In Silico Investigation of Intracranial Blast Mitigation with Relevance to Military Traumatic Brain Injury

Nyein, Michelle K.; Jason, Amanda M.; Liu, Yu; Pita, Claudio; Joannopoulos, John D.; Moore, David F.; Radovitzky, Raúl

doi:10.21236/ada533075

Cited by 36 publications

(54 citation statements)

References 16 publications

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“…(a) Comparing the time-history for shear strain in the frontal and occipital portions of the brain between models and (b) the distribution of the relative increase in the peak brain strain due to cavitation for the 1000 kPa/4 ms blast condition. the simulation past 2 ms, 30,37,50 only capturing the response of the brain during the incident wave and not the response caused by the coupling between the brain and the deforming skull. If high-rate strain response from skull deformation following blast exposure is the primary mechanism for blast TBI, then it is critical that models are simulated long enough to capture these effects.…”

Section: Brain Response To Blastmentioning

confidence: 99%

“…4 Finite element (FE) modeling is well suited for studying the mechanical response of the head to primary blast loading, and researchers have recently developed FE models to improve our understanding of blast TBI (Table 1). 9,11,30,32,37,40,50 However, current FE models for brain injury are exploratory until a robust set of validation data is available.…”

Section: Introductionmentioning

confidence: 99%

“…Typical IED exposures resulting in blast injury were reported to be from detonations of 105-and 155-mm artillery rounds (equivalent to 2.4 and 7.3 kg TNT, respectively) at a standoff distances between 5 and 10 m. 33 The Conventional Weapons Effects Program (CONWEP) 20 can calculate the blast exposures produced from these charges, and indicate that the real-world blast threat ranges from 50 to 1000 kPa peak overpressure and 2-6 ms in duration. Many FE models simulate exposures based on small charge sizes (<1 kg TNT) at a very close standoff (<1 m), 9,30,37 which may reproduce realistic peak overpressure but very low positive-phase duration or impulse. 20 Additionally, models that do simulate realworld blast events only consider a single blast condition, 32,50 making it difficult to assess the biomechanics that may cause injury from blast impact.…”

Section: Introductionmentioning

confidence: 99%

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Development of a Finite Element Model for Blast Brain Injury and the Effects of CSF Cavitation

et al. 2012

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Blast-related traumatic brain injury is the most prevalent injury for combat personnel seen in the current conflicts in Iraq and Afghanistan, yet as a research community,we still do not fully understand the detailed etiology and pathology of this injury. Finite element (FE) modeling is well suited for studying the mechanical response of the head and brain to blast loading. This paper details the development of a FE head and brain model for blast simulation by examining both the dilatational and deviatoric response of the brain as potential injury mechanisms. The levels of blast exposure simulated ranged from 50 to 1000 kPa peak incident overpressure and 1–8 ms in positive-phase duration, and were comparable to real-world blast events. The frontal portion of the brain had the highest pressures corresponding to the location of initial impact, and peak pressure attenuated by 40–60% as the wave propagated from the frontal to the occipital lobe. Predicted brain pressures were primarily dependent on the peak overpressure of the impinging blast wave, and the highest predicted brain pressures were 30%less than the reflected pressure at the surface of blast impact. Predicted shear strain was highest at the interface between the brain and the CSF. Strain magnitude was largely dependent on the impulse of the blast, and primarily caused by the radial coupling between the brain and deforming skull.The largest predicted strains were generally less than 10%,and occurred after the shock wave passed through the head.For blasts with high impulses, CSF cavitation had a large role in increasing strain levels in the cerebral cortex and periventricular tissues by decoupling the brain from the skull. Relating the results of this study with recent experimental blast testing suggest that a rate-dependent strain-based tissue injury mechanism is the source primary blast TBI.

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Section: Brain Response To Blastmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Development of a Finite Element Model for Blast Brain Injury and the Effects of CSF Cavitation

et al. 2012

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“…Collapse of cavitation bubbles and elastic rebound of the skull resulted in significant pressure spikes in CSF fluid regions. Other computational studies of blast propagation through the head and surrounding CSF spaces predict regions of negative pressure in contrecoup regions which also suggest cavitation may occur during blasts [13,14,19,20,25]. Tissue studies using ultrasound shock waves also support cavitation induced damage, e.g., hemorrhage and cellular membrane poration due to lithotripsy [26,27], though these studies occur at a different frequency range than blasts.…”

