A computerized spike detector was used to measure and localize interictal epileptiform discharges (IEDs) over prolonged, representative segments of recordings in 19 children with intractable, mostly extratemporal lobe epilepsy. Approximately 8 hours of IEEG, randomly selected 30-min segments of continuous interictal IEEG per patient, were analyzed over all intracranial electrode contacts. Spike frequency was averaged over the 16-time segments, and electrodes with the highest mean spike frequency were within the seizure-onset region in 11 of 19 patients. Large statistical samples of interictal activity were required for improved localization. Low-voltage fast EEG at seizure onset was the only factor predicting IED localization to the seizure-onset region. Automated IED detection over multiple samples of IEEG may be of value in planning epilepsy surgery for intractable epilepsy in children. [1]

COMMENT. Ictal recording is the mainstay of localizing epileptic foci for surgical resection. The inconsistent correlation with interictal spikes in previous reports may be related to the relatively short periods of observation. Further research is recommended to determine which patients may benefit from this technique.