Intro to TBI

• Traumatic brain injury is an alteration of brain function caused by an external force.
• Acquired brain injuries can be traumatic or non-traumatic.
• The leading causes of TBI are falls, assaults, and motor vehicle accidents.
• Adults older than 75 are at the highest risk for TBI.
• Hospitalizations and death from TBI is greatest in those older than 65.
• The primary injury occurs immediately after the event. The brain tissue is damaged as a result of the force.
• The secondary injury occurs after the primary injury. Cellular, molecular, and biochemical changes occur in the brain.
• The secondary injury will eventually evolve into hypoxia, edema, and elevated ICP.
• The primary injury is the result of brain tissue coming into contact with an internal or external object or rapid accelerations and decelerations of the brain.
• A coup-contrecoup injury occurs when the brain hits both the front and back of the skull. This commonly occurs with car accidents.
• Blast injuries result in a transient shock wave that causes damage. Typically, the vasculature of the brain is affected.
• The secondary injury is also known as the metabolic cascade. There are changes in the neurochemical and metabolic components of the brain.
• The metabolic cascade results in changes in cerebral blood flow, decreased access to energy stores, and decreased ability to heal.
• The metabolic cascade begins immediately after injury, but changes will continue to occur for weeks after the event.
• Hematoma is brain bleeding that leads to the collection of blood in brian tissues or empty spaces.
• Hematomas are the result of contact injuries.
• Epidural hematoma is blood outside the brain and the dura but under the skull.
• Epidural hematomas will happen very quickly and will result in a large buildup of ICP.
• Subdural hematoma is blood between the brain and the dura.
• Subdural hematomas are slow as a vein is affected. It will take hours for the decline to occur.
• Epidural hematomas affect an artery.
• Hemorrhage occurs when an artery bursts with localized bleeding due to acceleration and deceleration forces.
• Subarachnoid hemorrhage is bleeding within the layers of the dura, specifically under the arachnoid layer.
• Intraventricular hemorrhage is bleeding into the ventricles. This is the most severe and has the worst prognosis.
• Intraventricular hemorrhage will have a large increase of ICP in the entire brain.
• Diffuse axonal injuries occur with shearing type injuries leading to disruption of neurofilaments.
• Diffuse axonal injuries are typically caused by acceleration deceleration injuries.
• The Glasgow coma scale is a clinical scale that measures level of consciousness and helps define/classify the severity of injury.
• The GCS monitors and detects meaningful changes in neurobehavioral function.
• A score of 3 to 8 on the GCS indicates severe TBI.
• A scores of 9 to 12 on the GCS indicates moderate TBI.
• A score of 13 to 15 on the GCS indicates mild TBI.
• Anterograde amnesia is the inability to create new memories.
• Post-traumatic amnesia is the time between the incident and when the patient is able to recall recent events.
• Post-traumatic amnesia is the best indicator of severity after TBI.
• Retrograde amnesia is the inability to remember events prior to the injury.
• Loss of consciousness is a period of partial or total loss of awareness of self and surroundings.
• Post-traumatic amnesia typically lasts 1 day or less for mild TBI.
• Post-traumatic amnesia typically lasts 1 to 7 days for moderate TBI.
• Post-traumatic amnesia typically lasts greater than 7 days for severe TBI.