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Background: Neurosurgeons may resort to caffeine, alcohol, and various drugs to maintain peak performance as they grapple with work demands and escalated stress. The prevalence of this controversial strategy remains largely unexplored., Methods: An anonymous survey of 23 questions formulated by our research group was distributed through personal contacts and neurosurgical societies. Inquiries revolved around the use of medications and other substances for job-related reasons. Data were analyzed via regression and descriptive statistics in python., Results: In total, 215 neurosurgeons (43 residents) were included, with 213 disclosing their gender (94 females). Out of all, 9.3% were <30, 38.1% were 30-39, 44.6% were 40-59, and 7.9% were >60 years old. Most (70.7%) practiced in Europe, 18.6% in Asia, 6.5% in North and South America, and the rest in Africa or Australia. While 132 participants stated they consume caffeine to manage challenging schedules, drugs for cognitive and mood enhancement were utilized by 18 and 35 respectively. Alcohol was employed for stress relief by 28 with 4 reporting as heavy drinkers. Drugs posed a solution to sleep disorders for 82, and helped 8 others in strengthening their hand dexterity. Notably, 12 of those claiming drug use initiated it in medical school. Exercise, self-care activities, and relational support were the main alternatives sought. Ultimately, most responders recommended extending mental health assistance and raising awareness about drug use., Conclusions: Reflecting on our results on job-associated drug use by neurosurgeons, we propose the judicious use of pharmacological or nonpharmacological adjuncts, alongside the prioritization of neurosurgeons' well-being., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Introduction: Neurosurgery is one of the most demanding medical specialties. For neurosurgeons, balancing professional activity with personal life can be challenging., Research Question: To evaluate gender differences in contribution of neurosurgeons in the household and child-rearing, as well as their impact on personal life and career., Material and Methods: An anonymous, electronic, 59-item web-based survey was administered to National Neurosurgical Societies of Europe, and European Member Societies of the European Association of Neurosurgical Societies (June-October 2021)., Results: A total of 205 European neurosurgeons (87 females and 118 males, mean age 40.7) are included in our survey. In neurosurgery, females are significantly more likely to be alone (37.9%), while males are significantly more likely to have children (66.9%). In terms of household efforts, females spend more time than males on the same tasks. Most participants (71.2%) view gender issues as a disadvantage in career pursuing. Women feel less accepted (54.3%) and having fewer opportunities (58.6%), while men believe that pregnancy/child-rearing (65.8%) and having many roles (51.3%) are the main obstacles. Both genders (77.6%) favor more convenient working conditions for young parents. Discussion and Conclusion. In our study we found that, women neurosurgeons take more responsibilities at home, especially in the child-rearing years. Female neurosurgeons are more likely to live alone or stay childless more often compared to their male colleagues. Supportive facilities, flexible programs, universal life policies and presumably curbing of the social stereotypes are of importance to overcome gender inequities that women are still facing in neurosurgery., (© 2022 The Authors.)

Aim: To explore the perspectives of patients and laymen with regard to the development, use and storage of cerebral organoids, in order to contribute to the ethical debate about this technology. Materials & methods: In depth semi-structured interviews with 28 patients and laymen were conducted. A qualitative thematic analysis was undertaken using a constant comparative method. Results: Three interrelated themes emerged from the empirical material: moral value; willingness to donate; and elements of good governance. Conclusion: Patients and laymen are most concerned about cerebral organoids potentially developing consciousness and potential misuse. They support the use of cerebral organoids under the conditions that donors are adequately informed and that there will be good governance. Perspectives of patients and laymen are helpful to enable responsible development and use of cerebral organoids in practice.

Background: Although survival statistics in patients with glioblastoma multiforme (GBM) are well-defined at the group level, predicting individual patient survival remains challenging because of significant variation within strata., Objective: To compare statistical and machine learning algorithms in their ability to predict survival in GBM patients and deploy the best performing model as an online survival calculator., Methods: Patients undergoing an operation for a histopathologically confirmed GBM were extracted from the Surveillance Epidemiology and End Results (SEER) database (2005-2015) and split into a training and hold-out test set in an 80/20 ratio. Fifteen statistical and machine learning algorithms were trained based on 13 demographic, socioeconomic, clinical, and radiographic features to predict overall survival, 1-yr survival status, and compute personalized survival curves., Results: In total, 20 821 patients met our inclusion criteria. The accelerated failure time model demonstrated superior performance in terms of discrimination (concordance index = 0.70), calibration, interpretability, predictive applicability, and computational efficiency compared to Cox proportional hazards regression and other machine learning algorithms. This model was deployed through a free, publicly available software interface (https://cnoc-bwh.shinyapps.io/gbmsurvivalpredictor/)., Conclusion: The development and deployment of survival prediction tools require a multimodal assessment rather than a single metric comparison. This study provides a framework for the development of prediction tools in cancer patients, as well as an online survival calculator for patients with GBM. Future efforts should improve the interpretability, predictive applicability, and computational efficiency of existing machine learning algorithms, increase the granularity of population-based registries, and externally validate the proposed prediction tool., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Purpose: Deficits in neurocognitive functioning (NCF) frequently occur in glioma patients. Both treatment and the tumor itself contribute to these deficits. In order to minimize the harmful effects of surgery, an increasing number of patients undergo awake craniotomy. To investigate whether we can indeed preserve cognitive functioning after state-of-the art awake surgery and to identify factors determining postoperative NCF, we performed a retrospective cohort study., Methods: In diffuse glioma (WHO grade 2-4) patients undergoing awake craniotomy, we studied neurocognitive functioning both pre-operatively and 3-6 months postoperatively. Evaluation covered five neurocognitive domains. We performed analysis of data on group and individual level and evaluated the value of patient-, tumor- and treatment-related factors for predicting change in NCF, using linear and logistic regression analysis., Results: We included 168 consecutive patients. Mean NCF-scores of psychomotor speed and visuospatial functioning significantly deteriorated after surgery. The percentage of serious neurocognitive impairments (- 2 standard deviations) increased significantly for psychomotor speed only. Tumor involvement in the left thalamus predicted a postoperative decline in NCF for the domains overall-NCF, executive functioning and psychomotor speed. An IDH-wildtype status predicted decline for overall-NCF and executive functioning., Conclusions: In all cognitive domains, except for psychomotor speed, cognitive functioning can be preserved after awake surgery. The domain of psychomotor speed seems to be most vulnerable to the effects of surgery and early postoperative therapies. Cognitive performance after glioma surgery is associated with a combination of structural and biomolecular effects from the tumor, including IDH-status and left thalamic involvement.

