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Computational study of human head response to primary blast waves of five levels from three directions.

Wang C, Pahk JB, Balaban CD, Miller MC, Wood AR, Vipperman JS - PLoS ONE (2014)

Bottom Line: Human exposure to blast waves without any fragment impacts can still result in primary blast-induced traumatic brain injury (bTBI).Simulation results show that the blast wave directly transmits into the head and causes a pressure wave propagating through the brain tissue.Von Mises stress prevails in the cortex with a much higher magnitude than in the internal parenchyma.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.

ABSTRACT
Human exposure to blast waves without any fragment impacts can still result in primary blast-induced traumatic brain injury (bTBI). To investigate the mechanical response of human brain to primary blast waves and to identify the injury mechanisms of bTBI, a three-dimensional finite element head model consisting of the scalp, skull, cerebrospinal fluid, nasal cavity, and brain was developed from the imaging data set of a human female. The finite element head model was partially validated and was subjected to the blast waves of five blast intensities from the anterior, right lateral, and posterior directions at a stand-off distance of one meter from the detonation center. Simulation results show that the blast wave directly transmits into the head and causes a pressure wave propagating through the brain tissue. Intracranial pressure (ICP) is predicted to have the highest magnitude from a posterior blast wave in comparison with a blast wave from any of the other two directions with same blast intensity. The brain model predicts higher positive pressure at the site proximal to blast wave than that at the distal site. The intracranial pressure wave invariably travels into the posterior fossa and vertebral column, causing high pressures in these regions. The severities of cerebral contusions at different cerebral locations are estimated using an ICP based injury criterion. Von Mises stress prevails in the cortex with a much higher magnitude than in the internal parenchyma. According to an axonal injury criterion based on von Mises stress, axonal injury is not predicted to be a cause of primary brain injury from blasts.

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Predicted contusion injury severities at typical cerebral sites with respect to impinging BOPs for the right lateral blast scenario.
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pone-0113264-g008: Predicted contusion injury severities at typical cerebral sites with respect to impinging BOPs for the right lateral blast scenario.

Mentions: Ward et al. [40] proposed an intracranial pressure injury index to evaluate the occurrence and the injury severity of cerebral contusion. According to this intracranial pressure tolerance criterion/index, the peak intracranial pressure of more than 235 kPa would induce serious cerebral contusion, while minor or no brain injury would occur when the intracranial pressure was below 173 kPa.etween 173 kPa and 235 kPa, minor contusion or cortex hemorrhage would occur. Predicted intracranial pressure responses at the proximal side (frontal cortex) for all the blast simulation cases of the anterior exposure, except the 250 g TNT case, are higher than 173 kPa, and the 400 g TNT case has 252 kPa peak pressure which is more than the 235 kPa serious injury threshold. Therefore, people experiencing the anterior blast waves with the impinging BOP at the blast incident side from 321 kPa to 349 kPa would risk suffering a minor contusion or cerebral cortex hemorrhage, while people experiencing the anterior blast wave with the impinging BOP at the blast incident side with more than 379 kPa are expected to have serious cerebral contusion. All cases of right lateral blast exposures have peak positive pressures of more than 235 kPa at the cortex region proximal to the blast (right temporal cortex), indicating that subjects experiencing a lateral blast wave with the impinging BOP of more than 291 kPa at the blast incident side would have serious cerebral contusion. In the posterior scenario, the peak positive pressures at the proximal side (lower brainstem) are all more than 235 kPa. Therefore, subjects experiencing a posterior blast wave with the impinging BOP of more than 291 kPa are predicted to have serious cerebral contusion. The injury severities of the various cerebral locations including the cortex at the SSS, frontal cortex, occipital cortex, temporal cortexes, hypothalamus, and lower brainstem with respect to the five impinging BOPs at the blast incident side for the three exposure orientations are elucidated in Figure 7 (anterior exposure), Figure 8 (right lateral exposure), and Figure 9 (posterior exposure). Since the sharp transition from peak positive pressure to peak negative pressure may cause further damage to brain tissues than the uniform positive pressure or negative pressure, contusion predictions from the highest difference of the peak positive to negative pressure occurring within 1 ms are also made for the same locations by comparing the peak-to-peak pressure with the peak pressure based contusion criterion, and are illustrated in Figure 10 (anterior exposure), Figure 11 (right lateral exposure), and Figure 12 (posterior exposure).


