Subdural recording and electrical stimulation for cortical mapping and induction of usual seizures.

Chronic subdural strip electrodes were used for recording of seizure origin, cortical mapping and confirmation of seizure foci by electrical stimulation. Seventeen patients were comprehensively evaluated for epilepsy surgery. All patients had failed medical treatment. Intracranial recording was necessary in 12 patients. Speech area was determined in 50% of the patients stimulated. Seizure origin was confirmed by stimulation-induced usual seizures or aura in 75% of the patients stimulated. Intracranial chronic recordings were safe and added important prognostic information, as well as helped decide the extent of resection.