Neuropathology of the Head Injuries

Structural abnormalities develop progressively after trauma to the central nervous system suggesting that injury is a process of events rather than a singular event. Thus, numerous types of neuropathologies can occur, depending on the exact nature of the processes of cellular damage that are set into motion after injury. Four general interrelated processes of delayed cellular damage occur in different amounts and in different locations to result in the numerous types of traumatic brain damage. These include direct damage caused by calcium influx into cells, free radical-mediated damage, receptor-mediated damage, and inflammation. By these mechanisms, the general response of the brain to mechanical energy causes damage to vascular or neural components of the brain, and results in principally focal or diffuse brain damage, respectively. These form the phenotypic types of damage to the brain and the resulting clinically associated traumatic syndromes. Focal brain damage consists principally of vascular injury that results in confusions and hemorrhages in various locations. Diffuse brain damage mainly involves scattered damage to axons in the white matter (diffuse axonal injury) or secondary damage attributable to raised intracranial pressure, hypoxia, or ischemia.