The Role of Morphology and Residual Stress on Blast-induced Traumatic Brain Injury PDF Download

Author: Atacan Yucesoy
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 0

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Blast-induced traumatic brain injury (bTBI) is a widespread pathology and one of the leading causes of mortality and morbidity among military personnel. Exploring the mechanics of brain tissue is critical to predicting intracranial brain deformation and injuries resulting from severe blast loading. The research reported in this dissertation is aimed at investigating three aspects of bTBI research: (1) to build a numerical method with the ability to capture the complex deformation induced by blast loading of the human brain, and (2) to investigate the effects of morphological and volumetric differences on human brain dynamics under blast loading, and (3) to determine residual stresses resulting from cortical folding during brain growth via simulations of volumetric tissue expansion.Although shear stress, cavitation, and severe pressure gradients are suspected to induce brain injury, the details of the ensuing neuropathological consequences are largely unknown. Recent advances in computational tools allow exploring neuropathological damages occurring in human brain tissue resulting from exogenous mechanical forces that are present during bTBI. In this computational study, the numerical model is developed by using explicit nonlinear dynamic code LS-Dyna using Multi-Material Arbitrary Lagrange Eulerian formulation.In addition, this report includes a finite element analysis implemented with ABAQUS to predict the emerging morphological patterns and residual stresses of a developing brain as a result of cortical folding. One aim of the systematic approach presented in this research is to develop computational procedures that can assist in obtaining a prognosis and choosing adequate neurosurgical procedures before a physical intervention is needed.

Author: Alisa D. Gean
Publisher: Lippincott Williams & Wilkins
ISBN: 146988352X
Category : Medical
Languages : en
Pages : 356

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Book Description
Brain Injury: Applications from War and Terrorism is a single-authored book written by a world-class neuroradiologist with extensive experience in traumatic brain injury (TBI). It features six graphic-intense chapters depicting and expounding upon the complexity of TBI. Culled from nearly three decades of studying civilian TBI and five years of intensive study of TBI sustained from combat, terrorism, and natural disasters, this work is an exhaustive and innovative authority on the current approaches and applications of civilian and combat TBI. The text is sectored into six chapters based on pathophysiology, each augmented with numerous images and illustrations. The book gives special attention to neuroimaging, but is reinforced with relevant clinical correlation. This monograph is unique because it is first in class as an omnibus for the radiologist, neurologist, neurosurgeon, maxillofacial surgeon, emergency physician, pediatrician, ophthalmologist, and the rehabilitation team. Accompanied by detailed high resolution illustrations with meticulous annotation, Brain Injury: Applications from War and Terrorism contains over 500 curated radiological and clinical images that enhance the concepts detailed in each chapter. Complete with up-to-date references, it is a state of the art resource guide for any member of the team of professionals caring for those who have sustained a traumatic brain injury In the foreword, Bob Woodruff writes - “After the September 11 attacks, [Dr. Gean] realized the significant void in our understanding of brain Injury caused by war and terrorism (and) she was motivated to devote the last four years of her academic pursuits to understanding the similarities and differences between civilian TBI and TBI suffered in war, terrorism, and natural disasters... This extraordinary, magnificently illustrated and unique single-authored textbook, Brain Injury: Applications from War and Terrorism,is the culmination of Dr. Gean’s dedication and experience. It’s really not just a book – it is a telegraphed documentary of a lifelong conviction to recognizing and responding to TBI by an acknowledged global expert.”

Author: Eyitejumade A. Sogbesan
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Mahdi Sotudeh Chafi
Publisher:
ISBN:
Category : Brain
Languages : en
Pages : 408

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Author: U. S. Military
Publisher:
ISBN: 9781702765015
Category :
Languages : en
Pages : 74