Background: Impairments in neurocognitive functioning (NCF) frequently occur in glioma patients. Both the tumor and its treatment contribute to these impairments. We aimed to quantify NCF in glioma patients before treatment and to investigate which factors influence NCF., Methods: We performed a retrospective cohort study in diffuse glioma patients according to STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) criteria. All patients had undergone neuropsychological assessment as part of routine clinical care, before awake surgery. We studied "overall NCF" and NCF in 5 neurocognitive domains separately. For "overall NCF" and per domain, we performed analyses at 2 different levels of outcome measures: (1) group level: mean cognitive functioning of the study sample, and (2) individual level: the percentage of impaired patients. We performed multivariable logistic regression analyses to investigate which factors were associated with the occurrence of cognitive impairments., Results: From our cohort of glioma patients (2010-2016), 168 patients met all the inclusion criteria. All cognitive domains were significantly affected at the group level. The percentages of neurocognitive impairments (-2SD) were highest for Executive Functioning, Psychomotor Speed, and Memory (26.5%, 23.2%, and 19.3%, respectively). Patients with high-grade glioma were affected more severely than patients with low-grade glioma. Tumor volume, isocitrate dehydrogenase status, WHO grade, and histology were associated with the occurrence of domain-specific impairments., Conclusions: Cognitive impairment occurs in the majority of treatment-naive glioma patients. The domains Executive Functioning, Speed, and Memory are involved most frequently. These impairments in NCF are explained not only by tumor location and volume, but also by other (biological) mechanisms., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Neuro-Oncology and the European Association of Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Developmental incentives are fundamental to surgical progress, yet financial and professional incentives inherently create conflicts of interest (COI). Understanding how to manage COI held by neurosurgeons, industry, hospitals, and journal editors, without thwarting progress and innovation is critical., Objective: To present an overview of COI associated with innovation in neurosurgery, and review ways to manage these in an ethically sound manner., Methods: A review of the literature was performed to assess conflicts of interest that affect neurosurgical innovation, and review ways to manage COI of various parties while adhering to ethical standards., Results: COI are inherent to collaboration and innovation, and are therefore an unavoidable component of neurosurgery. The lack of a clear distinction between clinical practice and innovation, ability to use devices off-label, and unstandardized disclosure requirements create inconsistencies in the way that conflicts of interest are handled. Additionally, lack of requirements to compare innovation to the standard of care and inherent bias that affects study design and interpretation can have profound effects on the medical literature. Conflicts of interest can have both direct and downstream effects on neurosurgical practice, and it is possible to manage them while improving the quality of research and innovation., Conclusion: Conflicts of interest are inherent to surgical innovation, and can be handled in an ethically sound manner. Neurosurgeons, device companies, hospitals, and medical journals can take steps to proactively confront bias and ensure patient autonomy and safety. These steps can preserve public trust and ultimately improve evidence-based neurosurgical practice.

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles ("MISEV") guidelines for the field in 2014. We now update these "MISEV2014" guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points.

Purpose: Leptomeningeal metastases (LM) are a rare, but often debilitating complication of advanced cancer that can severely impact a patient's quality-of-life. LM can result in hydrocephalus (HC) and lead to a range of neurologic sequelae, including weakness, headaches, and altered mental status. Given that patients with LM generally have quite poor prognoses, the decision of how to manage this HC remains unclear and is not only a medical, but also an ethical one., Methods: We first provide a brief overview of management options for hydrocephalus secondary to LM. We then apply general ethical principles to decision making in LM-associated hydrocephalus that can help guide physicians and patients., Results: Management options for LM-associated hydrocephalus include shunt placement, repeated lumbar punctures, intraventricular reservoir placement, endoscopic third ventriculostomy, or pain management alone without intervention. While these options may offer symptomatic relief in the short-term, each is also associated with risks to the patient. Moreover, data on survival and quality-of-life following intervention is sparse. We propose that the pros and cons of each option should be evaluated not only from a clinical standpoint, but also within a larger framework that incorporates ethical principles and individual patient values., Conclusions: The decision of how to manage LM-associated hydrocephalus is complex and requires close collaboration amongst the physician, patient, and/or patient's family/friends/community leaders. Ultimately, the decision should be rooted in the patients' values and should aim to optimize a patient's quality-of-life.

Background: A recent survey showed that potentially hazardous levels of certain attitudes have been associated with worse patient outcomes in orthopedic surgery, based on a questionnaire that was adopted from aviation. This questionnaire aims to evaluate the prevalence of potentially hazardous levels of machismo, impulsiveness, anxiety, antiauthority, resignation, and invulnerability in attitudes and was adopted for use among neurosurgeons., Methods: All individual members of the European Association of Neurosurgical Societies (EANS) were invited to fill-out an online questionnaire. Questions were on a five-point Likert-scale ranging from strongly disagree to strongly agree with five questions per attitude and answers were collected together with neurosurgeon and practice characteristics. Participants could score five points for each question after which an overall score was calculated for each attitude. Like the orthopedic survey, a potentially hazardous level of any behavior was defined as a score >20., Results: Resignation (n = 21; 7.7%) and anxiety (n = 10; 3.7%) had the highest prevalence of potentially hazardous levels among neurosurgeons. Few neurosurgeons showed potentially hazardous levels of antiauthority (n = 4; 1.5%), self-confidence (n = 2; 0.7%), or impulsive attitudes (n = 1; 0.4%). None of the participants showed potentially hazardous levels of machismo. Overall, 12.2% of neurosurgeons had a potentially hazardous score for at least one of the evaluated attitudes., Conclusion: Findings of this study indicate a low prevalence of potentially hazardous levels of certain attitudes among neurosurgeons based on a questionnaire tailored to neurosurgery. However, the implications of this study are limited by various factors and warrant further evaluation and warrant further evaluation., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Machine learning (ML) is a domain of artificial intelligence that allows computer algorithms to learn from experience without being explicitly programmed., Objective: To summarize neurosurgical applications of ML where it has been compared to clinical expertise, here referred to as "natural intelligence.", Methods: A systematic search was performed in the PubMed and Embase databases as of August 2016 to review all studies comparing the performance of various ML approaches with that of clinical experts in neurosurgical literature., Results: Twenty-three studies were identified that used ML algorithms for diagnosis, presurgical planning, or outcome prediction in neurosurgical patients. Compared to clinical experts, ML models demonstrated a median absolute improvement in accuracy and area under the receiver operating curve of 13% (interquartile range 4-21%) and 0.14 (interquartile range 0.07-0.21), respectively. In 29 (58%) of the 50 outcome measures for which a P-value was provided or calculated, ML models outperformed clinical experts (P < .05). In 18 of 50 (36%), no difference was seen between ML and expert performance (P > .05), while in 3 of 50 (6%) clinical experts outperformed ML models (P < .05). All 4 studies that compared clinicians assisted by ML models vs clinicians alone demonstrated a better performance in the first group., Conclusion: We conclude that ML models have the potential to augment the decision-making capacity of clinicians in neurosurgical applications; however, significant hurdles remain associated with creating, validating, and deploying ML models in the clinical setting. Shifting from the preconceptions of a human-vs-machine to a human-and-machine paradigm could be essential to overcome these hurdles.

