The tumor expressed PD-L1, and the patient was treated with radiation and immune checkpoint inhibitors following en bloc resection. Although she had symptomatic improvement, she suffered early disease progression with local recurrence, and distant metastases, and died 18 months after resection. It has been suggested that the presence of GNAQ mutations can differentiate leptomeningeal melanocytic neoplasms and uveal melanoma from MMNST. This case and others demonstrate that GNAQ mutations may exist in malignant nerve sheath tumors; that GNAQ and PRKAR1A mutations are not always mutually exclusive and that neither can be used to differentiate MMNST or MPNST from all melanocytic lesions.

90-Day Bundled Payment Simulation, Health Care Utilization, and Complications following Craniopharyngioma Resection in Adult Patients

Context Bundled payment and health care utilization models inform cost optimization and surgical outcomes. Economic analysis of payment plans for craniopharyngioma resection is unknown.

Objective This study aimed to identify impact of endocrine and nonendocrine complications (EC and NEC, respectively) on health care utilization and bundled payments following craniopharyngioma resection.

Design This study is presented as a retrospective cohort analysis (2000–2016) with 2 years of follow-up.

Setting The study included national inpatient hospitalization and outpatient visits.

Patients Patients undergoing craniopharyngioma resection were divided into the following four groups: group 1, no complications (NC); group 2, only EC; group 3, NEC; and group 4, both endocrine and nonendocrine complications (ENEC).

Interventions This study investigated transphenoidal or subfrontal approach for tumor resection.

Main Outcome Hospital readmission, health care utilization up to 24 months following discharge, and 90-day bundled payment performances are primary outcomes of this study.

Results Median index hospitalization payments were significantly lower for patients in NC cohort ($28,672) compared with those in EC ($32,847), NEC ($36,259), and ENEC ($32,596; p < 0.0001). Patients in ENEC incurred higher outpatient services and overall median payments at 6 months (NC: 38,268; EC: 49,844; NEC: 68,237; and ENEC: 81,053), 1 year (NC: 46,878; EC: 58,210; NEC: 81,043; and ENEC: 94,768), and 2 years (NC: 58,391; EC: 70,418; NEC: 98,838; and ENEC: 1,11,841; p < 0.0001). The 90-day median bundled payment was significantly different among the cohorts with the highest in ENEC ($60,728) and lowest in the NC ($33,089; p < 0.0001).

Conclusion ENEC following surgery incurred almost two times the overall median payments at 90 days, 6 months, 1 year. and 2 years compared with those without complications. Bundled payment model may not be a feasible option in this patient population. Type of complications and readmission rates should be considered to optimize payment model prediction following craniopharyngioma resection.

Acute posterior reversible encephalopathy syndrome (PRES) in setting of interferon-beta use: case presentation with reduction of edema in 72 h after cessation of interferon-beta therapy with sub-clinical inflammation

Background

Posterior reversible encephalopathy syndrome (PRES) represents a transient change in mental status with associated vasogenic edema of cortical and subcortical brain structures. It is often attributed to multifactorial etiology including hypertension and altered hemodynamics and disruption of vessel integrity. Patients with autoimmune disease and certain immune modulator therapies are at greater risk.

Case presentation

A 54-year-old female with past medical history of well-controlled multiple sclerosis on interferon-beta since 2013, presented with witnessed tonic colonic seizure. She also was noted to demonstrate left gaze deviation and left-sided hemiparesis. MRI fluid-attenuated inversion recovery sequence showed hyperintensity of the subcortical U fibers, concentrated in the occipital, parietal lobes and frontal lobes. Systolic blood pressure was 160 mmHg on arrival. The patient was started on seizure prophylxis and Interferon beta was discontinued. The patient’s mentation, seizures and hemiapresis significantly improved in next 72 h with tight blood pressure control, and had notble improvement on MRI imaging and inflammatory markers. Lumbar puncture CSF results were devoid of infectious and autoimmune pathology.

Conclusions

A middle-aged female with multiple sclerosis who was on chronic IFN-beta presented to the emergency room with a witnessed tonic-clonic seizure, with MRI T2 FLAIR imaging consistent with PRES. She had notable clinical improvement with decreased edema on imaging and improved inflammatory markers 72 h after cessation of IFN-beta therapy.

Bioengineered Models to Study Microenvironmental Regulation of Glioblastoma Metabolism

Despite extensive research and aggressive therapies, glioblastoma (GBM) remains a central nervous system malignancy with poor prognosis. The varied histopathology of GBM suggests a landscape of differing microenvironments and clonal expansions, which may influence metabolism, driving tumor progression. Indeed, GBM metabolic plasticity in response to differing nutrient supply within these microenvironments has emerged as a key driver of aggressiveness. Additionally, emergent biophysical and biochemical interactions in the tumor microenvironment (TME) are offering new perspectives on GBM metabolism. Perivascular and hypoxic niches exert crucial roles in tumor maintenance and progression, facilitating metabolic relationships between stromal and tumor cells. Alterations in extracellular matrix and its biophysical characteristics, such as rigidity and topography, regulate GBM metabolism through mechanotransductive mechanisms. This review highlights insights gained from deployment of bioengineering models, including engineered cell culture and mathematical models, to study the microenvironmental regulation of GBM metabolism. Bioengineered approaches building upon histopathology measurements may uncover potential therapeutic strategies that target both TME-dependent mechanotransductive and biomolecular drivers of metabolism to tackle this challenging disease. Longer term, a concerted effort integrating in vitro and in silico models predictive of patient therapy response may offer a powerful advance toward tailoring of treatment to patient-specific GBM characteristics.

