Changes in cerebral vascular reactivity following mild repetitive head injury in awake rats: modeling the human experience

The changes in brain function in response to mild head injury are usually subtle and go undetected. Physiological biomarkers would aid in the early diagnosis of mild head injury. In this study we used hypercapnia to follow changes in cerebral vascular reactivity after repetitive mild head injury. We hypothesized head injury would reduce vascular reactivity. Rats were maintained on a reverse light-dark cycle and head impacted daily at 24 h intervals over three days. All head impacts were delivered while rats were fully awake under red light illumination. There was no neuroradiological evidence of brain damage. After the 3rd impact rats were exposed to 5% CO