Significant Head Accelerations Can Influence Immediate Neurological Impairments in a Murine Model of Blast Induced Traumatic Brain Injury

Abstract

Although blastinduced traumatic brain injury (bTBI) is well recognized for its significance in the military population, the unique mechanisms of primary bTBI remain undefined. Animate models of primary bTBI are critical for determining these potentially unique mechanisms, but the biomechanical characteristics of many bTBI models are poorly understood. In this study, we examine some common shock tube configurations used to study blastinduced brain injury in the laboratory and define the optimal configuration to minimize the effect of torso overpressure and blastinduced head accelerations. Pressure transducers indicated that a customized animal holder successfully reduced peak torso overpressures to safe levels across all tested configurations. However, high speed video imaging acquired during the blast showed significant head accelerations occurred when animals were oriented perpendicular to the shock tube axis. These findings of complex head motions during blast are similar to previous reports [Goldstein et al., 2012, “Chronic Traumatic Encephalopathy in BlastExposed Military Veterans and a Blast Neurotrauma Mouse Model,â€‌ Sci. Transl. Med., 4(134), 134ra160; Sundaramurthy et al., 2012, “BlastInduced Biomechanical Loading of the Rat: An Experimental and Anatomically Accurate Computational Blast Injury Model,â€‌ J. Neurotrauma, 29(13), pp. 2352–2364; Svetlov et al., 2010, “Morphologic and Biochemical Characterization of Brain Injury in a Model of Controlled Blast Overpressure Exposure,â€‌ J. Trauma, 69(4), pp. 795–804]. Under the same blast input conditions, minimizing head acceleration led to a corresponding elimination of righting time deficits. However, we could still achieve righting time deficits under minimal acceleration conditions by significantly increasing the peak blast overpressure. Together, these data show the importance of characterizing the effect of blast overpressure on head kinematics, with the goal of producing models focused on understanding the effects of blast overpressure on the brain without the complicating factor of superimposed head accelerations.