Section: Introductionmentioning

confidence: 98%

“…While limitations of current imaging techniques make in vivo cavitation measurements challenging, previous studies suggest that extensive cavitation caused by explosive blast might occur in the CSF surrounding human brain [19,20]. For example, negative pressures have been reported in CSF following exposure to blast waves generated by shock tubes in cadaver and animal models [21].…”

Section: Introductionmentioning

confidence: 99%

Localized Tissue Surrogate Deformation due to Controlled Single Bubble Cavitation

et al. 2015

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Cavitation-induced shock wave, as might occur in the head during exposure to blast waves, was investigated as a possible damage mechanism for soft brain tissues. A novel experimental technique was developed to visualize and control single bubble cavitation and its collapse, and the influence of this process on a nearby tissue surrogate was investigated. The experiment utilized a Hopkinson pressure bar system which transmits a simulated blast pressure wave (with over-pressure and under-pressure components) to a fluid-filled test chamber implanted with a seed gas bubble. Growth and collapse of this bubble was recorded during passage of the blast wave with a high speed camera. To investigate the potential for cavitation damage to a tissue surrogate, local changes in strain were measured in hydrogel slices placed in various configurations next to the bubble. The strain measurements were made using digital image correlation (DIC) technique by monitoring the motion of material points on the tissue surrogate. In one configuration, bubble contact dynamics resulted in compression contact (>60 μs) followed by inertially-driven tension (>140 μs). In another configuration, the influence of local shock waves emanating from collapsed bubbles was captured. Large compressive strains (0.25 to 0.5) that were highly localized (0.18 mm 2 ) were measured over a short time period (<24 μs) after bubble collapse. High bubble collapse pressures 29 to 125 times that of peak blast overpressure are predicted to be the source of these large strains. Consistent with theoretical predictions, these cavitation-based strains are far larger than the strains imposed by passage of the simulated blast wave alone. Finally, the value of this experimental platform to investigate the single bubble cavitation-induced damage in a biological tissue is illustrated with an example test on rat brain slices.

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Impact of complex blast waves on the human head: a computational study

Tan

Chew

Tse

et al. 2014

Numer Methods Biomed Eng

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Head injuries due to complex blasts are not well examined because of limited published articles on the subject. Previous studies have analyzed head injuries due to impact from a single planar blast wave. Complex or concomitant blasts refer to impacts usually caused by more than a single blast source, whereby the blast waves may impact the head simultaneously or consecutively, depending on the locations and distances of the blast sources from the subject, their blast intensities, the sequence of detonations, as well as the effect of blast wave reflections from rigid walls. It is expected that such scenarios will result in more serious head injuries as compared to impact from a single blast wave due to the larger effective duration of the blast. In this paper, the utilization of a head-helmet model for blast impact analyses in Abaqus(TM) (Dassault Systemes, Singapore) is demonstrated. The model is validated against studies published in the literature. Results show that the skull is capable of transmitting the blast impact to cause high intracranial pressures (ICPs). In addition, the pressure wave from a frontal blast may enter through the sides of the helmet and wrap around the head to result in a second impact at the rear. This study recommended better protection at the sides and rear of the helmet through the use of foam pads so as to reduce wave entry into the helmet. The consecutive frontal blasts scenario resulted in higher ICPs compared with impact from a single frontal blast. This implied that blast impingement from an immediate subsequent pressure wave would increase severity of brain injury. For the unhelmeted head case, a peak ICP of 330 kPa is registered at the parietal lobe which exceeds the 235 kPa threshold for serious head injuries. The concurrent front and side blasts scenario yielded lower ICPs and skull stresses than the consecutive frontal blasts case. It is also revealed that the additional side blast would only significantly affect ICPs at the temporal and parietal lobes when compared with results from the single frontal blast case. By analyzing the pressure wave flow surrounding the head and correlating them with the consequential evolution of ICP and skull stress, the paper provides insights into the interaction mechanics between the concomitant blast waves and the biological head model.

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In Silico Investigation of Intracranial Blast Mitigation with Relevance to Military Traumatic Brain Injury

Cited by 36 publications

References 16 publications

Development of a Finite Element Model for Blast Brain Injury and the Effects of CSF Cavitation

Development of a Finite Element Model for Blast Brain Injury and the Effects of CSF Cavitation

Localized Tissue Surrogate Deformation due to Controlled Single Bubble Cavitation

Impact of complex blast waves on the human head: a computational study

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