Current Source Distribution of Periodic Lateralized Epileptiform Discharge: Comparison With Diffusion-Wighted MR Imaging in Viral Encephalitis

BACKGROUND: Periodic lateralized epileptiform discharges (PLEDs) are the main electroencephalograph (EEG) findings that imply the existence of acute or subacute structural lesions. The purpose of this study was to investigate the electrophysiologic characteristics of PLEDs by identifying the relationship between the current-source distribution (CSD) of PLEDs and the high signal intensity of diffusion-weighted magnetic resonance imaging (MRI; HSI-DWI) in viral encephalitis. METHODS: Six patients were enrolled. Twenty typical EEG, 1-s epochs, including the negative peak of the PLEDs, were averaged into an averaged-PLED (a-PLED). The CSD at the negative peak point of the a-PLED was located on the Talairach human brain map in each patient. The CSDs of the patients were compared with the anatomic locations of encephalitic lesions observed on diffusion-weighted MRI. RESULTS: In all patients, the locations with HSI-DWI were observed in the cortical areas. In two out of the six patients the locations of CSD and those of HSI-DWI were matched. In the other patients, they were partly matched. The matched areas were observed in the frontal, temporal, and parietal areas. The additional areas of CSD were in both insular areas, and those of HSI-DWI were in the frontal, temporal, parietal, and occipital areas. CONCLUSIONS: This study showed that the CSDs of PLEDs in viral encephalitis were mostly matched with the HSI-DWI in the cortical area of the frontal, temporal, and parietal areas. The cortical lesion itself in viral encephalitis may be part of the neural generator of PLEDs.

A Study on the Clinical Significance of Periodic Lateralized Epileptiform Discharges and Relation to Brain Imaging Study in Children

PURPOSE: Periodic lateralized epileptiform discharges (PLEDs), initially described by Chatrian et al in 1964, are an EEG phenomenon characterized by lateralized or focal spike-and-wave complexes with moderate to high voltage which occur in a periodic or semiperiodic pattern. This study was performed to assess the clinical significance of PLEDs and its relation to an imaging study of the brain. MEHTODS: Twenty children (10 males and 10 females), from 2 days to 14 years of age, who had been hospitalized at Hanyang University Hospital were studied retrospectively. Their medical records, EEG results and brain imaging study were reviewed. RESULTS: Of the 20 patients studied, 15 patients showed unilateral PLEDs and 5 had bilateral PLEDs in EEG. Brain imaging studies were done for 18 of the patients, revealing abnormalities in 15 patients in this order of frequency: intracranial hemorrhage, diffuse cerebral atrophy, leukomalacia, cerebral infarctions, cerebral edema and hydrocephalus. PLED sites were not significantly correlated with the results of the imaging study. Finally, 3 patients died and 17 patients survived, and among the surviving 17 patients, 5 had recurrent seizures, 1 had recurrent seizures with mental regression, 3 had neurologic sequelae without seizures and 8 had no neurologic sequelae. CONCLUSION: We conclude that children who show PLEDs in EEG are more commonly associated with acute cerebral lesions and there is a high incidence of subsequent seizures and/or other neurological sequelae in surviving children with PLEDs.

A Study on the Clinical Significance of Periodic Lateralized Epileptiform Discharges and Relation to Brain Imaging Study in Children

PURPOSE: Periodic lateralized epileptiform discharges (PLEDs), initially described by Chatrian et al in 1964, are an EEG phenomenon characterized by lateralized or focal spike-and-wave complexes with moderate to high voltage which occur in a periodic or semiperiodic pattern. This study was performed to assess the clinical significance of PLEDs and its relation to an imaging study of the brain. MEHTODS: Twenty children (10 males and 10 females), from 2 days to 14 years of age, who had been hospitalized at Hanyang University Hospital were studied retrospectively. Their medical records, EEG results and brain imaging study were reviewed. RESULTS: Of the 20 patients studied, 15 patients showed unilateral PLEDs and 5 had bilateral PLEDs in EEG. Brain imaging studies were done for 18 of the patients, revealing abnormalities in 15 patients in this order of frequency: intracranial hemorrhage, diffuse cerebral atrophy, leukomalacia, cerebral infarctions, cerebral edema and hydrocephalus. PLED sites were not significantly correlated with the results of the imaging study. Finally, 3 patients died and 17 patients survived, and among the surviving 17 patients, 5 had recurrent seizures, 1 had recurrent seizures with mental regression, 3 had neurologic sequelae without seizures and 8 had no neurologic sequelae. CONCLUSION: We conclude that children who show PLEDs in EEG are more commonly associated with acute cerebral lesions and there is a high incidence of subsequent seizures and/or other neurological sequelae in surviving children with PLEDs.