Seizure disorders following periodic lateralized epileptiform discharges.

We reviewed 3,436 EEGs and found 24 patients with periodic lateralized epileptiform discharges (PLEDS). The etiology was unknown in 7, cerebrovascular occlusion in 7, tumor in 3, intracerebral hematoma in 2, and subdural hematoma, neonatal asphyxia, electrolyte imbalance, subarachnoid hemorrhage, and hypoglycemia in each of the remaining cases. We were successful in contacting 18 patients and/or their families for follow-up. Twenty of the 24 patients with PLEDS had seizures. Seven had focal motor alone, 10 had focal motor with secondary generalization, and 3 had generalized seizures without any observed focal features. Four patients had no seizures. Twelve patients had their first seizure at the time PLEDS were found. Fifteen adults and 3 infants were reevaluated. Only 1 adult was functionally independent. The 3 infants evidenced developmental delay. Six adults had seizures prior to observation of PLEDS, and 5 (83%) of them reported seizures after hospitalization. Nine of the 15 adults had their first seizure associated with PLEDS, 6 of whom (67%) also reported seizures after hospitalization. In 9 patients with serial EEGs during their hospitalization, PLEDS disappeared within 22 days. We concluded that most patients with PLEDS and concomitant seizures continue having seizures after hospitalization and need antiepileptic medication.