A Randomized, Double-Blind Study of Phenytoin for the Prevention of Post-Traumatic Seizures

Abstract

Background. Antiepileptic drugs are commonly used to prevent seizures that may follow head trauma. However, previous controlled studies of this practice have been inconclusive. Methods. To study further the effectiveness of phenytoin (Dilantin) in preventing post-traumatic seizures, we randomly assigned 404 eligible patients with serious head trauma to treatment with phenytoin (n = 208) or placebo (n = 196) for one year in a double-blind fashion. An intravenous loading dose was given within 24 hours of injury. Serum levels of phenytoin were maintained in the high therapeutic range (3 to 6 μmol of free phenytoin per liter). Follow-up was continued for two years. The primary data analysis was performed according to the intention to treat. Results. Between drug loading and day 7, 3.6 percent of the patients assigned to phenytoin had seizures, as compared with 14.2 percent of patients assigned to placebo (P < 0.001; risk ratio, 0.27; 95 percent confidence interval, 0.12 to 0.62). Between day 8 and the end of year 1, 21.5 percent of the phenytoin group and 15.7 percent of the placebo group had seizures; at the end of year 2, the rates were 27.5 percent and 21.1 percent, respectively (P > 0.2 for each comparison; risk ratio, 1.20; 95 percent confidence interval, 0.71 to 2.02). This lack of a late effect could not be attributed to differential mortality, low phenytoin levels, or treatment of some early seizures in patients assigned to the placebo group. Conclusions. Phenytoin exerts a beneficial effect by reducing seizures only during the first week after severe head injury. (N Engl J Med 1990; 323:497–502.). © 1990, Massachusetts Medical Society. All rights reserved.