Periodic lateralized epileptiform discharges (PLEDs) in herpetic encephalitis.

An 86-year-old male presented with confusion, fever and tonicclonic seizures. CSF analysis showed lymphocytic pleocytosis and high protein count, leading to initiation of acyclovir. EEG revealed PLEDs in the left hemisphere (figure 1C) and MRI demonstrated left hippocampal and insular hyperintensities (figure 1A, 1B). Herpes simplex virus (HSV) encephalitis was confirmed by PCR. PLEDs represent periodic sharp discharges lateralized to one hemisphere usually due to acute neuronal injury1,2. Since not all patients present seizures, the acronym LPDs (Lateralized Periodic Discharges) may be more accurate3. Besides encephalitis, several etiologies produce PLEDs, including stroke, metabolic disarrangements, brain tumors, intracranial hemorrhage, anoxic encephalopathy, among others1, 2. Nevertheless, HSV encephalitis should always be considered and CSF studies obtained in the appropriate clinical scenario4.