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Background Numerous neuromodulatory therapies are currently under investigation or in clinical use for the treatment of psychiatric conditions. Objective/hypothesis We sought to catalogue past and present human research studies on psychiatric neuromodulation and identify relevant trends in this field. Methods ClinicalTrials.gov ( https://www.clinicaltrials.gov/ ) and the International Clinical Trials Registry Platform ( https://www.who.int/ictrp/en/ ) were queried in March 2020 for trials assessing the outcome of neuromodulation for psychiatric disorders. Relevant trials were categorized by variables such as neuromodulation modality, country, brain target, publication status, design, and funding source. Results From 72,086 initial search results, 1252 unique trials were identified. The number of trials registered annually has consistently increased. Half of all trials were active and a quarter have translated to publications. The largest proportion of trials involved depression (45%), schizophrenia (18%), and substance use disorders (14%). Trials spanned 37 countries; China, the second largest contributor (13%) after the United States (28%), has increased its output substantially in recent years. Over 75% of trials involved non-convulsive non-invasive modalities (e.g., transcranial magnetic stimulation), while convulsive (e.g., electroconvulsive therapy) and invasive modalities (e.g., deep brain stimulation) were less represented. 72% of trials featured approved or cleared interventions. Characteristic inter-modality differences were observed with respect to enrollment size, trial design/phase, and funding. Dorsolateral prefrontal cortex accounted for over half of focal neuromodulation trial targets. The proportion of trials examining biological correlates of neuromodulation has increased. Conclusion(s) These results provide a comprehensive overview of the state of psychiatric neuromodulation research, revealing the growing scope and internationalism of this field.

Background The therapeutic challenge of glioblastoma (GBM) has catalyzed the development of clinical trials to evaluate novel interventions. With increased understanding of GBM biology and technological advances, the neurosurgeon's role in neuro-oncology has evolved. Objective To evaluate the current landscape of procedure-based clinical trials for GBM to characterize this evolution, gain insight into past failures, and accordingly outline implications for future research and practice that may inform future studies. Methods The ClinicalTrials.gov database was searched for surgical/procedural trials in individuals with GBM. Demographics, specific intervention, trial phase, and main outcome measures were abstracted. Results A total of 224 of 2311 GBM trials (9.7%) were identified as procedural, with the majority being based in the United States (155/224, 69.2%), single-center (155/224, 69.2%), and not randomized (176/224, 78.6%). Primary and recurrent GBMs were evenly addressed. The leading interventions were local delivery of therapeutics (50.0%), surgical techniques (33.9%), such as image-guided surgery, and novel device applications (14.3%). Phase I designs predominated (82/224, 36.6%). The top primary outcome was safety/tolerability/feasibility (88/224, 39.3%), followed by survival (46/224, 20.5%). Approximately 17% of studies were terminated, withdrawn, or suspended. Fifty-two linked publications were identified, among which 42 were classified as having a positive result. Conclusion Procedural interventions comprised ∼10% of all registered GBM trials. Local delivery of therapeutics, use of surgical imaging techniques and novel device applications, predominantly through phase I designs, represent the evolved role of the neurosurgeon in neuro-oncology. Improved reporting of trial designs, outcomes, and results are needed to better inform the field and increase efficiency.

Background Panic attacks affect a sizeable proportion of the population. The neurocircuitry of panic remains incompletely understood. Objective To investigate the neuroanatomical underpinnings of panic attacks induced by deep brain stimulation (DBS) through (1) connectomic analysis of an obsessive-compulsive disorder patient who experienced panic attacks during inferior thalamic peduncle DBS; (2) appraisal of existing clinical reports on DBS-induced panic attacks. Methods Panicogenic, ventral contact stimulation was compared with benign stimulation at other contacts using volume of tissue activated (VTA) modelling. Networks associated with the panicogenic zone were investigated using state-of-the-art normative connectivity mapping. In addition, a literature search for prior reports of DBS-induced panic attacks was conducted. Results Panicogenic VTAs impinged primarily on the tuberal hypothalamus. Compared to non-panicogenic VTAs, panicogenic loci were significantly functionally coupled to limbic and brainstem structures, including periaqueductal grey and amygdala. Previous studies found stimulation of these areas can also provoke panic attacks. Conclusions DBS in the region of the tuberal hypothalamus elicited panic attacks in a single obsessive-compulsive disorder patient and recruited a network of structures previously implicated in panic pathophysiology, reinforcing the importance of the hypothalamus as a hub of panicogenic circuitry.

