A critical need exists for a portable and objective noninvasive tool to evaluate physiological cerebral dysfunction in patients who have sustained concussive head injury (CHI). CHI is known to cause disturbances in brain blood flow as well as neuropsychological (NP) symptoms. Current clinical assessments rely entirely on NP testing, which lack objective diagnostic criteria and do not indicate the presence of actual brain injury. Many patients with normal NP test findings are cleared to resume previous activities, yet are in fact physically impaired and have heightened vulnerability to repeat injury. The proposed sensors and novel algorithms may provide crucially needed tools for initial detection, assessment, monitoring, and rehabilitation of individuals with CHI.
Concussion often causes physical brain injury and dysfunctional control of cerebral blood flow (CBF), which is often undetected by current neuropsychological test methods. Objective measurement of dysfunction is difficult with currently available tools. This problem will be investigated by implementing cerebral oximetry and rheoencephalography (cerebral bioimpedance), together with novel algorithms, to evaluate mechanisms that control CBF. The primary objective of this research is to determine whether these two easily implemented noninvasive devices can be used in combination, without the need for additional sensors, to assess cerebrovascular function, and to explore experimental protocols that could be used in clinical evaluations. Healthy volunteers will be used in the study in order to establish baseline norms and optimize test protocols. The research methods include inhalation of ambient air and a mixture of air and CO2 at predetermined intervals. Sensor responses to the expected vasodilatory response from CO2 inhalation will be analyzed for the effects of CO2 concentration, duration of inhalation, and repeated inhalation challenges (i.e., trending). The results will be used to develop protocols and adjust the sensor parameters for future studies in post-concussive individuals with impaired CBF control.