Stereotactic Radiosurgery With Versus Without Embolization for Brain Arteriovenous Malformations

BACKGROUND

Prior comparisons of brain arteriovenous malformations (AVMs) treated using stereotactic radiosurgery (SRS) with or without embolization were inherently flawed, due to differences in the pretreatment nidus volumes.

OBJECTIVE

To compare the outcomes of embolization and SRS, vs SRS alone for AVMs using pre-embolization malformation features.

METHODS

We retrospectively reviewed International Radiosurgery Research Foundation AVM databases from 1987 to 2018. Patients were categorized into the embolization and SRS (E + SRS) or SRS alone (SRS-only) cohorts. The 2 cohorts were matched in a 1:1 ratio using propensity scores. Primary outcome was defined as AVM obliteration. Secondary outcomes were post-SRS hemorrhage, all-cause mortality, radiologic and symptomatic radiation-induced changes (RIC), and cyst formation.

RESULTS

The matched cohorts each comprised 101 patients. Crude AVM obliteration rates were similar between the matched E + SRS vs SRS-only cohorts (48.5% vs 54.5%; odds ratio = 0.788, P = .399). Cumulative probabilities of obliteration at 3, 4, 5, and 6 yr were also similar between the E + SRS (33.0%, 46.4%, 56.2%, and 60.8%, respectively) and SRS-only (32.9%, 46.2%, 56.0%, and 60.6%, respectively) cohorts (subhazard ratio (SHR) = 1.005, P = .981). Cumulative probabilities of radiologic RIC at 3, 4, 5, and 6 yr were lower in the E + SRS (25.0%, 25.7%, 26.7%, and 26.7%, respectively) vs SRS-only (45.3%, 46.2%, 47.8%, and 47.8%, respectively) cohort (SHR = 0.478, P = .004). Symptomatic and asymptomatic embolization-related complication rates were 8.3% and 18.6%, respectively. Rates of post-SRS hemorrhage, all-cause mortality, symptomatic RIC, and cyst formation were similar between the matched cohorts.

CONCLUSION

This study refutes the prevalent notion that AVM embolization negatively affects the likelihood of obliteration after SRS.

Embolization of Brain Arteriovenous Malformations With Versus Without Onyx Before Stereotactic Radiosurgery

BACKGROUND

Embolization of brain arteriovenous malformations (AVMs) using ethylene-vinyl alcohol copolymer (Onyx) embolization may influence the treatment effects of stereotactic radiosurgery (SRS) differently than other embolysates.

OBJECTIVE

To compare the outcomes of pre-SRS AVM embolization with vs without Onyx through a multicenter, retrospective matched cohort study.

METHODS

We retrospectively reviewed International Radiosurgery Research Foundation AVM databases from 1987 to 2018. Embolized AVMs treated with SRS were selected and categorized based on embolysate usage into Onyx embolization (OE + SRS) or non-Onyx embolization (NOE + SRS) cohorts. The 2 cohorts were matched in a 1:1 ratio using de novo AVM features for comparative analysis of outcomes.

RESULTS

The matched cohorts each comprised 45 patients. Crude AVM obliteration rates were similar between the matched OE + SRS vs NOE + SRS cohorts (47% vs 51%; odds ratio [OR] = 0.837, P = .673). Cumulative probabilities of obliteration were also similar between the OE + SRS vs NOE + SRS cohorts (subhazard ratio = 0.992, P = .980). Rates of post-SRS hemorrhage, all-cause mortality, radiation-induced changes, cyst formation, and embolization-associated complications were similar between the matched cohorts. Sensitivity analysis for AVMs in the OE + SRS cohort embolized with Onyx alone revealed a higher rate of asymptomatic embolization-associated complications in this subgroup compared to the NOE + SRS cohort (36% vs 15%; OR = 3.297, P = .034), but the symptomatic complication rates were similar.

CONCLUSION

Nidal embolization using Onyx does not appear to differentially impact the outcomes of AVM SRS compared with non-Onyx embolysates. The embolic agent selected for pre-SRS AVM embolization should reflect both the experience of the neurointerventionalist and target of endovascular intervention.

Laser Ablation of Abnormal Neurological Tissue Using Robotic NeuroBlate System (LAANTERN): 12-Month Outcomes and Quality of Life After Brain Tumor Ablation

BACKGROUND

Laser Ablation of Abnormal Neurological Tissue using Robotic NeuroBlate System (LAANTERN) is an ongoing multicenter prospective NeuroBlate (Monteris Medical) LITT (laser interstitial thermal therapy) registry collecting real-world outcomes and quality-of-life (QoL) data.

OBJECTIVE

To compare 12-mo outcomes from all subjects undergoing LITT for intracranial tumors/neoplasms.

METHODS

Demographics, intraprocedural data, adverse events, QoL, hospitalizations, health economics, and survival data are collected; standard data management and monitoring occur.

RESULTS

A total of 14 centers enrolled 223 subjects; the median follow-up was 223 d. There were 119 (53.4%) females and 104 (46.6%) males. The median age was 54.3 yr (range 3-86) and 72.6% had at least 1 baseline comorbidity. The median baseline Karnofsky Performance Score (KPS) was 90. Of the ablated tumors, 131 were primary and 92 were metastatic. Most patients with primary tumors had high-grade gliomas (80.9%). Patients with metastatic cancer had recurrence (50.6%) or radiation necrosis (40%). The median postprocedure hospital stay was 33.4 h (12.7-733.4). The 1-yr estimated survival rate was 73%, and this was not impacted by disease etiology. Patient-reported QoL as assessed by the Functional Assessment of Cancer Therapy-Brain was stabilized postprocedure. KPS declined by an average of 5.7 to 10.5 points postprocedure; however, 50.5% had stabilized/improved KPS at 6 mo. There were no significant differences in KPS or QoL between patients with metastatic vs primary tumors.

