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Frontal and temporal lobe contusions that were caused by a single sagittal plane angular acceleration impulse were analyzed. At neuropathological exam the depth, extent, and location of contusions were mapped and described according to a classification previously developed for human use. Of 30 rhesus monkeys subjected to a single angular acceleration impulse, 13 had no frontal or temporal contusion (Group 1), 8 had only frontal contusion (Group 2) and 9 had temporal contusions (Group 3). Correlation with angular acceleration, tangential acceleration and tangential force showed that the three groups were statistically different. The mean peak positive tangential force for Groups 1-3 was 541, 659 and 766 newtons respectively (p<0.10). This suggested that as mechanical imput increased, frontal contusions occur before temporal contusions and that the threshold for frontal contusion is less than that for temporal contusion.

A series of forty experiments has been performed on Rhesus monkeys in which the heads were subjected to a controlled single approximately sinusoidal pulse of angular acceleration about a fixed axis perpendicular to the sagittal plane. The head was constrained to undergo planar motion with a total angular displacement of 60 degrees in each case. Angular acceleration values ranged up to 1.2 x 105 rad/sec2, and peak values of tangential acceleration at the center of the mass of the brain reached 1300 g's. Physiological and neurological data including EKG, EEG, systemic arterial pressure, intracranial pressure, respiration, corneal reflex, were recorded. The post insult state was evaluated for each subject in accordance with a scale of Experimental Trauma Severity (ETS) based on the observed changes in the physiological and neurological variables. The ETS scale ranges from 0 (absence of any changes) to 6 (instantaneous death with gross brain fragmentation).

Physical models of the skull-brain system have been subjected to controlled inertial loading experiments in which the deformation response of the surrogate brain was measured. The propose of this report is to present the results of these studies. Two types of models are examined herein; an idealized right circular cylinderical geometry and a baboon skull, sectioned in a midcoronal plane. The surrogate brain, consisting of an optically transparent silicone-gel, contains a painted grid of orthogonal lines with approximately 5mm spacing. The experimental data are presented in the form of nodal displacements and associated strains with one millisecond temporal resolution. The loading conditions are described by the rigid body accelerations of the skull or cylinder models. In each case the motion of the model is a noncentroidal rotation. The experimental results permit one to investigate the relations between the deformation and the acceleration magnitude and temporal characteristics.

DIFFUSE AXONAL INJURY (DAI) is a brain injury characterized by prolonged traumatic coma not due to mass lesions that has dysfunction or structural damage to brain axons. DAI can be produced by inertial loading of the head in a centroidal or non-centroidal manner. This paper compares the effect of varying the direction of head movement on the severity of DAI. Three groups of 13 monkeys are presented, each subjected to a single non-impact distributed inertial acceleration pulse with head motion constrained to a single plane. In groups 1 and 3, non-centroidal acceleration was produced in the sagittal (rotation about the y axis) and coronal (about the x axis) planes respectively, with the center of rotation in the lower cervical spine. Group 2 was subjected to centroidal acceleration in the horizontal plane (z axis). Deceleration pulse duration (6-8 msec), peak angular deceleration (1-2 × 105 rad/sec2) and angular velocity (475-510 rad/sec) were comparable in each group.

This report discusses the development of brain injury tolerance criteria based on the study of three model systems: the primate, inanimate physical surrogates, and isolated tissue elements. Although we are equally concerned with the neural and neurovascular tissue components of the brain, the report will focus on the former and, in particular, the axonal elements. Under conditions of distributed, impulsive, angularacceleration loading, the primate model exhibits a pathophysiological response ranging from mild cerebral concussion to massive, diffuse white matter damage with prolonged coma. When physical models are subjected to identical loading conditions it becomes possible to map the displacements and calculate the associated strains and stresses within the field simulating the brain. Correlating these experimental models leads to predictive levels of tissue element deformation that may be considered as a threshold for specific mechanisms of injury.

This study was conducted to collect data and gain insights relative to the mechanisms and factors involved in hip injuries during frontal crashes and to study the tolerance of hip injuries from this type of loading. Unembalmed human cadavers were seated on a standard automotive seat (reinforced) and subjected to knee impact test to each lower extremity. Varying combinations of flexion and adduction/abduction were used for initial alignment conditions and pre-positioning. Accelerometers were fixed to the iliac wings and twelfth thoracic vertebral spinous process. A 23.4-kg padded pendulum impacted the knee at velocities ranging from 4.3 to 7.6 m/s. The impacting direction was along the anteroposterior axis, i.e., the global X-axis, in the body-fixed coordinate system. A load cell on the front of the pendulum recorded the impact force. Peak impact forces ranged from 2,450 to 10,950 N. The rate of loading ranged from 123 to 7,664 N/msec. The impulse values ranged from 12.4 to 31.9 Nsec.

This study was conducted to quantify intracranial biomechanical responses and external blast overpressures using physical head model to understand the biomechanics of blast traumatic brain injury and to provide experimental data for computer simulation of blast-induced brain trauma. Ellipsoidal-shaped physical head models, made from 3-mm polycarbonate shell filled with Sylgard 527 silicon gel, were used. Six blast tests were conducted in frontal, side, and 45° oblique orientations. External blast overpressures and internal pressures were quantified with ballistic pressure sensors. Blast overpressures, ranging from 129.5 kPa to 769.3 kPa, were generated using a rigid cannon and 1.3 to 3.0 grams of pentaerythritol tetranitrate (PETN) plastic sheet explosive (explosive yield of 13.24 kJ and TNT equivalent mass of 2.87 grams for 3 grams of material).