Blast injury

Mild traumatic brain injury from primary blast vs. blunt forces: Post-concussion consequences and functional neuroimaging

Authors: Mendez MF, Owens EM, Reza Berenji G, Peppers DC, Liang LJ, Licht EA.

INTRODUCTION: Primary blast forces may cause dysfunction from mild traumatic brain injury (mTBI).
OBJECTIVE: To investigate the effects of primary blast forces, independent of associated blunt trauma and post-traumatic stress disorder, on sensitive post-concussive measures.
METHODS: This study investigated post-concussive symptoms, functional health and well-being, cognition, and positron emission tomography (PET) neuroimaging among 12 Iraq or Afghanistan war veterans who sustained pure blast-force mTBI, compared to 12 who sustained pure blunt-force mTBI.
RESULTS: Both groups had significantly lower scores than published norms on the Rivermead Post-Concussion Questionnaire (RPQ) and the SF36-V Health Survey. Compared to the Blunt Group, the Blast Group had poorer scores on the Paced Auditory Serial Addition Test (PASAT) and greater PET hypometabolism in the right superior parietal region. Only the Blast Group had significant correlations of their RPQ, SF36-V Mental Composite Score, and PASAT scores with specific regional metabolic changes.
CONCLUSION: This pilot study suggests that pure blast force mTBI may have greater post-concussive sequelae including deficits in attentional control and regional brain metabolism, compared to blunt mTBI. A disturbance of a right parietal-frontal attentional network is one potential explanation for these findings.

Understanding and treating blast traumatic brain injury in the combat theater

Authors: Wang EW, Huang JH.

OBJECTIVES: Blast injury is a frequent cause of traumatic brain injury (TBI) in the modern combat theater. We sought to explain the research and treatment associated with this injury.
METHODS: We reviewed literature on the prevalence of blast TBI (bTBI), blast injury mechanisms, research, and perspectives on the neurosurgical experience treating bTBI.
RESULTS: A majority of combat-related casualties in recent wars are due to blast. A majority of survivors of blast injuries are diagnosed with TBI. Blast injury may induce changes in the brain not seen with non-blastrelated mechanisms. However, long-term symptoms are not significantly different from non-blast mechanisms. Aggressive decompressive craniectomies are commonly performed in the combat theater.
DISCUSSION: Due to the prevalence and debilitating nature of bTBI, understanding injury mechanisms is crucial in treating the injury before symptoms become permanent. Treatment is currently limited to decompressive craniectomies, which are the most effective treatment for a relatively young and fit military population.

Blast traumatic brain injury in the rat using a blast overpressure model

Authors: Yarnell AM, Shaughness MC, Barry ES, Ahlers ST, McCarron RM, Grunberg NE.

Traumatic brain injury (TBI) is a serious health concern for civilians and military populations, and blast-induced TBI (bTBI) has become an increasing problem for military personnel over the past 10 years. To understand the biological and psychological effects of blast-induced injuries and to examine potential interventions that may help to prevent, attenuate, and treat effects of bTBI, it is valuable to conduct controlled animal experiments. This unit discusses available paradigms to model traumatic brain injury in animals, with an emphasis on the relevance of these various models to study blast-induced traumatic brain injury (bTBI). This paper describes the detailed methods of a blast overpressure (BOP) paradigm that has been used to conduct experiments with rats to model blast exposure. This particular paradigm models the pressure wave created by explosions, including improvised explosive devices (IEDs). Curr. Protoc. Neurosci. 62:9.41.1-9.41.14. © 2013 by John Wiley & Sons, Inc.

Neuropathology of Explosive Blast Traumatic Brain Injury

Authors: Magnuson J, Leonessa F, Ling GS.

During the conflicts of the Global War on Terror, which are Operation Enduring Freedom (OEF) in Afghanistan and Operation Iraqi Freedom (OIF), there have been over a quarter of a million diagnosed cases of traumatic brain injury (TBI). The vast majority are due to explosive blast. Although explosive blast TBI (bTBI) shares many clinical features with closed head TBI (cTBI) and penetrating TBI (pTBI), it has unique features, such as early cerebral edema and prolonged cerebral vasospasm. Evolving work suggests that diffuse axonal injury (DAI) seen following explosive blast exposure is different than DAI from focal impact injury. These unique features support the notion that bTBI is a separate and distinct form of TBI. This review summarizes the current state of knowledge pertaining to bTBI. Areas of discussion are: the physics of explosive blast generation, blast wave interaction with the bony calvarium and brain tissue, gross tissue pathophysiology, regional brain injury, and cellular and molecular mechanisms of explosive blast neurotrauma.

A Multiscale Approach to Blast Neurotrauma Modeling: Part I - Development of Novel Test Devices for in vivo and in vitro Blast Injury Models

Authors: Panzer MB, Matthews KA, Yu AW, Morrison B 3rd, Meaney DF, Bass CR.

The loading conditions used in some current in vivo and in vitro blast-induced neurotrauma models may not be representative of real-world blast conditions. To address these limitations, we developed a compressed-gas driven shock tube with different driven lengths that can generate Friedlander-type blasts. The shock tube can generate overpressures up to 650 kPa with durations between 0.3 and 1.1 ms using compressed helium driver gas, and peak overpressures up to 450 kPa with durations between 0.6 and 3 ms using compressed nitrogen. This device is used for short-duration blast overpressure loading for small animal in vivo injury models, and contrasts the more frequently used long duration/high impulse blast overpressures in the literature. We also developed a new apparatus that is used with the shock tube to recreate the in vivo intracranial overpressure response for loading in vitro culture preparations. The receiver device surrounds the culture with materials of similar impedance to facilitate the propagation of a single overpressure pulse through the tissue. This method prevents pressure waves reflecting off the tissue that can cause unrealistic deformation and injury. The receiver performance was characterized using the longest helium-driven shock tube, and produced in-fluid overpressures up to 1500 kPa at the location where a culture would be placed. This response was well correlated with the overpressure conditions from the shock tube (R(2) = 0.97). Finite element models of the shock tube and receiver were developed and validated to better elucidate the mechanics of this methodology. A demonstration exposing a culture to the loading conditions created by this system suggest tissue strains less than 5% for all pressure levels simulated, which was well below functional deficit thresholds for strain rates less than 50 s(-1). This novel system is not limited to a specific type of culture model and can be modified to reproduce more complex pressure pulses.

Primary Blast Injuries-An Updated Concise Review

Authors: Yeh DD, Schecter WP.

Blast injuries have been increasing in the civilian setting and clinicians need to understand the spectrum of injury and management strategies. Multisystem trauma associated with combined blunt and penetrating injuries is the rule. Explosions in closed spaces increase the likelihood of primary blast injury. Rupture of tympanic membranes is an inaccurate marker for severe primary blast injury. Blast lung injury manifests early and should be managed with lung-protective ventilation. Blast brain injury is more common than previously appreciated.


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