 The goal of this study is to improve our understanding of cortical spreading depolarizations CSDs as a mechanism of secondary injury in severe traumatic brain injury TBI. The primary obstacles to advancing treatment of TBI are its heterogeneity in terms of cause, severity, pathophysiology and the paucity of therapeutic targets. At the current time, there is no intervention to reverse or restore the function of brain tissue damaged or lost during the initial traumatic insult; therefore the therapeutic focus is centered on minimizing secondary insults that result in expansion of the initial brain injury. 