Abstracts

RATIONALE: Alfentanil is a short duration opioid of rapid onset which has been shown to activate interictal epileptiform discharges (IEDs) within the mesial temporal structures of patients undergoing recording during temporal lobe resection. (Cascino et. al., J of Clin Neurophysiol 1993;10:520-525). The specificity of this activation for the underlying epileptogenic zone is unknown.
METHODS: We identified 31 intractable partial epilepsy patients who received alfentanil (50ug/kg) intraoperatively following insertion of bitemporal depth electrodes. Video-EEG monitoring with the depth electrodes disclosed unitemporal seizure onsets in 15 of the 31 patients. We reviewed the intraoperative EEGs recorded in these 15 patients when the bitemporal depth electrodes were inserted. The depth EEGs recorded before and after alfentanil were compared to determine the rate of activation by alfentanil, and to assess whether the activation was concordant with the onset of seizures recorded during subsequent video-EEG monitoring.
RESULTS: Baseline intraoperative depth recordings before alfentanil was given showed bitemporal IEDs in 9 patients, unitemporal in 3, and none in 3. After alfentanil was administered, 14/15 (93%) had activation of discharges; all of which were bitemporal. However, activation by alfentanil was predominant at one temporal region in 9/14 (64%) patients. The side of predominant activation in 7/9 (78%) patients was concordant with the side of seizure onset recorded during subsequent video-EEG monitoring.
Five patients had seizures activated by alfentanil. The side of the activated seizures in 3 patients (60%) was concordant with the side of onset of video-EEG recorded seizures.
CONCLUSIONS: This study would suggest that while alfentanil is a potent activator of IEDs, it may not be a reliable indicator of the epileptic temporal lobe. The relationship between the alfentanil activation and surgical outcome also needs to be determined.