lateral sclerosis in all veteran populations resulted in Amyotrophic Lateral Sclerosis in Veterans, a request for an examination of all health effects in veterans deployed to the Persian Gulf irrespective of specific exposures resulted in Gulf War and Health, Volume 4: Health Effects of Serving in the Gulf War, and a request for a review of long-term health effects that might be associated with deployment-related stress resulted in Gulf War and Health, Volume 6: Health Effects of Deployment-Related Stress. The present report is in response to a VA request regarding whether traumatic brain injury has long-term health effects.

TRAUMATIC BRAIN INJURY

Damage to the brain after trauma (for example, a blow or jolt to the head, a penetrating head injury, or exposure to an external energy source) is referred to as traumatic brain injury (TBI). TBI may be open (penetrating) or closed and is categorized as mild, moderate, or severe, depending on the clinical presentation. A brain injury that results from something passing through the skull, such as a bullet discharged from a gun or fragments from a missile, would be referred to as a penetrating or open head injury. A brain injury that results from something hitting the head or from the head hitting something forcefully, such as the dashboard of a car, is referred to as a nonpenetrating or closed head injury. According to the Centers for Disease Control and Prevention, mild TBI is manifested as a brief change in mental status or unconsciousness, whereas severe TBI results in an extended period of unconsciousness or amnesia. According to the World Health Organization Collaborating Task Force on Mild Traumatic Brain Injury, mild TBI might also be referred to as a concussion, a minor brain injury, a mild head injury, or a minor head injury. Furthermore, it has been noted that the term concussion, often used to indicate a mild or moderate brain injury, refers to a disturbance in neurologic function caused by the mechanical force of rapid acceleration or deceleration, and can include varied symptoms and severity.


With regard to determining TBI severity, different methods have been used in the last three decades to measure the magnitude of brain damage and to predict its outcome. The most widely used tool for measuring severity is the Glasgow Coma Scale (GCS), which was developed in 1974 by Teasdale and Jennett as a measure of neurologic deficits after TBI and was an important contribution to the standardization of early assessment of TBI. It is based on a simple method of scoring three domains—eye opening, verbal response, and motor function—and yields a total score of 3 (comatose or nonresponsive) to 15 (no deficits in any of the three domains). The interpretation of scores at the ends of the scale is relatively straightforward, but scores like 8 or 9 or 11 or 12 might be subject to judgment error. Although the GCS is relatively straightforward, the classification of severity has been inconsistent. Many incidence studies have classified severity according to GCS scores of 3–8 as severe, 9–12 as moderate, and 13–15 as mild or minor.


Other methods and instruments have been used to determine injury severity, such as the Abbreviated Injury Scale (AIS) and the International Classification of Diseases. Clinical measures—such as loss of consciousness (LOC), duration of posttraumatic amnesia (PTA), and computed tomography of brain lesions—have also been used to assess TBI severity.


During peacetime, over 7,000 Americans with a TBI diagnosis are admitted to military and veterans hospitals each year. During the Vietnam War, 12–14% of all combat casualties had a TBI, and another 2–4% had a TBI plus a lethal wound of the chest or abdomen. In the recent



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