Increased spike frequency during general anesthesia with etomidate for magnetoencephalography in patients with focal epilepsies

ObjectiveMagnetoencephalography (MEG) is used for focus localization in presurgical evaluation of patients with focal epilepsies. In this proof-of-concept study, general anesthesia with etomidate was used to improve effectiveness of MEG-recordings.MethodsMEG-recordings of six patients with focal epilepsy were performed before and after application of etomidate. Spike frequency and localization accuracy of MEG with general anesthesia were compared with spontaneous MEG.ResultsAfter application of etomidate, an increase in spike frequency occurred in all patients, and movement artifacts were prevented. In one patient, spikes could only be detected by invasive EEG but not by MEG. The results were in accordance with spontaneous MEG or presurgical hypotheses about localizations of neocortical foci in three patients. Dipole localizations were distributed over fronto-temporal areas in three patients with ipsilateral temporo-mesial focus hypotheses.ConclusionsEtomidate ameliorated spike yield and stopped movement artifacts during MEG recordings in patients with focal epilepsy. Localization results were especially accurate in patients with neocortical epilepsy.SignificanceThese results could facilitate larger studies on the usefulness and safety of general anesthesia with etomidate that record and localize epileptic activity in patients with focal epilepsy by MEG.