What is the 'L' in LPDs? Localized as well as lateralized

Background Periodic discharges (PDs) are well established as either periodic lateralized epileptiform discharges (LPDs) or generalized discharges. However, PDs in the midline can currently not be adequately classified as they are not generalized and not lateralized. Aims of the study To propose a modification of the current LPD classification. Methods We here present a paradigmatic case series of three adult patients with midline LPDs. Results In our patients, ictal electroencephalography (EEG) recordings revealed periodic epileptiform discharges in the midline region. All three patients were non-lesional. Conclusion We, thus, suggest to include periodic localized non-lateralized epileptiform discharges into the term LPDs (in addition to periodic lateralized epileptiform discharges), as they can also be recorded as localized EEG phenomenon in the midline region.