Correlation of EEG, neuroimaging and histopathology in an epilepsy patient with diffuse cortical dysplasia.

The correlation between scalp EEG, intraoperative electrocorticogram, neuroimaging and histopathology was examined in an epileptic child with diffuse cortical dysplasia. The 6-year-old girl with moderate mental retardation had suffered from intractable complex partial and generalized epilepsies since the age of 2 years. MR images demonstrated unilateral large macrogyria/polymicrogyria and schizencephaly in the right occipital lobe. The epileptic focus was detected on the macrogyria by EEG and single photon emission tomography. However, the intraoperative electrocorticogram showed frequent spikes from the polymicrogyria and no paroxysmal activity in the macrogyria. The polymicrogyria and the macrogyric lesion were resected, using an image-guided system. The histological findings revealed that the macrogyria was covered with and separated by glial bundles. It has been reported that epileptogenicity is produced from abnormal neurons and their arrangement in cortical dysplasia; in this case, however, the major dysplastic lesion had no epileptogenicity; rather the focus might be in the polymicrogyria around the lesion.