Potential participants include patients between the ages of 18 and 50 years who are admitted to Parkland Memorial Hospital with a diagnosis of severe traumatic brain injury. Blood, urine, and CSF (if patient requires a clinically indicated ventriculostomy) will be collected over the first 5 days post-injury. Clinically-relevant patient progress, clinically required interventions, neuro-imaging results, and demographics will be tracked while the patient is hospitalized, with final neurological outcome measured at 3 months.