CONCLUSION

Results from the ongoing LAANTERN registry demonstrate that LITT stabilizes and improves QoL from baseline levels in a malignant brain tumor patient population with high rates of comorbidities. Overall survival was better than anticipated for a real-world registry and comparative to published literature.

Stereotactic radiosurgery with versus without prior Onyx embolization for brain arteriovenous malformations

OBJECTIVE

Investigations of the combined effects of neoadjuvant Onyx embolization and stereotactic radiosurgery (SRS) on brain arteriovenous malformations (AVMs) have not accounted for initial angioarchitectural features prior to neuroendovascular intervention. The aim of this retrospective, multicenter matched cohort study is to compare the outcomes of SRS with versus without upfront Onyx embolization for AVMs using de novo characteristics of the preembolized nidus.

METHODS

The International Radiosurgery Research Foundation AVM databases from 1987 to 2018 were retrospectively reviewed. Patients were categorized based on AVM treatment approach into Onyx embolization (OE) and SRS (OE+SRS) or SRS alone (SRS-only) cohorts and then propensity score matched in a 1:1 ratio. The primary outcome was AVM obliteration. Secondary outcomes were post-SRS hemorrhage, all-cause mortality, radiological and symptomatic radiation-induced changes (RICs), and cyst formation. Comparisons were analyzed using crude rates and cumulative probabilities adjusted for competing risk of death.

RESULTS

The matched OE+SRS and SRS-only cohorts each comprised 53 patients. Crude rates (37.7% vs 47.2% for the OE+SRS vs SRS-only cohorts, respectively; OR 0.679, p = 0.327) and cumulative probabilities at 3, 4, 5, and 6 years (33.7%, 44.1%, 57.5%, and 65.7% for the OE+SRS cohort vs 34.8%, 45.5%, 59.0%, and 67.1% for the SRS-only cohort, respectively; subhazard ratio 0.961, p = 0.896) of AVM obliteration were similar between the matched cohorts. The secondary outcomes of the matched cohorts were also similar. Asymptomatic and symptomatic embolization-related complication rates in the matched OE+SRS cohort were 18.9% and 9.4%, respectively.

CONCLUSIONS

Pre-SRS AVM embolization with Onyx does not appear to negatively influence outcomes after SRS. These analyses, based on de novo nidal characteristics, thereby refute previous studies that found detrimental effects of Onyx embolization on SRS-induced AVM obliteration. However, given the risks incurred by nidal embolization using Onyx, this neoadjuvant intervention should be used judiciously in multimodal treatment strategies involving SRS for appropriately selected large-volume or angioarchitecturally high-risk AVMs.

Management trends for anaplastic meningioma with adjuvant radiotherapy and predictors of long-term survival

OBJECTIVEThe purpose of this study was to describe effects of adjuvant radiotherapy (RT) for anaplastic meningiomas (AMs) on long-term survival, and to analyze patient and RT characteristics associated with long-term survival.METHODSThe authors queried a retrospective cohort of patients with AM from the National Cancer Database (NCDB) diagnosed between 2004 and 2015 to describe treatment trends. For outcome analysis, patients with at least 10 years of follow-up were included, and they were stratified based on adjuvant RT status and propensity matched to controls for covariates. Survival curves were compared. A data-driven approach was used to find a biologically effective dose (BED) of RT with the largest difference between survival curves. Factors associated with long-term survival were quantified.RESULTSThe authors identified 2170 cases of AM in the NCDB between 2004 and 2015. They observed increased use of adjuvant RT in patients treated with higher doses. A total of 178 cases met the inclusion criteria for outcome analysis. Forty-five percent (n = 80) received adjuvant RT. Patients received a BED of 80.23 ± 16.6 Gy (mean ± IQR). The median survival time was not significantly different (32.8 months for adjuvant RT vs 38.5 months for no RT; p = 0.57, log-rank test). Dichotomizing the patients at a BED of 81 Gy showed maximal difference in survival distribution with a decrease in median survival in favor of no adjuvant RT (31.2 months for adjuvant RT vs 49.7 months for no RT; p = 0.03, log-rank test), but this difference was not significant after false discovery rate correction. Age was a significant predictor for long-term survival.CONCLUSIONSAMs are aggressive tumors that carry a poor prognosis. Conventional adjuvant RT improves local control. However, the effect of adjuvant radiation on overall survival is unclear. Further investigation into this area is warranted.

Contemporaneous Clipping of Unruptured Anterior Cerebral Artery Proximal A1 Segment Aneurysm and Resection of Dural-Based Brain Tumor

The coexistence of brain tumors and unruptured intracranial aneurysms is uncommon, so there is limited data regarding management strategies for these cases. Tumor, aneurysm, and patient factors must be considered in the decision-making process. We present a case of a dural-based left temporal brain tumor with an incidental ipsilateral unruptured anterior cerebral artery (ACA) proximal A1 segment aneurysm.

