scholarly journals Computational Modeling and Simulation of Stenosis of Aqueduct of Sylvius Due to Brain Tumor

2021 ◽  
Author(s):  
Uzair Ul Haq ◽  
Ali Ahmed ◽  
Zartasha Mustansar ◽  
Arslan Shaukat ◽  
Sasa Cukovic ◽  
...  
Keyword(s):  
Brain Tumor ◽  
Significant Contribution ◽  
Numerical Models ◽  
Third Ventricle ◽  
Cerebral Aqueduct ◽  
Ventricular Wall ◽  
Pressure Gradients ◽  
Simulation Studies ◽  
Computational Modeling And Simulation ◽  
Challenging Situation

Abstract Background: Stenosis of cerebral aqueduct (CA) is featured in many studies related to elevated intracranial cerebral pressures (ICP). It also presents a challenging situation to clinicians. Compressive forces play a lead role in pathological situations like tumor presence and hence can cause obstruction to the flow of cerebrospinal fluid (CSF). Due to this barrier, excessive retention of CSF in ventricles can occur. This in turn could contribute to increased pressure gradients inside the cranium. In literature, most of the numerical models are restricted to modeling the CSF flow by considering ventricle walls as rigid material unlike its behavior a deformable character. This paper, therefore, addresses the same from a holistic perspective by taking into consideration the dynamics of the flexible character of the ventricular wall. This adds to the novelty of this work by reconstructing an anatomically realistic ventricular wall behavior. To do this, the authors aim to develop a computational model of stenosis of CA due to brain tumor by invoking a fluid-structure interaction (FSI) method. The proposed 3D FSI model is simulated under two cases. First, simulation of pre-stenosis case with no interaction of tumor forces and secondly, a stenosis condition together-with dynamic interaction of tumor forces. Results: Comparing the forces with and without tumor reveals a marked obstruction of CSF outflow post third ventricle and the cerebral aqueduct. Not only this but a drastic rise of CSF velocity from 21.2 mm/s in pre-stenosis case to 54.1 mm/s stenosis case is also observed along with a net deformation increase of 0.144 mm on walls of ventricle. Conclusions: This is a significant contribution to brain simulation studies for pressure calculations, wherein the presence of tumors is a major concern.

Neuroendoscopic Aspiration of Blood Clots in the Cerebral Aqueduct and Third Ventricle During Posterior Fossa Surgery in the Prone Position

2018 ◽  
Vol 17 (2) ◽  
pp. 143-148 ◽  
Author(s):  
Alberto Feletti ◽  
Riccardo Stanzani ◽  
Matteo Alicandri-Ciufelli ◽  
Giuliano Giliberto ◽  
Matteo Martinoni ◽  
...  
Keyword(s):  
Prone Position ◽  
Posterior Fossa ◽  
Fourth Ventricle ◽  
Blood Clot ◽  
Third Ventricle ◽  
Cerebral Aqueduct ◽  
Posterior Fossa Surgery ◽  
The Third ◽  
Blood Clots ◽  
Surgical Field

AbstractBACKGROUNDDuring surgery in the posterior fossa in the prone position, blood can sometimes fill the surgical field, due both to the less efficient venous drainage compared to the sitting position and the horizontally positioned surgical field itself. In some cases, blood clots can wedge into the cerebral aqueduct and the third ventricle, and potentially cause acute hydrocephalus during the postoperative course.OBJECTIVETo illustrate a technique that can be used in these cases: the use of a flexible scope introduced through the opened roof of the fourth ventricle with a freehand technique allows the navigation of the fourth ventricle, the cerebral aqueduct, and the third ventricle in order to explore the cerebrospinal fluid pathways and eventually aspirate blood clots and surgical debris.METHODSWe report on one patient affected by an ependymoma of the fourth ventricle, for whom we used a flexible neuroendoscope to explore and clear blood clots from the cerebral aqueduct and the third ventricle after the resection of the tumor in the prone position. Blood is aspirated with a syringe using the working channel of the scope as a sucker.RESULTSA large blood clot that was lying on the roof of the third ventricle was aspirated, setting the ventricle completely free. Other clots were aspirated from the right foramen of Monro and from the optic recess.CONCLUSIONWe describe this novel technique, which represents a safe and efficient way to clear the surgical field at the end of posterior fossa surgery in the prone position. The unusual endoscopic visual perspective and instrument maneuvers are easily handled with proper neuroendoscopic training.

