Intraoperative electrocorticography in children with medically intractable epilepsy.

Intraoperative electrocorticography (ECoG) was performed to localize epileptic foci in 20 children undergoing temporal and extratemporal surgery for intractable epilepsy under modified neuroleptanalgesia. Nitrous oxide gas was discontinued at least 15 minutes before and during preresection ECoG recording, which lasted for 30 minutes. Seventeen patients showed epileptiform discharges on preresection ECoG. Hyperventilation loading, monitored by electroencephalography or ECoG in all patients, induced enhanced or induced epileptiform activities in 17 patients and provoked electroencephalographic seizures in 10 patients. All foci in non-eloquent areas were resected. Fifteen patients have been seizure-free with reduced medication, and two patients have achieved worthwhile improvement. Habitual seizures have remained in three patients. Two of these patients had foci in eloquent areas which could not be resected. Intraoperative ECoG can improve the outcome of surgery for intractable epilepsy by localizing epileptic foci for resection.