Design and Analysis of Blast Induced Traumatic Brain Injury Mechanism Using a Surrogate Headform PDF Download

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

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Author: Soroush Assari
Publisher:
ISBN:
Category :
Languages : en
Pages : 91

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The focus of this dissertation was the biomechanics of blast-induced traumatic brain injury (bTBI). This study had three specific aims. One of the specific aims was to investigate the thoracic mechanism of bTBI by characterizing the cerebral blood pressure change during local blast exposure to head or chest in a rat model. This model utilized a shock tube to simulate the blast wave. The results showed that there is a blood pressure rise with high amplitude and short duration during both Head-Only and Chest-Only exposure conditions. It was shown that cerebral blood pressure rise was significantly higher in Chest-Only exposure, and resulted in astrocyte reactivation, and infiltration of blood-borne macrophages into the brain. It was concluded that due to chest exposure to a blast wave, high amplitude pressure waves that transfer from thoracic large vessels to cerebrovasculature can lead to blood-brain barrier disruption or perivascular injury and consequently trigger secondary neuronal damage. The second and third aims were related to the viscoelasticity and heterogeneity of brain tissue respectively for blast rate loading conditions. For the second specific aim, a novel test method was developed to apply shear deformation to samples of brain tissue with strain rates in the range of 300 to 1000 s-1. The results of shear tests on cylindrical samples of bovine brain showed that the instantaneous shear modulus (about 6 kPa) increased about 3 times compared to the values reported in the literature. For the third specific aim, local viscoelastic behavior of rat brain was characterized using a micro-indentation setup with the spatial resolution of 350 mm. The results of micro-indentation tests showed that the heterogeneity of brain tissue was more pronounced in long-term shear moduli. Moreover, the inner anatomical regions were generally more compliant than the outer regions and the gray matter generally exhibited a stiffer response than the white matter. The results of this study can enhance the prediction of brain injury in finite element models of TBI in general and models of bTBI in particular. These results contribute to development of more biofidelic models that can determine the extent and severity of injury in blast loadings. Such predictions are essential for designing better injury mitigation devices for soldiers and also for improving neurosurgical procedures among other applications.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 19

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Traumatic brain injury [TBI] has become a signature injury of current military conflicts, with debilitating, costly, and long-lasting effects. Although mechanisms by which head impacts cause TBI have been well-researched, the mechanisms by which blasts cause TBI are not understood. From numerical hydrodynamic simulations, we have discovered that non-lethal blasts can induce sufficient skull flexure to generate potentially damaging loads in the brain, even without a head impact. The possibility that this mechanism may contribute to TBI has implications for injury diagnosis and armor design.

Author: Firas H. Kobeissy
Publisher: CRC Press
ISBN: 1466565993
Category : Medical
Languages : en
Pages : 718

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With the contribution from more than one hundred CNS neurotrauma experts, this book provides a comprehensive and up-to-date account on the latest developments in the area of neurotrauma including biomarker studies, experimental models, diagnostic methods, and neurotherapeutic intervention strategies in brain injury research. It discusses neurotrauma mechanisms, biomarker discovery, and neurocognitive and neurobehavioral deficits. Also included are medical interventions and recent neurotherapeutics used in the area of brain injury that have been translated to the area of rehabilitation research. In addition, a section is devoted to models of milder CNS injury, including sports injuries.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 10

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This study was designed to investigate the contributions of direct impact of blast on the skull in two different orientations: face-on and side-on orientation. To assess a loading force on a target with different impact areas two piezoelectric (PCB) sensors were placed inside a shock tube in parallel and perpendicular orientations to the blast wave. Results show that the face-on pressure is much higher than the static, side-on pressure. In addition, the integral area under the pressure wave increases with the target size as a consequence of pressure wave reflection with increasing target. Rats were placed in a blast tube and exposed to 30-40 kPa blast overpressures in two different orientations: (1) with the head facing the blast wave, and (2) with one side of the body exposed to the blast. Pressure waves inside the rat brain and lateral cerebral ventricle was measured simultaneously with Samba pressure microsensors and compared with the outside pressure waves. Pressure wave characteristics such as rise time, duration, and amplitude were found to differ with respect to the orientation to the blast. Characterization of the shock wave after blast produced in the shock tube was achieved by installing two piezoelectric sensors inside the shock tube. The basic characteristics of the blast wave measured by fiber optic pressure sensors was similar to the piezoelectric sensors. This justifies the use of microfiber sensors for animal experiments. Shock wave after blast was detected simultaneously in two locations of the rat brain, and in two different orientations to the blast wave. The results show some differences that could be very important for understanding the mechanisms of pressure wave propagation and penetration into the brain and the mechanisms of brain blast injury.