Glioblastomas are heterogeneous and invariably lethal tumours. They are characterized by genetic and epigenetic variations among tumour cells, which makes the development of therapies that eradicate all tumour cells challenging and currently impossible. An important component of glioblastoma growth is communication with and manipulation of other cells in the brain environs, which supports tumour progression and resistance to therapy. Glioblastoma cells recruit innate immune cells and change their phenotype to support tumour growth. Tumour cells also suppress adaptive immune responses, and our increasing understanding of how T cells access the brain and how the tumour thwarts the immune response offers new strategies for mobilizing an antitumour response. Tumours also subvert normal brain cells - including endothelial cells, neurons and astrocytes - to create a microenviron that favours tumour success. Overall, after glioblastoma-induced phenotypic modifications, normal cells cooperate with tumour cells to promote tumour proliferation, invasion of the brain, immune suppression and angiogenesis. This glioblastoma takeover of the brain involves multiple modes of communication, including soluble factors such as chemokines and cytokines, direct cell-cell contact, extracellular vesicles (including exosomes and microvesicles) and connecting nanotubes and microtubes. Understanding these multidimensional communications between the tumour and the cells in its environs could open new avenues for therapy.

Background: Innovation is a part of the daily practice of neurosurgery. However, a clear definition of what constitutes innovation is lacking and opinions vary from continent to continent, from hospital to hospital, and from surgeon to surgeon., Methods: In this study, we distributed an online survey to neurosurgeons from multiple countries to investigate what neurosurgeons consider innovative, by gathering opinions on several hypothetical cases. The anonymous survey consisted of 52 questions and took approximately 10 minutes to complete., Results: A total of 355 neurosurgeons across all continents excluding Antarctica completed the survey. Neurosurgeons achieved consensus (>75%) in considering specific cases to be innovative, including laser resection of meningioma, focused ultrasonography for tumor, oncolytic virus, deep brain stimulation for addiction, and photodynamic therapy for tumor. Although the new dura substitute case was not considered innovative, there was consensus among neurosurgeons indicating that institutional review board approval was still necessary to maintain ethical standards. Furthermore, although 90% of neurosurgeons considered an oncolytic virus for glioblastoma multiforme to be innovative, only 78% believed that institutional review board approval was necessary before treatment., Conclusions: Our results indicate that innovation is a heterogeneous concept among neurosurgeons that necessitates standardization to ensure appropriate patient safety without stifling progress. We discuss both the ethical drawbacks of not having a clear definition of innovation and the challenges in achieving a unified understanding of innovation in neurosurgery and offer suggestions for uniting the field., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Machine learning (ML) is a branch of artificial intelligence that allows computers to learn from large complex datasets without being explicitly programmed. Although ML is already widely manifest in our daily lives in various forms, the considerable potential of ML has yet to find its way into mainstream medical research and day-to-day clinical care. The complex diagnostic and therapeutic modalities used in neurosurgery provide a vast amount of data that is ideally suited for ML models. This systematic review explores ML's potential to assist and improve neurosurgical care., Method: A systematic literature search was performed in the PubMed and Embase databases to identify all potentially relevant studies up to January 1, 2017. All studies were included that evaluated ML models assisting neurosurgical treatment., Results: Of the 6,402 citations identified, 221 studies were selected after subsequent title/abstract and full-text screening. In these studies, ML was used to assist surgical treatment of patients with epilepsy, brain tumors, spinal lesions, neurovascular pathology, Parkinson's disease, traumatic brain injury, and hydrocephalus. Across multiple paradigms, ML was found to be a valuable tool for presurgical planning, intraoperative guidance, neurophysiological monitoring, and neurosurgical outcome prediction., Conclusions: ML has started to find applications aimed at improving neurosurgical care by increasing the efficiency and precision of perioperative decision-making. A thorough validation of specific ML models is essential before implementation in clinical neurosurgical care. To bridge the gap between research and clinical care, practical and ethical issues should be considered parallel to the development of these techniques.

Although biopsies and tumor resection are prognostically beneficial for glioblastomas (GBM), potential negative effects have also been suggested. Here, using retrospective study of patients and intravital imaging of mice, we identify some of these negative aspects, including stimulation of proliferation and migration of non-resected tumor cells, and provide a strategy to prevent these adverse effects. By repeated high-resolution intravital microscopy, we show that biopsy-like injury in GBM induces migration and proliferation of tumor cells through chemokine (C-C motif) ligand 2 (CCL-2)-dependent recruitment of macrophages. Blocking macrophage recruitment or administrating dexamethasone, a commonly used glucocorticoid to prevent brain edema in GBM patients, suppressed the observed inflammatory response and subsequent tumor growth upon biopsy both in mice and in multifocal GBM patients. Taken together, our study suggests that inhibiting CCL-2-dependent recruitment of macrophages may further increase the clinical benefits from surgical and biopsy procedures.

The field of oncology is currently undergoing a paradigm shift. Advances in the understanding of tumor biology and in tumor sequencing technology have contributed to the shift towards precision medicine, the therapeutic framework of targeting the individual oncogenic changes each tumor harbors. The success of precision medicine therapies, such as targeted kinase inhibitors and immunotherapies, in other cancers have motivated studies in brain cancers. The high specificity and cost of these therapies also encourage a shift in clinical trial design away from randomized control trials towards smaller, more exclusive early phase clinical trials. While these new trials advance the clinical application of increasingly precise and individualized therapies, their design brings ethical challenges . We review the pertinent ethical considerations for clinical trials of precision medicine in neuro-oncology and discuss methods to protect patients in this new era of trial design.

