The rate of occurrence of a second seizure after a single unprovoked generalized tonic-clonic seizure was compared in 45 patients who received immediate anticonvulsant therapy and 42 untreated patients followed for 36 months at the Edith Wolfson Medical Center, Holon, and the Sackler Faculty of Medicine, Tel Aviv, Israel. A second epileptic attack occurred in 29 (71%) of the untreated group and in 10 (22%) of the treated group. The risk rates for relapse in untreated patients were 0.33, 0.62, and 0.77 and, in the treated group, 0.1, 0.2, and 0.4, after 12, 24, and 36 months, respectively. Treated men were less susceptible to recurrence than treated women. EEG abnormalities were observed in 20% of both treated and untreated patients, and rate of seizure recurrence was not correlated with EEG epileptiform activity. Treatment consisted of carbamazepine (10 mg/kg/day) in 36 (80%) patients; it had to be changed to valproic acid (600-1200 mg/d) in 9 (20%). 
COMMENT. The age range of these patients was 18 to 50, mean 30 years. Studies in children and adolescents might show different results. The benefits of immediate anticonvulsant treatment in these adults is apparent, but the decision to begin treatment after a single seizure must be made on an individual basis, having regard to drug toxicity on the one hand and the adverse consequences of a seizure recurrence on the other. Risk factors for recurrence of seizures, with and without therapy, require further study in children and adult populations. Previous studies have shown seizure recurrence rates varying from 33 to 80%.