Every year millions of people in the United States suffer from a head or brain injury. These injuries are also called acquired brain injury because they happen afterbirth. More than half are bad enough that people must go to the hospital and the worst can lead to permanent brain damage or death. Statistics show that half of all traumatic brain injuries are due to motor vehicle accidents. Treatment and outcome of the injury will depend upon the area which was injured and the physiological changes in the brain following the injury.
It is important for physicians and rehabilitation specialists to understand the pathophysiology after a traumatic brain injury to adequately recommends patients oriented rehabilitation. During of traumatic brain injury (TBI) there is damage or destruction to the brain tissue as a result of a blow to the head, gunshot wound, fall or assaults. In the majority of cases these are closed head injuries which means that brain matter is not exposed to the air.
In a closed head injury, damage happens when a blow to the head moves the head either foreword, backward or side to side at high velocity. This causes the brain to collide against the bony skull that jars tissue and tears blood vessels. This is particularly injurious where the inside surface of the skull is rough and uneven. Most often the frontal and temporal lobes are damaged because the damage often occurs opposite of the point of impact.
This rapid acceleration and subsequent deceleration also can cause a diffuse brain injury when the rapid movement stretches and injures neuronal axons. These are the arms of nerve cells in the brain that links the cells one to another as well as links them to very is parts of the brain and then the rest of the body. Widespread damage cannot usually be detected through current available imaging technology as can focal damage that is detected through MRI and CT scans. However, the existence of diffuse damage is very clear in the individual\’s physical and cognitive functioning.
These initial injuries, due to bruising and bleeding as well as stretching and destroyed axons, result in a specific types of injury to the brain. They tend to affect broad areas of functioning primarily due to the nerve injury and is correlated with the forcible blow to the head. For instance, traumatic brain injuries which occur at a higher rate of speed will sustain more damage than those injured at a lower rate of speed.
These specific injuries are only the first injury. Immediately afterwards there can be a secondary injury related to a lack of oxygen supply to the brain. Following an accident, individuals may choke on their vomit, blood may block a person\’s airway or the position in which an individual is lying can obstruct their airway. In other instances they believe into the brain can also cause a more focal anoxic (lack of oxygen) injury.
Individuals who suffer an anoxic injury, as well as an axonal or brain bleed, will have a more challenging rehabilitation process because of these secondary injury. Unfortunately, there can also be a third injury to tissue that is already compromised. Within the days and weeks which follow the initial injury blood clots can develop as a result of bleeding bruising or swelling. Blood leaking from torn blood vessels or other body fluids can leak into the area and also cause the brain to swell.
Swelling in the brain is a serious problem because the skull is a fixed area of space and there is no room for the brain to expand. For instance, if an individual sprains their ankle and the tissue begins to swell, the area can swell as large as the skin will accommodate. However, inside the brain, when the brain swells it can only swell as large as was skull. And, because the brain takes up the majority of the inside of the skull, that amount of swelling is minimal. When the brain swells at can squeeze the blood vessels and limit the blood circulation, causing another anoxic injury. This brain swelling can be fatal.
Immediately after a traumatic brain injury there are two types of effects seen in the body. In the first place, the brain tissue reacts to trauma and damage with a series of biochemical responses. Neurotransmitters and other physiological biochemical substances that were once safely encased within the cells now flood the brain which can further destroy brain cells.
Based on the overall injury and damage done to the brain the individual\’s response can range from a mild headache to a complete loss of consciousness for several days or months. Some individuals never regain consciousness and go on to die. A variety of neurological symptoms can occur in those who do awakened from a loss of consciousness and include irritability, aggression and posttraumatic amnesia. Posttraumatic amnesia refers to the period in time after awakening in which they feel a sense of confusion and disorientation.
For many individuals, as time passes, these responses can subside and the brain and other body systems will regain a physiological stability. But, unlike other tissues in the body the brain cells do not mend themselves and new nerves do not grow. Certain areas of the brain will remain damaged and the functions that were controlled by those areas of the brain can be a significant challenge to the individual and their families.