December 13, 2019
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Traumatic brain injury (TBI) represents a significant global public health problem facing the United States and other countries around the world. In the United States, estimates of the frequency of TBI range between 2.5 and 4 million cases per year, depending on the study and methods used to define and include cases. Age-specific rates show a bimodal distribution, with highest risk in younger individuals and older adults. The most common mechanism of injury in the young is motor vehicle accidents and is more common in men, while in older adults falls are the major cause of injury and are more likely to occur in women.
TBI imposes substantial demands on health care systems. Worldwide, at least 10 million TBIs are serious enough to result in death or hospitalization; even many mild TBI patients are still experiencing symptoms 12 months following their injury. In the United States, the estimated annual cost is >$76 billion. Due to advances in medical care and other factors, more people are surviving traumatic brain injury than ever before. Brain injury accounts for more lost productivity at work among Americans than any other form of injury. An estimated 5.3 million Americans are living with significant disabilities resulting from TBI that complicate their return to a full and productive life. Increased media attention to military and sports-related TBI has highlighted the growing concern that injuries that were previously dismissed can have life-long consequences for some individuals.
Head injuries are so common that almost all physicians will be called upon to provide some aspect of immediate care or to see patients who are suffering from various sequelae. Patients initially need education regarding the natural history of TBI along with treatment of acute symptoms such as headache. Follow-up of TBI patients is important to make sure that the sequelae that some patients experience—such as postconcussive disorder (PCD), depression, or sleep disorders—can be identified and treated by a coordinated multidisciplinary team.
DEFINITION AND CLASSIFICATION
TBI is commonly defined as an alteration in brain function, or other evidence of brain pathology, caused by an external force, and characterized by the following: (1) any period of loss or decreased level of consciousness (LOC), (2) any loss of memory for events immediately before (retrograde) or after (posttraumatic) the injury, (3) any neurological deficits, and/or (4) any alteration in mental state at the time of injury.
Evidence of TBI can include visual, neuroradiologic, or laboratory confirmation of damage to the brain, but TBI is more often diagnosed on the basis of acute clinical criteria. In addition to standard computed tomography (CT) imaging, modern structural magnetic resonance imaging (MRI), and functional imaging (resting state functional MRI) techniques show increasing sensitivity, and it is likely that sensitive blood-based biomarkers will be developed in the near future.