Seizures after head trauma: a population study.

A cohort of 2747 patients with head injuries was followed for 28,176 person-years to determine the magnitude and duration of the risk of posttraumatic seizures. Injuries were classified as severe (brain contusion, intracerebral or intracranial hematoma, or 24 hours of eight unconsciousness of amnesia), moderate (skull fracture or 30 minutes to 24 hours of unconsciousness or amnesia), and mild (briefer unconsciousness or amnesia). The risk of posttraumatic seizures after severe injury was 7.1% within 1 year and 11.5% in 5 years, after moderate injury the risk was 0.7 and 1.6%, and after mild injury the risk was 0.1 and 0.6%. The incidence of seizures after mild head injuries was not significantly greater than in the general population.