The Systemic Nature of Severe Traumatic Brain Injury

Inclusion Criteria: * All patients must be between the ages of 18 to 65 at time of enrollment * Study group cohort will consist of at least 20 patients admitted with severe TBI, defined as a GSC less than or equal to 8 with evidence of intracranial pathology on imaging. * Trauma control cohort will include at least 10 patients matched on demographics and injury patterns without traumatic brain injury. * Healthy control cohort will be comprised of 10 patients without acute traumatic injury or illness, matched to the sTBI patients based on demographics and medical comorbidities. Exclusion Criteria: * Pregnant Patients * Prisoners * Patients less than 18 years of age or greater than 65 years of age * Patients with a penetrating brain injury mechanism, known neurodegenerative or psychiatric disorders, prior known traumatic brain injury, intracranial neoplasm, patients receiving massing transfusion or blood products prior to arrival, terminal illness or not expected to survive, confirmed or suspected brain death, known autoimmune or immunological condition, receiving immunosuppressant or immunomodulatory therapies, having a cardiac event leading to the injury, or for whom consent is unable to be obtained.