Alfentanil-induced activation: a promising tool in the presurgical evaluation of temporal lobe epilepsy patients

Pharmacologic activation of epileptic foci has been used experimentally wit h the hope that it may accelerate the presurgical evaluation of patients wi th medically intractable epilepsy. In this article, we will review the exis ting literature on these activating tests giving emphasis on the opioid ana logs, and particularly alfentanil. Alfentanil is an opioid analog with rapi d anesthetic effect, which has been known to trigger epileptiform discharge s in epilepsy patients. 58 temporal lobe epilepsy (TLE) patients were studi ed with alfentanil activation during electrocorticography, at the Epilepsy Surgery Unit (ING, Brazil). An increase of the interictal epileptiform disc harges was observed originating from hippocampal and parahippocampal region s (96.5%). To a lesser extent, alfentanil activated the basal and lateral t emporal regions. Electrographic seizures were observed in 38%. In addition, we performed continuous video-EEG (VT/EEG) monitoring, with scalp and bila teral foramen ovale electrodes, in 12 TLE patients. The results of spontane ously observed seizures were compared with the electrographic changes follo wing alfentanil activation (50-75 mu g/kg, i.v.). In seven cases, alfentani l triggered focal electrographic seizures, ipsilaterally to the side genera ting the spontaneous seizures and in two patients it produced bilateral seq uential activation of the temporal lobes. Ictal SPECTs during the alfentani l test showed hyperperfusion at the lateral temporal regions, ipsilaterally to the activated area or bilaterally. In summary, our study confirms the a ctivating effect of alfentanil, and provides a strong evidence for its sele ctive activating effect on the temporal lobes of TLE patients. The ictal SP ECT during alfentanil activation did not offer any additional advantage for the localization of the ictal onset. (C) 2000 Elsevier Science B.V. All ri ghts reserved.