Methohexital-Induced Changes in Spectral Power of Neuromagnetic Signals: Reduced β-Band Enhancement Over the Hemisphere Ipsilateral to the Epileptogenic Focus

Effects of anesthetics on electroencephalographic (EEG) activity are used to localize brain lesions as well as epileptogenic areas. Small doses of barbiturates (up to 200 mg) result in an increase of fast activity in the β-band of the EEG. This increase of β-band activity is known to be larger over normal brain areas as compared to areas with cerebral lesions (e.g. [1]). Furthermore, it has been reported that some barbiturates as amobarbital, thiopental, or methohexital or other narcotics as propofol may provoke epileptiform activity resulting in spike activity and spike-burst-suppression patterns. As an additional feature, various authors ([1] [2]) described qualitatively a loss of methohexital-induced β-band activity in the electrocorticogramm (ECoG) over the epileptogenic area. A quantitative analysis of the spectral contents of the ECoG is mandatory before the clinical use of methohexital induced changes in β-band activity can be rated.