Animal models have demonstrated altered metabolic profiles of the brain tissue which resolves within hours of initial insult. Other animal models have demonstrated a change in the integrity of the microvascular endothelium after TBI. It can be hypothesized that there are areas of "microcontusion" and pericontusional edema that maybe responsible for alterations in brain chemistry which may ultimately lead to the clinical symptoms associated with mild TBI. Multiple other studies have theorized that the direct and indirect effects of trauma on cerebral vasculature may lead to a vasoconstrictive phenomenon that may be responsible for postconcussive symptoms.