Computational study of human head response to primary blast waves of five levels from three directions.

Wang C, Pahk JB, Balaban CD, Miller MC, Wood AR, Vipperman JS - PLoS ONE (2014)

Predicted contusion injury severities at typical cerebral sites with respect to impinging BOPs for the right lateral blast scenario.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4237386&req=5

pone-0113264-g008: Predicted contusion injury severities at typical cerebral sites with respect to impinging BOPs for the right lateral blast scenario.
Mentions: Ward et al. [40] proposed an intracranial pressure injury index to evaluate the occurrence and the injury severity of cerebral contusion. According to this intracranial pressure tolerance criterion/index, the peak intracranial pressure of more than 235 kPa would induce serious cerebral contusion, while minor or no brain injury would occur when the intracranial pressure was below 173 kPa.etween 173 kPa and 235 kPa, minor contusion or cortex hemorrhage would occur. Predicted intracranial pressure responses at the proximal side (frontal cortex) for all the blast simulation cases of the anterior exposure, except the 250 g TNT case, are higher than 173 kPa, and the 400 g TNT case has 252 kPa peak pressure which is more than the 235 kPa serious injury threshold. Therefore, people experiencing the anterior blast waves with the impinging BOP at the blast incident side from 321 kPa to 349 kPa would risk suffering a minor contusion or cerebral cortex hemorrhage, while people experiencing the anterior blast wave with the impinging BOP at the blast incident side with more than 379 kPa are expected to have serious cerebral contusion. All cases of right lateral blast exposures have peak positive pressures of more than 235 kPa at the cortex region proximal to the blast (right temporal cortex), indicating that subjects experiencing a lateral blast wave with the impinging BOP of more than 291 kPa at the blast incident side would have serious cerebral contusion. In the posterior scenario, the peak positive pressures at the proximal side (lower brainstem) are all more than 235 kPa. Therefore, subjects experiencing a posterior blast wave with the impinging BOP of more than 291 kPa are predicted to have serious cerebral contusion. The injury severities of the various cerebral locations including the cortex at the SSS, frontal cortex, occipital cortex, temporal cortexes, hypothalamus, and lower brainstem with respect to the five impinging BOPs at the blast incident side for the three exposure orientations are elucidated in Figure 7 (anterior exposure), Figure 8 (right lateral exposure), and Figure 9 (posterior exposure). Since the sharp transition from peak positive pressure to peak negative pressure may cause further damage to brain tissues than the uniform positive pressure or negative pressure, contusion predictions from the highest difference of the peak positive to negative pressure occurring within 1 ms are also made for the same locations by comparing the peak-to-peak pressure with the peak pressure based contusion criterion, and are illustrated in Figure 10 (anterior exposure), Figure 11 (right lateral exposure), and Figure 12 (posterior exposure).

Bottom Line: Human exposure to blast waves without any fragment impacts can still result in primary blast-induced traumatic brain injury (bTBI).Simulation results show that the blast wave directly transmits into the head and causes a pressure wave propagating through the brain tissue.Von Mises stress prevails in the cortex with a much higher magnitude than in the internal parenchyma.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.

ABSTRACT
Human exposure to blast waves without any fragment impacts can still result in primary blast-induced traumatic brain injury (bTBI). To investigate the mechanical response of human brain to primary blast waves and to identify the injury mechanisms of bTBI, a three-dimensional finite element head model consisting of the scalp, skull, cerebrospinal fluid, nasal cavity, and brain was developed from the imaging data set of a human female. The finite element head model was partially validated and was subjected to the blast waves of five blast intensities from the anterior, right lateral, and posterior directions at a stand-off distance of one meter from the detonation center. Simulation results show that the blast wave directly transmits into the head and causes a pressure wave propagating through the brain tissue. Intracranial pressure (ICP) is predicted to have the highest magnitude from a posterior blast wave in comparison with a blast wave from any of the other two directions with same blast intensity. The brain model predicts higher positive pressure at the site proximal to blast wave than that at the distal site. The intracranial pressure wave invariably travels into the posterior fossa and vertebral column, causing high pressures in these regions. The severities of cerebral contusions at different cerebral locations are estimated using an ICP based injury criterion. Von Mises stress prevails in the cortex with a much higher magnitude than in the internal parenchyma. According to an axonal injury criterion based on von Mises stress, axonal injury is not predicted to be a cause of primary brain injury from blasts.

Show MeSH
Related in: MedlinePlus