Activation of epileptogenic activities by etomidate in electrocorticoencephalography (ECoG) during operation for epilepsy.

Epileptic surgery is a radical and ablative treatment for medically refractory epilepsy. Electrocorticoencephalography (ECoG) obtained by subdural strip electrodes should always be used during operation for precise localization of epileptic focus and mapping the extent of its involvement. But difficulties and ambiguities exist when the patient's ECoG is suppressed, either owing to the anticonvulsant used, being at the stage of posterictal period, or the effects of anesthetics during operation. Then, intentional activation of epileptogenic activity should be performed to locate the pathological focus in order to accomplish a successful surgical treatment. Etomidate has been considered as an abnormal electroencephalogram (EEG) activator and its use is not recommended in patients with epilepsy. But lesser dose of etomidate as an activator for ECoG has not been investigated. The study reported here established that etomidate as an hypnotic has not only anesthetic properties but, paradoxically, also activates epileptogenic activity. With the latter pharmacologic characteristic, etomidate can be used to deliberately activate the spikes of the potentially epileptogenic tissue, the delineation and localization of which may help the surgeon determine to what extent the pathological cortex be resected in surgical treatment of a refractory epilepsy. The current recommended dosage of etomidate at veterans General Hospital-Taipei for ECoG in epileptic surgery is 0.1-0.15 mg/kg/iv.