Immediately following a brain injury, two things occur:
First, brain tissue reacts to the trauma from the injury with a series of biochemical and other physiological responses. Substances that once were housed safely within these cells now flood the brain, further damaging and destroying brain cells in what is called secondary cell death.
The second effect depends on the severity of brain injury and can range from temporary loss of consciousness or coma, respiratory (breathing) problems, and/or damaged motor functions.
Unlike what is seen in the movies, waking up following loss of consciousness is not immediate and sometimes can be quite difficult for the individual and their loved ones. It is important to be aware of the various neurologically-based symptoms that may occur during this period, such as irritability, aggression, posturing, and other issues. Post-traumatic amnesia (PTA) is also typically experienced as an injured person regains consciousness. PTA refers to the period when the individual feels a sense of confusion and disorientation (i.e., wondering who or where they are and what has happened to them) and an inability to remember recent events.
As time passes, these responses typically subside, and the brain and other body systems approach stability. Unlike bones or muscle tissue, the neurons in the brain do not mend themselves. New nerves do not grow in ways that lead to full recovery. In fact, certain areas of the brain remain damaged, and the functions that were controlled by those areas may be disrupted and lead to challenges in the individual's life.