Traumatic Brain Injury: What Happens to the Blood-Brain Barrier? Introduction Traumatic brain injury (TBI) is a leading cause of death and disability worldwide for which there is no cure. Many patients who survive TBI may experience permanent cognitive loss, behavioral problems, and emotional disturbances, requiring daily medical or social attention.[1, 2] More than 2% of the U.S. population is believed to be experiencing TBI-associated disabilities that create an annual burden estimated at $60 billion in direct (medical service) and indirect (lost productivity) costs.[3, 4] Traumatic brain injury is complex and consists of mechanical trauma (primary injury) and a subsequent cascade biochemical (secondary injury), and lead to a wide variety of symptoms.[5]The blood-brain barrier (BBB) ​​is a highly specialized endothelial barrier that separates circulating blood components from neurons.[6] The BBB serves as an interface between the vascular system and the brain that limits and regulates the exchange of substances.[7] The blood brain barrier is responsible for maintaining brain homeostasis through regulation of the chemical environment, entry of xenobiotics, and transport of immune cells.[8, 9] The concentration of water, ions, amino acids, hormones, and neurotransmitters in the brain blood undergoes fluctuations. If such fluctuations were allowed to occur in the brain, it would lead to local disruption of signal propagation and uncontrolled neural activity.[8, 10] Disruption of cerebral blood flow would result in neuronal death.[11] Disruption of the blood brain barrier has been frequently documented in patients with traumatic brain injury which can also be used as a biomarker in clinical and drug trials.[12] The blood-brain barrier... at the center of the paper... activates local microglia.[63] Activated microglia can contribute to the opening of the blood brain barrier.[64] Inflammation resulting from breakdown of the blood brain barrier after traumatic brain injury could be vital for the implementation of tissue repair and reorganization or even cell death.[65] Summary The pathological processes that develop following injury brain inevitably lead to neuronal death, which can be immediate or delayed. Blood-brain barrier disruption, resulting in neuronal loss, could also influence long-term traumatic brain injury complications characterized by neuronal death.[66, 67] Blood-brain barrier disruption is the central role of traumatic brain injury in the pathophysiology . Prevention of secondary damage following traumatic brain injury represents an important position in the treatment of traumatic brain injury or blood brain barrier disruption.