Background: Cognitive impairment following transsphenoidal surgery (TSS) among patients with pituitary tumors has been intermittently reported and is not well established. We performed a systematic review to summarize the impact of TSS on cognitive function., Methods: We conducted a systematic search of the literature using the PubMed, Cochrane, and Embase databases through October 2014. Studies were selected if they reported cognitive status after surgery and included at least 10 adult patients with pituitary tumors undergoing either endoscopic or microscopic TSS., Results: After removing 69 duplicates, 758 articles were identified, of which 24 were selected for full text review after screening titles and abstracts. After reviewing full texts, nine studies with a combined total of 682 patients were included in the final analysis. Eight studies were cross-sectional and one was longitudinal. These studies used a wide variety of neurocognitive tests to assess memory, attention and executive function post-operatively. Of the eight studies, six reported impairments in verbal and non-verbal memory post-operatively, while others found no association related to memory, and some reported an improvement in episodic, verbal, or logical memory. While four studies found an impaired association between TSS and attention or executive function, another four studies did not., Conclusion: The current literature on cognitive impairments after TSS is limited and inconsistent. This review demonstrates that patients undergoing TSS may experience a variety of effects on executive function and memory post-operatively, but changes in verbal memory are most common., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: In patients with one to three brain metastases who undergo resection, options for post-operative treatments include whole-brain radiotherapy (WBRT) or stereotactic radiosurgery (SRS) of the resection cavity. In this meta-analysis, we sought to compare the efficacy of each post-operative radiation modality with respect to tumor recurrence and survival., Methods: Pubmed, Embase and Cochrane databases were searched through June 2016 for cohort studies reporting outcomes of SRS or WBRT after metastasis resection. Pooled effect estimates were calculated using fixed-effect and random-effect models for local recurrence, distant recurrence, and overall survival., Results: Eight retrospective cohort studies with 646 patients (238 with SRS versus 408 with WBRT) were included in the analysis. Comparing SRS to WBRT, the overall crude risk ratio using the fixed-effect model was 0.59 for local recurrence (95%-CI: 0.32-1.09, I 2 : 3.35%, P-heterogeneity = 0.36, 3 studies), 1.09 for distant recurrence (95%-CI: 0.74-1.60, I 2 : 50.5%, P-heterogeneity = 0.13; 3 studies), and 2.99 for leptomeningeal disease (95% CI 1.55-5.76; I 2 : 14.4% p-heterogeneity: 0.28; 2 studies). For the same comparison, the risk ratio for median overall survival was 0.47 (95% CI: 0.41-0.54; I 2 : 79.1%, P-heterogeneity < 0.01; 4 studies) in a fixed-effect model, but was no longer significant (0.63; 95%-CI: 0.40-1.00) in a random-effect model. SRS was associated with a lower risk of leukoencephalopathy (RR: 0.15, 95% CI: 0.07-0.33, 1 study), yet with a higher risk of radiation-necrosis (RR: 19.4, 95% CI: 1.21-310, 1 study)., Conclusion: Based on retrospective cohort studies, the results of this study suggest that SRS of the resection cavity may offer comparable survival and similar local and distant control as adjuvant WBRT, yet may be associated with a higher risk for developing leptomeningeal disease. Future research on SRS should focus on achieving a better understanding of the various factors that may favor SRS over WBRT.

Introduction: The Woven Endobridge (WEB) device is an innovative endovascular device for treatment of intracranial aneurysms, especially bifurcation and wide-neck aneurysms. Although not approved by the U.S. Food and Drug Administration, it has been available in Europe since 2011. The aim of this review is to evaluate the outcomes of WEB device use for intracranial aneurysm treatment., Methods: A systematic review was conducted with MEDLINE search engines PubMed and Embase from 2011. The search strategy provided 6229 articles, and 19 articles were included., Results: A total of 19 papers were identified describing the use of WEB devices in 687 patients with 718 aneurysms. The 2 largest prospective multicenter studies (WEBCAST and the French Observatory Trial) reported successful treatment, defined as complete closure or a neck remnant, in 85% and 79% of aneurysms, respectively. The use of a WEB device in combination with coiling or stenting was described with varying results in multiple small series. Outcomes of WEB device use in ruptured aneurysms in 2 studies showed 94% and 80% adequate treatment. Thromboembolic events were described in 71 patients (10.3% of all patients) and infarctions in 8 patients (1.2% of all patients)., Conclusions: Despite initial promising results, the WEB device should be used with caution given its potentially large learning curve and because it has primarily been investigated only in wide-neck and bifurcation aneurysms. In addition, currently available prospective studies have short follow-up, and the device has not been directly compared with other treatment modalities., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The application of stem cell transplants in clinical practice has increased in frequency in recent years. Many of the stem cell transplants in neurologic diseases, including stroke, Parkinson disease, spinal cord injury, and demyelinating diseases, are unproven-they have not been tested in prospective, controlled clinical trials and have not become accepted therapies. Stem cell transplant procedures currently being carried out have therapeutic aims, but are frequently experimental and unregulated, and could potentially put patients at risk. In some cases, patients undergoing such operations are not included in a clinical trial, and do not provide genuinely informed consent. For these reasons and others, some current stem cell interventions for neurologic diseases are ethically dubious and could jeopardize progress in the field. We provide discussion points for the evaluation of new stem cell interventions for neurologic disease, based primarily on the new Guidelines for Stem Cell Research and Clinical Translation released by the International Society for Stem Cell Research in May 2016. Important considerations in the ethical translation of stem cells to clinical practice include regulatory oversight, conflicts of interest, data sharing, the nature of investigation (e.g., within vs outside of a clinical trial), informed consent, risk-benefit ratios, the therapeutic misconception, and patient vulnerability. To help guide the translation of stem cells from the laboratory into the neurosurgical clinic in an ethically sound manner, we present an ethical discussion of these major issues at stake in the field of stem cell clinical research for neurologic disease., (© 2016 American Academy of Neurology.)

Accurate characterization of extracellular vesicles (EVs), including exosomes and microvesicles, is essential to obtain further knowledge on the biological relevance of EVs. Tunable resistive pulse sensing (tRPS) has shown promise as a method for single particle-based quantification and size profiling of EVs. Here, we describe the technical background of tRPS and its applications for EV characterization. Besides the standard protocol, we describe an alternative protocol, in which samples are spiked with polystyrene beads of known size and concentration. This alternative protocol can be used to overcome some of the challenges of direct EV characterization in biological fluids.

