EXPERIMENTAL DIFFUSE AXONAL INJURY

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Because of the importance of traumatic damage to axons and of diffuse axonal injury (DAI) in specific, this project will continue to characterize a unique new model of DAI. The model was recently developed in this Center with only three animal experiments by first producing physical and mathematical models derived from biomechanics principles determined from previous research. DAI is created by applying a non- impact impulsive load to the snout of minipig thereby producing rotational acceleration to the brain. Preliminary studies show that traumatic axonal damage is produced in isolation and that at least some of this damage can be detected non-invasively by magnetic transfer imaging (MTI), a magnetic resonance technique sensitive to white matter changes. In-vivo biochemical changes determined by 31/P or 1/H magnetic resonance spectroscopy (MRS) show marked immediate reduction of intracellular magnesium that was temporary and of n-acetyl-aspartate which was not. These changes were very different if a contusion was superimposed on DAI around which cerebral blood flow (CBF), phosphocreatine (PCr), and the PCr/Pi ratio markedly decreased. We will extend these findings by further characterizing this model with MTI, MRS and CBF studies that have immediate clinical application.