Neurologic Disease aND DysfuNctioN Chapter 117 neurologic injury : Prevention and initial care

Traumatic brain injury (TBI) is defined as a disruption in the normal function of the brain or other evidence of brain pathology caused by an external force including a bump, blow, acceleration or deceleration forces, blast, or penetrating injury (1–3). Worldwide, TBI is the leading cause of death and disability in children and young adults and is involved in nearly half of all trauma-related deaths (1). In the United States, unintentional injury is also the leading cause of death between age 1 and 44 years (4). In 2010, 2.5 million people sustained a TBI (2); of those, an estimated 280,000 were hospitalized, and over 50,000 died. Over the period of 2001 to 2010 in the United States, TBI-related emergency department (ED) visits increased by 70%, although the hospitalization rate only increased by 11%, and death rates decreased by 7% (5). Estimates of the global incidence of hospitalizations due to TBI is highest in Sweden with approximately 450, Brazil with 360, South Africa with 320, the United States with 92, and Pakistan with 50 cases/100,000 people/yr (6). A meta-analysis of reports from 23 European countries reported an incidence of 235 cases/100,000 people/yr (7). The average TBI-associated mortality rate in Europe is estimated to be 15 deaths/100,000 population/yr (7) compared to 10 in Scandinavia, 20 in India, 30 in the United States, 38 in the Province of Taiwan in China, 81 in South Africa, and 120 in Columbia (8). Globally, males have at least double the risk of TBI compared to females (1,9). In the United States in 2010, the rate of TBI-related death was more than two times higher in men than in women (25.4 in males vs. 9.0/100,000 in females). Death rates were highest in persons aged 65 years or older at 45.2/100,000 population (10). Worldwide, the leading cause of head injury is road traffic accidents, which account for 40% to 50% of hospitalizations due to TBI (1). The World Health Organization (WHO) estimates that 3,000 people die daily and 30,000 people are seriously injured on the roads and nearly half suffer head injury; most are from lowor middle-income countries and are pedestrians, cyclists, motorcyclists, and bus passengers (11). In Australia, India, Northern Europe, and the United States, the leading causes of TBI are due to falls (7,12). In the United States, falls account for 40.5% of TBI; while 15.5% of TBI are due to “struck by/against” events, which include colliding with a moving or stationary object; 14.3% are from motor vehicle crashes (MVC) and 10.7% from assault; the remainder are not documented (13). The youngest (age 0–4 years) and oldest (age >65 years) are at highest risk for falls at 72.8% and 81.8% respectively (13). The leading cause of TBI-related death also varies by age. In the United States, falls were the leading cause of death for persons over 65 years, assault for those under 4 years, and MVC for those between 5 and 24 years (13). For mechanism of injury, firearm-inflicted TBI has the highest mortality at 90.4% compared with 10.2% associated with falls (14,15). In the military population, mild TBI or concussion is the most common traumatic injury with most occurring in the garrison or home station environment (16). However, during combat, TBI is often due to blast injuries with concussion, contusion, subdural hematoma (SDH), and axonal shear injury as a result (17). During the recent wars, 81% of injuries in Afghanistan and Iraq were explosion related compared to 65% in Vietnam, and 73% during World War II (18). The economic impact includes the direct cost of hospitalization, outpatient and rehabilitation, and indirect costs for lost productivity both of the patient and caregiver. There are other less tangible social and psychological costs to the patient, family and friends related to death or the reduced quality of life. Over 5.3 million Americans require assistance with activities of daily living (ADL) as a consequence of the long-term effects on cognition and behavior with emotional and physical impairment following TBI (2,19,20). In the United States, lifetime costs of TBI, including medical costs and lost productivity, have been estimated at $60 billion annually (21).