Epidemiology of posttraumatic epilepsy: a critical review.

PROBLEM Traumatic brain injury (TBI) is a major cause of epilepsy. We need to understand its frequency and its contribution to the total spectrum of the convulsive disorders. METHODS A review of selected articles dealing with epilepsy after brain trauma was undertaken. RESULTS The number of epidemiologic studies of posttraumatic seizures has increased substantially over the past 40-50 years, offering steadily increasing knowledge of the frequency, natural history, and risk factors of this well-recognized complication of TBI. In general, the incidence of posttraumatic seizures varies with the time period after injury and population age range under study, as well as the spectrum of severity of the inciting injuries, and has been reported to be anywhere from 4 to 53%. As high as 86% of patients with one seizure after TBI will have a second in the next 2 years. Longer-term remission rates of 25-40% have been reported. Significant risk factors for the development of seizures in the first week after injury include acute intracerebral hematoma (especially subdural hematoma), younger age, increased injury severity, and chronic alcoholism. Significant risk factors for the development of seizures >1 week after TBI include seizures within the first week, acute intra-cerebral hematoma (especially subdural hematoma), brain contusion, increased injury severity, and age >65 years at the time of injury. CONCLUSIONS Epilepsy is a frequent consequence of brain injury in both civilian and military populations. We understand some factors associated with its development, but there remain many unanswered questions.