Traumatic brain injury (TBI) refers to damage or destruction of brain tissue due to a blow to the head, resulting from an assault, a car crash, a gunshot wound, a fall, or the like. In closed head injury, damage occurs because the person receives a blow to the head that whips the head forward and back or from side to side (as in a car crash), causing the brain to collide at high velocity with the bony skull in which it is housed. This jarring bruises brain tissue and tears blood vessels, particularly where the inside surface of the skull is rough and uneven; damage occurs at (and sometimes opposite) the point of impact. Thus, specific areas of the brain – most often the frontal and temporal lobes – are damaged. This focal damage often can be detected through MRI and CAT scans.
As an individual regains consciousness (those with the severest injuries may never do so), a variety of neurologically based symptoms may occur: irritability, aggression and other problems. Post-traumatic amnesia (PTA) is also typically experienced when an injured person regains consciousness. PTA refers to the period when the individual feels a sense of confusion and disorientation – Where am I? What happened? – and an inability to remember recent events. As time passes, these responses typically subside, and the brain and other body systems again approach physiological stability. But, unlike tissues such as bone or muscle, the neurons in the brain do not mend themselves. New nerves do not grow in ways that lead to full recovery. Certain areas of the brain remain damaged, and the functions that were controlled by those areas may emerge as challenges in the individual’s life.
Before discussing in greater detail what happens to the person after injury, which depends to great extent on the severity of injury, “severity” needs to be defined (in the next question). Recovery after injury is usually quite different for those with moderate-to-severe injuries versus those with mild injuries. And, as must be constantly kept in mind, recovery varies greatly from person to person. Thus, recovery will not be the same for any two people with TBI.
In more severe injuries, recovery is a multistage process, which typically continues in a variety of ways for months and years. However, the length of this recovery process is not uniform, and the stages of recovery that are typical when considering the population as a whole, may be very different for any specific individual. Stages may not proceed step-wise but may overlap, one stage with the next, or one or more stages may be skipped altogether. The early recovery process is discussed more fully in the next question.