Deep brain stimulation targeting the subcallosal cingulate area, a hub with multiple axonal projections, has shown therapeutic potential for treatment-resistant mood disorders. While subcallosal cingulate deep brain stimulation drives long-term metabolic changes in corticolimbic circuits, the brain areas that are directly modulated by electrical stimulation of this region are not known. We used 3.0 T functional MRI to map the topography of acute brain changes produced by stimulation in an initial cohort of 12 patients with fully implanted deep brain stimulation devices targeting the subcallosal cingulate area. Four additional subcallosal cingulate deep brain stimulation patients were also scanned and employed as a validation cohort. Participants underwent resting state scans (n = 78 acquisitions overall) during (i) inactive deep brain stimulation; (ii) clinically optimal active deep brain stimulation; and (iii) suboptimal active deep brain stimulation. All scans were acquired within a single MRI session, each separated by a 5-min washout period. Analysis of the amplitude of low-frequency fluctuations in each sequence indicated that clinically optimal deep brain stimulation reduced spontaneous brain activity in several areas, including the bilateral dorsal anterior cingulate cortex, the bilateral posterior cingulate cortex, the bilateral precuneus and the left inferior parietal lobule (PBonferroni These results provide insight into the network-level mechanisms of subcallosal cingulate deep brain stimulation and point towards potential acute biomarkers of clinical response that could help to optimize and personalize this therapy.

Subcallosal cingulate deep brain stimulation produces long-term clinical improvement in approximately half of patients with severe treatment-resistant depression. We hypothesized that both structural and functional brain attributes may be important in determining responsiveness to this therapy.In a treatment-resistant depression subcallosal cingulate deep brain stimulation cohort, we retrospectively examined baseline and longitudinal differences in MRI-derived brain volume (n = 65) and 18F-fluorodeoxyglucose-PET glucose metabolism (n = 21) between responders and non-responders. Support vector machines were subsequently trained to classify patients’ response status based on extracted baseline imaging features. A machine learning model incorporating preoperative frontopolar, precentral/frontal opercular and orbitofrontal local volume values classified binary response status (12 months) with 83% accuracy [leave-one-out cross-validation (LOOCV): 80% accuracy] and explained 32% of the variance in continuous clinical improvement. It was also predictive in an out-of-sample subcallosal cingulate deep brain stimulation cohort (n = 21) with differing primary indications (bipolar disorder/anorexia nervosa; 76% accuracy). Adding preoperative glucose metabolism information from rostral anterior cingulate cortex and temporal pole improved model performance, enabling it to predict response status in the treatment-resistant depression cohort with 86% accuracy (LOOCV: 81% accuracy) and explain 67% of clinical variance. Response-related patterns of metabolic and structural post-deep brain stimulation change were also observed, especially in anterior cingulate cortex and neighbouring white matter. Areas where responders differed from non-responders—both at baseline and longitudinally—largely overlapped with depression-implicated white matter tracts, namely uncinate fasciculus, cingulum bundle and forceps minor/rostrum of corpus callosum. The extent of patient-specific engagement of these same tracts (according to electrode location and stimulation parameters) also served as an independent predictor of treatment-resistant depression response status (72% accuracy; LOOCV: 70% accuracy) and augmented performance of the volume-based (88% accuracy; LOOCV: 82% accuracy) and combined volume/metabolism-based support vector machines (100% accuracy; LOOCV: 94% accuracy).Taken together, these results indicate that responders and non-responders to subcallosal cingulate deep brain stimulation exhibit differences in brain volume and metabolism, both pre- and post-surgery. Moreover, baseline imaging features predict response to treatment (particularly when combined with information about local tract engagement) and could inform future patient selection and other clinical decisions.