Many studies have implicated operative length as a predictor of post-operative complications, including venous thromboembolism [deep vein thrombosis (DVT) and pulmonary embolism (PE)]. We analyzed the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database from 2006 to 2014, to evaluate whether length of operation had a statistically significant effect on post-operative complications in patients undergoing surgical resection of meningioma. Patients were included for this study if they had a post-operative diagnosis of meningioma. Patient demographics, pre-operative comorbidities, and post-operative 30-day complications were analyzed. Of 3743 patients undergoing craniotomy for meningioma, 13.6 % experienced any complication. The most common complications and their median time to occurrence were urinary tract infection (2.6 %) at 10 days postoperatively (IQR 7-15), unplanned intubation (2.5 %) at 3 days (IQR 1-7), failure to wean from ventilator (2.4 %) at 2.0 days (IQR 2-4), and DVT (2.4 %) at 6 days (IQR 11-19). Postoperatively, 3.6 % developed VTE; 2.4 % developed DVT and 1.7 % developed PE. Multivariable analysis identified older age (third and upper quartile), obesity, preoperative ventilator dependence, preoperative steroid use, anemia, and longer operative time as significant risk factors for VTE. Separate multivariable logistic regression models demonstrated longer operative time as a significant risk factor for VTE, all complications, major complications, and minor complications. Meningioma resection is associated with various post-operative complications that increase patient morbidity and mortality risk. this large, multi-institutional patient sample, longer operative length was associated with increased risk for postoperative venous thromboembolisms, as well as major and minor complications.

Background: Fluorescence-guided surgery (FGS) is a technique used to enhance visualization of tumor margins in order to increase the extent of tumor resection in glioma surgery. In this paper, we systematically review all clinically tested fluorescent agents for application in FGS for glioma and all preclinically tested agents with the potential for FGS for glioma., Methods: We searched the PubMed and Embase databases for all potentially relevant studies through March 2016. We assessed fluorescent agents by the following outcomes: rate of gross total resection (GTR), overall and progression-free survival, sensitivity and specificity in discriminating tumor and healthy brain tissue, tumor-to-normal ratio of fluorescent signal, and incidence of adverse events., Results: The search strategy resulted in 2155 articles that were screened by titles and abstracts. After full-text screening, 105 articles fulfilled the inclusion criteria evaluating the following fluorescent agents: 5-aminolevulinic acid (5-ALA) (44 studies, including three randomized control trials), fluorescein (11), indocyanine green (five), hypericin (two), 5-aminofluorescein-human serum albumin (one), endogenous fluorophores (nine) and fluorescent agents in a pre-clinical testing phase (30). Three meta-analyses were also identified., Conclusions: 5-ALA is the only fluorescent agent that has been tested in a randomized controlled trial and results in an improvement of GTR and progression-free survival in high-grade gliomas. Observational cohort studies and case series suggest similar outcomes for FGS using fluorescein. Molecular targeting agents (e.g., fluorophore/nanoparticle labeled with anti-EGFR antibodies) are still in the pre-clinical phase, but offer promising results and may be valuable future alternatives., Competing Interests: Compliance with ethical standards Funding No funding was received for this research. Conflict of interest None. Human and animal consent This article does not contain any studies with human participants or animals performed by any of the authors.

Background: Since the turn of the last century, the prospect of head transplantation has captured the imagination of scientists and the general public. Recently, head transplant has regained attention in popular media, as neurosurgeons have proposed performing this procedure in 2017. Given the potential impact of such a procedure, we were interested in learning the history of the technical hurdles that need to be overcome, and determine if it is even technically possible to perform such a procedure on humans today., Method: We conducted a historical review of available literature on the technical challenges and developments of head transplantation. The many social, psychological, ethical, religious, cultural, and legal questions of head transplantation were beyond the scope of this review., Results: Our historical review identified the following important technical considerations related to performing a head transplant: maintenance of blood flow to an isolated brain via vessel anastomosis; availability of immunosuppressive agents; spinal anastomosis and fusion following cord transfection; pain control in the recipient. Several animal studies have demonstrated success in maintaining recipient cerebral perfusion and achieving immunosuppression. However, there is currently sparse evidence in favor of successful spinal anastomosis and fusion after transection. While recent publications by an Italian group offer novel approaches to this challenge, research on this topic has been sparse and hinges on procedures performed in animal models in the 1970s. How transferrable these older methods are to the human nervous system is unclear and warrants further exploration., Conclusions: Our review identified several important considerations related to performing a viable head transplantation. Besides the technical challenges that remain, there are important ethical issues to consider, such as exploitation of vulnerable patients and informed consent. Thus, besides the remaining technical challenges, these ethical issues will also need to be addressed before moving these studies to the clinic., Competing Interests: Compliance with ethical standards Funding No funding was received for this research. The sponsor had no role in the design or conduct of this research. Conflict of interest All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript. Animal experiments This article does not contain any studies with human participants or animals performed by any of the authors.

Background: Understanding the pathogenic role of extracellular vesicles (EVs) in disease and their potential diagnostic and therapeutic utility is extremely reliant on in-depth quantification, measurement and identification of EV sub-populations. Quantification of EVs has presented several challenges, predominantly due to the small size of vesicles such as exosomes and the availability of various technologies to measure nanosized particles, each technology having its own limitations., Materials and Methods: A standardized methodology to measure the concentration of extracellular vesicles (EVs) has been developed and tested. The method is based on measuring the EV concentration as a function of a defined size range. Blood plasma EVs are isolated and purified using size exclusion columns (qEV) and consecutively measured with tunable resistive pulse sensing (TRPS). Six independent research groups measured liposome and EV samples with the aim to evaluate the developed methodology. Each group measured identical samples using up to 5 nanopores with 3 repeat measurements per pore. Descriptive statistics and unsupervised multivariate data analysis with principal component analysis (PCA) were used to evaluate reproducibility across the groups and to explore and visualise possible patterns and outliers in EV and liposome data sets., Results: PCA revealed good reproducibility within and between laboratories, with few minor outlying samples. Measured mean liposome (not filtered with qEV) and EV (filtered with qEV) concentrations had coefficients of variance of 23.9% and 52.5%, respectively. The increased variance of the EV concentration measurements could be attributed to the use of qEVs and the polydisperse nature of EVs., Conclusion: The results of this study demonstrate the feasibility of this standardized methodology to facilitate comparable and reproducible EV concentration measurements., Competing Interests: and funding RV and MFB are contractors at Izon Science and their contributions to this paper were made as part of their contracts. AFH is funded by grants from the Australian National Health and Medical Research Council (grants 628946 and 400202; www.nhmrc.gov.au) and an Australian Research Council (www.arc.gov.au) Future Fellowship (grant FT100100560).

