Final answer:
Primary brain injuries occur immediately during the traumatic event and include concussions and skull fractures, while secondary brain injuries develop over time due to biological processes such as excitotoxicity and can lead to permanent disabilities.
Step-by-step explanation:
The primary and secondary impact brain injuries are two distinct phases of traumatic brain injury (TBI). A primary brain injury refers to the immediate damage caused at the moment of impact. This can involve bruising of the brain, known as a concussion, as well as skull fractures, such as linear, comminuted, depressed, and contrecoup fractures. Primary injuries result directly from the traumatic event, for example, during contact sports like football or as a result of car accidents, falls, or violent blows.
A secondary brain injury, on the other hand, develops over time after the initial trauma. This can occur hours to days later as a result of inflammatory responses, swelling, and disruptions in cerebral blood flow. Secondary injuries can be exacerbated by complications such as bleeding, raised intracranial pressure, or infections. Unlike primary injuries, secondary injuries typically involve a more diffuse, complex array of biological processes, including excitotoxicity due to glutamate dysregulation, which can lead to neuronal necrosis beyond the site of the original injury.
While mild brain injuries like concussions may heal on their own, serious brain injuries can lead to permanent physical and mental disabilities, and may affect an individual's ability to communicate, move, and process information. Symptoms of severe brain injuries include loss of consciousness, confusion, and profound behavioral changes.