Traumatic brain injury (TBI) is a disruption or alteration of brain function due to external forces. The disruption of function may be transient or long lasting and may vary in severity. The external forces creating the injury may be the result of a variety of insults including acceleration or deceleration, direct compression, penetrating objects, combined effects, and complex mechanisms such as in blast. It may produce subtle effects not discernible on radiological imaging, focal injuries such as fractures, contusion, subarachnoid hemorrhage (SAH), subdural hemorrhage (SDH), epidural hemorrhage (EDH), or intraparenchymal hemorrhage (IPH), or more widespread damage such as diffuse axonal injury (DAI). All injuries and symptoms, even if apparently minor on initial presentation, should be taken seriously since injuries may rapidly progress and become life-threatening.
The exact number of people suffering TBI is unknown since many individuals suffering mild or moderate TBI do not seek medical attention, and some who suffer severe traumatic injuries do not survive to receive medical attention.
Of those who do receive medical attention in an emergency department, approximately 1.4 million people per year suffer TBI. Of these patients, approximately 1.1 million are treated and released, 240,000 are hospitalized, and 50,000 die.1
Common causes for TBI are falls (28%), motor vehicle accidents (20%), pedestrian impact (19%), and assault (11%). TBI has a bimodal age distribution with the greatest risk in 0–4 and 15- to 19-year-olds. Males have 1.5 times the risk of females. The younger group is often the victim of abuse and cannot protect itself. The older group practices greater risk-taking behavior, and includes the population of new drivers and teenagers exposed to drugs and alcohol. Military personnel comprise a statistically small number of the overall TBI injuries per year, but have a higher incidence of penetrating and blast injuries resulting from combat operations.
TBI is a dynamic process and management must be tailored throughout the patient’s course. Primary injuries of the brain result from the forces imparted at the time of the accident. This includes disruption of scalp (lacerations), bone (cranial vault, skull base, facial bones), vasculature (SDH/EDH/IPH/intraventricular hemorrhage [IVH], traumatic aneurysm), or brain parenchyma (contusion, DAI).
Secondary injuries occur after the initial impact and may be more insidious and more difficult to control. They are often due to failure of autoregulation and loss of normal homeostasis. These injuries include hypoxemia, ischemia, initial hyperemia, cerebral edema, and expansion of hemorrhages leading to increased intracranial pressure (ICP), seizures, metabolic abnormalities, and systemic insults.
Systemic Evaluation and Resuscitation
Assessment and treatment of head-injured patients often begins in the prehospital setting with family, bystanders, and off-duty medical personnel. Care continues with the primary care physician or emergency medical technician (EMT), transfers to the physician in the emergency department, and eventually involves the trauma team, neurologist, neurosurgeon, and neurointensivist. Treatments may be started at any point along the patient’s journey based on ...