The aim of the present article was to systematically review the ethics of surgical innovation and introduce the components of the learning health care system to guide future research and debate on surgical innovation.Although the call for evidence-based practice in surgery is increasingly high on the agenda, most surgeons feel that the format of the randomized controlled trial is not suitable for surgery. Innovation in surgery has aspects of, but should be distinguished from both research and clinical care and raises its own ethical challenges.To answer the question "What are the main ethical aspects of surgical innovation?", we systematically searched PubMed and Embase. Papers expressing an opinion, point of view, or position were included, that is, normative ethical papers.We included 59 studies discussing ethical aspects of surgical innovation. These studies discussed 4 major themes: oversight, informed consent, learning curve, and vulnerable patient groups. Although all papers addressed the ethical challenges raised by surgical innovation, surgeons hold no uniform view of surgical innovation, and there is no agreement on the distinction between innovation and research. Even though most agree to some sort of oversight, they offer different alternatives ranging from the formation of new surgical innovation committees to establishing national registries. Most agree that informed consent is necessary for innovative procedures and that surgeons should be adequately trained to assure their competence to tackle the learning curve problem. All papers agree that in case of vulnerable patients, alternatives must be found for the informed consent procedure.We suggest that the concept of the learning health care system might provide guidance for thinking about surgical innovation. The underlying rationale of the learning health care system is to improve the quality of health care by embedding research within clinical care. Two aspects of a learning health care system might particularly enrich the necessary future discussion on surgical innovation: integration of research and practice and a moral emphasis on "learning activities." Future research should evaluate whether the learning health care system and its adjacent moral framework provides ethical guidance for evidence-based surgery., Competing Interests: The authors have no funding and conflicts of interest to disclose.

Background: Epileptogenic glioblastomas are thought to convey a favorable prognosis, either due to early diagnosis or potential antitumor effects of antiepileptic drugs. We investigated the relationship between survival and epilepsy at presentation, early diagnosis, and antiepileptic drug therapy in glioblastoma patients., Methods: Multivariable Cox regression was applied to survival data of 647 consecutive patients diagnosed with de novo glioblastoma between 2005 and 2013 in order to investigate the association between epilepsy and survival in glioblastoma patients. In addition, we quantified the association between survival and valproic acid (VPA) treatment., Results: Epilepsy correlated positively with survival (HR: 0.75 (95% CI: 0.61-0.92), P < .01). This effect is independent of age, sex, performance status, type of surgery, adjuvant therapy, tumor location, and tumor volume, suggesting that this positive correlation cannot be attributed solely to early diagnosis. For patients who presented with epilepsy, the use of the antiepileptic drug VPA did not associate with survival when compared with patients who did not receive VPA treatment., Conclusion: Epilepsy is an independent prognostic factor for longer survival in glioblastoma patients. This prognostic effect is not solely explained by early diagnosis, and survival is not associated with VPA treatment., (© The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Glioblastoma multiforme (GBM) is the most common primary brain tumor and is without exception lethal. GBMs modify the immune system, which contributes to the aggressive nature of the disease. Particularly, cells of the monocytic lineage, including monocytes, macrophages and microglia, are affected. We investigated the influence of GBM-derived extracellular vesicles (EVs) on the phenotype of monocytic cells. Proteomic profiling showed GBM EVs to be enriched with proteins functioning in extracellular matrix interaction and leukocyte migration. GBM EVs appeared to skew the differentiation of peripheral blood-derived monocytes to alternatively activated/M2-type macrophages. This was observed for EVs from an established cell line, as well as for EVs from primary cultures of GBM stem-like cells (GSCs). Unlike EVs of non-GBM origin, GBM EVs induced modified expression of cell surface proteins, modified cytokine secretion (e.g., an increase in vascular endothelial growth factor and IL-6) and increased phagocytic capacity of the macrophages. Most pronounced effects were observed upon incubation with EVs from mesenchymal GSCs. GSC EVs also affected primary human microglia, resulting in increased expression of Membrane type 1-matrix metalloproteinase, a marker for GBM microglia and functioning as tumor-supportive factor. In conclusion, GBM-derived EVs can modify cells of the monocytic lineage, which acquire characteristics that resemble the tumor-supportive phenotypes observed in patients., (© 2015 UICC.)

Glioblastoma multiforme (GBM) is the most common primary brain tumor that is invariably lethal. Novel treatments are desperately needed. In various cancers, heparin and its low molecular weight derivatives (LMWHs), commonly used for the prevention and treatment of thrombosis, have shown therapeutic potential. Here we systematically review preclinical and clinical studies of heparin and LMWHs as anti-tumor agents in GBM. Even though the number of studies is limited, there is suggestive evidence that heparin may have various effects on GBM. These effects include the inhibition of tumor growth and angiogenesis in vitro and in vivo, and the blocking of uptake of extracellular vesicles. However, heparin can also block the uptake of (potential) anti-tumor agents. Clinical studies suggest a non-significant trend of prolonged survival of LMWH treated GBM patients, with some evidence of increased major bleedings. Heparin mimetics lacking anticoagulant effect are therefore a potential alternative to heparin/LMWH and are discussed as well.

Nano-sized extracelullar vesicles (EVs) released by various cell types play important roles in a plethora of (patho)physiological processes and are increasingly recognized as biomarkers for disease. In addition, engineered EV and EV-inspired liposomes hold great potential as drug delivery systems. Major technologies developed for high-throughput analysis of individual EV include nanoparticle tracking analysis (NTA), tunable resistive pulse sensing (tRPS) and high-resolution flow cytometry (hFC). Currently, there is a need for comparative studies on the available technologies to improve standardization of vesicle analysis in diagnostic or therapeutic settings. We investigated the possibilities, limitations and comparability of NTA, tRPS and hFC for analysis of tumor cell-derived EVs and synthetic mimics (i.e. differently sized liposomes). NTA and tRPS instrument settings were identified that significantly affected the quantification of these particles. Furthermore, we detailed the differences in absolute quantification of EVs and liposomes using the three technologies. This study increases our understanding of possibilities and pitfalls of NTA, tRPS and hFC, which will benefit standardized and large-scale clinical application of (engineered) EVs and EV-mimics in the future., (Copyright © 2015. Published by Elsevier B.V.)

