Intraoperative alfentanil is known to increase the epileptic discharge in the adult seizure patients. This study hypothesized that alfentanil might localize an epileptogenic focus in pediatric seizure patients.

This study was performed in the pediatric seizure patients who undergo second-staged operation. Thirteen pediatric patients were enrolled and their epileptic foci were already suspected from first operation. After anesthetic induction, sevoflurane was maintained at 0.6% end-tidal concentration for study period. Electrocorticography (ECoG) was recorded for 5 minutes before and 5 minutes after alfentanil 20µg/kg IV. During the ECoG recordings, the mean arterial pressure (MAP) and heart rate (HR) were continuously monitored. After the surgery, a pediatric neurologist analyzed the changes of spike frequencies of suspected ictal zone. The spike frequencies of suspected non-ictal zone were also calculated in five patients. The suspected ictal zone was defined as the most abundant spontaneous spiking area observed after first staged grid insertion.

Alfentanil induced a significant increase in spike activity of suspected ictal zone in 12 out of 13 patients (median of 20 [ranged 10 to 100] vs 38 [ranged 20 to 100], P < 0.05). Alfentanil-induced increase of spike activity was prominent in the suspected ictal zone rather than non-ictal zone. There were no significant changes in the MAP and HR after administration of alfentanil.

Alfentanil activates epileptiform activity of suspected ictal zone in pediatric patients with seizure disorder and can be used to assist in the localization of the epileptogenic focus during seizure surgery.