scholarly journals REFLECTIONS FROM COASTAL STRUCTURES

1988 ◽  
Vol 1 (21) ◽  
pp. 58 ◽  
Author(s):  
N.W.H. Allsop ◽  
S.S.L. Hettiarachchi
Keyword(s):  
Wave Motion ◽  
Significant Contribution ◽  
Numerical Models ◽  
Coastal Structures ◽  
Wave Reflections ◽  
Reflected Waves ◽  
Sea Bed ◽  
Wide Range ◽  
Alternative Structure ◽  
General Reduction

Wave reflections at and within a coastal harbour may make a significant contribution to wave disturbance in the harbour. Reflected waves may lead to danger to vessels navigating close to structures, and may reduce the availability of berths within the harbour. Wave reflections may also increase local scour or general reduction in sea bed levels. In the design of breakwaters, sea walls, and coastal revetments, it is therefore important to estimate and compare the reflection performance of alternative structure types. In the use of numerical models of wave motion within harbours, it is essential to define realistically the reflection properties of each boundary. This paper presents results from a study of the reflection performance of a wide range of structures used in coastal and harbour engineering.

scholarly journals Cilia-driven flows in the brain third ventricle

2019 ◽  
Vol 375 (1792) ◽  
pp. 20190154 ◽  
Author(s):  
Gregor Eichele ◽  
Eberhard Bodenschatz ◽  
Zuzana Ditte ◽  
Ann-Kathrin Günther ◽  
Shoba Kapoor ◽  
...  
Keyword(s):  
Third Ventricle ◽  
Biochemical Properties ◽  
Brain Parenchyma ◽  
Ventricular Wall ◽  
Brain Ventricles ◽  
Cellular Targets ◽  
Signalling Molecules ◽  
The Third ◽  
Directional Transport ◽  
The Brain

The brain ventricles are interconnected, elaborate cavities that traverse the brain. They are filled with cerebrospinal fluid (CSF) that is, to a large part, produced by the choroid plexus, a secretory epithelium that reaches into the ventricles. CSF is rich in cytokines, growth factors and extracellular vesicles that glide along the walls of ventricles, powered by bundles of motile cilia that coat the ventricular wall. We review the cellular and biochemical properties of the ventral part of the third ventricle that is surrounded by the hypothalamus. In particular, we consider the recently discovered intricate network of cilia-driven flows that characterize this ventricle and discuss the potential physiological significance of this flow for the directional transport of CSF signals to cellular targets located either within the third ventricle or in the adjacent hypothalamic brain parenchyma. Cilia-driven streams of signalling molecules offer an exciting perspective on how fluid-borne signals are dynamically transmitted in the brain. This article is part of the Theo Murphy meeting issue ‘Unity and diversity of cilia in locomotion and transport’.

THREE-DIMENSIONAL ASPECTS OF RE-ENTRY IN EXPERIMENTAL AND NUMERICAL MODELS OF VENTRICULAR FIBRILLATION

1999 ◽  
Vol 09 (04) ◽  
pp. 695-704 ◽  
Author(s):  
V. N. BIKTASHEV ◽  
A. V. HOLDEN ◽  
S. F. MIRONOV ◽  
A. M. PERTSOV ◽  
A. V. ZAITSEV
Keyword(s):  
Ventricular Fibrillation ◽  
Numerical Simulations ◽  
Numerical Models ◽  
Three Dimensional ◽  
Spiral Waves ◽  
Excitable Media ◽  
Ventricular Wall ◽  
Two Dimensional ◽  
Key Features ◽  
Scroll Waves

Ventricular fibrillation is believed to be produced by the breakdown of re-entrant propagation waves of excitation into multiple re-entrant sources. These re-entrant waves may be idealized as spiral waves in two-dimensional, and scroll waves in three-dimensional excitable media. Optically monitored, simultaneously recorded endocardial and epicardial patterns of activation on the ventricular wall do not always show spiral waves. We show that numerical simulations, even with a simple homogeneous excitable medium, can reproduce the key features of the simultaneous endo- and epicardial visualizations of propagating activity, and so these recordings may be interpreted in terms of scroll waves within the ventricular wall.

