Brain Injury

The brain serves as the control center for all of the body's functions including conscious activities (walking and talking) and unconscious ones (breathing, heart rate, etc.). The brain also controls thought, comprehension, speech and emotion. Injury to the brain, whether the result of severe head trauma or a closed head injury in which there is no fracture or penetration of the skull, can disrupt some or all of these functions.

Brain injury can have serious and lifelong effects on physical and mental functioning, including loss of consciousness, altered memory and/or personality, and partial or complete paralysis.

Traumatic brain injury (TBI) results mainly from motor vehicle incidents, falls, acts of violence, and sports injuries. It is more than twice as likely in males than in females. The estimated incidence rate is 100 per 100,000 persons with 52,000 annual deaths. The highest incidence is among persons 15 to 24 years of age and 75 years and older.

Enclosed within the bony framework of the skull, the brain is a gelatinous material that floats within a sea of cerebrospinal fluid. This fluid supports the brain and acts as a shock absorber in rapid head movements. The outer surface of the skull is smooth, but the inner surface is jagged – this can cause significant damage in closed head injuries as the brain rebounds within the skull over rough bony structures.

Injury to the brain can be caused by fracture or penetration of the skull (such as in the case of a vehicle accident, fall or gunshot wound), a disease process (neurotoxins, infections, tumors, metabolic abnormalities, etc.) or a closed head injury such as in the case of Shaken Baby Syndrome or rapid acceleration or deceleration of the head.

When the injury results from 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.

A closed head injury often occurs without leaving obvious external signs but 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 result may be minor if that area was not a critical one.

In contrast, closed head injuries often result in more widespread damage and extensive neurologic deficits, including partial to complete paralysis, cognitive, behavioral, and memory dysfunction, persistent vegetative state, and death.

Injured brain tissue can recover over a short period of time. However, once brain tissue is dead or destroyed, there is no evidence that new brain cells can regrow. The process of recovery usually continues even though new cells do not grow, perhaps as other parts of the brain take over the function of the destroyed tissue.

The rehabilitation process begins immediately. Once memory begins to be restored, the rate of recovery often increases. However, many problems may persist, including those related to movement, memory, attention, complex thinking, speech and language, and behavioral changes.

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.

Sources:

Brain Injury Resource Center, National Institute on Deafness and Other Communication Disorders, National Institute of Neurological Disorders and Stroke.