Traumatic brain injury is sudden physical damage to the brain. The damage can result from a closed head injury, such as that caused by impact of the head with an object like the windshield or the dashboard of a car. The damage can also result from a penetrating brain injury, such as that caused by a bullet piercing the skull. Approximately 200,000 people die each year in the US from brain injuries, with an additional 500,000 hospitalized for treatment. About 10% of surviving individuals have continuing disabilities that may impair their ability to live independently.
Traumatic spinal cord injury is damage to the spinal cord that results in loss of mobility or feeling. In most cases, the spinal cord remains intact, but the damage results in loss of nerve function. The spinal cord is a dense bundle of nerves that lies in a narrow canal in the center of the vertebrae. The spinal cord carries all of the major nerve pathways that connect the brain to the rest of the body. Injuries to the neck or back may damage the spinal cord, causing loss of function of the nerves below the injury. In the US, approximately 8,000 new cases of spinal cord injury occur each year, and an estimated 450,000 people in the country live with the condition.
Automobile accidents are the most common cause of brain and spinal cord injuries. Other common causes of brain and spinal cord injuries include acts of violence and sports injuries. In infants, toddlers, and elderly people, brain injury is often caused by falls in or around the home. Very young children who are violently shaken can experience severe and potentially permanent brain damage.
Spinal column fracture or dislocation resulting in spinal cord compression (such as that caused by diving into shallow water) can cause injury to the spinal cord. Severe spinal cord injury usually occurs after dislocation or compression of the spinal cord. Severing the spinal cord results in immediate paralysis and loss of sensation below the break. Less severe damage to the spinal cord generally results in less severe loss of function.
The extent of secondary damage such as inflammation or hemorrhage following brain or spinal injury often determines the permanence of the initial damage. One of the body’s responses to injury is inflammation. Inflammation occurs when certain cells of the immune system move towards the area of injury and release potent chemicals. Among other effects, these chemicals cause fluid to build up in the injured area. Because both the brain and spinal cord are confined in tight spaces, inflammation or internal bleeding can cause pressure on the nerves. If the pressure does not subside, the nerves will start to die in a few hours. Rapid treatment to reduce the pressure caused by inflammation or internal bleeding may prevent permanent damage to the brain or spinal cord.