Predictive value of paroxysmal EEG abnormalities for future epilepsy in focal febrile seizures

To reassess the predictive role of clinical parameters and epileptiform paroxysmal EEG abnormalities for subsequent epilepsy in patients with febrile seizures.

179 patients with febrile seizures were included in a prospective study investigating the impact of some clinical parameters and EEG abnormalities that could be important for future epilepsy. EEGs were performed in afebrile patients after hospital discharge. The follow-up period from the first presentation ranged from 2.1 to 9.2 years (mean, 6.6 years). The correlation between the development of epileptic seizures and the presence of epileptiform EEG abnormalities in the two groups was evaluated with the Mann-Whitney and chi-square test. Statistical significance was set at p<0.05.

Febrile seizures occurred more than once in 58 (32.5%) patients, with one recurrence in 32 (17.9%) patients and multiple recurrences in 26 (14.5%) patients. The incidence of paroxysmal abnormalities was 16.8%. Of these, 15 patients (50%) showed generalized paroxysms only, while in 15 patients (50%), focal abnormalities were found. Epilepsy developed in 12 patients (6.7%). There were 27 patients with clinically focal features of the first febrile seizure, five (18.5%) of whom developed epilepsy. With focal EEG abnormalities included, the incidence of epilepsy increased to 50%.

Generalized EEG discharges in patients with febrile seizures are not predictive of later epilepsy, but focal discharges are.