Traumatic Brain Injury
The term “traumatic brain injury” refers to any injury of the brain caused by a trauma to the head. The injury can be caused by fracture or penetration of the skull (such as in the case of a vehicle accident, fall or gunshot wound), or a closed head injury such as in the case of rapid acceleration or deceleration of the head, including Shaken Baby Syndrome (1). These injuries can have devastating lifelong effects on physical and mental functioning (2).
Depending on the location and severity of the injury, the body can be affected in a myriad of ways. When the injury results from head trauma, damage to the brain may occur at the time of impact or may develop later due to swelling (cerebral edema) and bleeding into the brain (intracerebral hemorrhage) or bleeding around the brain (epidural or subdural hemorrhage). When the head is hit with sufficient force, the brain turns and twists on its axis (the brain stem), interrupting normal nerve pathways and causing a loss of consciousness. If this unconsciousness persists over a long period of time, the injured person is considered to be in a coma, a condition caused by the disruption of the nerve fibers going from the brain stem to the cortex.
If the injury is severe, as in the case of an acceleration-deceleration injury in which the moving head impacts against a hard, fixed surface, multiple areas of the brain are damaged. For example, a compression fracture occurs in the area where the head impacted the fixed surface. Upon impact, the brain rebounds forward and backward against the skull (this is called coup-contracoup), which tears the subdural veins, causes damage to the temporal lobes as they move across the rough bony structures within the skull, and results in bleeding, swelling of the brain stem, and shearing of the blood vessels and nerve fibers.
The term “closed head injury” is used when the brain has been damaged without penetration of the skull by another object. One example of this is Shaken Baby Syndrome, in which the brain is damaged by severe and violent shaking or twisting. Such injury often occurs without leaving obvious external signs. The difference between closed and penetrating injuries can be profound. In a bullet wound to the head, for example, a large area of the brain may be destroyed but the resulting neurologic deficit may be minor if that area was not a critical one. In contrast, closed head injuries result in more widespread damage and can result in more extensive neurologic deficits. These deficits can include partial to complete paralysis, cognitive, behavioral, and memory dysfunction, persistent vegetative state, and death. These last two are the most feared outcomes in cases of brain injury, however advances in trauma care have led to decreased rates for both in recent years.
Traumatic brain injury can have serious and lifelong effects on the physical and mental functioning of the survivor. Numerous studies have documented the physical, cognitive, social, emotional and behavioral impairments caused by TBI (2-5). Loss of consciousness, permanently altered memory and/or personality, partial or complete paralysis, and persistent vegetative state are just some of the devastating possibilities brain injury survivors and their families face. The Centers for Disease Control and Prevention (CDC) estimates that each year, 80,000 to 90,000 people will experience long-term disability as a result of a TBI (6). Beyond the obvious physical effects of brain injury, survivors frequently cope with depression, anxiety, loss of self esteem, altered personality, and in some cases, a lack of self-awareness by the injury survivor of any existing deficits.