A 56-year-old female presented with progressive headaches and convulsions without focal neurological deficits. Neuroimaging showed a large dural-based left temporal tumor with adjacent vasogenic edema. The patient underwent a cerebral angiography for preoperative tumor embolization, which revealed a small, unruptured intracranial aneurysm arising from the left ACA proximal A1 segment. We performed a left frontotemporal craniotomy for concurrent resection of the dural-based tumor and clipping of the left A1 aneurysm. She elected to proceed, so she underwent a left-sided craniotomy for tumor resection and clipping of the aneurysm. Postoperatively, the patient developed transient, mild right-sided hemiparesis from a left anterior thalamic infarct that resolved before discharge. Follow-up brain magnetic resonance imaging and catheter cerebral angiography showed gross total resection of the tumor and complete aneurysm obliteration, respectively. Patients with dual diagnoses of a brain tumor and intracranial aneurysm can be challenging to manage. When intervention is indicated for each lesion and both can be safely accessed from the same operative approach, contemporaneous surgical treatment of the tumor and aneurysm is reasonable in appropriately selected cases.

National Trends and Factors Predicting Outcomes Following Laser Interstitial Thermal Therapy for Brain Lesions: Nationwide Inpatient Sample Analysis

BACKGROUND

Laser interstitial thermal therapy (LITT) is a stereotactic-guided technique, which is increasingly being performed for brain lesions. The aim of our study was to report the national trends and factors predicting the clinical outcomes following LITT using the Nationwide Inpatient Sample.

METHODS

We extracted data from 2011-2016 using ICD-9/10 codes. Patients with a primary procedure of LITT were included. Patient demographics, complications, length of hospital stay, discharge disposition, and index-hospitalization charges were analyzed.

RESULTS

A cohort of 1768 patients was identified from the database. Mean length of hospital stay was 3.2 days, 82% of patients were discharged to home, and in-hospitalization cost was $124,225. Complications and mortality were noted in 12.9% and 2.5% of patients following LITT, respectively. Non-Caucasian patients (estimate ratio [ER] 4.26), those with other insurance (compared with commercial, ER: 5.35), 3 and 4+ comorbidity indexes, patients with higher quartile median household income (second, third, and fourth quartile compared with first quartile), and those who underwent nonelective procedures were likely to have higher complications and less likely to be discharged home. Patients with 4+ comorbidity indexes were likely to have longer length of hospital stay (ER 1.39) and higher complications (ER: 7.95) and were less likely to be discharged home (ER: 0.17) and have higher in-hospitalization cost (ER: 1.21).

CONCLUSIONS

LITT is increasingly being performed with low complication rates. Non-Caucasian race, higher comorbidity index, noncommercial insurance, and nonelective procedures were predictors of higher complications and being less likely to be discharged home. In-hospitalization charges were higher in patients with higher comorbidity index and those with noncommercial insurance.

Stereotactic radiosurgery for central neurocytomas: an international multicenter retrospective cohort study

OBJECTIVE

Central neurocytomas (CNs) are uncommon intraventricular tumors, and their rarity renders the risk-to-benefit profile of stereotactic radiosurgery (SRS) unknown. The aim of this multicenter, retrospective cohort study was to evaluate the outcomes of SRS for CNs and identify predictive factors.

METHODS

The authors retrospectively analyzed a cohort of patients with CNs treated with SRS at 10 centers between 1994 and 2018. Tumor recurrences were classified as local or distant. Adverse radiation effects (AREs) and the need for a CSF shunt were also evaluated.

RESULTS

The study cohort comprised 60 patients (median age 30 years), 92% of whom had undergone prior resection or biopsy and 8% received their diagnosis based on imaging alone. The median tumor volume and margin dose were 5.9 cm3 and 13 Gy, respectively. After a median clinical follow-up of 61 months, post-SRS tumor recurrence occurred in 8 patients (13%). The 5- and 10-year local tumor control rates were 93% and 87%, respectively. The 5- and 10-year progression-free survival rates were 89% and 80%, respectively. AREs were observed in 4 patients (7%), but only 1 was symptomatic (2%). Two patients underwent post-SRS tumor resection (3%). Prior radiotherapy was a predictor of distant tumor recurrence (p = 0.044). Larger tumor volume was associated with pre-SRS shunt surgery (p = 0.022).

CONCLUSIONS

Treatment of appropriately selected CNs with SRS achieves good tumor control rates with a reasonable complication profile. Distant tumor recurrence and dissemination were observed in a small proportion of patients, which underscores the importance of close post-SRS surveillance of CN patients. Patients with larger CNs are more likely to require shunt surgery before SRS.

Trans-labyrinthine Infra-trigeminal Approach for Recurrent Pontomedullary Cavernoma: A Step-wise Technical Note

Recurrent brainstem cavernoma is a challenging lesion due to the neurological risks associated with different surgical approaches. In this technical report, we present a 35-year-old female with a history of multiple brain cavernomas. She underwent midline suboccipital craniotomy and trans-fourth ventricle approach for resection of the brain stem cavernoma following two major bleeding episodes, one year prior to the presentation. Following the trans-labyrinthine infra-trigeminal approach, the patient recovered well postoperatively with a baseline neuro exam and was discharged to acute rehab on postoperative day 5 (POD5). The translabyrinthine approach is a safe and effective corridor for pontine or pontomedullary lesions in carefully selected patients. Appropriate selection of surgical approach (based on location), meticulous surgical technique, and intraoperative neuromonitoring help in maximizing surgical resection while minimizing neurological deficits.

