Ictal midline epileptiform discharges

Epileptiform discharges arising from the midline (Fz, Cz, Pz) are relatively uncommon. They have been found more frequently in children, are often activated by sleep, and correlate well with clinical seizures. Only a few studies discuss the issue of midline spikes, and all of them deal with interictal activity. We report 8 patients (age range 5 weeks to 17 years) in whom ictal midline discharges were recorded from scalp EEG. The following clinical seizures were recorded: complex partial, simple sensory and myoclonic. The ictal EEG showed spike and spike and slow wave complexes, rhythmic theta, background attenuation, and paroxysmal fast activity. Based on reports of animal experiments and on the variety of types of clinical seizures and their ictal EEG correlates in the patients reported here, it is suggested that the midline scalp EEG discharges do not represent the anatomical focus of origin of the seizures. They probably reflect secondary extension and summation of a remote source of epileptogenic activity.