Rarefaction and Compressibility Effects in Gas Microflows

1996 ◽  
Vol 118 (3) ◽  
pp. 448-456 ◽  
Author(s):  
Ali Beskok ◽  
George Em Karniadakis ◽  
William Trimmer
Keyword(s):  
Incompressible Flows ◽  
Numerical Models ◽  
Slip Flow ◽  
Slip Boundary Condition ◽  
Partial Slip ◽  
Micro Electro Mechanical Systems ◽  
Slip Boundary ◽  
Gas Microflows ◽  
Computational Modeling And Simulation ◽  
Compressibility Effects

Gas microflows are encountered in many applications of Micro-Electro-Mechanical Systems (MEMS). Computational modeling and simulation can provide an effective predictive capability for heat and momentum transfer in microscales as well as means of evaluating the performance of a new microdevice before hardware fabrication. In this article, we present models and a computational methodology for simulating gas microflows in the slip-flow regime for which the Knudsen number is less than 0.3. The formulation is based on the classical Maxwell/Smoluchowski boundary conditions that allow partial slip at the wall. We first modify a high-order slip boundary condition we developed in previous work so that it can be easily implemented to provide enhanced numerical stability. We also extend a previous formulation for incompressible flows to include compressibility effects which are primarily responsible for the nonlinear pressure distribution in micro-channel flows. The focus of the paper is on the competing effects of compressibility and rarefaction in internal flows in long channels. Several simulation results are presented and comparisons are provided with available experimental data. A specific set of benchmark experiments is proposed to systematically study compressibility, rarefaction and viscous heating in microscales in order to provide validation to the numerical models and the slip-flow theory in general as well as to establish absolute standards in this relatively young field of fluid mechanics.

scholarly journals Attenuation of lipopolysaccharide anorexia by antagonism of caudal brain stem but not forebrain GLP-1-R

2004 ◽  
Vol 287 (5) ◽  
pp. R1190-R1193 ◽  
Author(s):  
Harvey J. Grill ◽  
Jill S. Carmody ◽  
L. Amanda Sadacca ◽  
Diana L. Williams ◽  
Joel M. Kaplan
Keyword(s):  
Food Intake ◽  
Brain Stem ◽  
Third Ventricle ◽  
Cerebral Aqueduct ◽  
Relative Importance ◽  
The Third ◽  
Native Peptide ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Rule Out

The central glucagon-like peptide-1 (GLP-1) system has been implicated in the control of feeding behavior. Here we explore GLP-1 mediation of the anorexic response to administration of systemic LPS and address the relative importance of caudal brain stem and forebrain GLP-1 receptor (GLP-1-R) for the mediation of the response. Fourth-intracerebroventricular delivery of the GLP-1-R antagonist exendin-(9–39) (10 μg) did not itself affect food intake in the 24 h after injection but significantly attenuated the otherwise robust (∼60%) reduction in food intake obtained after LPS (100 μg/kg) treatment. This result highlights a role for caudal brain stem GLP-1-R in the mediation of LPS anorexia but does not rule out the possibility that forebrain receptors also contribute to the response. Forebrain contribution was addressed by delivery of the GLP-1-R antagonist to the third ventricle with the caudal flow of cerebrospinal fluid blocked by occlusion of the cerebral aqueduct. Exendin-(9–39) delivery thus limited to forebrain did not attenuate the anorexic response to LPS. These data suggest that LPS anorexia is mediated, in part, by release of the native peptide acting on GLP-1-R within the caudal brain stem.

scholarly journals Comparative anatomical analysis of the transcallosal-transchoroidal and transcallosal-transforniceal-transchoroidal approaches to the third ventricle

2017 ◽  
Vol 127 (1) ◽  
pp. 209-218 ◽  
Author(s):  
João Luiz Vitorino Araujo ◽  
José C. E. Veiga ◽  
Hung Tzu Wen ◽  
Almir F. de Andrade ◽  
Manoel J. Teixeira ◽  
...  
Keyword(s):  
Corpus Callosum ◽  
Third Ventricle ◽  
Anterior Region ◽  
Cerebral Aqueduct ◽  
Tuber Cinereum ◽  
The Third ◽  
Longitudinal Plane ◽  
The Mean ◽  
The Right ◽  
Longitudinal Diameter