Predictors of Thirty-day Mortality and Length of Stay in Operative Subdural Hematomas

The rate of postoperative morbidity and mortality after subdural hematoma (SDH) evacuation is high. The aim of this study was to compare mortality statistics from a high-volume database to historical figures and determine the most significant preoperative predictors of mortality and length of stay (LOS). The National Surgical Quality Improvement Program registry was searched (2005-2016) for patients with operatively treated SDHs, of which 2709 were identified for univariate analysis. After exclusion for missing data, 2010 individuals were analyzed with multivariable logistic regression. Primary outcome was 30-day mortality. The average patient age was 68.8 ± 14.9 years, and 64.1% were males. Upon multivariate analysis, nine variables were found to be associated with increased mortality: platelet count < 135,000 (OR 2.04, 95% CI 1.39-2.99), INR >1.2 (OR 1.87, 95% CI 1.34-2.6), bleeding disorder (OR 1.80, 95% CI 1.32-2.46), need for dialysis within two weeks preoperatively (OR 5.69, 95% CI 3.15-10.27), ventilator dependence in the 48 hours preceding surgery (OR 3.99, 95% CI 2.82-5.63), disseminated cancer (OR 2.95, 95% CI 1.34-6.47), WBC count >10,000 (OR 1.55, 95% CI 1.15-2.08), totally dependent functional status (OR 1.84, 95% CI 1.2-2.8), and each increasing year of age (OR 1.04, 95% CI 1.031-1.05). It is not surprising that chronic conditions and functional status were associated with increased mortality. However, specific laboratory abnormalities were also associated with increased mortality at levels generally considered within normal limits. More studies are needed to determine if correcting lab abnormalities preoperatively can improve outcomes in patients with intrinsic coagulopathy.

Mitochondrial NIX Promotes Tumor Survival in the Hypoxic Niche of Glioblastoma

Cancer cells rely on mitochondrial functions to regulate key survival and death signals. How cancer cells regulate mitochondrial autophagy (mitophagy) in the tumor microenvironment as well as utilize mitophagy as a survival signal is still not well understood. Here, we elucidate a key survival mechanism of mitochondrial NIX-mediated mitophagy within the hypoxic region of glioblastoma, the most malignant brain tumor. NIX was overexpressed in the pseudopalisading cells that envelop the hypoxic-necrotic regions, and mitochondrial NIX expression was robust in patient-derived glioblastoma tumor tissues and glioblastoma stem cells. NIX was required for hypoxia and oxidative stress-induced mitophagy through NFE2L2/NRF2 transactivation. Silencing NIX impaired mitochondrial reactive oxygen species clearance, cancer stem cell maintenance, and HIF/mTOR/RHEB signaling pathways under hypoxia, resulting in suppression of glioblastoma survival in vitro and in vivo. Clinical significance of these findings was validated by the compelling association between NIX expression and poor outcome for patients with glioblastoma. Taken together, our findings indicate that the NIX-mediated mitophagic pathway may represent a key therapeutic target for solid tumors, including glioblastoma. SIGNIFICANCE: NIX-mediated mitophagy regulates tumor survival in the hypoxic niche of glioblastoma microenvironment, providing a potential therapeutic target for glioblastoma.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/20/5218/F1.large.jpg.

Posterior reversible encephalopathy syndrome with lumbar drainage and surgery: coincidence or correlation? A case report

BACKGROUND

Posterior reversible encephalopathy syndrome (PRES) is a rare neurological disorder usually associated with specific medical conditions that cause a disturbance of the CNS homeostasis. It has seldom been reported to be a consequence of an iatrogenic intervention causing intracranial hypotension.

CASE PRESENTATION

We report the case of an individual 69-year-old male presenting with headache and blurred vision following cerebrospinal fluid (CSF) leak from resection of a sellar mass. The patient developed the condition following removal of the lumbar drain post-operatively. Magnetic Resonance Imaging showed bilateral occipital, parieto-occipital, and cerebellar T2 FLAIR hyper-intensities, suggesting a radiological diagnosis of posterior reversible encephalopathy syndrome (PRES). The patient's symptoms started to improve shortly afterwards and had completely resolved at 3 months follow-up.

CONCLUSIONS

The absence of severe hypertension and presence of an intraoperative CSF leak requiring placement of the lumbar drain suggests that decreased CSF volume and associated reactive hyperemia could have a role in the pathophysiology of the disease.

Feasibility of Bundled Payments in Anterior, Middle, and Posterior Cranial Fossa Skull Base Meningioma Surgery: MarketScan Analysis of Health Care Utilization and Outcomes

BACKGROUND

The aim of our study was to compare the health care utilization and outcomes after surgery for anterior cranial fossa skull base meningioma (AFM), middle cranial fossa skull base meningioma (MFM), and posterior cranial fossa skull base meningioma (PFM) across the United States.

METHODS

We queried the MarketScan database using International Classification of Diseases, Ninth Revision and Current Procedural Terminology 4, from 2000 to 2016. We included adult patients who had at least 24 months of enrollment after the surgical procedure. The outcome of interest was length of hospital stay, disposition, complications, and reoperation after the procedure.

RESULTS

A cohort of 1191 patients was identified from the database. Less than half of patients (43.66%) were in the AFM cohort, 32.24% were in the MFM cohort, and only 24.1% were in the PFM cohort. Patients who underwent surgery for PFM had longer hospital stay (P = 0.0009), high complication rate (P = 0.0011), and less likely to be discharged home (P = 0.0013) during index hospitalization. There were no differences in overall payments at 12 months and 24 months among the cohorts. There was no significant difference in 90-day median payments among the groups ($66,212 [AFM] vs. $65,602 [MFM] and $71,837 [PFM]; P = 0.198). Male gender, commercial insurance (compared with Medicare), and higher comorbidity scores (score 3 compared with score 0) were associated with higher 90-day payments in the PFM cohort.

CONCLUSIONS

Overall payments (at 12 months and 24 months) and 90-day payments were not different among the cohorts. Patients with PFM had longer hospital stay and higher complication rate and were less likely to be discharged home with higher utilization of outpatient services at 12 months and 24 months.