Extracellular vesicles (EVs), including 'microvesicles' and 'exosomes', are highly abundant in bodily fluids. Recent years have witnessed a tremendous increase in interest in EVs. EVs have been shown to play important roles in various physiological and pathological processes, including coagulation, immune responses, and cancer. In addition, EVs have potential as therapeutic agents, for instance as drug delivery vehicles or as regenerative medicine. Because of their small size (50 to 1,000 nm) accurate quantification and size profiling of EVs is technically challenging. This protocol describes how tunable resistive pulse sensing (tRPS) technology, using the qNano system, can be used to determine the concentration and size of EVs. The method, which relies on the detection of EVs upon their transfer through a nano sized pore, is relatively fast, suffices the use of small sample volumes and does not require the purification and concentration of EVs. Next to the regular operation protocol an alternative approach is described using samples spiked with polystyrene beads of known size and concentration. This real-time calibration technique can be used to overcome technical hurdles encountered when measuring EVs directly in biological fluids.

Background: Euthanasia and physician assisted suicide (PAS) are two controversial topics in neurosurgical practice. Personal attitudes and opinions on these important issues may vary between professionals, and may also depend on their location since current legislation differs between European countries. As these issues may have significant impact on clinical practice, the goal of the present study was to survey the opinions of neurosurgical residents and young neurosurgeons across Europe with respect to euthanasia and physician assisted suicide., Design: We performed a survey among the participants of the European Association of Neurosurgical Societies (EANS) training courses (2011-2012), asking residents and young neurosurgeons nine questions on euthanasia and PAS. For the analysis of this survey, we divided all 295 participants into four European regions (North, South, East, West)., Results: We found that even though most residents are aware of regulations about euthanasia or PAS in their country or hospital, a substantial number were not aware of the regulations. We observed no significant differences in terms of their opinions on euthanasia and PAS among the four European regions. While most are actually in favor of euthanasia or PAS, if legally allowed, under appropriate circumstances, very few neurosurgeons would be willing to actively participate in these end-of-life practices., Conclusions: The results of this first survey on neurosurgical residents' attitudes towards euthanasia and PAS show that a significant number of residents is not familiar with national and/or local regulations regarding euthanasia and PAS. If legally allowed, most residents would be in favor of euthanasia and PAS, but only a minority would be willing to actively participate in these practices. We did not observe a difference in stances on euthanasia and PAS among residents from different regions in Europe.

Background: Cells secrete different types of membrane vesicles (MVs), which may act as important entities in normal human physiology and in various pathological processes. The established methods for quantification of MVs require purification or preanalytical handling of samples with labeling moieties., Aim: The authors' aim was to develop a method for high-throughput, labeling-free quantification of nonpurified MVs., Materials & Methods: Scanning ion occlusion sensing technology, which relies on the detection of particles upon their movement through a nanopore, was investigated for the ability to quantify nanosized MVs (<400 nm) in bodily fluids and cell culture supernatants., Results: Scanning ion occlusion sensing allowed for rapid and easy measurement of the concentration of MVs in all biological fluids tested., Conclusion: Scanning ion occlusion sensing technology enables the quantification of MVs in biological samples without the requirement of MV isolation and/or labeling. This offers a highly valuable addition to the currently used repertoire of MV quantification methods.

Many neurosurgeons remove their patients' hair before surgery. They claim that this practice reduces the chance of postoperative surgical site infections, and facilitates planning, attachment of the drapes, and closure. However, most patients dread this procedure. The authors performed the first systematic review on shaving before neurosurgical procedures to investigate whether this commonly performed procedure is based on evidence. They systematically reviewed the literature on wound infections following different shaving strategies. Data on the type of surgery, surgeryrelated infections, preoperative shaving policy, decontamination protocols, and perioperative antibiotics protocols were collected. The search detected 165 articles, of which 21 studies-involving 11,071 patients-were suitable for inclusion. Two of these studies were randomized controlled trials. The authors reviewed 13 studies that reported on the role of preoperative hair removal in craniotomies, 14 on implantation surgery, 5 on bur hole procedures, and 3 on spine surgery. Nine studies described shaving policies in pediatric patients. None of these papers provided evidence that preoperative shaving decreases the occurrence of postoperative wound infections. The authors conclude that there is no evidence to support the routine performance of preoperative hair removal in neurosurgery. Therefore, properly designed studies are needed to provide evidence for preoperative shaving recommendations.

Exosomes are a subtype of vesicles released by cells of both healthy and neoplastic origin. Preclinical studies suggest a role for tumour-derived exosomes in tumour progression, mainly through the transfer of RNA and proteins from tumour cells to other cells. The transfer of RNA and proteins by tumour-derived exosomes seems to mediate stimulation of angiogenesis and suppression of immune cells; in contrast, exosomes from healthy cells of the immune system appear to have anti-tumour characteristics. Characterisation of the RNA or protein profile of tumour-derived exosomes could have diagnostic or prognostic value, for example, in brain tumours. Anti-tumour therapies could be based on exosomes, for example, by blocking the formation of tumour-derived exosomes or having exosomes release therapeutic agents at specific sites. The most advanced application of this is the use of exosomes from dendritic cells in tumour vaccination; the safety of this has been demonstrated in phase I studies.

Background: GM1-gangliosidosis is a glycosphingolipid (GSL) lysosomal storage disease caused by a genetic deficiency of acid β-galactosidase (βgal), which results in the accumulation of GM1-ganglioside and its asialo-form (GA1) primarily in the CNS. Age of onset ranges from infancy to adulthood, and excessive ganglioside accumulation produces progressive neurodegeneration and psychomotor retardation in humans. Currently, there are no effective therapies for the treatment of GM1-gangliosidosis., Methodology/principal Findings: In this study we examined the effect of thalamic infusion of AAV2/1-βgal vector in adult GM1 mice on enzyme distribution, activity, and GSL content in the CNS, motor behavior, and survival. Six to eight week-old GM1 mice received bilateral injections of AAV vector in the thalamus, or thalamus and deep cerebellar nuclei (DCN) with pre-determined endpoints at 1 and 4 months post-injection, and the humane endpoint, or 52 weeks of age. Enzyme activity was elevated throughout the CNS of AAV-treated GM1 mice and GSL storage nearly normalized in most structures analyzed, except in the spinal cord which showed ∼50% reduction compared to age-matched untreated GM1 mice spinal cord. Survival was significantly longer in AAV-treated GM1 mice (52 wks) than in untreated mice. However the motor performance of AAV-treated GM1 mice declined over time at a rate similar to that observed in untreated GM1 mice., Conclusions/significance: Our studies show that the AAV-modified thalamus can be used as a 'built-in' central node network for widespread distribution of lysosomal enzymes in the mouse cerebrum. In addition, this study indicates that thalamic delivery of AAV vectors should be combined with additional targets to supply the cerebellum and spinal cord with therapeutic levels of enzyme necessary to achieve complete correction of the neurological phenotype in GM1 mice.

