Clinical significance of periodic lateralized epileptiform discharges: relationship with status epilepticus.

A retrospective study was carried out in 147 patients who had been found to have periodic lateralized epileptiform discharges (PLEDs). Clinical, laboratory, radiological, and pathological correlation was performed for all patients. As in previously published works, we found a high correlation with cerebrovascular accidents in our population. A large number of patients, however, had no evidence of focal central nervous system pathology. An attempt was made to find a temporal relationship between the onset of seizure activity (or neurological dysfunction in those patients without seizure activity) and the recording of an EEG with PLEDs. We found that most of the EEGs with PLEDs were obtained within the first 4 days of seizure activity or status epilepticus condition. We postulate that the EEG phenomenon of PLEDs could be considered a part of the status epilepticus condition. Suggestive of this was the fact that the first EEG record obtained in one-third of our patients showed electrographic partial status epilepticus. In a small percentage of our patients, a transitional record showed first status epilepticus and then PLEDs. We found that PLEDs usually disappeared from the EEG tracing within 9 days post-ictus flash status. They were most frequently replaced by focal slowing or random spike activity.