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Book Description
Traumatic Brain Injury (TBI) has become a major health concern in the U.S. Army. Since October 2001, over 2.6 million service members have deployed in support of combat operations, where TBI, primarily caused by blast, has been underreported and underdiagnosed. The Department of Defense (DoD) reports that nearly 384,000 service members serving in the Global War on Terror have suffered a TBI, classifying eighty two percent as mild TBI (mTBI). Labeled an "invisible wound," mTBI has proven difficult to both prevent and diagnose. In addition, blast injuries further complicate mTBI diagnosis, adding to the problem's complexity. In this light, protecting soldiers from blast-induced TBI (bTBI) has attracted attention from the public, senior DoD officials, and the government. The DoD has funded studies to help medical professionals diagnose bTBI and help identify its associated effects in order to treat those injured and return them to service. As the Army races to test and field new equipment to better protect soldiers, diagnosing mTBI, especially those induced by blast, remains a problem for health professionals and the Army at large. Thus, further research is needed that will spark new strategies to help alleviate blast-induced brain injuries and their ramifications in soldier's lives.This compilation also includes a reproduction of the 2019 Worldwide Threat Assessment of the U.S. Intelligence Community.1. Introduction * Background: TBI Defined * Background: History of TBI * Literature Review * Methodology * 2. Department of Defense (DoD) Milestones * Incremental improvements since 2005 * TBI screening * Blast Physics * Neurological Impairments * Mechanism for Blast Transport * Three possible pathways to the brain * Theories of how blast-induced brain damage occurs * Causes include the recoilless rifle * 3. Distinctive bTBI Characteristics * bTBI and Disease Risk * bTBI injuries correlate with incidents of PTSD * Combat MOSs show disproportional rates of mTBI * Blood test helps identify TBI * Prognosis and Recovery * 4. Treatment for TBI * TBI and Long-Term Health or Disability Outcomes * Challenges and Issues * Soldier Protection from Blast * Combat helmet improvements * Development of robotic teammates * 5. Analysis and Recommendations * Analysis * RecommendationsFor hundreds of thousands of soldiers who have served in the U.S. Army since the beginning of the Global War on Terror (GWOT), the likelihood of suffering a Traumatic Brain Injury (TBI) during active duty has changed from a statistical possibility to a personal, often life-changing reality. Since October 2001, over two million service members have deployed in support of combat operations in Iraq, Afghanistan, and Syria; of those, studies show that up to twenty-three percent - or more than 380,000 - have suffered a TBI of some degree or category. As mounting health issues have accompanied service members returning home, concern from soldier's loved ones, the medical community, and U.S. governmental agencies has risen as well. In response, independent study groups, task forces, and a Presidential Commission in 2012 were formed to study the effects of TBI and make recommendations.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 25

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The objective of this modeling and simulation study was to establish the role of stress wave interactions in the genesis of traumatic brain injury (TBI) from exposure to explosive blast. A high resolution (1 mm3 voxels), 5 material model of the human head was created by segmentation of color cryosections from the Visible Human Female dataset. Tissue material properties were assigned from literature values. The model was inserted into the shock physics wave code, CTH, and subjected to a simulated blast wave of 1.3 MPa (13 bars) peak pressure from anterior, posterior and lateral directions. Three dimensional plots of maximum pressure, volumetric tension, and deviatoric (shear) stress demonstrated significant differences related to the incident blast geometry. In particular, the calculations revealed focal brain regions of elevated pressure and deviatoric (shear) stress within the first 2 milliseconds of blast exposure. Calculated maximum levels of 15 KPa deviatoric, 3.3 MPa pressure, and 0.8 MPa volumetric tension were observed before the onset of significant head accelerations. Over a 2 msec time course, the head model moved only 1 mm in response to the blast loading. Doubling the blast strength changed the resulting intracranial stress magnitudes but not their distribution. We conclude that stress localization, due to early time wave interactions, may contribute to the development of multifocal axonal injury underlying TBI. We propose that a contribution to traumatic brain injury from blast exposure, and most likely blunt impact, can occur on a time scale shorter than previous model predictions and before the onset of linear or rotational accelerations traditionally associated with the development of TBI.

Author: Michelle Kyaw Nyein
Publisher:
ISBN:
Category :
Languages : en
Pages : 113

