Midline spikes: is it another benign EEG pattern of childhood?

Clinical and electrographic features were retrospectively studied in 57 patients with midline (Fz, Cz, Pz) spikes as the only epileptiform activity in their EEG to determine possible predictors of outcome. Our study confirmed previous reports of early age of onset, activation by sleep, and Cz as the most frequent spike location. In contrast to previous studies with smaller numbers of patients, midline spikes were more common in males and most often associated with partial complex seizures and were not activated by sleep at an older age. Of the 29 patients who were followed for 6 months to 9 years, only 15 (52%) achieved good seizure control. Although a tendency toward a poor outcome was noted with several independent variables (positive family history of epilepsy, later age of seizure onset, abnormal EEG background activities, abnormal neuroimaging, abnormal neurologic examination), none was of statistical significance. This study suggests that epilepsy with midline spikes is not necessarily benign and that future studies with larger patient groups may be necessary to identify factors that influence prognosis.