Time-related configuration change in benign focal epileptiform discharges of childhood: from a dipole to a negative monopole in a patient with generalized epilepsy.

The case of a 6-year-old child with generalized epilepsy and benign focal epileptiform discharges (BFEDs) of childhood is presented. During his first EEG, performed when he was 6 years old, the patient had three staring episodes accompanied by bursts of 3-Hz spike-and-wave complexes. Interictally, frequent BFEDs were seen, configured as dipoles with a right temporal negativity and a right frontal positivity. The patient was administered ethosuximide and the staring spells disappeared. On follow-up EEG performed 2 years later, no generalized discharges were seen. However, the EEG again showed frequent spikes with a characteristic morphology of BFEDs. This time they were not configured as dipoles, but as monopoles with a maximum negativity over the right frontal region. The change in the generator's orientation over time (from a horizontal to a vertical dipole) is discussed, as well as the prognostic implications of the morphology and configuration of focal spikes. In addition, the authors review the coexistence of BFEDs and 3-Hz spike-and-wave complexes in their patient database.