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Book Description
Blast-induced TBI has gained prominence in recent years due to the conflicts in Iraq and Afghanistan, yet little is known about the mechanical effects of blasts on the human head; no injury thresholds have been established for blast effects on the head, and even direct transmission of the shock wave to the intracranial cavity is disputed. Still less is known about how personal protective equipment such as the Advanced Combat Helmet (ACH) affect the brain's response to blasts. The goal of this thesis is to investigate the mechanical response of the human brain to blasts and to study the effect of the ACH on the blast response of the head. To that end, a biofidelic computational model of the human head consisting of 11 distinct structures was developed from high-resolution medical imaging data. The model, known as the DVBIC/MIT Full Head Model (FHM), was subjected to blasts with incident overpressures of 6 atm and 30 atm and to a 5 m/s lateral impact. Results from the simulations demonstrate that blasts can penetrate the intracranial cavity and generate intracranial pressures that exceed the pressures produced during impact; the results suggest that blasts can plausibly directly cause traumatic brain injury. Subsequent investigation of the effect of the ACH on the blast response of the head found that the ACH provided minimal mitigation of blast effects. Results from the simulations conducted with the FHM extended to include the ACH suggest that the ACH can slightly reduce peak pressure magnitudes and delay peak pressure arrival times, but the benefits are minimal because the ACH does not protect the main pathways of load transmission from the blast to brain tissue. A more effective blast mitigation strategy might involve altering the helmet design to more completely surround the head in order to protect it from direct exposure to blast waves.

Author: Sowmya N. Sundaresh
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Together, this illustrated the ability of these two enzymes to regulate the response to exposure of bTBI-induced pathogenic forms of tau. This study indicates the potential of targeting PP2A activity as a viable strategy for therapeutic intervention. In conclusion, this research expands our understanding of the complexity of brain tissue injury mechanics to inform computational models of TBI, illustrates the deleterious effect of pathogenic forms of tau induced by blast injury on cognitive function, and presents a potential target mechanism for the investigation of therapeutic strategies.

Author: Nicholas Stephen Race
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: Frank David Corwin
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Blast wave induced traumatic brain injury (bTBI) is a modality of injury that has come into prominence at the current time due to the large number of military and civilian personnel who have experienced the localized shock wave produced by explosive devices. The shock wave will travel concentrically outward from the explosive center, being absorbed and transmitted thru soft objects, such as tissue, and reflecting off stationary obstructions. Transmission and absorption in tissues can result in a number of physiological measureable injuries, the most common of which being what is frequently called "blast lung". Blast lung involves the spalling effect at air-tissue interfaces. Another documented effect involves the asynchronous motion of tissue, particularly in the cranium, as the shock wave passes by. This predominately manifests itself in what is believed to be diffuse axonal injury and initiation of secondary injury mechanism. This study is designed to explore the relationship between shock waves and bTBI. A blast device was constructed for generating a free field shock wave through the high pressure rupture of a polycarbonate membrane. Air pressure in a small chamber is increased to a value several orders of magnitude greater than ambient air pressure and is held in place with the polycarbonate member. At the rupture of this membrane a shock wave is created. Measurements of this blast event, carried out with a piezoelectric pressure transducer, have shown that this shock wave is reproducible for the different membrane materials tested and is symmetrical with respect to the central axis of the high pressure chamber and exit nozzle. Having characterized the shock wave properties in the blast field, a location was chosen at which maximum shock wave pressure could be applied to the cranium for inducing bTBI. Experiments involving blast wave exposure were performed on two separate groups of animals in an attempt at establishing injury. One group was placed at a fixed distance directly below the blast nozzle, thereby experiencing both the shock wave and the associated air blast from the residual air in the chamber, and one placed at a defined distance off-axis to avoid the air blast, yet receiving two sequential blast exposures. All animal studies were approved by the VCU Institutional Animal Care and Use Committee. The degree of injury was then assessed with the use of magnetic resonance imaging (MRI) and spectroscopy (MRS). Image Data was acquired on a 2.4 Tesla magnet for assessing changes in either the total percent water concentration or the apparent diffusion coefficients (ADC) of selected regions of interest in the brain of rats. Localized proton spectroscopic data was acquired from a voxel placed centrally in the brain. The baseline values of these parameters were established before the induction of bTBI. After the blast exposure, the animals were followed up with MRI and MRS at defined intervals over a period of one week. The first group of animals received blast exposure directly underneath the blast device nozzle and the MR data does suggest changes in some of the measureable parameters from baseline following blast exposure. This blast wave data though is confounded with additional and undesirable characteristics of the blast wave. The second group of animals that received a pure shock wave blast exposure revealed no remarkable changes in the MR data pre- to post- blast exposure. The percent water concentration, ADC and spectroscopic parameters were for statistical purposes identical before and after the blast. The resolution of this negative result will require reconsideration of the free field blast exposure concept.