National trends in cerebral bypass for unruptured intracranial aneurysms: a National (Nationwide) Inpatient Sample analysis of 1998–2015

OBJECTIVE

The development and recent widespread dissemination of flow diverters may have reduced the utilization of surgical bypass procedures to treat complex or giant unruptured intracranial aneurysms (UIAs). The aim of this retrospective cohort study was to observe trends in cerebral revascularization procedures for UIAs in the United States before and after the introduction of flow diverters by using the National (Nationwide) Inpatient Sample (NIS).

METHODS

The authors extracted data from the NIS database for the years 1998–2015 using the ICD-9/10 diagnostic and procedure codes. Patients with a primary diagnosis of UIA with a concurrent bypass procedure were included in the study. Outcomes and hospital charges were analyzed.

RESULTS

A total of 216,212 patients had a primary diagnosis of UIA during the study period. The number of patients diagnosed with a UIA increased by 128% from 1998 (n = 7718) to 2015 (n = 17,600). Only 1328 of the UIA patients (0.6%) underwent cerebral bypass. The percentage of patients who underwent bypass in the flow diverter era (2010–2015) remained stable at 0.4%. Most patients who underwent bypass were white (51%), were female (62%), had a median household income in the 3rd or 4th quartiles (57%), and had private insurance (51%). The West (33%) and Midwest/North Central regions (30%) had the highest volume of bypasses, whereas the Northeast region had the lowest (15%). Compared to the period 1998–2011, bypass procedures for UIAs in 2012–2015 shifted entirely to urban teaching hospitals (100%) and to an elective basis (77%). The median hospital stay (9 vs 3 days, p < 0.0001), median hospital charges ($186,746 vs $66,361, p < 0.0001), and rate of any complication (51% vs 17%, p < 0.0001) were approximately threefold higher for the UIA patients with bypass than for those without bypass.

CONCLUSIONS

Despite a significant increase in the diagnosis of UIAs over the 17-year study period, the proportion of bypass procedures performed as part of their treatment has remained stable. Therefore, advances in endovascular aneurysm therapy do not appear to have affected the volume of bypass procedures performed in the UIA population. The authors’ findings suggest a potentially ongoing niche for bypass procedures in the contemporary treatment of UIAs.

Endoscopic Endonasal Surgery for the Resection of a Cavernous Hemangioma with a Sellar Extension

Cavernous hemangiomas with an intrasellar extension are very rare, generally benign lesions that manifest by the compression of nearby structures. The presenting symptoms usually range from visual disturbances to an endocrine imbalance. Occasional extension into the cavernous sinus has been reported, which can cause cranial nerve compression. We present the case of a 69-year-old man presenting with facial pain and decreased libido. On investigation, a lesion was identified and the parasellar region was homogeneously hyper-intense on gadolinium-enhanced magnetic resonance imaging (MRI). Endoscopic endonasal surgery remains one of the favored approaches for the resection of sellar lesions. Such pathology needs to remain on the neurosurgeon’s differential diagnosis, making an intraoperative frozen section of these lesions a useful tool in the surgeon's armamentarium, to guide further surgical resection.

Hitomi X-ray studies of Giant Radio Pulses from the Crab pulsar

To search for giant X-ray pulses correlated with the giant radio pulses (GRPs) from the Crab pulsar, we performed a simultaneous observation of the Crab pulsar with the X-ray satellite Hitomi in the 2 - 300 keV band and the Kashima NICT radio observatory in the 1.4 - 1.7 GHz band with a net exposure of about 2 ks on 25 March 2016, just before the loss of the Hitomi mission. The timing performance of the Hitomi instruments was confirmed to meet the timing requirement and about 1,000 and 100 GRPs were simultaneously observed at the main and inter-pulse phases, respectively, and we found no apparent correlation between the giant radio pulses and the X-ray emission in either the main or inter-pulse phases. All variations are within the 2 sigma fluctuations of the X-ray fluxes at the pulse peaks, and the 3 sigma upper limits of variations of main- or inter-pulse GRPs are 22% or 80% of the peak flux in a 0.20 phase width, respectively, in the 2 - 300 keV band. The values become 25% or 110% for main or inter-pulse GRPs, respectively, when the phase width is restricted into the 0.03 phase. Among the upper limits from the Hitomi satellite, those in the 4.5-10 keV and the 70-300 keV are obtained for the first time, and those in other bands are consistent with previous reports. Numerically, the upper limits of main- and inter-pulse GRPs in the 0.20 phase width are about (2.4 and 9.3) ×10^-11 erg cm^-2, respectively. No significant variability in pulse profiles implies that the GRPs originated from a local place within the magnetosphere and the number of photon-emitting particles temporally increases. However, the results do not statistically rule out variations correlated with the GRPs, because the possible X-ray enhancement may appear due to a > 0.02% brightening of the pulse-peak flux under such conditions.

The p38 signaling pathway mediates quiescence of glioma stem cells by regulating epidermal growth factor receptor trafficking

EGFR pathway is upregulated in malignant gliomas, and its downstream signaling is important for self-renewal of glioma cancer stem-like cells (GSC). p38 mitogen-activated protein kinase (MAPK) signaling, a stress-activated signaling cascade with suppressive and permissive effects on tumorigenesis, can promote internalization and ubiquitin ligase mediated degradation of EGFR. In this study, we investigated the role of p38 MAPK signaling on the self-renewal of GSCs with the hypothesis that inhibition may lead to enhanced self-renewal capacity by retention of EGFR. Inhibition of p38 MAPK pathway led to increase in EGFR expression but surprisingly, reduced proliferation. Additional functional evaluation revealed that p38 inhibition was associated with decrease in cell death and maintenance of undifferentiated state. Further probing the effect of p38 inhibition demonstrated attenuation of EGFR downstream signaling activity in spite of prolonged surface expression of the receptor. In vitro observations were confirmed in xenograft in vivo experiments. These data suggest that p38 MAPK control of EGFR signaling activity may alter GSC cell cycle state by regulating quiescence and passage into transit amplifying state.