OBJECTIVEAccess to the third ventricle is a veritable challenge to neurosurgeons. In this context, anatomical and morphometric studies are useful for establishing the limitations and advantages of a particular surgical approach. The transchoroidal approach is versatile and provides adequate exposure of the middle and posterior regions of the third ventricle. However, the fornix column limits the exposure of the anterior region of the third ventricle. There is evidence that the unilateral section of the fornix column has little effect on cognitive function. This study compared the anatomical exposure afforded by the transforniceal-transchoroidal approach with that of the transchoroidal approach. In addition, a morphometric evaluation of structures that are relevant to and common in the 2 approaches was performed.METHODSThe anatomical exposure provided by the transcallosal-transchoroidal and transcallosal-transforniceal-transchoroidal approaches was compared in 8 fresh cadavers, using a neuronavigation system. The working area, microsurgical exposure area, and angular exposure on the longitudinal and transversal planes of 2 anatomical targets (tuber cinereum and cerebral aqueduct) were compared. Additionally, the thickness of the right frontal lobe parenchyma, thickness of the corpus callosum trunk, and longitudinal diameter of the interventricular foramen were measured. The values obtained were submitted to statistical analysis using the Wilcoxon test.RESULTSIn the quantitative evaluation, compared with the transchoroidal approach, the transforniceal-transchoroidal approach provided a greater mean working area (transforniceal-transchoroidal 150 ± 11 mm2; transchoroidal 121 ± 8 mm2; p < 0.05), larger mean microsurgical exposure area (transforniceal-transchoroidal 101 ± 9 mm2; transchoroidal 80 ± 5 mm2; p < 0.05), larger mean angular exposure area on the longitudinal plane for the tuber cinereum (transforniceal-transchoroidal 71° ± 7°; transchoroidal 64° ± 6°; p < 0.05), and larger mean angular exposure area on the longitudinal plane for the cerebral aqueduct (transforniceal-transchoroidal 62° ± 6°; transchoroidal 55° ± 5°; p < 0.05). No differences were observed in angular exposure along the transverse axis for either anatomical target (tuber cinereum and cerebral aqueduct; p > 0.05). The mean thickness of the right frontal lobe parenchyma was 35 ± 3 mm, the mean thickness of the corpus callosum trunk was 10 ± 1 mm, and the mean longitudinal diameter of the interventricular foramen was 4.6 ± 0.4 mm. In the qualitative assessment, it was noted that the transforniceal-transchoroidal approach led to greater exposure of the third ventricle anterior region structures. There was no difference between approaches in the exposure of the structures of the middle and posterior region.CONCLUSIONSThe transforniceal-transchoroidal approach provides greater surgical exposure of the third ventricle anterior region than that offered by the transchoroidal approach. In the population studied, morphometric analysis established mean values for anatomical structures common to both approaches.

scholarly journals Framework for comprehensive enhancement of brain tumor images with single-window operation

2020 ◽  
Vol 10 (1) ◽  
pp. 801
Author(s):  
Deepthi Murthy T. S. ◽  
Sadashivappa G.
Keyword(s):  
Brain Tumor ◽  
Image Enhancement ◽  
Medical Image ◽  
Significant Contribution ◽  
Linear Filter ◽  
Radiological Images ◽  
Multi Level ◽  
Image Enhancing ◽  
Non Linear Filter

Usage of grayscale format of radiological images is proportionately more as compared to that of colored one. This format of medical image suffers from all the possibility of improper clinical inference which will lead to error-prone analysis in further usage of such images in disease detection or classification. Therefore, we present a framework that offers single-window operation with a set of image enhancing algorithm meant for further optimizing the visuality of medical images. The framework performs preliminary pre-processing operation followed by implication of linear and non-linear filter and multi-level image enhancement processes. The significant contribution of this study is that it offers a comprehensive mechanism to implement the various enhancement schemes in highly discrete way that offers potential flexibility to physical in order to draw clinical conclusion about the disease being monitored. The proposed system takes the case study of brain tumor to implement to testify the framework.

scholarly journals Retractorless interforniceal approach for microsurgical resection of a papillary tumor of the pineal region: operative video and technical nuances

2021 ◽  
Vol 5 (1) ◽  
pp. V12
Author(s):  
James K. Liu ◽  
Neil Majmundar
Keyword(s):  
Obstructive Hydrocephalus ◽  
Third Ventricle ◽  
Lateral Position ◽  
Pineal Region ◽  
Gross Total Resection ◽  
Cerebral Aqueduct ◽  
Papillary Tumor ◽  
Total Resection ◽  
Microsurgical Resection ◽  
Neurologically Intact

In this illustrative video, the authors demonstrate microsurgical resection of a papillary tumor of the pineal region using a retractorless interforniceal approach via the anterior interhemispheric transcallosal route. The tumor presented to the posterior third ventricle occluding the cerebral aqueduct, resulting in obstructive hydrocephalus. The retractorless interforniceal approach is performed in the lateral position with BICOL collagen spacers to keep the corridor open. Gross-total resection was achieved, and the patient was neurologically intact without needing a permanent shunt. The operative nuances and pearls of technique for safe microdissection and gentle handling of the retractorless interforniceal approach are demonstrated. The video can be found here: https://stream.cadmore.media/r10.3171/2021.4.FOCVID2139.

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