Traumatic brain injury, or TBI, is caused by a blow, bump or jolt to the head or a penetrating head injury that leads to disruption in the normal function of the brain. The top three causes of TBI are: car accident, firearms and falls. Firearm injuries are often fatal: 9 out of 10 people die from their injuries. Young adults and the elderly are the age groups at highest risk for TBI. Prevention of brain injury is the best approach since there is no cure.
Brain injury happens through the following mechanisms: open head injury, closed head injury, deceleration injuries, chemical/toxic, hypoxia, tumors, infections and stroke. The different injuries of TBI include closed head injury (there is no penetration of the skull); open head injury (penetration of the skull with direct injury to the head); diffuse axonal injury (diffuse cellular injury to the brain from rapid rotational movement, usually seen in motor vehicle accidents or shaking injuries); contusion (a bruise to a part of the brain); penetrating trauma (any object that enters the brain); and secondary injury (swelling and release of chemicals that promote inflammation and cell injury or death).
There are a two main systems which medical practitioners use to diagnose the symptoms of TBI. These include:
- The Glasgow Coma Scale, which is based on a 15-point scale which estimates and categorizes the effects of brain injury on the basis of overall social capability or dependence on others. The test measures the eye opening response, verbal response and motor response.
- The Ranchos Los Amigos Scale, which measures the levels of awareness, behavior, cognition and interaction with the environment.
Brain injuries can range in scope from mild to severe. Traumatic brain injuries result in permanent neurobiological damage that can produce lifelong deficits to varying degrees. A traumatic brain injury can be classified as mild if loss of consciousness and/or disorientation and confusion lasts less than 30 minutes. While computerized magnetic resonance imaging (MRI) and axial tomography (CAT) scan results are often normal, the individual experiences problems such as headache, memory problems, difficulty thinking, attention deficits, frustration and mood swings. These symptoms are often subtle. They may not be present or may not be noticed by the injured person, family or doctors at the time of injury. They could even appear days or weeks later. Other names for mild TBI include concussion, minor head trauma, minor TBI, minor brain injury, minor head injury.
Moderate brain injury is defined as a brain injury resulting in a loss of consciousness from 20 minutes to 6 hours and a Glasgow Coma Scale of 9 to 12. In contrast, severe brain injury is defined as a brain injury resulting in a loss of consciousness of greater than 6 hours and a Glasgow Coma Scale of 3 to 8. With moderate or severe traumatic brain injury, the diagnosis is often self evident. Mild traumatic brain injury may not be diagnosed until the individual begins to have problems in what were once easy tasks or social situations. A detailed neurological examination is important and will show evidence of any damage to the brain.
Brain imaging with MRI and CAT scans, single-photon emission computed tomography (SPECT), positron emission tomography (PET) scan, and electroencephalography (EEG) may be used in this field of medicine. Cognitive evaluations by a neuropsychologist with formal neuropsychological testing and evaluations by physical, occupational and speech therapists can help to clarify the specific condition of an individual.
There are various types of treatments available for patients of traumatic brain injury. Initial treatment stabilizes the patient immediately following an injury. Acute treatment of traumatic brain injury is aimed at avoiding and minimizing secondary injury and life support. Doctors may resort to surgical treatment to avoid secondary injury by helping maintain blood and oxygen flow to the brain and minimize swelling and pressure. Rehabilitative treatment helps restore the patient to daily life.
Recovery from a traumatic brain injury varies based on the individual and the degree of brain injury. Returning to daily life can take months, and even years, after the initial injury. The degree of TBI recovery remains hard to forecast. Indicators used for prognosis include duration of coma, post-traumatic amnesia and age. Some common theories regarding the mechanisms of recovery of brain function suggest that depressed areas of the brain that are not injured but linked to injured areas start functioning again, while the affected function is taken over by a part of the brain that does not usually perform that task.