Laser interstitial thermal therapy for palliative ablation of a chordoma metastasis to the spine: case report

The authors present the first report of laser interstitial thermal therapy (LITT) ablation of a recurrent chordoma metastasis to the cervical spine. This patient was a 75-year-old woman who was diagnosed and treated for a sacral chordoma, and then developed metastases to the lung and upper thoracic spine. Unfortunately she experienced symptomatic recurrence at the C-7 spinous process. She underwent an uncomplicated LITT to the lesion. The patient convalesced without incident and was discharged on postoperative Day 1. She received stereotactic spinal radiosurgery to the lesion at a dose of 24 Gy in 1 fraction. At the 3-month follow-up evaluation she had radiographic response and improvement in her symptoms.

Primary versus revision transsphenoidal resection for nonfunctioning pituitary macroadenomas: matched cohort study

OBJECTIVE

The object of this study was to compare the outcomes of primary and revision transsphenoidal resection (TSR) of nonfunctioning pituitary macroadenomas (NFPMAs) using endoscopic methods.

METHODS

The authors retrospectively reviewed the records of 287 consecutive patients who had undergone endoscopic endonasal TSR for NFPMAs at their institution in the period from 2005 to 2011. Fifty patients who had undergone revision TSR were retrospectively matched for age, sex, and duration of follow-up to 46 patients who had undergone primary TSR. Medical and surgical complications were documented, and Kaplan-Meier analysis was performed to assess rates of radiological progression-free survival (PFS).

RESULTS

The median follow-up periods were 45 and 46 months for the primary and revision TSR groups, respectively. There were no significant differences between the primary and revision groups in rates of new neurological deficit (0 in each), vascular injury (2% vs 0), postoperative CSF leak (6% vs 2%), transient diabetes insipidus (DI; 15% vs 12%), chronic DI (2% vs 2%), chronic sinusitis (4% vs 6%), meningitis (2% vs 2%), epistaxis (7% vs 0), or suprasellar hematoma formation (0 vs 2%). However, patients who underwent primary TSR had significantly higher rates of syndrome of inappropriate antidiuretic hormone (SIADH; 17% vs 4%, p = 0.04). Patients who underwent primary operations also had significantly higher rates of gross-total resection (GTR; 63% vs 28%, p < 0.01) and significantly lower rates of adjuvant radiotherapy (13% vs 42%, p < 0.01). Radiological PFS rates were similar at 2 years (98% vs 96%) and 5 years (87% vs 80%, p = 0.668, log-rank test).

CONCLUSIONS

Patients who underwent primary TSR of NFPMAs experienced higher rates of SIADH than those who underwent revision TSR. Patients who underwent revision TSR were less likely to have GTR of their tumor, although they still had a PFS rate similar to that in patients who underwent primary TSR. This finding may be attributable to an increased rate of adjuvant radiation treatment to subtotally resected tumors in the revision TSR group.

An X-ray and Radio Study of the Varying Expansion Velocities in Tycho's Supernova Remnant

We present newly obtained X-ray and radio observations of Tycho's supernova remnant using Chandra and the Karl G. Jansky Very Large Array in 2015 and 2013/14, respectively. When combined with earlier epoch observations by these instruments, we now have time baselines for expansion measurements of the remnant of 12-15 year in the X-rays and 30 year in the radio. The remnant's large angular size allows for proper motion measurements at many locations around the periphery of the blast wave. We find, consistent with earlier measurements, a clear gradient in the expansion velocity of the remnant, despite its round shape. The proper motions on the western and southwestern sides of the remnant are about a factor of two higher than those in the east and northeast. We showed in an earlier work that this is related to an offset of the explosion site from the geometric center of the remnant due to a density gradient in the ISM, and using our refined measurements reported here, we find that this offset is ∼ 23'' towards the northeast. An explosion center offset in such a circular remnant has implications for searches for progenitor companions in other remnants.

The role of radiosurgery in the management of WHO Grade II and III intracranial meningiomas

Object

WHO Grade II and III intracranial meningiomas are uncommon, but they portend a significantly worse prognosis than their benign Grade I counterparts. The mainstay of current management is resection to obtain cytoreduction and histological tissue diagnosis. The timing and benefit of postoperative fractionated external beam radiation therapy and stereotactic radiosurgery remain controversial. The authors review the stereotactic radiosurgery outcomes for Grade II and III meningiomas.

Methods

A comprehensive literature search was performed using PubMed to identify all radiosurgery series reporting the treatment outcomes for Grade II and III meningiomas. Case reports and case series involving fewer than 10 patients were excluded.

Results

From 1998 to 2013, 19 radiosurgery series were published in which 647 Grade II and III meningiomas were treated. Median tumor volumes were 2.2–14.6 cm3. The median margin doses were 14–21 Gy, although generally the margin doses for Grade II meningiomas were 16–20 Gy and the margin doses for Grade III meningiomas were 18–22 Gy. The median 5-year PFS was 59% for Grade II tumors and 13% for Grade III tumors, which may have been affected by patient age, prior radiation therapy, tumor volume, and radiosurgical dose and timing. The median complication rate following radiosurgery was 8%.

Conclusions

The current data for radiosurgery suggest that it has a role in the management of residual or recurrent Grade II and III meningiomas. However, better studies are needed to fully define this role. Due to the relatively low prevalence of these tumors, it is unlikely that prospective studies will be feasible. As such, well-designed retrospective analyses may improve our understanding of the effect of radiosurgery on tumor recurrence and patient survival and the incidence and impact of treatment-induced complications.

