Periodic epileptiform discharges in the midline.

Five patients had electroencephalograms (EEGs) that showed periodic epileptiform discharges in the midline (PEDIM); other than location, this activity has the same characteristics as periodic lateralized epileptiform discharges (PLEDs). All 5 patients had acute onset of partial motor seizures involving the lower extremity. The location of the PEDIM corresponded to the seizure type and focal neurologic deficits. All 5 patients had sustained a cerebrovascular insult, either old or new, and the PEDIM and seizures suggested an origin from the watershed area between the anterior, middle, and posterior cerebral arteries, involving predominantly the parasagittal region of the cerebral hemisphere.