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

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

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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: Shailesh Govind Ganpule
Publisher:
ISBN: 9781303028649
Category : Blast effect
Languages : en
Pages : 288

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In the second part of this dissertation, the response of post-mortem human specimen (PMHS) heads is studied. Three PMHS heads are subjected to primary blast of varying peak incident intensities or overpressures (70 kPa, 140 kPa and 200 kPa). When the incident blast intensity is increased, there is a statistically significant increase in the peak intracranial pressure (ICP) and total impulse (p

Author: Molly M. Simmons
Publisher:
ISBN: 9781977402929
Category : Business & Economics
Languages : en
Pages : 0

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There is increasing concern over the common, repetitive forms of blast to which military members are exposed during service, and how those exposures could affect the central nervous system. The authors of this report review the relevant literature.

Author: Terri L. Tanielian
Publisher: Rand Corporation
ISBN: 0833044540
Category : Business & Economics
Languages : en
Pages : 499

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Since October 2001, approximately 1.64 million U.S. troops have been deployed for Operations Enduring Freedom and Iraqi Freedom (OEF/OIF) in Afghanistan and Iraq. Early evidence suggests that the psychological toll of these deployments -- many involving prolonged exposure to combat-related stress over multiple rotations -- may be disproportionately high compared with the physical injuries of combat. In the face of mounting public concern over post-deployment health care issues confronting OEF/OIF veterans, several task forces, independent review groups, and a Presidential Commission have been convened to examine the care of the war wounded and make recommendations. Concerns have been most recently centered on two combat-related injuries in particular: post-traumatic stress disorder and traumatic brain injury. With the increasing incidence of suicide and suicide attempts among returning veterans, concern about depression is also on the rise. The study discussed in this monograph focuses on post-traumatic stress disorder, major depression, and traumatic brain injury, not only because of current high-level policy interest but also because, unlike the physical wounds of war, these conditions are often invisible to the eye, remaining invisible to other servicemembers, family members, and society in general. All three conditions affect mood, thoughts, and behavior; yet these wounds often go unrecognized and unacknowledged. The effect of traumatic brain injury is still poorly understood, leaving a large gap in knowledge related to how extensive the problem is or how to address it. RAND conducted a comprehensive study of the post-deployment health-related needs associated with these three conditions among OEF/OIF veterans, the health care system in place to meet those needs, gaps in the care system, and the costs associated with these conditions and with providing quality health care to all those in need. This monograph presents the results of our study, which should be of interest to mental health treatment providers; health policymakers, particularly those charged with caring for our nation's veterans; and U.S. service men and women, their families, and the concerned public. All the research products from this study are available at http://veterans.rand.org. Data collection for this study began in April 2007and concluded in January 2008. Specific activities included a critical reviewof the extant literature on the prevalence of post-traumatic stress disorder, major depression, and traumatic brain injury and their short- and long-term consequences; a population-based survey of service members and veterans who served in Afghanistan or Iraq to assess health status and symptoms, as well asutilization of and barriers to care; a review of existing programs to treat service members and veterans with the three conditions; focus groups withmilitary service members and their spouses; and the development of a microsimulation model to forecast the economic costs of these conditions overtime. Among our recommendations is that effective treatments documented in the scientific literature -- evidence-based care -- are available for PTSD and major depression. Delivery of such care to all veterans with PTSD or majordepression would pay for itself within two years, or even save money, by improving productivity and reducing medical and mortality costs. Such care may also be a cost-effective way to retain a ready and healthy military force for the future. However, to ensure that this care is delivered requires system-level changes across the Department of Defense, the Department of Veterans Affairs, and the U.S. health care system.