Gamma Knife surgery for large vestibular schwannomas: a single-center retrospective case-matched comparison assessing the effect of lesion size

Object

Gamma Knife surgery (GKS) is a safe and effective treatment for patients with small to moderately sized vestibular schwannomas (VSs). Reports of stereotactic radiosurgery for large VSs have demonstrated worse tumor control and preservation of neurological function. The authors endeavored to assess the effect of size of VSs treated using GKS.

Methods

This study was a retrospective comparison of 24 patients with large VSs (> 3 cm in maximum diameter) treated with GKS compared with 49 small VSs (≤ 3 cm) matched for age, sex, radiosurgical margin and maximal doses, length of follow-up, and indication.

Results

Actuarial tumor progression-free survival (PFS) for the large VS cohort was 95.2% and 81.8% at 3 and 5 years, respectively, compared with 97% and 90% for small VSs (p = 0.009). Overall clinical outcome was better in small VSs compared with large VSs (p < 0.001). Patients with small VSs presenting with House-Brackmann Grade I (good facial function) had better neurological outcomes compared with patients with large VSs (p = 0.003). Treatment failure occurred in 6 patients with large VSs; 3 each were treated with resection or repeat GKS. Treatment failure did not occur in the small VS group. Two patients in the large VS group required ventriculoperitoneal shunt placement. Univariate analysis did not identify any predictors of treatment failure among the large VS cohort.

Conclusions

Patients with large VSs treated using GKS had shorter PFS and worse clinical outcomes compared with age-, sex-, and indication-matched patients with small VSs. Nevertheless, GKS has efficacy for some patients with large VSs and represents a reasonable treatment option for selected patients.

Measuring nonequilibrium vesicle dynamics in neurons under tension

Vesicle transport in neurons is a highly complex nonequilibrium process. Their subcellular environment is undergoing constant fluctuations from thermal energy and molecular motors. Vesicle transport is an interplay between random motion (passive) and directed motion (active) driven by molecular motors along cytoskeletal filaments. It has been shown that growth, guidance, and vesicle dynamics of neurons is affected by mechanical tension. Here we present a method to analyze vesicle transport via a temporal Mean Square Displacement (tMSD) analysis while applying mechanical strain to neurons. The tMSD analysis allows characterization of active and passive vesicle motion as well as many other parameters including: power law scaling, velocity, direction, and flux. Our results suggest: (1) The tMSD analysis is able to capture vesicle motion alternating between passive and active states, and indicates that vesicle motion in Aplysia neurons is primarily passive (exhibiting active motion for ~8% of the time). (2) Under mechanical stretch (increased neurite tension), active transport of vesicles increases to ~13%, while vesicle velocity remains unchanged. (3) Upon unstretching (decreased tension), the level of active transport returns to normal but vesicle velocity decreases. These results suggest that vesicle transport in neurons is highly sensitive to mechanical stimulation. Our method allows precise characterization of vesicle dynamics in response to applied mechanical strain.

Stereotactic radiosurgery for WHO II and III meningiomas: analysis of long-term clinical and radiographic outcomes

BACKGROUND/AIM

WHO grade II and III meningiomas are challenging tumors to treat, and the role of stereotactic radiosurgery (SRS) in their treatment is not well defined. We evaluate our experience to better define its role and assess for clinical and radiographic predictors of failure.

METHODS

This is a retrospective analysis of all patients with histological diagnosis of WHO II or III meningioma. Thirteen patients were included. The mean dose to the periphery was 16 Gy (12-20), the mean maximum dose was 31 Gy (13-40), and the mean isodose line was 49% (35-50).

RESULTS

The median age was 48 years. The median follow up was 50 months (7-67). All cases had undergone at least one previous resection, and six patients had undergone external beam radiation (EBRT). The median pre SRS Karnofsky performance score (KPS) was 90. The progression free survival (PFS) was 92% and 31% at 1 and 4 years, respectively. Eleven patients required further treatment after SRS. The final tumor volume was decreased in 7 patients, stable in 1, and increased in 6.

CONCLUSIONS

WHO grade II and III meningiomas are aggressive tumors that will require multiple treatments. SRS may be a useful as an adjuvant treatment or for recurrence.

Decompressive craniectomy in pediatric traumatic brain injury: a review of the literature

BACKGROUND

Pediatric traumatic brain injury accounts for approximately 37,000 hospitalizations and 2,685 deaths in the United State annually. The 2003 guidelines consolidated and summarized the body of literature on this subject. Among the material covered was the role of surgical management of elevated intracranial pressure. Here we review the guideline recommendations, recent literature on the topic, and important recent results in the adult population.

METHODS

A Medline literature review was performed to identify studies published since 2000 addressing decompressive craniectomy in the pediatric and adult populations. Important articles included in the 2003 guidelines were also reviewed. All references were reviewed to identify additional relevant studies.

RESULTS

There is little new data that addresses the key issues for investigation proposed in the 2003 pediatric guidelines. The only randomized trial in the pediatric population remains a 2001 study, which demonstrated a benefit of decompressive craniectomy. One recent randomized trial in adults demonstrated no benefit of the procedure and an additional randomized trial in adults is underway. No pediatric randomized trial is planned. Smaller, non-randomized series appear to support the practice.

CONCLUSION

Based on the only randomized trial in children and the abundance of smaller studies, it is our belief that decompressive craniectomy does provide a benefit in terms of the management of intracranial hypertension and overall outcome in children.