GM1-gangliosidosis is a lysosomal storage disease (LSD) caused by an autosomal recessive deficiency of lysosomal acid beta-galactosidase (betagal). This leads to accumulation of GM1-ganglioside and its asialo derivative GA1 in the central nervous system (CNS), and progressive neurodegeneration. Therapeutic AAV-mediated gene delivery to the brain for LSDs has proven very successful in several animal models. GM1-gangliosidosis is also a prime candidate for AAV-mediated gene therapy in the CNS. As global neuropathology characterizes the most severe forms of this disease, therapeutic interventions need to achieve distribution of betagal throughout the entire CNS. Therefore, careful consideration of routes of administration and target structures from where metabolically active enzyme can be produced, released and distributed throughout the CNS, is necessary. The goal of this study was to investigate the pattern and mechanism of distribution of betagal in the adult GM1-gangliosidosis mouse brain upon hippocampal injection of an AAV vector-encoding betagal. We found evidence that three different mechanisms contribute to its distribution in the brain: (1) diffusion; (2) axonal transport within neurons from the site of production; (3) CSF flow in the perivascular space of Virchow-Robin. In addition, we found evidence of axonal transport of vector-encoded mRNA.

Glioblastoma multiforme (GBM) is a devastating form of brain cancer for which there is no effective treatment. Here, we report a novel approach to brain tumor therapy through genetic modification of normal brain cells to block tumor growth and effect tumor regression. Previous studies have focused on the use of vector-based gene therapy for GBM by direct intratumoral injection with expression of therapeutic proteins by tumor cells themselves. However, as antitumor proteins are generally lethal to tumor cells, the therapeutic reservoir is rapidly depleted, allowing escape of residual tumor cells. Moreover, it has been difficult to achieve consistent transduction of these highly heterogeneous tumors. In our studies, we found that transduction of normal cells in the brain with an adeno-associated virus (AAV) vector encoding interferon-beta (IFN-beta) was sufficient to completely prevent tumor growth in orthotopic xenograft models of GBM, even in the contralateral hemisphere. In addition, complete eradication of established tumors was achieved through expression of IFN-beta by neurons using a neuronal-restricted promoter. To our knowledge this is the first direct demonstration of the efficacy of targeting gene delivery exclusively to normal brain cells for brain tumor therapy.

Beckwith-Wiedemann syndrome (BWS) is a rare congenital syndrome characterized by gigantism, macroglossia, exophthalmos, postpartum hypoglycemia, and multiple midline defects such as omphalocele. The authors describe, to the best of their knowledge, the first case of a child in whom BWS was diagnosed and who was subsequently treated for a nasal encephalocele. Because the authors believe that this feature might not be an incidental finding in patients with BWS, intranasal masses in these patients should be carefully differentiated, as complications might be severe.

GM1-gangliosidosis is a glycosphingolipid (GSL) lysosomal storage disease caused by autosomal recessive deficiency of lysosomal acid beta-galactosidase (betagal), and characterized by accumulation of GM1-ganglioside and GA1 in the brain. Here we examined the effect of neonatal intracerebroventricular (i.c.v.) injection of an adeno-associated virus (AAV) vector encoding mouse betagal on enzyme activity and brain GSL content in GM1-gangliosidosis (betagal(-/-)) mice. Histological analysis of betagal distribution in 3-month-old AAV-treated betagal(-/-) mice showed that enzyme was present at high levels throughout the brain. Biochemical quantification showed that betagal activity in AAV-treated brains was 7- to 65-fold higher than in wild-type controls and that brain GSL levels were normalized. Cerebrosides and sulfatides, which were reduced in untreated betagal(-/-) mice, were restored to normal levels by AAV treatment. In untreated betagal(-/-) brains, cholesterol was present at normal levels but showed abnormal cellular distribution consistent with endosomal/lysosomal localization. This feature was also corrected in AAV-treated mice. The biochemical and histological parameters analyzed in this study showed that normal brain neurochemistry was achieved in AAV-treated betagal(-/-) mice. Therefore we show for the first time that neonatal AAV-mediated gene delivery of lysosomal betagal to the brain may be an effective approach for treatment of GM1-gangliosidosis.

Adeno-associated virus (AAV) vectors have gained a preeminent position in the field of gene delivery to the normal brain through their ability to achieve extensive transduction of neurons and to mediate long-term gene expression with no apparent toxicity. In adult animals direct infusion of AAV vectors into the brain parenchyma results in highly efficient transduction of target structures. However AAV-mediated global delivery to the adult brain has been an elusive goal. In contrast, widespread global gene delivery has been obtained by i.c.v. injection of AAV1 or AAV2 in neonates. Among the novel AAV serotypes cloned and engineered for production of recombinant vectors, AAV8 has shown a tremendous potential for in vivo gene delivery with nearly complete transduction of many tissues in rodents after intravascular infusion. Here we compare the efficiency of an AAV8 serotyped vector with that of AAV1 and AAV2 serotyped vectors for the extent of gene delivery to the brain after neonatal injection into the lateral ventricles. The vectors all encoded green fluorescent protein (GFP) under control of a hybrid CMV enhancer/chicken beta-actin promoter with AAV2 inverted terminal repeats, but differed from each other with respect to the capsid type. A total of 6.8 x 10(10) genome copies were injected into the lateral ventricles of postnatal day 0 mice. Mice were killed at postnatal day 30 and brains analyzed for distribution of GFP-positive cells. AAV8 proved to be more efficient than AAV1 or AAV2 vectors for gene delivery to all of the structures analyzed, including the cerebral cortex, hippocampus, olfactory bulb, and cerebellum. Moreover the intensity of gene expression, assessed using a microarray reader, was considerably higher for AAV8 in all structures analyzed. In conclusion, the enhanced transduction achieved by AAV8 compared with AAV1 and AAV2 indicates that AAV8 is the superior serotype for gene delivery to the CNS.