Deep brain stimulation (DBS) of the subthalamic nucleus, pallidum, and thalamus is an established therapy for various movement disorders. Limbic targets have also been increasingly explored for their application to neuropsychiatric and cognitive disorders. The brainstem constitutes another DBS substrate, although the existing literature on the indications for and the effects of brainstem stimulation remains comparatively sparse. The objective of this review was to provide a comprehensive overview of the pertinent anatomy, indications, and reported stimulation-induced acute and long-term effects of existing white and grey matter brainstem DBS targets. We systematically searched the published literature, reviewing clinical trial articles pertaining to DBS brainstem targets. Overall, 164 studies describing brainstem DBS were identified. These studies encompassed 10 discrete structures: periaqueductal/periventricular grey (n = 63), pedunculopontine nucleus (n = 48), ventral tegmental area (n = 22), substantia nigra (n = 9), mesencephalic reticular formation (n = 7), medial forebrain bundle (n = 8), superior cerebellar peduncles (n = 3), red nucleus (n = 3), parabrachial complex (n = 2), and locus coeruleus (n = 1). Indications for brainstem DBS varied widely and included central neuropathic pain, axial symptoms of movement disorders, headache, depression, and vegetative state. The most promising results for brainstem DBS have come from targeting the pedunculopontine nucleus for relief of axial motor deficits, periaqueductal/periventricular grey for the management of central neuropathic pain, and ventral tegmental area for treatment of cluster headaches. Brainstem DBS has also acutely elicited numerous motor, limbic, and autonomic effects. Further work involving larger, controlled trials is necessary to better establish the therapeutic potential of DBS in this complex area.

BACKGROUND Surgery continues to be part of the mainstay of therapy for most primary CNS tumors. However, neurosurgical innovations advancing treatment options have stagnated. An understanding of past and current investigational trends is necessary to catalyze innovation in surgical trials. OBJECTIVE To evaluate the landscape of surgical clinical trials for non-diffusely infiltrating primary CNS tumors. METHODS ClinicalTrials.gov was searched on May 14th, 2019 for surgical/procedural trials based on non-diffusely infiltrating primary CNS tumors, with a focus on meningiomas, ependymomas, medulloblastomas, pituitary adenomas, vestibular scwhannomas, and chordomas. Key trial design parameters were extracted. Purely surgical interventions were classified as “technical” while fluorescence-guided and other intraoperative imaging modalities were classified as image-guided surgery. Any invasive mode of drug delivery (e.g. intra-arterial or intra-ventricular, local chemotherapy wafers, and oncolytic virus injection) was considered. RESULTS Among 944 total trial records (257 medulloblastomas, 254 ependymomas, 179 meningiomas, 156 pituitary adenomas, 56 vestibular schwannomas, and 48 chordomas) only 54 (5.7%) were procedural in nature. Ependymomas had the highest absolute number (18/254, 7%) while vestibular schwannomas had the highest percentage (6/56, 10.7%) of surgical trials. The majority of records were not randomized (41/54, 75.9%), not industry-funded (45/54, 83.3%), and were early Phase (30/54, 55.6%); there were only three Phase III trials. The relative number of new surgical trial registrations has not changed significantly over time (1990s: 5, 2000s: 19, and 2010s: 30). Approaches integrated with other disciplines, such as image-guided surgery (16/54, 29.6%) and local drug delivery (16/24, 29.6%), were among the leading categories of trials. CONCLUSIONS Despite the clinical role of surgery in management of non-diffusely infiltrating primary CNS tumors, a paucity of innovative surgical trials has been put forth. Multi-disciplinary approaches appear to be necessary for pushing the therapeutic envelope for individuals affected by these tumors, with imaging and drug development at the forefront.

