Background The semi-sitting position in neurosurgical procedures is still under debate due to possible complications such as venous air embolism (VAE) or postoperative pneumocephalus (PP). Studies reporting a high frequency of the latter raise the question about the clinical relevance (i.e., the incidence of tension pneumocephalus) and the efficacy of a treatment by an air replacement procedure. Methods This retrospective study enrolled 540 patients harboring vestibular schwannomas who underwent posterior fossa surgery in a supine (n = 111) or semi-sitting (n = 429) position. The extent of the PP was evaluated by voxel-based volumetry (VBV) and related to clinical predictive factors (i.e., age, gender, position, duration of surgery, and tumor size). Results PP with a mean volume of 32 ± 33 ml (range: 0–179.1 ml) was detected in 517/540 (96%) patients. The semi-sitting position was associated with a significantly higher PP volume than the supine position (40.3 ± 33.0 ml [0–179.1] and 0.8 ± 1.4 [0–10.2], p < 0.001). Tension pneumocephalus was observed in only 14/429 (3.3%) of the semi-sitting cases, while no tension pneumocephalus occurred in the supine position. Positive predictors for PP were higher age, male gender, and longer surgery duration, while large (T4) tumor size was established as a negative predictor. Air exchange via a twist-drill was only necessary in 14 cases with an intracranial air volume > 60 ml. Air replacement procedures did not add any complications or prolong the ICU stay. Conclusion Although pneumocephalus is frequently observed following posterior fossa surgery in semi-sitting position, relevant clinical symptoms (i.e., a tension pneumocephalus) occur in only very few cases. These cases are well-treated by an air evacuation procedure. This study indicates that the risk of postoperative pneumocephalus is not a contraindication for semi-sitting positioning.

It is widely accepted that the gut microbiome can affect various aspects of brain function, includ-2 ing anxiety, depression, learning, and memory. However, we know little about how individual microbial species contribute to communication along the gut-brain axis. Vertebrate microbiomes 4 are comprised of hundreds of species, making it difficult to systematically target individual microbes and their interactions. Here, we use Drosophila melanogaster as a simple model organism 6 to tease apart individual and combined effects of gut microbes on cognition. We used an aversive phototactic suppression assay to show that two dominant gut commensals in our lab stock, 8 Lactobacillus and Acetobacter, are necessary and sufficient for normal learning and short-term memory relative to flies with a conventional microbiome. We also demonstrate that microbes 10 did not affect their hosts' ability to detect the aversive learning stimulus (quinine), suggesting that our results were due to decreased cognition and not sensory deficits. We thus establish 12 Drosophila as a model for elucidating mechanisms of gut-brain communication at the level of individual bacterial species. 14 IntroductionWithin the last decade, there has been an explosion of studies showing that gut microbes affect 16 critical organismal functions, particularly communication along the gut-brain axis [1]. Early studies found a link between the gut microbiota and anxiety [2][3][4], depression [5], learning [6], 18 and memory [7] suggesting that gut microbes impact more than just their immediate surroundings. Since then, other studies have found that disrupting the gut microbiota through diet [7], 20 pathogens [8], antibiotics [9, 10], or probiotics [11-14] can all affect learning. Moreover, disease models for inflammatory bowel disease [15, 16], diabetes [17], and schizophrenia [18] have associ-22ated the loss of homeostasis of the gut community (dysbiosis) with learning and memory deficits in experimental animals. These deficits were ameliorated with probiotic treatment, suggesting 24 that symptoms experienced by patients may be treated with probiotics as well.If probiotic therapy is to become an effective treatment for dysbiosis of the microbial commu-26 nity, we need a better understanding of how individual community members influence cognition alone and in combination. We will then be able to target specific microbes or species combina-28 tions to more effectively address underlying issues in brain function. We know that diversity of the gut microbiota plays a role (some beneficial species have been identified), but it is not fully 30 understood how individual members of the microbiota contribute, because significantly variable communities can nonetheless be healthy [19][20][21]. 32 We chose to test learning and memory in Drosophila, because the microbiota in flies is much simpler than in vertebrates [22], allowing us to generate single and combinatorial microbial as-34 sociations that comprise the bulk of the total microbiota. In this way we can begin ...

