Purpose: Traumatic brain injury has long been known to be a cause of epilepsy. Most information on risk factors for developing posttraumatic seizures is from before computed tomography (CT) scanning became universal. This article looks at factors about the injury or individual that put people at especially high risk of developing posttraumatic seizures.
Methods: We considered 783 cases at high risk of developing seizures, followed up for 2 years as part of seizure prophylaxis studies. Cumulative incidence of seizures in subgroups and standardized incidence ratios were used to identify factors related to unprovoked seizure risk.
Results: Subgroups with significantly elevated risk include those with evacuation of a subdural hematoma; surgery for an intracerebral hematoma; Glasgow Coma Scale in the severe range of 3 to 8; early seizures, especially delayed early seizures; time to following commands of a week or more; depressed skull fracture that was not surgically elevated; dural penetration by injury; at least one nonreactive pupil; and parietal lesions on CT scan.
Conclusions: Both the risk factors and the time course of the risk are important for designing seizure-prophylaxis studies and, if an effective prophylactic regimen is identified, for deciding on appropriate candidates for prophylaxis.