Spatio-temporal analysis by voltage topography of ictal electroencephalogram on MR surface anatomy scan for the localization of epileptogenic areas.

A 15-year-old girl developed intractable epilepsy following a right transcallosal resection of the intraventricular teratoma. Magnetic resonance (MR) imaging showed a T (2)-prolonged subcortical lesion in the right frontal lobe as well as a residual intraventricular tumor. The integration of the voltage topography of ictal onset activities of the scalp-recorded electroencephalogram (EEG) and a surface anatomy scan of MR images clearly revealed the epileptogenic area on the cortex above the subcortical lesion, with the propagation pattern towards the frontopolar area. Excision of the epileptogenic cortex and underlying gliosis resulted in a successful cessation of the epilepsy. This non-invasive EEG technique provided useful information that accurately localized the epileptogenic area on a large structural abnormality without invasive intracranial electrocorticographic monitoring.