Platelet Bioenergetics in TBI

Eligibility Details: Inclusion Criteria: - Patients must have moderate to severe traumatic brain injury (Glasgow Coma Scale (GCS) 3-13) to be enrolled in the TBI or TBI with trauma groups. - Patients enrolled in the TBI with polytrauma group must also exhibit polytrauma including concomitant traumatic brain injury, major trauma to the chest, abdomen, pelvis or extremities. - Patients must be greater than or equal to 18 years of age and must be less than or equal to 50 years of age. - Patients must be able to cooperate for a detailed neurologic exam. - Patients must be consented and undergo first blood sampling within the first 12 hours (+/- 2 hours) after their traumatic brain injury to be enrolled in the TBI or TBI with trauma groups. - Patients must be expected to survive to discharge, as assessed by their admitting neurosurgery team Exclusion Criteria: - For the control group only, patients who have experienced a TBI in the last 6 months. - Diagnosis of platelet diseases or disorders, such as thrombocytopenia, thrombocytosis, or Von Willebrand disease. - Platelet transfusion within the last six months. - Comorbid regimen of Metformin within the last 6 months.