Post-traumatic epilepsy (PTE) is a form of acquired epilepsy that results from brain damage caused by physical trauma to the brain (traumatic brain injury, abbreviated TBI). A person with PTE experiences repeated post-traumatic seizures (PTS, seizures that result from TBI) more than a week after the initial injury. PTE is estimated to constitute 5% of all cases of epilepsy and over 20% of cases of acquired epilepsy (in which seizures are caused by an identifiable organic brain condition).It is not known who will develop epilepsy after TBI and who will not. However, the likelihood that a person will develop PTE is influenced by the severity and type of injury; for example penetrating injuries and those that involve bleeding within the brain confer a higher risk. The onset of PTE can occur within a short time of the physical trauma that causes it, or months or years after. People with head trauma may remain at a higher risk for post-traumatic seizures than the general population even decades after the injury. PTE may be caused by several biochemical processes that occur in the brain after trauma, including overexcitation of brain cells and damage to brain tissues by free radicals.Diagnostic measures include electroencephalography (EEG) and brain imaging techniques such as magnetic resonance imaging, but these are not totally reliable. Antiepileptic drugs do not prevent the development of PTE after head injury, but may be used to treat the condition if it does occur. When medication does not work to control the seizures, surgery may be needed.
Repeated intracranial surgery confers a high risk for late PTE, possibly because people who need more surgery are more likely to have factors associated with worse brain trauma such as large hematomas or cerebral swelling. In addition, the chances of developing PTE differ by the location of the brain lesion: brain contusion that occurs on in one or the other of the frontal lobes has been found to carry a 20% PTE risk, while a contusion in one of the parietal lobes carries a 19% risk and one in a temporal lobe carries a 16% chance. When contusions occur in both hemispheres, the risk is 26% for the frontal lobes, 66% for the parietal, and 31% for the temporal. Post-traumatic seizures
The risk that a person will develop PTE is heightened but not 100% if PTS occur. Because many of the risk factors for both PTE and early PTS are the same, it is unknown whether the occurrence of PTS is a risk factor in and of itself. However, even independent of other common risk factors, early PTS have been found to increase the risk of PTE to over 25% in most studies. A person who has one late seizure is at even greater risk for having another than one who has early PTS; epilepsy occurs in 80% of people who have a late seizure.