[123I]N,N,N'-trimethyl-N'-(2 hydroxy-3-methyl-5-123I-iodobenzyl)- 1,3-propane-diamine 2HCl single-photon-emission computed tomography (HIPDM-SPECT) brain imaging in one patient with periodic lateralized epileptiform discharges (PLEDs) on the EEG demonstrated increased regional cerebral perfusion in the PLEDs focus suggesting that PLEDs are the manifestation of abnormally enhanced neuronal activities. This may explain the frequent association of mental confusion, focal neurologic signs, and occurrence of seizures in association with PLEDs.