BACKGROUND The therapeutic challenge of glioblastoma (GBM) has catalyzed the active pursuit of a high volume of clinical trials to evaluate novel interventions for this deadly disease. Our enhanced understanding of the biology of GBMs has translated into an evolution of the role of the neurosurgeon as well. In this study, we have evaluated the current landscape of surgical clinical trials in GBM to characterize this evolution, describe current trends, and identify potential gaps in methodological features. METHODS The ClinicalTrials.gov database was searched for surgical/procedural trials in individuals with GBM on May 14th, 2019 without date limitations. Demographics, specific intervention (e.g. technical, device use, or local drug delivery), phase, sample size, and main outcome measures were abstracted. RESULTS 270 of 2140 trials (12.6%) were identified as procedural. The majority were based in the USA (189/270, 70%), single-center (188/270, 70%), and not randomized by design (215/270, 80%). Primary and recurrent GBMs were evenly addressed. Industry-funding supported 106/270 (39%) of studies. The leading test intervention was local delivery of therapeutics (44.8%), followed by use of novel devices (33%). Surgical technique/procedures comprised 20%. Early Phase designs predominated (177/270, 65.5%) but 67 (24.8%) did not report Phase. The greatest surge in new registrations over the last decade was seen in Phase I trials. The top primary outcome was safety/tolerability/ feasibility (107/270, 39%), followed by survival (62/270, 22%); 35 (12.6%) did not report a primary outcome. Approximately 15% of studies were terminated, withdrawn or suspended. Only 6 records were associated with reported results. CONCLUSIONS In GBMs, procedural interventions comprise a notable proportion of trials. Local delivery of therapeutics and novel device applications, predominantly through Phase I designs, represent the evolved role of the neurosurgeon in neuro-oncology. Improved documentation of design, outcomes, and reporting of results are needed to better inform the field and increase efficiency.

Background Deep brain stimulation (DBS) is a surgical neuromodulation procedure with a historically wide range of possible therapeutic indications, including movement disorders, neuropsychiatric conditions, and cognitive disorders. Ongoing research in this field is critical to gain further insights into the mechanisms of DBS, to discover novel brain targets for new and existing indications, and to refine targeting and post-operative programming techniques for the optimization of therapeutic outcomes. Objective To update on the state of DBS-related clinical human research by cataloging and summarizing clinical trials that have been completed or are currently ongoing in this field worldwide. Methods A search was conducted for clinical trials pertaining to DBS, currently listed on the ClinicalTrials.gov database. Trials were analyzed to generate a detailed overview of ongoing DBS-related research. Specifically, trials were categorized by trial start date, study completion status, clinical phase, projected subject enrollment, disorder, brain target, country of origin, device manufacturer, funding source, and study topic. Results In total, 384 relevant clinical trials were identified. The trials spanned 28 different disorders across 26 distinct brain targets, with almost 40% of trials being for conditions other than movement disorders. The majority of DBS trials have been US-based (41.9% of studies) but many countries are becoming increasingly active. The ratio of investigator-sponsored to industry-sponsored trials was 3:1. Emphasizing the need to better understand the mechanism of action of DBS, one-third of the studies predominantly focus on imaging or electrophysiological changes associated with DBS. Conclusions This overview of current DBS-related clinical trials provides insight into the status of DBS research and what we can anticipate in the future concerning new brain targets, indications, techniques, and developing a better understanding of the mechanisms of action of DBS.

We consider the question of finding communities in large social networks. In literature and practice, “communities” refer to a well-connected subgraph of the entire network. For instance, the notion of graph density has been considered as a reasonable measure of a community. Researchers have also looked at the minimum degree of a subgraph as a measure of the connectedness of the community.

In this paper we study the problem of clustering entities that are described by two types of data: attribute data and relationship data. While attribute data describe the inherent characteristics of the entities, relationship data represent associations among them. Attribute data can be mapped to the Euclidean space, whereas that is not always possible for the relationship data. The relationship data is described by a graph over the vertices with edges denoting relationship between pairs of entities that they connect. We study clustering problems under the model where the relationship data is constrained by 'internal connectedness,' which requires that any two entities in a cluster are connected by an internal path, that is, a path via entities only from the same cluster. We study the k-median and k-means clustering problems under this model. We show that these problems are Ω(log n) hard to approximate and give O(log n) approximation algorithms for specific cases of these problems.