Post-traumatic Seizure - Pathophysiology

Pathophysiology

It is not completely understood what physiological mechanisms cause seizures after injury, but early seizures are thought to have different underlying processes than late ones. Immediate and early seizures are thought to be a direct reaction to the injury, while late seizures are believed to result from damage to the cerebral cortex by mechanisms such as excitotoxicity and iron from blood. Immediate seizures occurring within two seconds of injury probably occur because the force from the injury stimulates brain tissue that has a low threshold for seizures when stimulated. Early PTS are considered to be provoked seizures, because they result from the direct effects of the head trauma and are thus not considered to be actual epilepsy, while late seizures are thought to indicate permanent changes in the brain's structure and to imply epilepsy. Early seizures can be caused by factors such as cerebral edema, intracranial hemorrhage, cerebral contusion or laceration. Factors that may result in seizures that occur within two weeks of an insult include the presence of blood within the brain; alterations in the blood brain barrier; excessive release of excitatory neurotransmitters such as glutamate; damage to tissues caused by free radicals; and changes in the way cells produce energy. Late seizures are thought to be the result of epileptogenesis, in which neural networks are restructured in a way that increases the likelihood that they will become excited, leading to seizures.