The influence of heterogeneous meninges on the brain mechanics under primary blast loading

Gu, Linxia; Chafi, Mehdi Sotudeh; Ganpule, Shailesh; Chandra, Namas

doi:10.1016/j.compositesb.2012.04.014

Cited by 36 publications

(30 citation statements)

References 21 publications

(24 reference statements)

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“…We conducted finite element analysis on a hyperviscoelastic cell model, 34,35 and it showed that a shear pulse of 20 dyn/cm 2 and 10-ms width produced a maximum strain of 16%, followed by an oscillatory decay with relaxation time of *100 ms (Supplementary Materials S2) (see online supplementary material at http://www.liebertpub.com), consistent with our experimental observations.…”

Section: Ca 2 + Response To Repeated Shear Pulsessupporting

confidence: 70%

A Threshold Shear Force for Calcium Influx in an Astrocyte Model of Traumatic Brain Injury

Maneshi

Sachs

Hua

2015

Journal of Neurotrauma

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Traumatic brain injury (TBI) refers to brain damage resulting from external mechanical force, such as a blast or crash. Our current understanding of TBI is derived mainly from in vivo studies that show measurable biological effects on neurons sampled after TBI. Little is known about the early responses of brain cells during stimuli and which features of the stimulus are most critical to cell injury. We generated defined shear stress in a microfluidic chamber using a fast pressure servo and examined the intracellular Ca 2 + levels in cultured adult astrocytes. Shear stress increased intracellular Ca 2 + depending on the magnitude, duration, and rise time of the stimulus. Square pulses with a fast rise time (*2 ms) caused transient increases in intracellular Ca 2 + , but when the rise time was extended to 20 ms, the response was much less. The threshold for a response is a matrix of multiple parameters. Cells can integrate the effect of shear force from repeated challenges: A pulse train of 10 narrow pulses (11.5 dyn/cm 2 and 10 ms wide) resulted in a 4-fold increase in Ca 2 + relative to a single pulse of the same amplitude 100 ms wide. The Ca 2 + increase was eliminated in Ca 2 + -free media, but was observed after depleting the intracellular Ca 2 + stores with thapsigargin suggesting the need for a Ca 2 + influx. The Ca 2 + influx was inhibited by extracellular Gd 3 + , a nonspecific inhibitor of mechanosensitive ion channels, but it was not affected by the more specific inhibitor, GsMTx4. The voltage-gated channel blockers, nifedipine, diltiazem, and verapamil, were also ineffective. The data show that the mechanically induced Ca 2 + influx commonly associated with neuron models for TBI is also present in astrocytes, and there is a viscoelastic/plastic coupling of shear stress to the Ca 2 + influx. The site of Ca 2 + influx has yet to be determined.

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Section: Ca 2 + Response To Repeated Shear Pulsessupporting

confidence: 70%

A Threshold Shear Force for Calcium Influx in an Astrocyte Model of Traumatic Brain Injury

Maneshi

Sachs

Hua

2015

Journal of Neurotrauma

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“…The angular and linear accelerations of the head, peak ICP, maximum shear and tensile stresses and strains, skull flexure, cavitation, and the acoustic impedance mismatch have been mentioned as major factors in evaluating the injury risk and level of bTBI [11,13,20,[30][31][32][33][34][35][36]. Hence, two major tissue parameters, ICP and MSS, that are responsible for the concussive and diffuse injuries, respectively [37], were studied in all blast scenarios.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of brain tissue responses because of the underwash overpressure of helmet and faceshield under blast loading

Sarvghad-Moghaddam

Rezaei

Ziejewski

et al. 2016

Numer Methods Biomed Eng

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Head protective tools such as helmets and faceshields can induce a localized high pressure region on the skull because of the underwash of the blast waves. Whether this underwash overpressure can affect the brain tissue response is still unknown. Accordingly, a computational approach was taken to confirm the incidence of underwash with regards to blast direction, as well as examine the influence of this effect on the mechanical responses of the brain. The variation of intracranial pressure (ICP) as one of the major injury predictors, as well as the maximum shear stress were mainly addressed in this study. Using a nonlinear finite element (FE) approach, generation and interaction of blast waves with the unprotected, helmeted, and fully protected (helmet and faceshield protected) FE head models were modeled using a multi-material arbitrary Lagrangian-Eulerian (ALE) method and a fluid-structure interaction (FSI) coupling algorithm. The underwash incidence overpressure was found to greatly change with the blast direction. Moreover, while underwash induced ICP (U-ICP) did not exceed the peak ICP of the unprotected head, it was comparable and even more than the peak ICP imposed on the protected heads by the primary shockwaves (Coup-ICP). It was concluded that while both helmet and faceshield protected the head against blast waves, the underwash overpressure affected the brain tissue response and altered the dynamic load experienced by the brain as it led to increased ICP levels at the countercoup site, imparted elevated skull flexure, and induced high negative pressure regions. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

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“…In the last decade, over 60% of the soldiers deployed in Iraq and Afghanistan have been diagnosed with symptoms of TBI due to exposure to blasts. Blast-induced TBI has been studied extensively using computational modeling [4][5][6][7][8][9][10][11][12][13][14][15][16] techniques. TBI has also been found to be a critical issue in contact sports where sudden head impacts are very common occurrences [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Biofidelic human brain tissue surrogates

Chanda

Callaway

Clifton

et al. 2016

Mechanics of Advanced Materials and Structures

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Traumatic brain injury (TBI) due to blast exposure or head impacts in accidents or contact sports is one of the most critical and poorly understood areas of research in the 21st century. To date, the unavailability of human brain tissues (grey and white matter especially) due to ethical and biosafety issues has not allowed for much experimental research into the study of the mechanics of brain tissues under impact or dynamic loading. In the current work, for the first time, biofidelic brain tissue surrogates have been developed using a low cost, castable (to any shape or size), two-part silicone-based material system to precisely mimic the nonlinear mechanical properties of both the white and the grey matter. The fabrication methodology involves the iterative mixing of the two parts of silicone at certain mix ratios (by weight) to generate a biomechanical behavior similar to the white and the grey matter tissues, respectively, at two different strain rates (low and high). The nonlinear behavior of these novel brain tissue surrogates have been characterized using five hyperelastic material models. These brain tissue simulant materials would be indispensable not only for the study of TBI, but also to allow doctors to practice brain surgeries (for training purposes) in a clinical setting. Additionally, crucial brain tissue modifications in Alzheimer's disease and dementia can be studied in the future with such accessible biofidelic brain tissue surrogate materials.

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The influence of heterogeneous meninges on the brain mechanics under primary blast loading

Cited by 36 publications

References 21 publications

A Threshold Shear Force for Calcium Influx in an Astrocyte Model of Traumatic Brain Injury

A Threshold Shear Force for Calcium Influx in an Astrocyte Model of Traumatic Brain Injury

Evaluation of brain tissue responses because of the underwash overpressure of helmet and faceshield under blast loading

Biofidelic human brain tissue surrogates

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