Object: There is an increasing interest in preoperative diffusion tensor imaging-based fiber tracking (DTI-FT) to preserve function during surgeries in motor eloquent brain regions. However, DTI tractography is challenged by inherent presumptions during particular tracking steps [e.g., deterministic vs. probabilistic DTI, fractional anisotropy (FA) and fiber length (FL) thresholding] and the missing "ground truth" information. In the present study, we intended to establish an objective, neurophysiology-driven approach for parameter selection during DTI-FT of the corticospinal tract integrating both imaging and neurophysiological information. Methods: In ten patients with lesions in eloquent motor areas, preoperative navigated transcranial magnetic stimulation (nTMS) was performed, followed by individual deterministic DTI-FT from a grid of cortical seed points. We investigated over 300 combinations of FA and FL thresholds and applied subsequently a multidimensional mathematical modeling of this empirical data. Optimal DTI parameters were determined by the relationship between DTI-FT (i.e., number of fibers, NoF) and nTMS (i.e., amplitudes of motor-evoked potentials) results. Finally, neurophysiological DTI parameters and the resulting tractography were compared to the current standard approaches of deterministic DTI fiber tracking with a 75% and 50% FA and a FL threshold of 110 mm as well as with intraoperative direct cortical and subcortical stimulation. Results: There was a good goodness-of-fit for the mathematical model (r 2 = 0.68 ± 0 13; range: 0.59-0.97; n = 8) except of two cases. Neurophysiology-driven parameter selection showed a high correlation between DTI-FT and nTMS results (r = 0.73 ± 0.16; range: 0.38-0.93). In comparison to the standard approach, the mathematically calculated thresholds resulted in a higher NoF in 75% of patients. In 50% of patients

The influence of environmental factors on the development of autoimmune disease is being broadly investigated to better understand the multifactorial nature of autoimmune pathogenesis and to identify potential areas of intervention. Areas of particular interest include the influence of lifestyle, nutrition, and vitamin deficiencies on autoimmunity and chronic inflammation. In this review, we discuss how particular lifestyles and dietary patterns may contribute to or modulate autoimmunity. We explored this concept through a spectrum of several autoimmune diseases including Multiple Sclerosis (MS), Systemic Lupus Erythematosus (SLE) and Alopecia Areata (AA) affecting the central nervous system, whole body, and the hair follicles, respectively. A clear commonality between the autoimmune conditions of interest here is low Vitamin D, a well-researched hormone in the context of autoimmunity with pleiotropic immunomodulatory and anti-inflammatory effects. While low levels are often correlated with disease activity and progression in MS and AA, the relationship is less clear in SLE. Despite strong associations with autoimmunity, we lack conclusive evidence which elucidates its role in contributing to pathogenesis or simply as a result of chronic inflammation. In a similar vein, other vitamins impacting the development and course of these diseases are explored in this review, and overall diet and lifestyle. Recent work exploring the effects of dietary interventions on MS showed that a balanced diet was linked to improvement in clinical parameters, comorbid conditions, and overall quality of life for patients. In patients with MS, SLE and AA, certain diets and supplements are linked to lower incidence and improved symptoms. Conversely, obesity during adolescence was linked with higher incidence of MS while in SLE it was associated with organ damage. Autoimmunity is thought to emerge from the complex interplay between environmental factors and genetic background. Although the scope of this review focuses on environmental factors, it is imperative to elaborate the interaction between genetic susceptibility and environment due to the multifactorial origin of these disease. Here, we offer a comprehensive review about the influence of recent environmental and lifestyle factors on these autoimmune diseases and potential translation into therapeutic interventions.