Defining the role of structural lesions and metabolic abnormalities in periodic lateralized epileptiform discharges

We reviewed the EEG, clinical manifestations, computed tomography (CT) and magnetic resonance imaging (MRI) scans of 39 patients with periodic lateralized epileptiform discharges (PLEDs) or bilateral periodic lateralized epileptiform discharges (BIPLEDs) to determine the role of structural lesions (SL) and metabolic abnormalities (MA) in their pathogenesis. Thirty-eight patients had CT and 7 had MRI scans. Thirty-eight had lesions on CT or MRI. All those with PLEDs consistently had lesions on the side of the discharges, and 5 of 6 with BIPLEDs had lesions on both hemispheres. A subgroup of 23 patients with metabolic determination within 24 h of EEG all showed mild to moderate MA. They all also had SL. These findings support a primary role for SL but cannot exclude an additional role for MA.